NZASE #124

science teacher 2010

Featuring: Iron Weathering steel Black sand Iron in the stars Iron and origin of life Iron fertilisation Dietary iron Iron, oxygen, and life Plus: Ripping yarns Science writing and the media What is ‘Western’ about science And more...

Number 124

ISSN 0110-7801

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Mailing Address: NZASE PO Box 1254 Nelson 7040 Tel: 03 546 6022 Fax: 03 546 6020 email:nzase@confer.co.nz

Editorial 2 From the President’s desk 3 Feature: Iron Iron − essential for life since its inception 10

Editorial Address: lyn.nikoloff@xtra.co.nz Editorial Board: Rosemary Hipkins, Chris Joyce, Suzanne Boniface, Beverley Cooper, Mavis Haigh, Barbara Benson, Miles Barker and Anne Hume

Dietary iron 13

Journal Staff: Editor: Lyn Nikoloff Sub editor: Teresa Connor Cover Design and Typesetting: Pip’s Pre-Press Services, Palmerston North Printing: K&M Print, Palmerston North Distribution: NZ Association of Science Educators

Rusty beauty of weathering steel 18

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Subscription includes membership and one copy of NZST per issue (i.e. three copies a year). All prices are inclusive of GST. Please address all subscription enquiries to the NZASE, PO Box 1254 , Nelson 7040. Subscriptions: nzase@confer.co.nz Advertising: Advertising rates are available on request from nzst@nzase.org.nz Deadlines for articles and advertising: Issue 125 - Nitrogen 20 August 2010 (publication date 1 October)

NZST welcomes contributions for each journal but the Editor reserves the right to publish articles it receives. Please contact the Editor before submitting unsolicited articles: nzst@nzase.org.nz Disclaimer: The New Zealand Science Teacher is the journal of the NZASE and aims to promote the teaching of science, and foster communication between teachers, scientists, consultants and other science educators. Opinions expressed in this publication are those of the various authors, and do not necessarily represent those of the Editor, Editorial Board or the NZASE. Websites referred to in this publication are not necessarily endorsed.

Iron, oxygen, and life 15 Iron in the stars 21 Black sand − New Zealand’s vast iron resources 24 Iron fertilisation 28 Regular features Education research: Should students learn to ‘read’ science writing from the media 4 Ripping yarns: science in Asia 32 Cores and PaP-eRs 38 History Philosophy of Science: What is ‘Western’ about science is not from religion 7 Resources: Alpha 106 – Iron Hypothesis 41 National Library 42 Ask-a-scientist 9, 27, 41 Subject Associations: Biology 43 Chemistry 44 Physics 45 Primary Science 46 Science/PEB 47 Technicians 48

Front cover: Weathering steel cladding was used to maximise the sustainability merits of the award-winning Ironbank Building, which is located on Karangahape Road in Auckland.

Photograph courtesy of Raed El Sarraf.

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Reflections As I read Raed El Sarraf’s article about weathering steel (p.18) I was reminded of a student trip I took many years ago to the European Economic Community (EEC) in Luxembourg, where the rusted steel outer cladding of the European Courts matched our zealous environmental aspirations.

While time may dim youthful optimism, it does not as Jenny Pollock notes, alter the need for a deep commitment to Earth literacy (p.47).

I also pondered as I read articles by Rose Hipkins (p.4) about using the media in science programmes, Miles Barker’s ripping yarns (p.32), Anne Hume’s paper on professional knowledge (p.38) and Philip Catton’s article ‘What is “Western” about Science is not from Religion’ (p.7) how I would use articles in the NZST if I was still in the classroom − I would first show students how challenging it is to write about science for the popular media.

Try this − ask one of your senior classes to rewrite an article in this issue using only 300 words or less, including a provocative headline. The article must be engaging, have a reading level of age 11, and yet still retain the article’s central thesis. I am sure you will end up with some ‘groundbreaking new science’ that even the original author was unaware they had contributed to. If nothing else it is a useful lesson in perception, which leads me onto the review of the NZST. I believe there is much that is good about the current content of the NZST, which relies on the goodwill of the research community, and I am as yet unconvinced that teachers have the time or the resources to be its main contributors.

So the NZST review is also a time of reflection for me. I have now been engaged in science education for almost thirty years, and I recall that Kay Memmot taught me how to dissect rats (she is mentioned on p. 48). I also recall that it is twenty years since I attended my first SciCon, where I met colleagues who are now highly-regarded contributors of the NZST: Anne Hume, John Campbell (ask-a-scientist), Miles Barker and Rosemary Hipkins. So I concur with your President, Lindsey Conner (p.3) SciCon is a great place for

The ‘rusting’ EEC building in Luxemburg was photographed in November 1979 by Lyn Nikoloff.

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networking and there are few places warmer in winter than sunny Nelson (see back inside cover).

I also reflect that during my science education career there were two colleagues who have directly impacted on my role as editor of the NZST. First, back in the early 1980s, during my first term of teaching, Father O’Callaghan at St John’s College advised me that: if I was to be a good teacher I needed to be an interesting person. His advice rings in my ears every time I put together an issue of the NZST, and this issue is no exception.

I hope you (and your students) are inspired by articles about iron sand (Tony Christie, GNS, p.24), iron in the diet (Fran Wolber, Massey University, p.13), iron and life on Earth (Andy Pratt, University of Canterbury, p.10), iron and the stars (Jeffrey Simpson, University of Canterbury, p.21), iron, oxygen, and life (Cather Simpson, University of Auckland, p.15) and fertilising the oceans with iron (Cliff Law, NIWA, p.28).

The other colleague to whom I am indebted in my current role as editor of the NZST is Dr Peter Davie. In 1993 at a Massey University hosted biology teachers’ meeting, my tardiness led me to miss his demonstration of a stifle joint dissection. At that time, Animal Welfare legislation was on the table with huge ramifications for zoology programmes in schools—some of you may recall grappling with its potential impact on gaining ethical approval for the internally assessed bursary (Y13) animal study.

After the meeting, I invited Peter to demonstrate the dissection to my students whereby he encouraged me to engage in writing and publishing. Together we developed some small animal experiments for schools that did not require ethical approval, including the stifle joint, chicken wing and squid dissections, and an enhanced bull ’s eye dissection. We published our work in Investigating Vertebrates (1994), and Investigating Whales (1996). I am still immensely proud of our books, even if they have been consigned to the dustbin of history. There is no doubt that the classroom of today is a world away from when the books were originally conceived, nonetheless, I would like to acknowledge the deep gratitude I have to Peter for giving me the opportunity to hone my editorial skills.

During the past four years as Editor of the NZST, I have brought NZ scientific endeavour into your classrooms, and hopefully, I have also built a bridge between science educators and the research community. Along the way, I have met so many wonderful people who gave of their time and expertise willingly and freely, sadly too many to thank personally in this editorial, but to whom I am indebted.

But it is now time for members of the NZASE to decide what the future holds for the NZST. I wish you well in your deliberations.

And as I recall those three days in Luxemburg in 1979, I never imagined that weathering steel would complete the circle.

Kind regards

Lyn Nikoloff

Kia ora koutou, I would like to take this opportunity to highlight some current initiatives of the New Zealand Association of Science Educators (NZASE), the Ministry of Education and the Royal Society of New Zealand (RSNZ) by showing how they can be used to enhance science teaching.

Website and NZST Communication of innovative ideas for teaching science is a key goal of NZASE. Our website and the New Zealand Science Teacher (NZST) journal are two flagships that can help us to achieve this goal. There will be several opportunities for members to contribute creative ideas about future directions and to discuss possible developments for both. For example, there will be an online survey about NZST and a members’ forum at SciCon, our biennial conference in Nelson this year, 4-8 July, 2010. We have also expanded the NZASE executive recently and welcomed Matt Balm who will oversee any new directions for NZST, and Robert Shaw who will manage the NZASE website developments.

The NZASE executive would like to see the organisation build on our existing initiatives particularly the wonderful work of our standing committees (STANZ, Primary Science, BEANZ, Chemistry group, Physics group and SCIPED) and bring forth some new ideas about future projects. The forum at SciCon is a chance for you to have a say about how NZASE can enhance science teaching, and how NZASE can assist and support your professional development.

Therefore, I strongly encourage you to attend this forum at SciCon. The SciCon committee have put together a very stimulating programme and have been working tirelessly to ensure it is a great success. However, it is not only the formal programme that is stimulating. Often it is the conversations and interesting people that make these conferences an event not to be missed.

Literacy and numeracy The second set of initiatives that can be used to promote science is the Ministry of Education emphases on literacy and numeracy. I’m sure many of you have participated in professional learning sessions over the past eighteen months or so on either or both of these initiatives. Our challenge as teachers of science is to use these as vehicles to promote science more directly through stimulating and relevant contexts, so that students can gain multiple skills simultaneously. We are very fortunate in New Zealand, compared with many other countries, in that we can choose, to a large extent, both what we teach and how we teach because our curriculum is not very prescriptive and we are able to use a wide range of resources. Therefore, using or adapting literacy and numeracy activities in science contexts seems sensible and might allow more class learning time to include science, especially at primary and intermediate levels.

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It is also becoming more and more important that we help students to make connections not only between the big ideas in science and their implications, but also to highlight the connections with other subjects and students’ learning processes. The new curriculum emphasises personalised learning and developing cooperative and relational skills as students develop key competencies. These include abilities in literacy and numeracy. Melding these skills with science will expand new units of work.

I recently found my copy of an OECD description of scientific literacy, and reproduce it here because it captures the essence of science. It indicates how thinking skills are embedded and link with a consideration of the nature of science, which is an important strand in our new curriculum. It also reveals the broader relational aspects of science.

OECD (2006) description of scientific literacy: An individual’s scientific knowledge and use of that knowledge to identify questions, to acquire new knowledge, to explain scientific phenomena, and to draw evidence-based conclusions about science-related issues, understanding of the characteristics of science as a form of human knowledge and inquiry, awareness of how science and technology shape our material, intellectual and cultural environments, and willingness to engage in science-related issues, and with the ideas of science, as a reflective citizen.

Although this statement relates to scientific literacy, it is not difficult to see how aspects of literacy and numeracy could be integral in the teaching of science. We might want to consider how we can develop and share activities that incorporate some aspects of literacy and numeracy as one of the new projects of NZASE.

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RSNZ and the Science Teacher Fellowship The third initiative is the support being provided by the Royal Society for primary science teachers in the Wellington area, especially for those teachers who have been part of the Science Teacher Fellowship scheme. I would like to applaud the Royal Society for expanding their fellowship programme to teachers of science in primary schools. This has helped to build capacity and capability (confidence) amongst these teachers. It is likely that the Royal Society will extend their support to include teachers in other cities in the near future. No doubt these teachers will share their knowledge and creative works with colleagues and at more public forums such as NZASE conferences. Of more importance though, is how all of these initiatives lead to better science learning outcomes for our students.

Noho ora mai Lindsey Conner President

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should students learn to‘read’ science writing from the media?

Recently Miles Barker asked what might ‘lifelong science learning’ actually look like? This article adds to that conversation, with a specific focus on the possibility of using science in the media as a source of teaching and learning materials as Rosemary Hipkins, NZCER explains: By studying science students will … use scientific knowledge and skills to make informed decisions about the communication, application, and implications of science as these relate to their own lives and cultures and to the sustainability of the environment. (Ministry of Education, 2007, p28).

This overarching aim from the ‘essence statement’ of the New Zealand Curriculum conveys good intentions but also, I think, a certain amount of wishful thinking. As for many other nations, our most recent national curriculum framework aspires to have students use their science knowledge both now and in the years beyond school.

It also aspires to the education of students who will be “confident, connected, lifelong learners” (vision statement, page 8). Most of us would happily sign up to these noble sentiments but, as Miles Barker recently asked, what might “lifelong science learning” actually look like, and what we might need to do differently at school to try and foster such outcomes? (Barker, 2010). I hope this article will add to that conversation, with a specific focus on the possibility of using science in the media as a source of teaching and learning materials.

Public attitudes to science To begin, I want to outline some very recent research findings that take us straight to the future target of the above aim − i.e. interaction with science in everyday life in the years beyond school. At the start of 2010, the market research company The Nielsen Company carried out a repeat survey of public attitudes to science, funded by the Ministry of Research Science and Technology (MoRST).

Now in its third iteration, this survey includes a section on adults’ views of the media reporting of science issues. In the 2010 survey respondents were asked to think about an environmental issue that might concern them, and then to rate various sources of information they might (or might not) trust if they wanted to find out more. (The 2005 survey also used an issue to do with environmental pollution, whereas the 2002 research used a health-related issue of personal concern.) Finding out about an issue of concern is exactly the sort of activity we might expect adults to undertake if they really do leave school prepared to continue to engage with science issues in the manner suggested by the NZC quote above. So what did the survey find?

Figure 1 compares responses from all three research rounds: 2002, 2005 and 2010. There are several patterns in the data worth noting. First, there are no real surprises here. The sources more or less likely to be trusted are those we might predict based on our own instincts and experience. Second, there is a relative stability of responses across the first decade of this century. There will always be some sampling variation but there are few strong trends to a decline or increase in trust in any specific source of information New Zealand Association of Science Educators

(the arrows show significant shifts). Given the ongoing controversy about climate change, which could be seen as the ultimate environmental issue, I had wondered if we would see some shifts to greater distrust of all sources. Third, notice the comparatively high levels of trust in television documentaries and news reporting − much higher than for newspapers (which were added to the survey in 2005) or the Internet.

If we break the data down by respondents’ age groups, an interesting pattern emerges. Table 1 shows this breakdown for all the media sources, with industry scientists and lobby groups added to show that the pattern holds for other types of information sources as well. Caution is needed in reading the teenage column because the sample is only half the size of the other groups (it does only cover half the decade cohort − fifteen and up). Nevertheless, the data do show a consistent trend. As people get older they are more likely to become less trusting of all information sources. The difference between younger and older groups is statistically significant for TV documentaries and TV news and current affairs.

Again, we might say there are no surprises here. For most of us, age and accumulating experience do bring a certain level of scepticism to our interactions in the world.

Nevertheless, for most people − including scientists seeking information in areas of science outside their own expertise (Jarman & McClune, 2010) − communication media are the most likely point of access to discussion about science and issues that new scientific research throws up. Should we be teaching our young people how to ‘read’ media sources more critically, rather than seemingly waiting for age and experience to do the job for us? Could we change the pattern shown in the table so that young people leave school as more critical consumers of science-related information in the media? (See Osborne, 2007, for an easily accessible discussion of the curriculum implications of this type of change of focus − this is an international debate, not just a New Zealand one.) If we did want to teach students to be more critical consumers of media information about science, what might we need to do differently? A recent research project that investigated this question (Jarman & McClune, 2010) throws some interesting light on potential answers. It is the focus of the rest of the article.

Building students’ media awareness The ideas outlined in this section come from a large UK project funded by the Welcome Trust, called the Newsroom Project. Ruth Jarman and Billy McClune are science education researchers from Queen’s University in Belfast.

Newsroom began with conversations with 26 individuals with specific areas of expertise in science communication (science journalists, scientists who do a lot of media work, science educators with expertise in this area, media experts) and then built on insights from these to work with science teachers to develop approaches to making better use of the media in science lessons. From the initial conversations the researchers developed four “domains of knowledge, skills and habits of mind” which contribute to willingness and ability to engage critically with science in the news.

(As an aside, this linking of knowledge, skills and attitudinal

Jarman and McClune identify media awareness as an area of expertise where science teachers have little knowledge compared to their colleagues who teach media studies (indeed they suggest teaming up with these colleagues when developing units of work that draw on media sources). They outline five areas of knowledge/awareness

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dimensions resonates strongly with the idea of key competencies in the New Zealand Curriculum). These four areas are: science knowledge; literacy skills; enquiring habits of mind; and media awareness. All of these are worthy of further discussion, but it is the media awareness dimensions I want to focus on here.

Figure 1: Comparative trustworthiness of different sources of scientific information.

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Table 1: Data breakdown by age of respondents (mean response—the higher the number, the greater the likely trust in the source).

Source

Industry scientists TV documentaries TV news and current affairs Newspapers Internet Lobby groups

Teens N = 92

20s N = 193

30s N = 243

40s N = 225

50s N = 193

Over 60s N = 251

4.04 3.94 3.83 3.39 3.12 2.79

4.07 3.73 3.62 3.28 3.09 2.66

3.84 3.67 3.53 3.18 3.07 2.63

3.61 3.42 3.31 2.95 3.04 2.58

3.64 3.48 3.25 2.92 2.99 2.45

3.55 3.35 3.2 2.76 2.93 2.33

of particular pertinence to science reporting (Jarman and McClune, 2010, p.52) which are further explained in McClune and Jarman (2010). What follows is my summary of their key ideas.

Science-related stories are prevalent in the media: Notwithstanding doubts held by teachers and scientists, these stories can be well researched and reported, and they can bring important science issues to public notice. Even when journalists − or in some cases their publications − do have an “agenda”, it is important that students learn how to figure this out.

Science-in-the-news is a distinct genre with different features to other types of science writing: What is reported is selected and constructed for newsworthiness and usually relates to science-in-the-making rather than science ideas about which consensus already exists. Unlike scientists, who would prefer to see a full and ‘objective’ account of their work, writing news about science is selective − perceived inaccuracies are likely to be omissions, simplifications, sensationalism, or misinterpretations rather than deliberate deception.

Journalists work within constraints that shape how they write: Different types of media reports (news, editorial, features) have different conventions and presentation features (word length, style, language, narrativization, use of ‘experts’). If journalists don’t get published their work doesn’t get read so they are mindful of these constraints and conventions as they construct each story. Editors make final decisions on whether and how work will be published, and the reporter is often not the person who writes the headline for their work.

All news is value-laden: Every form of communication has inbuilt values and the news is no different. Journalists themselves, their news organisations, sources they cite, and the audiences they serve, all have particular interests and perspectives. The selection of “language, content, sources, images, presentation and placing are all potentially value laden” (Jarman & McClune, 2010, p.52).

Readers are active meaning makers too: Just as writing science news is an effortful, active process of construction, so is making meaning from this news as it has been presented. A critical, reflective response is called for, bearing in mind all the above themes. As one of the participants in the Newsroom study said: Young people would need the ability to read critically answering questions like: Who wrote the article? What do I know about the methodology of a study being reported?

Who is the source of information? Newspapers are great for developing these skills and capacities. (McClune & Jarman, 2010, p.744) Jarman and McClune suggest that science teachers could work with media studies’ teachers − or other teachers

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with relevant subject expertise − to develop their own media literacy and knowledge of teaching and learning approaches that help students develop media awareness in all the outlined dimensions. In the Newsroom research they found that cross-curriculum collaborations were a fruitful way to build teacher knowledge and confidence, and they commented that having a purpose such as this provided a more meaningful cross-curriculum framing than some of the rather contrived cross-curriculum approaches that have been tried elsewhere.

Much has been written about the trend to disengagement with science learning that occurs across the teenage years, arguably starting even in upper primary school (for a recent review in the New Zealand context see Bolstad and Hipkins, 2008). A recent UK study of students’ attitudes to science identified several features of science lessons that students said would help keep them engaged in science: being made to think; variety in activity; and seeing how science relates to life (Bennett and Hogarth, 2009). Arguably, using science stories from the news to develop media awareness would meet all three of these conditions in one activity structure!

However, returning the focus to the aspiration for lifelong science learning with which this article began, Bennett and Hogarth also reported that over 70% of the nearly 300 students in their sample said they never read anything to do with science in newspapers or magazines, and between half and three-quarters of them would never watch a TV programme related to science. (They were divided into three different age groups, 11, 14 and 16 hence the range given here, with younger students more likely to watch than older ones). If we really do think continuing engagement with science in the years beyond school does matter, it is up to us to contribute to change by supporting our students to have direct experiences of the benefits and rewards of engaging critically with science in the news.

For further information contact: Rose.Hipkins@nzcer.org.nz

References Barker, M. (2010). Lifelong science learning. The New Zealand Science Teacher, 123, 32-36.

Bennett, J., & Hogarth, S.I., 31 (14) 1975-1998. (2009). Would you want to talk to a scientist at a party? High school students’ attitudes to school science and to science. International Journal of Science Education, 31(14), 1975-1998.

Bolstad, R., & Hipkins, R. (2008). Seeing yourself in science: The importance of the middle school years. Wellington: New Zealand Council for Educational Research. http://www.nzcer.org.nz/default.php?cpath=139_ 133&products_id=2261 Jarman, R., & McClune, B. (2010). Developing students’ ability to engage critically with science in the news: identifying elements of the ‘media awareness’ dimension. The Curriculum Journal, 21(1), 47-64.

McClune, B. & Jarman, R. (2010) Critical reading of science-based news reports: Establishing a knowledge, skills and attitudes framework. International Journal of Science Education, 32(6) 727-752 Ministry of Education. (2007). The New Zealand Curriculum. Wellington: Learning Media.

Osborne, J. (2007). Science education for the twenty-first century. Eurasia Journal of Mathematics, Science and Technology Education, 3 (3), 173-184. http://www. ejmste.com/v3n3/EJMSTE_v3n3_Osborne.pdf, accessed April 8, 2010

Can we adequately explain why science is ‘Western’ by treating the phenomenon of burgeoning exact science as a product of Western, perhaps even Christian, religion? In The Roots of Science: an Investigative Journey through the World’s Religions1 New Zealander, Harold Turner, proffers just such a putative explanation. Philip Catton, who teaches History and Philosophy of Science at the University of Canterbury, discusses why he opposes the Turner view.

Starting with an article in NZST 123 on Newton on ‘absolute’ time, I am presently embarked on an examination of what is ‘Western’ about ‘Western science’. In this article I lay out what I am not saying. Specifically, I am not arguing that the possibility of science reduces to conditioning of culture by ‘Western’ religion. Towards completing the series, I shall be discussing Greek geometry (next issue) and thereafter Newton again (examining first his mathematics in the context of the Greek mathematical tradition, and thereafter what proceeded from that as literal ignition of experimental natural science). My summary of what I am saying about ‘Western’ characteristics of ‘Western science’ is still several issues away. Here I take up critically a stark thesis by Turner.

This is, that burgeoning exact science comes about precisely because of characteristics unique to ‘Western’ religion, specifically Christianity. I oppose this understanding.

Harold Turner, science and religion According to Turner, polytheistic ‘tribal’ peoples cannot aspire to create science. Before such aspirations could develop anywhere on Earth, a great change in religion was needed. Eventually some peoples transcended their former ‘tribal’ identities and foreswore polytheism typically in favour of monotheism. This marked the advent of ‘universalising’ religions. After this change, the peoples in question had some aspiration to do science. However, only one such people − those in the Judeo-Christian tradition − enjoyed intellectual conditions under which inquirers could successfully fulfil the aspirations for science. This is because the ‘Hebraic’ cosmology of Judeo-Christianity both ‘de-sacralizes’ space, time and matter, yet views them as orderly. In Turner’s view, the eventual rise of science was encouraged by Christian religion and could not have happened outside its sphere. It is on the basis of these contentions that Turner insists that science is importantly rooted in religion.

The case that Turner presents is neither as novel as it claims to be, nor as cogent as it needs to be. That A and B were historical correlates is poor evidence that the principal connection causally is that A caused B. It may instead be that, in the main, A and B were concomitant effects of some third alteration C. Moreover, because history is causally complex, the claim that A caused B could be partially true (and thus have something to be said for it) even if, in the main, A and B were concomitant effects of some third alteration C (and it would therefore be seriously misleading to assert simply that A caused B).

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The DeepSight Trust, A New Zealand Initiative for Religion and Cultures, 1998; 204 pages; $29.95.

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Turner attempts to establish boldly some historical claims of the form ‘A caused B’ without beginning to acknowledge adequately the actual difficulty of doing so. Moreover, his particular claims have been advanced, in roughly the same forms, before, and telling criticisms against them are well known.

For example, consider the advent of scientific aspirations (B). It is true that, antecedently to B, newly ‘universalistic’ forms of religious life had eventuated (A). Turner urges that A caused B. But he has totally left out of the account an important literature (by historians of science, anthropologists, and linguists) which identifies instead a common cause C. According to this literature, C was the rise of literacy. The rise of literacy caused a host of cultural changes which included both A and B. I will address this view in a moment, and in so doing I will criticise Turner’s A-caused-B analysis quite sharply.

First, however, I will comment on a second causal claim of Turner’s. Turner boldly contends that science is rooted specifically in Judeo-Christianity. This claim, if true, would naturally tell us why it was that when at last science truly ignited this event was in a Christian part of the world. Many historians place this ignition-point in 16th to 17th century Europe. Turner prefers to look in part to earlier times, but still within historical Christendom.

The causal claim has two parts: that Judeo-Christianity was causally necessary for the ignition of science, and that it was sufficient for it. Because contributions from Arab, Greek, Indian, Chinese, and other still more ancient geniuses were indisputably key for the eventual ignition of science, it is a radical thing to suggest that Judeo-Christianity was causally sufficient for science. Take away the Arab, Greek, Indian, etc. philosophers, mathematicians, metallurgists, astronomers, and so on. Would Christians inevitably have started science, without the support of any such contributions? Apparently Turner insists that they would have.

The converse, necessity claim is no less remarkable, but in some ways is more difficult to assess. The ignition of science as a going concern is so wondrous it is amazing that it ever happened anywhere. Even relatively weak supporting conditions might therefore have been causally necessary, so unlikely was the ignition to occur at all.

But such a case, if it could be made at all, would establish only a contextualised necessity. Similarly, Turner could argue for a contextualised sufficiency − Judeo-Christianity was sufficient for the rise of science given that the Greeks, Indians, Chinese, Arabs etc. had already done their work. Turner boldly asserts, however, a stronger causal thesis than this. Turner implies (apparently) that science would have come about for Christians whether or not the Greek, Indian etc. philosophers, mathematicians etc. had existed at all. Moreover, he insists (explicitly) that science was bound not to ignite for the Greeks, Indians, Chinese and other non-Judeo-Christian peoples. Science could not ignite for these peoples because of the religions to which those peoples held.

One problem for assessing this contention is that there were many differences, besides religious differences, between late renaissance Europe and ancient Greece, India, China etc. The other differences are also clearly material New Zealand Association of Science Educators

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to the prospect that there would have been for an ignition of science. Historians of science have examined the role of economic systems and conditions, institutions, political forms, political stability and instability, extent of trade, technologies of communication, rates of communication, sizes of research communities, protocols of publication, disease, warfare, geographical exploration, advent of a public sphere (between state and religion), religious turmoil, and novelties in the way ancient Greek intellectual accomplishments re-presented themselves (out of Arab hands, with the benefit of Indian and Chinese influences) in the European context. Each of these considerations brings to view contrasts between late renaissance Europe and ancient peoples that are arguably no less pertinent to why science ignited where and when it did than the religious contrast that Turner explores. The alternative contrasts beg to be examined if Turner is adequately to support his claims.

However, Turner’s book does not consider them.

Pierre Duhem informs Turner The claims about Judeo-Christianity that Turner does advance overlap those of the well-known historian of science Pierre Duhem (whom Turner extensively cites). Like Duhem, Turner proposes that the ignition of science derives from work by much earlier Christians than Galileo. Like Duhem, Turner believes that when (in the 13th century) the Church challenged Aristotelianism, it significantly aided the eventual ignition of science. Thus Turner, like Duhem, attempts to treat science and Christianity as not opposed historically (in a way that the Galileo debacle epitomises) but rather importantly synergistic. (Of course, because history is causally complex, it is possible that there is some truth in the idea of conflict and opposition, and some truth in the idea of synergy. But Turner boldly urges us to dismiss this possibility. He wishes us to repudiate the one view and fulsomely embrace the other.)

Duhem’s position was still fresh half a century ago, and despite its unseemly polemical character, it was a welcome challenge to the then orthodox historiography of science.

Without any doubt, Duhem has taught the history of science some important lessons. Yet in the many decades since he wrote, much critical work has been done. It has been roundly shown that Duhem seriously underestimated not only Galileo’s originality and importance, but also the great distance conceptually and methodologically between medieval physicists and Descartes (let alone Newton).

Moreover, during those many decades historians have connected their understanding of the ignition of science ever more to reaches of inquiry that Duhem, a physicist, scarcely addressed at all: to biology, alchemy, anatomy and physiology, geology and so on. Duhem’s position is by now largely passé, because it is understood to be limited, one-sided, and distorted by its polemical intent. Turner has, however, grasped it very fulsomely and uncritically in this book.

The importance of literacy Let me now return to Turner’s first A-caused-B claim. A in this case is the replacement of tribe-specific polytheistic thoughtforms by the ‘universalising’ typically monotheistic religions that followed. B is in this case the rise of human aspiration for rationally fathoming the world. I have mentioned that some historians see A and B as concomitant effects of C, the rise of literacy. I want to explore some strengths of this conception, and then criticise Turner’s claim that A caused B. The advent of a technology of writing could be expected to have sweeping effects culturally and intellectually. The thought structures of non-literate peoples must serve the art of memory, whereas those of literate peoples are freed of this requirement. Before the invention of writing, art-of New Zealand Association of Science Educators

memory requirements seriously limited both the extent of the articulation of thought and the development of social diversity. Prior to the advent of agriculture, general culture was by and large universally shared in a society, because the means of preserving and propagating it was mostly by using the public memory store. Thus the ambient culture of a people as a whole could not become much richer than what could be held (by the arts of memory) in any one individual’s mind. Each new member of a society was ultimately inheritor to virtually the entire culture. A skill might not be as fully developed in one member of the society as in the next, but everyone would have known intimately what anyone else in the society could do. The ways of working and being were in this sense universally shared.

After the advent of agriculture, specialisms developed, and thus the diversity of society increased. But without any technology of writing, the extent of this growth in diversity was severely limited. By the time that writing was invented, societies were pressing the upper limits of the diversity that a non-literate myth-making art-of-memory form for general culture can sustain.

Language prior to literacy needed first and foremost to serve the art of memory, and could not grow in size or complexity beyond limits imposed by this desideratum. Without writing, memory must be employed in order to track the intricacies of language itself. The greater the articulation of language, the greater the demands will be on human memory to track this very intricacy, and the less language will serve to enhance the power and reach of memory. Thus the total vocabulary of a non-literate people typically weighs in at a mere 10,000 words. Yet with a mere 10,000 words a people cannot aim for univocality or specificity. They can afford neither specialist vocabularies nor precision in thought.

Mnemonics cultivate playfulness rather than systematicity of thought. Each of the non-literate people’s 10,000 words will be used in many ways, and these ways will be the more helpful to memory the more they playfully create intriguing new connections in thought. No wherewithal will exist for identifying whether a word is being used ‘standardly’ or not. (Literate peoples would use a dictionary; non-literate peoples have no such recourse.) Thus, the very distinction between ‘literal’ and ‘non-literal’ uses of words cannot exist without writing. For non-literate peoples, language use has the playfulness of poetry rather than the seriousness of science. The thought forms that are sustained in this circumstance are less an early attempt at science, than its cognitive antithesis.

After the invention of writing, substantially new possibilities of social and intellectual organisation begin to be realised.

Technical vocabularies become intellectually affordable.

The total number of words in the language grows. Precision becomes possible. Thought structures adapt themselves to new demands of specificity and rational orderliness. Once writing catches on, a people will be challenged to codify in (written) law how in general it wants its social world to be.

Legal systems are the more important because of the yawning social diversity that now exists. A tradition will spring up of rationally interpreting the law, i.e. of determining the laws’ significance for particular cases.

People will thus learn to conceive of order in terms of laws and their application to specific cases. Their society itself will seem to them a somewhat mysterious unity in a diversity.

Projecting this idea outward they will form for the first time the idea of nature or cosmos or world, i.e. of the overall unity of the diversity of things. They will be able to conceive of order in the cosmos in terms of the idea of law.

Additionally, the rise of writing will affect people’s

Literal truth A concern about the literal truth links directly to a new and vaulting concern for rational systematicity. What is the literal truth? A belief is literally true if someone would still hold it, in the ideal situation of their having considered every last thing, and systematised their thinking rationally as well as it might be. People personify the ideal of literal truth when they call the all-things-considered, rationallybest-systematised way of thinking ‘God’. Literate peoples can afford to be rationalistic. They can aspire to believe the literal truth. Monotheism is an intellectual symptom that this is their cultural condition.

Thus, the rise of literacy can explain a lot both about new religious forms of life and the advent of the cognitive ideals of science. And this explanation cuts across Turner’s in many ways. It is questionable whether the new religious forms of life replaced forms of life that could be called ‘religious’ in an identical sense. Turner roundly insists that ‘tribal’ thoughtstructures are genuine religions (and cosmologies!) but he does not actually justify this point of view. And when Turner calls the tribal thought-structures ‘faiths’, he betrays what is tendentious in his point of view. Faith entails conviction, and a conviction concerns what is literally the case. Just as the thought-structures of non-literate peoples are cognitively very different from science, they are arguably cognitively very different from ‘faiths’. We misunderstand the very purpose of those thought structures if we regard them as attempts to fathom ‘the world’ or ‘the cosmos’. Non-literate peoples typically lack these very concepts. Yet to fathom the world or cosmos is importantly what religions and science aim to do.

Turner suggests that it represents a kind of religious progress for a people to move from tribe-specific polytheistic thought forms to a ‘universalising’ monotheistic religion. Clearly this is tendentious. It depends on the tendentious supposition, criticised above, that the non-literate people’s thoughtforms comprise a religion. But it also ignores the obvious point that a ‘universalising’ monotheistic religion would be neither possible nor desirable in a non-literate condition. A people that depended for their very survival and well-being on the public art of memory would not be well served by cognitive aspirations for universal truth, or for systematic ways of thinking about nature, world or cosmos. These aspirations are affordable only to a literate people. Thus, contrary to

Turner, it is not the ‘progress’ of religion that moves a people from the one intellectual circumstance to the other, but a far more pervasive and radical alteration of their overall cultural condition.

Turner of course identifies as further ‘progress’ in religion both the development of ‘Hebraic cosmology’ and its subsequent adjustments by Christians to include, among other things, the doctrine of the Holy Trinity. Turner’s points in this connection about ‘desacralization’ are interesting.

He does develop a coherent view of why the cosmology in question − if it registered with people − could actually help them to think in ways that would be amenable to science.

He also explores some reasons why the cosmologies of the various non-Hebraic ‘Axial Religions’ would be different in this regard. Over against Turner, however, we can question whether the cosmological conceptions of the actual progenitors of science (the likes of, say, Copernicus, Kepler, Galileo, Descartes, and Newton) were all that ‘Hebraic’ or indeed trinitarian. For what it is worth, Kepler passionately endorsed the doctrine of the Trinity, but Newton passionately rejected it. Galileo seems not to have been exercised about it much at all. Moreover, all these important figures were far more significantly influenced in their personal world conception by Greek thinkers than by the ambient religion. Alexandre Koyre made an excellent case that Plato stands behind each of the thinkers mentioned in a particularly important way. Can Turner make sense of his assertions psychologically, in the cases of the actual progenitors of science? It is doubtful whether he can, and notable that he doesn’t try.

For what it is worth, I have always thought of Christianity (with its Trinity, its angels, and even its Satan, or beyond him the demons which are ever popular amongst the vulgar) as just about the most polytheistic religion possible that could officially wear the label ‘monotheistic’. I have also wondered whether this helps explain the ill fortune of rational inquiry in the early centuries of the advancement of Christianity.

When I think of the preservation and cultivation of ancient learning in the hands of Islamic Arab thinkers during the Christian Dark Ages, I hear in my head the way that Islamic people express so forcefully their religious monotheism.

Was this what explains why they were interested in rational inquiry into this world, when the Christians to the north and west of them had, for the most part, descended into comparative darkness? I wonder this, but not with much hope that I could answer my question. I know that it would be enormously difficult to justify the causal claim involved.

For further information contact: philip.catton@canterbury.ac.nz

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How and when were magnets first mass-produced?

Shane Wohlers, Aparima College School Colin Hooker, a physicist at the University of Canterbury, responded: The first magnets were lodestones, a naturally occurring mineral of an oxide of iron called magnetite.

Compass needles were first made at least 2000 years ago by stroking pieces of hard steel with a lodestone.

The production of relatively large permanent magnets in commercial quantities appears to have taken place shortly after 1730. Using a technique pioneered by Servington Savery, Gowan Knight, a librarian at the British Museum, manufactured and sold several standard types of bar magnets comprised of bundles of hard steel wires which had been magentized by stroking them with a lodestone.

Although expensive (typically three weeks of a librarian’s salary) they sold throughout Europe. Faraday used a Knight magnet in his experiment that led to the electric generator.

Hard steel permanent magnets, magentized by currents passed through a coil surrounding the steel, continued in use in electrical machinery until the mid-nineteenth century when they were replaced by powerful electromagnets.

It was not until after 1931 that the powerful permanent magnets based on alloys such as alnico (aluminium, nickel, cobalt and iron) became available and replaced electromagnets in some applications such as in loud speakers and small motors. In the last few years these in turn have been replaced by even more powerful magnets based on neodymium.

Send questions to: questions@ask-a-scientist.net New Zealand Association of Science Educators

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understanding of historical time. A literal record of human history can now be kept. Anecdotes about ancestors need no longer primarily serve a role in the art of memory, whereby skills of contemporary significance are encouraged to survive. With literacy, people can concern themselves with what was the literal truth about history.

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iron − essential for life since its inception More than three billion years ago, iron sulfide was the rock upon which life was founded, as Andy Pratt, Department of Chemistry, University of Canterbury explains: Introduction Iron is one of the essential elements for life. NZ-led research has shown that it is a limiting nutrient in the Southern Oceans. Why did it get to be that life is so dependent on a scarce resource? Following this trail will lead us back through the history of life on Earth to before the time when the Earth’s surface became rusty.

It was in this earlier anaerobic world, more than three billion years ago, that iron − more properly iron sulfide − was the rock upon which life was founded.

Fertilising the ocean One of the interesting features of life is that the composition of living cells is closely related to the elemental composition of seawater. This reflects the fact that life and the oceans have been co-evolving over more than three billion years. Every living cell is, to a greater or lesser extent, a little bag of seawater! Of the atoms in seawater, 62.8% are hydrogen and 25.4% are oxygen − reflecting the chemical composition of water.

Most interestingly, from a chemist’s perspective, are the elements that are enriched in cells, relative to their surroundings. These have been selected by evolution for their chemical function. It is no surprise that carbon and nitrogen are much more plentiful in cells than the sea at large. These elements are available both in the atmosphere and in solution, and are key building blocks for making complex molecules. If elements are not freely available, but chemically indispensable to biochemistry, they can become limiting nutrients, e.g. nitrogen is often a limiting macronutrient for life.

Amongst the other key elements that are conspicuously enriched in cells − and for which life hungers − are iron and phosphorus. It is not the total quantities that are the issue, after all the Earth’s core contains enormous supplies of molten metallic iron. It is their availability to the aqueous biosphere that is crucial. Neither of these elements is present in gaseous form on the Earth, and the solubility of ferric and phosphate ions in the oceans is limited due to their high charge density. Phosphate has probably been a limiting nutrient for life through most of life’s history. Although phosphate is hard to come by, it performs many key roles in biochemical systems that have been described nicely in an article by Frank Westheimer entitled ‘Why Nature Chose Phosphates’ (see further reading).

Everyone who drives a rust-bucket, myself included, knows that on the modern aerobic Earth iron is predominantly found as rust: insoluble iron oxides. These cannot be dissolved in neutral solution to any significant extent, hence the shortage of iron in seawater.

An Otago research team led by Philip Boyd, Keith Hunter and Doug Mackie has been studying the low levels of

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iron off our shores and how they limit the fertility of the Southern Ocean. They have shown that windblown iron oxide dust is a significant source of iron for the oceans.

The paucity of large landmasses to supply iron in this way may be one of the reasons for the differences in fertility of the Northern, Equatorial and Southern Oceans.

Aside from the fundamental importance of understanding the cycling of iron in our waters, there are potential practical applications of their work. One possibility is that the oceans could be fertilised by adding iron salts as a way to increase the uptake of carbon dioxide. If significant amounts of the resulting fixed carbon metabolites are buried, then this could decrease atmospheric carbon dioxide levels and thereby address concerns about anthropogenic climate change.

Iron and the history of the Earth Unlike phosphate, the availability of iron for life has not always been as dire as it is now. As alluded to earlier, it is the aerobic atmosphere that is the main culprit. The surface environment of the Earth has become more oxidizing throughout its history. Firstly, as the light gas, hydrogen, was lost to space and then by the advent of oxygenic photosynthesis. With cyanobacteria pumping out their deadly pollutant, and not all of the carbon they fixed being recycled, oxygen accumulated in the atmosphere. As far as the Earth was concerned an overall transformation of CO2 → C + O2 was in hand.

Since about halfway through life’s history, 2.3 billion years ago (Gya), there has been significant free oxygen in the atmosphere. The resulting oxidation of iron(II) to iron(III) on a colossal scale is written in the geological record. The ‘banded iron formations’ throughout the period of 2-3 Gya show oxidation of iron(II) to iron(III) in progress; the ‘red bands’ from 2 Gya show the final triumph of oxygen over iron. These rocks are testament to the fact that iron(II) salts, such as sulfides are soluble at μM concentrations, whereas iron(III) oxides are less soluble by roughly twelve orders of magnitude.

Once oxygen was being produced, the Earth rusted and the planet was changed in the greatest biologically created environmental catastrophe before humans. Ever since the iron was lost by precipitation, life has been scavenging to make a living. The problem is that iron is indispensable for life. Once we understand why, we will be better placed to understand why and how life originated in the first place.

Iron: geochemistry and biochemistry All life depends on electron-transfer chemistry to provide biochemical ‘energy’. By transferring electrons from a high energy source, to an electron acceptor, a thermodynamic gradient can be milked. The principal conduits for these electrons are iron centres within proteins found in cell membranes. Many of these centres are iron sulfur clusters. Iron sulfur clusters have varied roles in biochemistry; they can catalyse acid-base and free radical chemistry as well as electron-transfer.

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Figure 1: Iron sulfur minerals and catalytic biochemical clusters. 1: mackinawite sub-structure; 2: greigite sub-structure; 3: [2Fe,2S] electron-transfer cluster; 4: [4Fe,4S] electron-transfer cluster; 5: acid-base catalyst (aconitase with citrate bound).

Essentially, their catalysis is controlled by the chemical environment of the requisite iron centres. Interestingly, the iron sulfur centres in enzymes resemble iron sulfide mineral structures (Figure 1). For example: ferrous sulfide is deposited geochemically as mackinawite (1) which on partial oxidation creates greigite (2). These structures are related to centres in enzymes that catalyse electron-transfer (3 and 4) and acid-base e.g.

(5) chemistry. This connection provides a hint of the fundamental connection between biochemistry and geochemistry. Anaerobic organisms make more plentiful use of iron centres than aerobic organisms, because of the availability issues in the local environment; even aerobic organisms, however, have not been able to wean themselves off iron entirely − and never will.

Iron and the origin of life It is time to travel to the original rendezvous point of anaerobic biochemistry and geochemistry. It was only in 1977 that deep-sea hydrothermal vent systems were discovered. Gratifyingly, from a biological history perspective, these oases of novel life were discovered along the Galapagos Ridge. The active geological activity on the boundary of two of the Earth’s plates that has produced the Galapagos Islands creates yet more biological marvels in the submarine depths nearby.

Where geological plates collide, seawater cycles through cracks in the Earth’s crust. As it is heated the water dissolves minerals, including iron and sulfide.

The resulting hydrothermal fluids then spew into the sea creating new mineral deposits that are exciting the attentions of prospective miners. Such sites are awash with life (even those more than 5km below the surface of the ocean, as reported recently). Here are Gardens of Eden, bereft of sun, with only chemical energy to fuel them.

As we learn more about hydrothermal systems, we are starting to build a picture of how this environment, present since the Earth’s beginnings, may have been the venue for the origin of life.

One geochemist in particular, Mike Russell, has proposed that the reason that life originated in the first place is because of the intrinsic geochemistry of these sites.

When the Earth formed, an electron-rich core, rich in

molten iron, was segregated from a weakly oxidizing atmosphere rich in carbon dioxide and nitrogen. A vast amount of chemical energy was (and is) stored in this divide, but the question is how to access it?

There are both physical and chemical barriers for electrons to be relocated to dissipate this redox gradient.

Only in the hydrothermal systems is there a mixing of electron donors from the crust, such as hydrogen and iron(II), with the potential electron acceptors above. Even then, there is a kinetic barrier to the transfer of electrons.

Only when appropriate catalysts are available is it possible to reduce carbon dioxide efficiently and thereby produce organic molecules. The relevant catalysts were forerunners of enzymes. Networks of these catalysts are more efficient than individual catalysts alone, and these networks, linked together, are the first makings metabolism and hence life.

Overall, this environment provides the continuous input of redox energy that life needs; and in a place shielded from the harmful effects of solar and cosmic rays. This chemistry can all take place in individual pores within the porous rocks, providing the first compartmentalization that ultimately allows the evolution of individual cells.

One of the biochemical routes to carbon fixation in the anaerobic world is the Wood-Ljungdahl pathway.

One enzyme, CO dehydrogenase (CODH), reduces CO2 to CO. The CO is then transferred to a second enzyme, Acetyl CoA synthase (ACS), where it reacts with a thiol, Coenzyme A, and a methyl group (transferred from a neighbouring cobalt centre) (Figure 2(i)). The catalysis of CODH and ACS is mediated by clusters built from iron, nickel and sulfide. It has now been shown that an analogue of the ACS reaction can be brought about by simply treating CO and methane thiol with an aqueous mixture of iron, nickel sulfide (Figure 2(ii)). Thus the seeds of metabolism were sown by simple geochemical processes.

In general, metabolism provides two things for life: building blocks and biochemical energy. WoodLjungdhal chemistry is special in this regard, in that it produces both organic molecules and dehydrating power (the latter being synonymous with biochemical New Zealand Association of Science Educators

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(i) CO2

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CODH CH3-CoIII-R +

CO

ACS

H3C

HSCoA

CH3SH+CO

(ii)

Fe,N,S

H3C

SCoA

HSCH3

SCH3

Figure 2: Overview of (i) Wood-Ljungdahl carbon fixation pathway and (ii) biomimetic geochemical analogue.

energy). In the memorable words of Everett Shock, the Wood-Ljungdahl pathway provides “a free lunch that you’re paid to eat”.

Some of the organic molecules that were produced by carbon fixation could bind to the mineral surfaces and modify their catalytic capabilities (all core metabolites, like various carboxylic acids, are ligands for metals, e.g. Figure 1: (5)). Thioesters (like Acetyl CoA) and polyphosphates (like ATP) are synonymous with biochemical energy since they are water-compatible dehydrating agents. Carrying out dehydration chemistry in water is a clever trick, and one of life’s critical discoveries. It allows small molecules to be linked together as condensation polymers. All biological macromolecules are of this kind: proteins (from amino acids), nucleic acids (from nucleotides) and polysaccharides from sugars). Not only can building blocks be linked together, but in water they hydrolyse back to their component building blocks, unless they are useful, and can be recycled.

As the carbon fixation chemistry produced amphipathic organic compounds, cell membranes became possible and catalytic networks could become encapsulated within the resulting vesicles to produce protocells.

Simple reproducing (autocatalytic) networks of catalysts of this kind are close to life, but have not stepped over the starting line because only limited amounts of information can be reproduced in this way.

However, in some of the hydrothermal pores were

deposits of phosphate. If and when phosphate was incorporated into the catalytic networks then the possibility of nucleic acids emerged. We now know that the critical feature of nucleic acids, that allows them to carry genetic information, is their regular ionic structure with information carried in hydrogen-bonding patterns. Phosphate is an ideal foundation for these structures. Once RNA had been invented a source of digital information was available and now an openended source of information was at hand. The resulting reproducing autocatalytic vesicles could more accurately reproduce metabolic information and Darwinian natural selection was born. Iron and phosphate had come together; chemistry had come alive.

For further information contact: andy.pratt@canterbury.ac.nz

Further reading Further reading on iron, phosphate and the geochemical origin of life: de Duve, C. (1991) Blueprint for a Cell: The Nature and Origin of Life (Patterson, Burlington, NC).

Pratt, A. J. (2006) The Curious Case of Phosphate Solubility, Chemistry in New Zealand October, pp. 78-80.

Trefil, J., Morowitz, H. J., & Smith, E. (2009) The origin of life a case is made for the descent of electrons. American Scientist, 97(3), 206-208.

Westheimer, F. H. (1987) Why nature chose phosphates.

Science, 235, 1173-1178.

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Iron is a metal found in abundance on Earth and is essential to life. The human body cannot produce iron, so this trace mineral must be present in the diet at a level sufficient to meet the body’s needs. Like most nutrients, iron needs to be ingested at a rate that is neither too low nor too high.

Iron deficiency is one of the most prevalent heath problems worldwide, and is the single most common nutritional deficiency. Iron deficiency results in anaemia, fatigue, decreased immune function, and decreased work performance. Excess iron can be toxic, as it will build up in the body and may lead to coronary heart disease and cancer. The upper limit of intake for adults is 45 milligrams per day; in children, ingesting 200 milligrams of iron can cause death.

Dietary iron comes in two forms: haem and non-haem.

Haem iron is more bioavailable than non-haem iron because haem iron remains soluble and can be easily absorbed by the cells in the gut. Non-haem iron forms insoluble complexes in the digestive system due to the alkaline nature of the small intestine and thus is more poorly absorbed. Non-haem iron can be found as either the reduced ferrous form or the oxidized ferric form. Ferrous non-haem iron is more bioavailable than ferric non-haem iron.

Haem iron comes from meat. Red meat is the richest source of haem iron, so beef and lamb contain more haem iron than chicken or fish. Liver contains more iron than other cuts of meat. Non-haem iron comes from vegetables, grains, and iron supplements. Popeye the Sailor made spinach the most famous iron-containing vegetable (Figure 1), but beans, lentils, and molasses are also good sources of nonhaem iron. Most of the iron in our diet is non-haem iron.

Centuries ago, the constant rusting and wear and tear on iron cooking pots and utensils caused iron to leach into cooked food and acted as a form of iron supplementation. In the post-industrial age, non-rusting steel replaced iron in the kitchen, and nowadays iron comes almost exclusively from the foods we eat and from dietary supplements.

vessels that carry nutrients away from the gut. The divalent metal transporter (DMT-1) transports ferrous iron across the apical cell membrane and into the cell. Ferrous iron can be stored inside the cell within a complex of ferritin protein.

Or, the iron can be bound to ferroportin, which interacts with hephaestin to convert the ferrous iron to ferric iron, which is then bound to transferrin and transported out the basolateral cell membrane and into the blood.

Overall, only 10 – 15% of the iron in the diet is absorbed by the body. The efficiency of iron uptake is dependent on a number of factors. The type of dietary iron plays a role: absorption of haem iron from meat is twice as efficient as absorption of non-haem iron from vegetables and grains.

Iron uptake is carefully regulated by the body because it has no means of excreting excess iron, other than the non-specific loss associated with the daily shedding of cells from the skin and mucosa. Gut cells are able to interact with both the iron in the gut contents and the iron in the blood.

If blood iron levels are high, the cells will allow more of the iron present in the food being digested in the gut lumen to remain unabsorbed. If blood iron levels are low, the cells will synthesise more iron-binding proteins in order to be able to absorb more iron.

Iron uptake is also dependent on iron bioavailability; that is, how accessible a given iron atom is to the gut cells. This is influenced by the interactions between different foods consumed in a meal. Non-haem iron uptake in the gut is enhanced when the pH of its environment becomes more acidic, so the consumption of acidic foods such as orange juice or tomato juice in combination with iron-containing foods increases the bioavailability of non-haem iron in the meal. A number of dietary components can also decrease non-haem iron uptake. Antacids increase the alkalinity of the intestinal environment and make non-haem iron less bioavailable; calcium, copper, zinc, and manganese compete with iron for the transport proteins that allow cells to absorb non-haem iron; tannins in tea and coffee inhibit absorption of non-haem iron.

iron

The human body cannot produce iron, so this trace mineral must be present in the diet at a level sufficient to meet the body’s needs, as Dr Fran Wolber, Institute of Food, Nutrition, and Human Health, Massey University, explains: What is iron?

How does the body take up iron?

Iron absorption is dependent on a complex series of iron-transporting proteins found inside or on the surface of the cells that line the gut.

These cells are polarized: that is, their ‘top’ and ‘bottom’ are quite different.

The top, or apical side, interacts with the digested food inside the gut lumen. The bottom, or basolateral side, interacts with the blood and blood

Figure 1: Spinach is a well-known source of non-haem iron. Ref: Public domain photograph released by Miansari66.i New Zealand Association of Science Educators

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Figure 2: Haemoglobin in red blood cells uses the iron atom to bind oxygen.

Ref: Creative Commons Attribution image by Mrbean427.

What happens to iron in the body?

Iron is best known for its role in oxygen transport. Nearly two-thirds of iron in the body is found in haemoglobin, the major protein in red blood cells. The iron atoms, located in the centre of each of the four haem subunits that make up the haemoglobin protein, are required for oxygen binding.

Haemoglobin in the red blood cells picks up oxygen in the lungs, which is transported via the bloodstream to all the tissues of the body. When the oxygen is released, the haemoglobin binds spent carbon dioxide, a cellular waste product. The red blood cells return to the lungs, where the haemoglobin releases the carbon dioxide and binds new oxygen atoms as respiration occurs.

Haemoglobin saturated with bound oxygen is termed oxyhaemoglobin; without bound oxygen, it is called deoxyhaemoglobin (Figure 2). Light absorption between the two forms differs. This results in oxyhaemoglobin appearing to have a red colour, and deoxyhaemoglobin having a blue colour. As arteries carry oxygenated blood away from the lungs, and veins carry deoxygenated blood back to the heart and lungs, arteries in the body appear red while veins, which are most easily visible on the inside of the wrist and the back of the hand, appear blue (Figure 3).

Iron is a structural component of many enzymes in the body, which carry out an array of essential metabolic functions ranging from the synthesis of new DNA to neurotransmitter activity. Iron is also located in myoglobin, a protein that supplies oxygen to muscles. About 15% of the body’s iron is stored and available for use when dietary iron levels temporarily drop. Iron is usually stored inside proteins because free iron can react with peroxides to produce free radicals, which can damage DNA and other cellular components.

The need for iron varies depending on age, health, sex, and other factors. Infants are born with enough iron to last for 4 – 6 months, and get sufficient iron in their diet from breast milk. After that, babies are recommended to have 7 – 11 milligrams of iron per day. Teenage boys require 11 milligrams, while teenage girls need 15 - 18. Pregnant women need 27 milligrams per day. While iron supplements are available in pill form, they may not be well absorbed and they often cause side effects such as nausea, diarrhoea, or constipation. Therefore, it is preferable to ensure the diet is higher in iron when iron losses (through menstruation) or iron requirements (through pregnancy or intense exercise) are increased.

The average adult has approximately 3500 milligrams of iron in their body. Changes in iron status are slow and gradual, and occur when daily loss (via shed gut and skin cells, bleeding, or pregnancy) and daily intake (via the diet or dietary supplements) are unequal. When iron stores in the body become too low and are not replenished, new hemoglobin is no longer produced and the number of functional red blood cells drops, resulting in anaemia.

For further information contact: F.M.Wolber@massey.ac.nz

References Figure 3: Iron in the haemoglobin of red blood cells transports oxygen throughout the body via the bloodstream.

Ref: Creative Commons Attribution image by Sansculotte.

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Zhang, A. S., & Caroline, A. (2009). Molecular mechanisms of normal iron homeostasis.” Hematology, 207-214.

Ur-Rehman, S., Huma, N., Tarar, O. M., & Shah, W. H. (2010). Efficacy of Non-heme Iron Fortified Diets: A Review. Critical Reviews in Food Science and Nutrition, 50, 403-413.

Nathan, A. T., & Singer, M. (1999). The oxygen trail: tissue oxygenation. British Medical Bulletin, 55, 96-108.

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iron, oxygen and life Peruse any biochemistry book and it quickly becomes evident that iron is a central element of life.1 Ferrous iron literally carries the oxygen in the air we breathe from our lungs to our tissues, where iron also warehouses this precious resource. Iron enables a critical step in passing our biological heritage to our children when it catalyzes the biosynthesis of the deoxyribonucleotide building blocks of our genetic material.2 And iron plays the leading role in the complex performance of redox chemistry in the mitochondrial electron transport chain. This collection of Fe-containing proteins gives us the energy we need to move, our hearts to beat, and our bodies and minds to stay awake while we read moving essays.

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called the R (relaxed) form; the low-affinity structure is the T (tense) form. The change in structure is so significant that if a crystal of deoxyhaemoglobin is exposed to O2, the crystal changes shape dramatically and sometimes shatters. 3 How can binding at one haem be communicated to another haem active site? Especially when the first haeme-O2 is embedded in a protein subunit that interacts with the other subunits only through non-covalent contacts? Two models are currently being explored to explain this co-operative transition of the haemoglobin molecule from TTTT (all four subunits in the low-affinity T-form) with no O2 bound to high-affinity RRRR with all four Fe2+ sites occupied.

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Ferrous iron literally carries the oxygen in the air we breathe from our lungs to our tissues, with the protein controlling its reactivity every step of the way, as Cather Simpson, The Photon Factory and the Chemistry and Physics Departments, University of Auckland, explains:

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Haemoglobin: using iron to transport O2 cooperatively In vertebrates, haemoglobin (Figure 1) is the ironcontaining protein that shuttles O2 about (Figure 1).

This protein has four subunits − two a and two b − and each one contains an iron in its Fe2+ oxidation state. Each metal ion sits within a macrocyclic porphyrin ring called protoporphyrin IX that, by virtue of the iron at its centre, is called a haem. The porphyrin provides four nitrogen atoms to co-ordinate to the Fe2+; a histidine nitrogen from the protein supplies the fifth ligand. When O2 is dissolved in the blood, it can access the sixth ligation site on the iron in a relatively open area in the protein called the haem distal pocket.

One of the fascinating, and fortuitous, aspects of O2 transport by haemoglobin is that the binding of dioxygen by the four haem groups is co-operative. That is, the four haemes in haemoglobin do not function independently. If one haem attaches to an O2, the other three subunits respond by binding more readily to O2 themselves. This co-operativity makes haemoglobin nearly twice as effective at binding and transporting O2 to the tissues.

At high partial pressures of O2 − like in the lungs − the vast majority of haemoglobin molecules are saturated with O2. A much higher proportion of haemoglobin molecules (nearly 100%) have four O2 molecules bound than would be observed if each subunit behaved autonomously (~80%). Further, this co-operative behaviour leads to more effective O2 release in the capillaries as well, where the partial pressure of O2 is roughly 5-fold lower. Simply put, with four binding sites working co-operatively, haemoglobin responds much more nimbly and more extremely to changes in O2 partial pressure.

O2 binding to the Fe2+ in one subunit’s haem pocket induces a major change in the tertiary structure of that subunit that is then communicated through subunit interfaces to drastically alter the quaternary structure.

Probably the largest adjustment is that one ab pair rotates by 15° relative to the other. The conformation of the protein when the O2 binding is high-affinity is

Figure 1. Human deoxyhaemoglobin with four subunits a2b2 (top). The a-subunits are light grey and the darker grey ones are b-subunits. Each subunit has a porphyrin linked to the protein through histidine-Fe2+ co-ordination. One a-subunit is shown to the lower left, and the haem region is expanded to the lower right. O2 diffuses into the protein to the distal pocket, where it binds the Fe2+ on the haem face opposite the proximal histidine.

The crystal structure was downloaded from the protein database (www.pdb.org) with PDB-ID 1XZ2. From Kavanaugh, J.S., Rogers, P.H., Arnone, A., Hui, H.L., Wierzba, A., Deyoung, A., Kwiatkowski, L.D., Noble, R.W., Juszczak, L.J., Peterson, E.S., & Friedman, J.M. (2005) “Intersubunit interactions associated with Tyr42 alpha stabilize the quaternary-T tetramer but are not major quaternary constraints in deoxyhaemoglobin.”

Biochemistry, 44, 3806-3820.

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In the sequential model, O2 binding to one subunit in TTTT deoxyhaemoglobin transforms the tertiary structure of that subunit to the R-form. Simultaneously, it increases the affinity of neighbouring subunits for O2, without converting them from T to R. Those ‘nudged’ subunits display a higher affinity for O2, but it is only when they bind the O2 ligand themselves that they undergo the T-to-R transition. The concerted model differs in that the protein converts as a whole unit rather than in a step-wise fashion.4 The first step is the same as in the sequential model: O2 binds to the Fe2+ in one haem in TTTT deoxyhaemoglobin. In the concerted model, that binding event shifts the equilibrium between the TTTT and the RRRR quaternary structures. Additional O2 binding leads to structures that even further favour the RRRR form, so that by the time that four O2 ligands are bound, the RRRR configuration is very highly preferred energetically. The key distinguishing feature between the two paradigms is that the sequential picture imagines the presence of mixed RTTT, RRTT, and RRRT intermediates; the concerted model does not. Which model dominates in haemoglobin allosteric behaviour is still a matter of debate.

Iron is the trigger All of this large-scale protein motion may seem rather remote from the iron at the centre of each haeme. However, it is the detailed distribution of electrons in the iron dorbitals that supplies the trigger for all of the downstream tertiary and quaternary structure changes, for the cooperative binding of O2, and ultimately for our ability to efficiently extract and use oxygen from the air we breathe.

Iron in its 2+ oxidation state has six valence d-electrons (d6). If there were no ligands, the five d-orbitals (Figure 2) on iron would energetically degenerate, and the electrons would occupy them according to Hund’s rule. In the haeme, however, the Fe2+ d-orbitals lose this degeneracy. The dx2-y2 orbital is oriented towards the N-atoms that chelate the metal, and the resulting repulsive interaction strongly destabilizes this orbital. Similarly, the Fe2+ dz2 orbital finds

itself at a higher energy because of its physical proximity to axial ligand(s). The other three orbitals (dxy, dxz, and dyz) are not as directly involved with the ligands, and therefore, are only weakly affected. The pattern of iron d-orbital energies seen in Figure 2 is typical for a perturbed square planar arrangement of ligands. The magnitude of the splitting among them depends upon the number and characteristics of the ligands. O2 binding to deoxyhaeme increases the energy separation and induces a change in the spin state of the iron. That spin state change is the first step in the cascade of events leading to co-operative O2 binding.

In the deoxyhaemoglobin state (TTTT), the Fe2+ has only five ligands, and they are all nitrogenous. The absence of the sixth ligand (i.e. O2, CO or other suitable molecule) causes the destabilization of the dz2 and dx2-y2 to be relatively small, and electrons are occupy these orbitals at room temperature (Figure 2). The 5-co-ordinate, Fe2+ has a valence configuration of [dxy2 dxz1 dyz1 dz21 dx2-y21] and is said to exhibit a high-spin state (S = 2). When O2 diffuses into the distal haeme pocket and binds to the Fe2+, the dz2 is destabilized significantly. Increased energy splitting leads to a valence configuration of [dxy2 dxz2 dyz2 dx2-y20 dz20] for the 6-coordinate, Fe2+. This configuration is low-spin (S = 0).5 The transition from a 5-co-ordinate, high-spin to a 6-coordinate, low-spin Fe2+ occurs extremely rapidly − on the subpicosecond (1 picosecond = 1 x 10-12 s) timescale.6 It is accompanied by a critical physical change: the size of the metal ion decreases by about 25%.7 A high-spin, Fe2+ ion like the one in the 5-co-ordinate haeme has a radius of about 80pm. This is too large for the Fe2+ to fit comfortably in the plane of the porphyrin, and crystal structures show that the iron is domed out of the macrocycle plane towards the fifth ligand (the proximal histidine) by several tenths of an angstrom (Figure 2). When the O2 binds, and Fe2+ adopts the low-spin electron configuration, the metal ion shrinks to about 60pm and the Fe2+ adopts a coplanar arrangement with the chelating nitrogens of the haeme macrocycle. This

Figure 2. Comparison of the characteristics of the immediate Fe environment in the unligated (left panel) and ligated (right panel) states for human deoxyhaemoglobin A. The iron spin state change with ligand binding (i.e. O2, CO, NO) induces the iron to move into the haem plane, giving a tug to the proximal histidine. This force is communicated through the a-helix (see lower left, Figure 1) to transform the subunit to its R (relaxed) configuration, and eventually through quaternary interactions to form the RRRR high affinity state. The crystal structures of the deoxyhaemoglobin (1XZ2) and CO-haemoglobin (1BBB) were downloaded from the protein database. See Figure 1 legend for reference to 1XZ2; 1BBB: Silva, M.M., Rogers, P.H., & Arnone, A. (1992). “A third quaternary structure of human haemoglobin A at 1.7-A resolution.” J.Biol.

Chem., 267, 17248-17256.

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motion would occur even if the protein were not attached through the proximal histidine. It is driven by the chemistry of the Fe2+ in the haeme.

The physical motion of the iron into the plane of the macrocycle accompanies binding of the O2 ligand at the sixth site on the iron. It significantly alters the bond on the other side of the haeme, between the Fe2+ and the proximal histidine (Figure 2). Time resolved spectroscopy, particularly Raman scattering and UV/Vis absorption, has been a powerful tool in elucidating the subsequent structural changes and their timescales.

Most of these studies have employed a clever experimental trick, in which a bound ligand such as CO is photolyzed from the haeme by one laser pulse, then the spectrum of the molecule is measured with another pulse at a set time delay.

These sorts of de-ligation studies reveal that the local structure of the haeme and the protein pocket undergoes the R-to-T (or T-to-R) transformation within the first few picoseconds after the bonding at the Fe2+ is changed.9 Examination of the Fe-His stretching motion indicates that the local structure of the porphyrin macrocycle and the immediate region of the protein reacts to this structural change on the time scale of 10s of picoseconds. The larger subsequent protein motions that lead to the final tertiary and quaternary structures occur over nanoseconds (1 nanosecond = 1 x 10-9 s) to microseconds (1 microsecond = 1 x 10-6 s).

Studies of the Fe-His vibrational spectrum indicate that a significant amount of the strain energy involved in the R-to-T conversion is localized near the haeme, most likely in the motion of the Fe2+ into the plane.11 A recent quantum mechanical study10 confirmed several elements of this modified “allosteric core” model.11 In haemoglobin, the energy in the system required to induce the tertiary and quaternary structural shifts associated with co-operative O2 binding appears to be associated with the coupling between a and b subunits, and in the Fe2+-His linkage to the protein.

The protein tunes the Fe reactivity Remarkably, the O2 binds to the Fe2+ in the iron without inducing oxidation.7 If the haeme group is extracted from the protein and put in solution, it rapidly oxidizes to the Fe3+ state. If that redox reaction occurred in haemoglobin in our blood, the protein’s ability to efficiently bind and release O2 would be dramatically impaired. It is vitally important from an evolutionary standpoint that the protein protect the Fe2+ in haemoglobin (and myoglobin) from oxidation.

The protein of cytochrome c must accomplish exactly the opposite: control of the haeme such that it shuttles between the Fe2+ and Fe3+ states. This enzyme is a soluble electron transport protein in the mitochondrial electron transport chain, the end product of which is energy in the form of ATP. Each cytochrome c protein has a single haeme active site. It is exactly the same haeme molecule as in haemoglobin and myoglobin (protoporphyrin IX).

In cytochrome c, though, the critical function is that oxidation-reduction cycle that is so effectively prevented in haemoglobin and myoglobin. Since the haemes are the same, the protein must be the factor responsible for their very different reactivities.

Though the detailed mechanism of this Fe-tuning by the protein is largely unknown, the attachment of the haeme to the protein in cytochrome c differs substantially from that in haemoglobin. In haemoglobin, the only bond to the protein is the tether between the Fe2+ and the proximal histidine. Cytochrome c holds onto its haeme group much more securely, with covalent linkages to targets outside: a

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Motion of the iron

histidine and a methionine. The haeme pockets of the two systems differ as well, which can lead to differences in the dielectric constant near the haeme, and changes in the redox state energies.

Finally, while large-scale protein motion is critical for haemoglobin function, spectroscopic studies have shown that such large-scale motions do not occur in cytochrome c. The electrons shuttle in and out of the iron centre of the haeme, buried in the protein, but the overall enzyme structure changes quite minimally.

The structure-function comparison between haemoglobin and cytochrome c illustrates the idea that while iron plays the leading role in many biochemical processes, its performance is heavily directed by the surrounding protein.

Iron is a required element for all life, as we know it. It is an evolutionary advantage for us, then, that this chemically promiscuous atom takes direction so well.

For further information contact c.simpson@auckland. ac.nz

Further reading Il Sistema Periodico (1975, by Primo Levi) is a collection of short stories. It is a beautiful and powerful book, and a masterpiece of science and metaphor. In 2006, The Periodic Table was named the best science book ever written in a competition held by The Royal Institution in London.

An account of this award can be found at: http://www. guardian.co.uk/science/2006/oct/21/uk.books (last accessed April 26, 2010). There is an excellent translation into English from the original Italian by Raymond Rosenthal (Schocken Books, New York, 1984).

References For those looking for a more thorough treatment of iron-containing proteins and processes, I recommend Biochemistry by Lubert Stryer. It is comprehensive, readable and the “Selected Readings” at the end of each chapter are very useful. It’s recently been updated in the 6th edition, and added co-authors Jeremy Berg and John Tymoczko. The haemoglobin and myoglobin section (Chapter 7) is particularly thorough.

2 The enzymes are ribonucleotide reductases. They use iron-oxygen centres, if oxygen is around, and iron-sulfur centres if it is not.

3 The crystals of deoxyhaemoglobin convert from hexagonal plates to elongated prisms if O2 is allowed to diffuse into the crystals, and sometimes shatter. This remarkable change, discovered by Felix Haurowitz in 1938, was the first observation of allosteric protein behaviour. It inspired the father of protein crystallography, Professor Max Perutz (Nobel Prize in Chemistry, 1962), to study haemoglobin. Office of the Home Secretary, National Academies of Sciences (1994) Biographical Memoirs, V.64 (The National Academies Press). http://www.nap.edu/openbook.php?record_id=4547&page=139 (last accessed April 26, 2010).

4 The concerted model is also known as the Monod-Wyman-Changeux model of allostery. Monod, J., Wyman, J., & Changeux, J.P. (1965). On the Nature of Allosteric Transitions: A Plausible Model” J. Mol. Biol., 12, 88-118.

5 Perutz, M.F. (1979) “Regulation of Oxygen Affinity of Haemoglobin. Influence of Structure of the Globin on the Heme Iron.” Ann Rev. Biochem, 48, 327-386. It should be noted that the actual spin states involved in the O2 bound species are still not entirely clear. In particular, the measured and predicted magnetic properties of intermediates are not resolved.

6 Several studies show this very rapid movement of the Fe2+ with respect to the haeme plane. This is one example: Franzen, S., Bohn, B., Poyart, C., & Martin, J.L. (1995) “Evidence for Subpicosecond Heme Doming in Haemoglobin and Myoglobin: A Time-Resolved Resonance Raman Comparison of Carbonmonoxy- and Deoxy- Species” Biochem, 34, 1224-1237.

7 Shannon, R.D. (1976) “Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides” Acta Cryst. A32:751-767.

The actual numbers reported are 78 and 61pm for high- and low-spin Fe2+, respectively. However, the ligands are different.

8 Franzen, S., Bohn, B., Poyart, C., DePillis, G., Boxer, S.G., & Martin, J.-L. (1995) “Functional aspects of ultra-rapid heme doming in haemoglobin, myoglobin, and the myoglobin mutant H93G”. J. Biol. Chem., 270, 1718-1720.

9 Findsen, E.W., Friedman, J.M., Ondrias, M.R., & Simon, S.R. (1985) “Picosecond time-resolved resonance raman studies of haemoglobin: Implications for reactivity”. Science, 229, 661-665.

10 Alcantara, R.E., Xu, C., Spiro, T.G., & Guallar, V. (2007) “A Quantum-chemical picture of haemoglobin affinity”. Proc. Nat. Acad. Sci. U.S.A., 104, 18451-18455.

11 Gelin, B.R., & Karplus, M. (1977) “Mechanism of tertiary structural change in haemoglobin”. Proc. Natl. Acad. Sci. U.S.A., 74, 801. Gelin, B.R., Lee, A.W.M., & Karplus, M. (1983) J. Mol. Biol., 171, 489.

12 Simpson, M.C., Millett, F., Fan, B., & Ondrias, M. R., (1995) “Transient resonance raman evidence for structural reorganizational dynamics during electron transfer in ruthenated yeast cytochrome c”. J. Am. Chem. Soc., 117, 3296.

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rusty beauty of weathering steel Why is rusty steel being used in our modern buildings and bridges? Raed El Sarraf, Structural Engineer, NZ Heavy Engineering Research Association (HERA) explains: What is weathering steel?

Weathering steel, or to use its technical title of ‘structural steel with improved atmospheric corrosion resistance’, is a high strength low alloy steel that, in suitable environments, may be left unpainted because it forms an adherent protective rust ‘patina’ that greatly reduces the corrosion rate. The alloys compose 2% of the steel make-up with specific alloying elements such as copper, chromium, silicon and, in some cases, phosphorous, in addition to the usual components that make up steel (carbon and iron).

All structural steel rusts at a rate which is governed by the access of moisture and oxygen to the metallic iron. As this process continues, the oxide (rust) layer becomes a barrier restricting further ingress of moisture and oxygen to the metal, and the rate of corrosion slows down.

The rust layers formed on most conventional carbon structural steels detach from the metal surface after a critical time, and the corrosion cycle commences again.

Hence, the rusting rate progresses as a series of incremental curves approximating to a straight line, the slope of which depends on the aggressiveness of the environment.

The weathering steel protective patina layer is initiated in the same way, but, due to the alloying elements in the steel, it produces a stable rust layer that adheres to the base metal and is much less porous. This layer develops under conditions of alternate wetting and drying to produce a protective barrier, which impedes further access of oxygen and moisture. Eventually, if the rust layer is sufficiently impervious and tightly adhering, the corrosion rate may diminish virtually to zero. The resulting reduction in corrosion rates is clearly illustrated in Figure 1.

In a suitable environment, this stable condition may be reached within five years, and the metal is then protected from significant future corrosion by the protective patina layer. Assuming that there is no significant change in the environment, and with regular inspection to determine and treat any isolated problem areas if they occur, the life of

Figure 1: Schematic comparison between the corrosion loss of weathering and carbon steel.

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weathering steel cladding or bridges can be more than 100 years.

Background information about weathering steel 1. Benefits Cost benefit: The material cost of weathering steel is usually 12% more expensive than ordinary structural steel. However, the cost savings from the elimination of the application of a protective coating system typically outweigh the additional material costs. This also equates to reduced future maintenance costs, especially since the lack of a protective coating system means that there are no future recoats required.

Reduced time of maintenance operations: Inspection, cleaning and, at worst, coating of limited areas of a weathering steel bridge, will take less time than the recoating of an ordinary coated structural steel. This also greatly reduces indirect costs such as those resulting from traffic disruption, providing on-site access whilst maintenance operations are carried out.

Environmental and safety benefits: Coating requires suitable health and safety protection for the applicators, and can also require special environmental considerations, such as containment of abrasive blast cleaning residue. Hence, the omission of coating by using weathering steel yields corresponding advantages.

Attractive appearance: Once the protective rust patina is fully formed and weathered, the appearance of this film is uniform, usually of a dark brown colour. This colour can blend nicely with the environment and improve with age.

Figure 2: Weathering steel cladding on the award-winning Ironbank building in Auckland.

Photograph courtesy of Raed El Sarraf.

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Figure 3: The underside of State Highway 1 Mercer to Longswamp weathering steel off-ramp.

Photograph courtesy of Raed El Sarraf.

2. Environmental impacts on durability As with other forms of construction, there are certain environments which can lead to durability problems. The performance of weathering steel in these environments may not be satisfactory, and its use in these environments should be avoided: Marine environment: Exposure to high concentrations of chloride ions, originating from sea water spray, salt fogs or coastal airborne salts, is detrimental. The hygroscopic nature of salt adversely affects the rust patina as it maintains a continuously damp environment on the metal surface.

In general, weathering steel should not be used within 5 to 20km of coastal waters, unless it can be established at a given site that chloride levels do not exceed an annual average deposition rate of 100mg/m2/day (which is the lower end of category S2 in ISO 9223); design guidance or readings for one year or more must be taken to determine this.

In the case that weathering steel is considered to be used closer than these general limits from the coast, the present author recommends that the site-specific conditions are determined by testing (Note: one year minimum record is required). If the first year corrosion rate including microclimate effects, calculated in accordance with HERA Report R4-133 (Clifton and El Sarraf, 2005), is greater than 50µm, then weathering steel should not be used.

It should be noted that the Japanese have developed a ‘Coastal Weathering Steel’, which is claimed to be able to be used in coastal areas (Usami, et al., 2003). Additional nickel has been added to the alloy mix, which improves its atmospheric corrosion resistance near the coast, with encouraging results.

Continuously wet/damp conditions: Alternate wet/dry cycles are required for the adherent patina to form; where this cannot occur due to excessively damp conditions, a corrosion rate similar to that of conventional carbonmanganese steel may be expected. Such conditions are to be avoided. As a consequence of this, in addition to the seacoast limits discussed above, weathering steel applications must not be immersed in water, in contact with soil or covered by vegetation.

Atmospheric pollution: Weathering steel should not be used in atmospheres where high concentrations of corrosive chemicals or industrial fumes (specifically SO2), are present.

Such environments with a pollution classification above P3 (SO2 > 250µg/m3 concentration or 200mg/m2/day deposition rate) to ISO 9223, rule out the use of weathering

Figure 4: Per Capita weathering steel sculpture.

Photograph courtesy of Raed El Sarraf.

steels. However, this is an extreme level that is rarely encountered.

In New Zealand, a SO2 level in excess of 250µg/m3 will occur where the site is exposed to drifting steam from active geothermal areas (for example, the area around Rotorua).

It may also occur within the vicinity of large industrial sites such as Marsden Point or coal burning towns and cities on the West Coast.

3. Some more limitations In addition to the above limitations, the following recommendations should also be considered: Surface preparation: All contaminants are to be removed from the surface to enable the formation of a proper protective patina, this includes grease, weld splatter and mill scale.

Run-off: Unless concrete staining is the ‘look’ that the architect is wanting, drainage should be provided beneath the steel as rust run-off will continue until the proper formation of the patina.

Compatibility with other materials: This is dependent on a number of conditions which are: elements buried in and below the soil surface should be painted to protect the steel, as the patina layer will not form in those conditions.

The corrosivity can be determined from design guidance such as HERA Report R4-133 (Clifton and El Sarraf, 2005).

Interfaces between steel and concrete should be sealed with an appropriate sealant as concrete retains moisture which hinders the patina formation. Connections to galvanically dissimilar materials, such as zinc and cadmiumplated bolts, should be avoided. The use of non-metallic washers between the metals to break the flow of current is recommended.

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All of the above and other guidance on the use of weathering steel is available from HERA Report R4-97:2005 entitled “New Zealand Weathering Steel Guide for Bridges” (El Sarraf and Clifton, 2005). Even though the Guide was written for weathering steel bridges, the guidance may also be applied to claddings and non-structural elements. However, it does not cover other issues such as perforation of thin steel sheets and corrosion of lapped joints that are commonly found on roofing. Thin gauge weathering steel is used in the Northern Hemisphere, in colder countries like Finland. Steel gauges less than 3mm are not recommended to be used in New Zealand due to the temperate climate.

The excellent Finnish publication entitled “Corten Facades”

by Ruukki (Rautaruukki Oyj, 2001) provides details that will minimise the chances of water ponding and increase the chances of optimum patina formation and weathering steel performance. Also, to kick-start the patina formation, and to give the patina a better chance of forming properly, it is best to allow the steel to weather or to be left out in the open at the fabrication shop. A post fabrication clean is recommended to give it a more even ‘look’ followed by the wet/dry weathering process before installation. A preweathered weathering steel in the correct location will have a smooth rusty patina layer, which starts as rusty red and becomes darker with time. Designers and architects should be made aware of the limitations of using weathering steel and specify the correct detailing requirements.

The devil is in the details, as they say, and that is never truer than when using weathering steel.

Case Studies 1. Ironbank Building − weathering steel cladding The Ironbank building is the latest award-winning multistorey structure gracing Auckland’s skyline, which is located on Karangahape Road. Completely cladded with weathering steel, the building is Ecologically Sustainably Designed (ESD) and is aiming for a 5 Green Star from the New Zealand Green Building Council.

The recyclability properties of steel and the self-protection properties of weathering steel convinced the designers to specify weathering steel as a cladding around the whole building. This, in turn, assists the designers’ desire to achieve the 5 Green Star rating, due to those sustainable properties.

Figure 2 demonstrates the beauty of weathering steel as a cladding.

The weathering steel cladding was installed in accordance to the guidance given by HERA and is performing as expected. The building is visible from Karangahape Road and the motorway with its distinctive rusty red weathering steel cladding. Within five years’ time the weathering steel will darken and have a more uniform colour as the protective patina is formed. In the meantime, the everchanging colours of the patina formation provide an aesthetic extravaganza to the passerby and the building tenants (further details on this building can be found at: www.ironbank.co.nz).

2. State Highway 1 Mercer to Longswamp weathering steel off-ramp Mercer to Longswamp off-ramp is New Zealand’s first weathering steel bridge. The protective patina layer on steel surface negates the need of a protective coating system, which equates to minimal future maintenance cost (protective coatings are one of the most expensive components in any bridge structure). This layer hardens which inhibits and greatly reduces further corrosion to

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the steel, hence, the maintenance cost saving. Figure 3 demonstrates the use of weathering steel in a bridge structure.

Since no protective paint system is needed, there is also no need for the disposal of blast cleaning debris, which represents a major environmental benefit. The minimal future maintenance requirements of weathering steel bridges mean that there will be saving on direct maintenance costs as well as on indirect costs arising from road and rail traffic delays. Now that’s something motorists keeping an eye on the weathering steel bridge can be pleased about!

3. Per Capita weathering steel sculpture The Per Capita sculpture is the first major public sculpture utilising the beauty of weathering steel, using 40mm thick plate. The sculpture was designed by Wellington artist Cathryn Monro, and is located on the corner of Cable Stret and Tory Street, outside the Museum Hotel, as shown in Figure 4.

The work consists of four gigantic portraits, up to four metres high. Two pieces are shaped as portraits in profile, and two have the profiles cut out from a square: i.e. two are in positive form and two in negative space − voking, in the artist’s words, “a visual conversation about the complexity of New Zealand’s cultural identity.”

The profiles are based on actual portraits of people who are connected through genealogy, “But” says artist Cathryn Monro, “the specific history of these people is not the point of the work. The portraits signify diversity in family histories throughout New Zealand and foremost are the notion that personal history is paramount in the formation of a national one.”

Weathering steel was chosen to assist in portraying the artist’s vision, due to its durable and self-healing properties by the reformation of the protective patina layer. This is especially the case with graffiti, which did occur within a month after it was officially opened on 1 December 2006.

Recent visits to the sculpture have shown that the earlier graffiti attacks are now only visible by the lighter patina layer colour. Even though graffiti is a menace that all artists have to tolerate, the use of weathering steel added character to the sculpture by turning it into a living everchanging sculpture.

Conclusion Weathering steel is a high strength low alloy steel that, in suitable environments, may be left without a protective coating system due to its self-forming adherent protective rust patina. Certain design criteria must be taken into account for the successful use of weathering steel.

A well-designed and detailed weathering steel structure, whether in a building façade, bridge or sculpture, can provide an attractive, very low maintenance, economic solution and extends the scope of cost-effective steel.

For further information contact: raed.elsarraf@hera.org.nz

References Clifton, G.C., &El Sarraf, R. (2005). “New Zealand Steelwork Corrosion Coatings Guide”, HERA Report R4-133:2005, HERA, Manukau City, New Zealand.

Usami, A., Kihira, H., & Kusunoki, T. (2003). “3%-Ni Weathering Steel Plate for Uncoated bridges at High Airborne Salt Environment”, Nippon Steel Technical Report No. 87. Tokyo, Japan.

ISO 9223 (1992). “Corrosion of metals and alloys - Classification of corrosivity of atmospheres”, International Organisation for Standardisation, 1992.

El Sarraf, R., & Clifton, G. C. (2005). “New Zealand Weathering Steel Guide for Bridges”, HERA Report R4-97:2005, HERA, Manukau City, New Zealand.

“Corten Facades” (2001). Rautaruukki Oyj, Helsinki, Finland.

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Average binding energy per nucleon (MeV)

9 8 7 6 5 4 3 2 1 0

0

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Number of nucleons in nucleus

Figure 1: As you change the number of nucleons in a nucleus, there is also a change in the binding energy per nucleon. Due to the interplay between the strong nuclear force and electromagnetic force there is a peak in this energy around iron-56.

As you move through the periodic table from hydrogen to sodium (the stable isotope of which has a nucleus containing 23 nucleons â&#x20AC;&#x201C; 11 protons and 12 neutrons), there is an increase in the binding energy per nucleon.

As more nucleons are added to the nucleus, the combined strong nuclear force packs the nucleus tighter, making it harder to break apart. The strong nuclear force is a fundamental force that keeps the positively charged protons in the nucleus together.

From magnesium (24 nucleons) to xenon (131 nucleons) there is a relatively flat section. This feature is associated with the growing importance of the electromagnetic repulsion between the protons. The strong nuclear force and the electromagnetic force are able to keep each other in balance, such that there is no real change in the energy needed to break apart the nucleus. Beyond caesium (134 nucleons), there is a slow decline as the nucleons on one side of the nucleus cannot exert a strong enough nuclear force on the nucleons on the other side but the electromagnetic repulsion is being felt.

It is this curve that tells us why a fission reactor uses uranium and a fusion power plant would use hydrogen.

To the left of the peak, atoms become more tightly bound if they are combined to form a single nucleus that lies nearer to the peak. This process is called fusion.

For atoms to the right of the peak, they would be more tightly bound by breaking into atoms that are nearer to the peak. This process is fission.

It is during the flat section from magnesium to xenon that there is a peak at around iron. The peak actually falls at nickel-62, not iron-56 as is commonly stated. In fact, iron-58 also has a higher binding energy per nucleon (Fewell). The reason why iron-56 is more important than these elements to the life cycle of some stars comes down to helium nucleus.

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Iron is the last element that is fused at the core of the star before it disintegrates in a supernova, as Jeffrey Simpson, post graduate student in the Department of Physics and Astronomy at the University of Canterbury, explains: Iron is only one of almost 100 elements of the periodic table that are found in the Sun and other stars, but it is one of the most important elements in how it affects the evolution of a star. Iron is the last element that is fused at the core of the star before it disintegrates in a supernova.

Since no more energy can be gained to hold up the star, the star undergoes gravitational collapse. The reason no more energy can be gained comes down to how the fundamental components of the nucleus combine together.

How is the nucleus held together?

If you measure the mass of an atomic nucleus and then add up the mass of the all its constituent protons and neutrons, you will find that they do not have the same value. The nucleus has less mass than the parts that make it up. If you convert this mass difference to an energy using E=mc2, this value is called the binding energy. It can be thought of as a measure of how much energy is required to break apart the nucleus. Dividing this binding energy by the number of nucleons (the number of protons plus the number of neutrons) gives the binding energy per nucleon. This number is the key reason why iron is so important to the life of stars (see Figure 1).

How do stars evolve and explode?

Stars shine as a result of the release of energy due to nuclear fusion. Their evolution is primarily controlled by their mass.

In a massive star (5 times the mass of the Sun or more), the evolution will follow a different track to that of the Sun. This is due to its size which allows for higher energies and pressures to be obtained at its core where the fusion takes place.

After it has exhausted its fuel of hydrogen at the core, by fusing it to helium, the core contracts under gravitational pressure. This pulls hydrogen down to deeper layers so that a shell of hydrogen fusion forms around the nonburning helium core. This shell of hydrogen then causes the outer layers to expand due to the increased thermal energy, producing a red giant. Eventually the pressure and temperature at the core reaches a level that helium fusion can take through what is known as the triplealpha process. Three helium nuclei are fused to form one carbon-12.

At a temperature of 200 million kelvin, a carbon atom can fuse with another helium nuclei or alpha particle to form oxygen-16. As the star ages, higher temperatures are reached as one source of fuel is used up and the starâ&#x20AC;&#x2122;s core contracts. Over time the conditions are reached such that more alpha particles can be captured to form neon-20, silicon-28, and then finally nickel-56 and iron-56 (see Figure 2).

The star is now like an onion (see Figure 3), with layers of different materials tracing its chemical evolution. At its core is iron and nickel. As stated above, nickel-62 is

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Figure 2: Carbon burning. Two carbon atoms fuse to form a neon-20 nucleus plus a helium nucleus and some energy in the form of a gamma ray.

Diagram adapted by Jeffrey Simpson from: http://en.wikipedia.org/wiki/File:CNO_Cycle.svg

actually the most stable element in terms of its nuclear binding energy per nucleon. But it is difficult to create in the interior of stars through the addition of abundant species. It is almost certainly produced in stars, but not in great enough quantities to compete with iron in terms of being relevant to stellar evolution.

The iron/nickel core mass increases until it reaches the Chandrasekhar limit, which is about 1.4 times the mass of the Sun. At this mass, electron degeneracy pressure is overcome. This is the pressure caused by the Pauli Exclusion Principle which forbids fermions (such as electrons) being in the same energy state. It is an extremely strong force but can be overcome. At this point, electrons and protons combine to form neutrons and the core collapses, leading to a supernova.

There are several different types of supernovae. In terms of our story of iron in astronomy, it is the type Ib, Ic and

Figure 3: This diagram shows a simplified (not to scale) cross-section of a massive, evolved star (with a mass greater than eight times the Sun). Where the pressure and temperature permit, concentric shells of Hydrogen (H), Helium (He), Carbon (C), Neon/Magnesium (Ne), Oxygen (O) and Silicon (Si) plasma are burning inside the star.

Ref: http://commons.wikimedia.org/wiki/File:Evolved_star_fusion_shells.svg

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II supernovae that we are interested in. These are the supernovae where iron plays a key role.

So iron having nearly the highest binding energy per nucleon is what causes a core collapse supernova such as the one that caused SN 1054, creating a source of light so bright it could be seen during the day. This was the progenitor of the Crab Nebula (see Figure 4).

Another example of a core-collapse supernova was SN 1987A, which occurred in the Large Magellanic Cloud (Figure 5). One of its discoverers was a New Zealander, amateur astronomer Albert Jones who has made 500,000 observations of variable stars.

The other type of supernova is Type 1a (Figure 6).

This is caused by a white dwarf star exceeding the Chandrasekhar limit. White dwarfs are the remnants of stars like our Sun which do not explode in supernova.

Instead, they do not have any more fusion at their core beyond carbon and oxygen. Their outer layers are lost and the core is left naked in space. In type 1a supernova, the white dwarf gains matter from a companion star which allows it to exceed the Chandrasekhar limit. Here iron is produced, but this is explosively in the core of the star. It is also produced by the radioactive decay of nickel-56 to cobalt-56 and then iron-56.

Figure 4: The Crab Nebula as seen by the Hubble Space Telescope in 2000. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054.

It is believed to be the result of a type II supernova.

Ref: http://hubblesite.org/newscenter/archive/releases/2005/37/)

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Figure 5: This Hubble Space Telescope image, taken in February 1994, with the Wide Field and Planetary Camera 2, shows the full system of three rings of glowing gas surrounding supernova 1987A. Courtesy of P. Challis (Harvard-Smithsonian Center for Astrophysics

Are there stars with no iron or other heavy elements in their atmosphere?

So far, no star has been observed that has no iron or other heavy elements in its atmosphere. But the current theories of Big Bang cosmology predict there must have been some stars which were composed almost only of hydrogen and helium. These are known as population III stars.

A few minutes after the Big Bang there was a period of primordial nucleosynthesis: the creation of elements from the sea of protons and neutrons that filled the Universe. This resulted in the production of deuterium (a hydrogen isotope of one proton and one neutron), helium-3 and -4, and lithium-6 and -7. It is from these elements that the first stars would have formed.

These population III stars are predicted to be much more massive than stars that exist today. Model simulations predict that they would have been over 100 times the mass of the Sun. Due to their massive size they would have lived for only a couple of million years before exploding in a supernova. For stars in the mass range of 130 solar masses, this would result in a supernova for which is predicted a large proportion of the heavy elements created would take the form of iron.

Population III stars have not been observed yet. This is due to the extremely short lifetimes and existing only in the very early Universe. The most metal-poor stars that are observed today are found in groups of stars called globular clusters. These are spherical conglomerations of between 10,000 and a million stars that form halos around galaxies.

One of the stars with the lowest known amount of heavy elements is HE0107-5240, with about 1/200,000 of the iron content of the Sun (Lau, Stancliffe and Tout).

What about the other extreme? That is, stars that have an

Figure 6: The spiral galaxy NGC 2770 and its two supernovae. The bright star at the edge of the galaxy in the top right is SN 2008D, while the star left of the centre is SN 2007uy.

Ref: http://www.eso.org/public/images/eso0823a/

equivalently high (200,000 times) abundances of iron?

No such stars are known, though it is theorized by some that the surfaces of neutron stars could consist of iron.

Neutron stars are the remnant of supernova. They consist of neutrons supported by the Pauli Exclusion Principle.

But their surface regions are thought to be composed of atomic nuclei, with the possibility of it being iron left from the core of the massive star that underwent the supernova.

Conclusion Through the interplay of the strong nuclear force and electromagnetic force, iron finds itself with one of the highest binding energies per nucleon. In addition, iron56 can be created by the addition of alpha particles in the interior of stars allowing it to be built up in the core of massive stars. It is here that iron acts as one of the final fusion products. With no more energy available, the star’s core collapses, causing a supernova.

For further information contact: jeffrey.simpson@pg.canterbury.ac.nz Bibliography Fewell, M. P. (1995). “The atomic nuclide with the highest mean binding energy.”

American Journal of Physics, 63.7, 653-658.

Fleurot, F. (2010). Evolution of Massive Stars. 20 April 2010, http://nu.phys. laurentian.ca/~fleurot/evolution/ Halliday, D., Resnick, R., & Walker, J. (2005). Fundamentals of Physics. 7th Edition.

Wiley.

Lau, Herbert H.B., Stancliffe, R. J., & Tout, C. A. (2007). “Carbon-rich extremely metal poor stars: signatures of Population III asymptotic giant branch stars in binary systems.” Monthly Notices of the Royal Astronomical Society, 378.2, 563-568.

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black sand − New Zealand’s vast iron resources Black sand on the west coast of the North Island contains the iron mineral titanomagnetite. Mining of the sand since 1969 has produced iron ore for export and for local steel production, and there is currently an exploration boom searching for new deposits, both onshore and offshore. Tony Christie, Senior Minerals Geologist, GNS Science Lower Hutt, explains: What is black sand?

Beaches along 480km of the west coast of the North Island, from Kaipara Harbour to Whanganui, are grey with patches of black sand, and some are completely black (see Figures 1 and 2). These black sands extend into the windblown dunes that back the beaches or form on the cliff tops. The black colour results from a concentration of black minerals including the mineral titanomagnetite, an iron oxide containing significant titanium.

The mineral industry refers to the black sand as ironsand.

The titanomagnetite is heavier than the common lightercoloured minerals such as quartz and feldspar, and therefore it gets concentrated by wave and wind action, just like gold is concentrated in similar environments and in rivers. The light minerals are winnowed away, leaving

the heavy minerals behind to accumulate as black sand. If you dig a hole in a black sand beach, you will find that the sand is in thin layers typically alternating between grey and black sand indicating that the zone of concentration moves back and forth with the tide, or in time with storms interspersed with more quiet periods.

Where does it come from?

The titanomagnetite originates as crystals in volcanic rocks, where it makes up a few percent of the rock.

When these rocks are eroded, their constituent minerals are transported by rivers to the coast, where the concentration process is most efficient. The relative proportion of the different minerals and their chemistry suggest a ‘fingerprint’ match to the rocks of the Taranaki volcanoes: Egmont and its older eroded neighbouring volcanoes Pouakai, Kaitake, and Paritutu (see Figures 3 and 4). However, other sources probably include the volcanoes in the Rotorua-Taupo area (Taupo Volcanic Zone) and the eroded volcanoes near Raglan (Karioi) and Kawhia (Pirongia).

Currents and waves generated by the predominant westerly winds transport the sand along the shore, northward and south-eastward from Cape Egmont by a process of long shore drift. As the sand moves along the

Figure 1: Titanomagnetite ironsand (black sand) occurs along the coast between Kaipara Harbour and Whanganui, both onshore and offshore. The offshore percent ironsand contours are based on bottom sampling reported by Carter (1980).

The titanomagnetite is sourced from the erosion of volcanic rocks. TVZ = Taupo Volcanic Zone.

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Figure 2: Titanomagnetite-rich black sand forming the beach at the Three Sisters near Tongaporutu, about 50km along the coast north-east of New Plymouth.

Photograph courtesy of Lloyd Homer.

coast, concentrations of black sand are formed beyond headlands or where river valleys have cut and eroded the coastal cliffs and the sand can be blown inland.

Exploration â&#x2C6;&#x2019; identifying the resource Reconnaissance exploration in the 1940s and 1950s consisted of sampling with a hand auger and measuring the quantity of magnetic minerals in the laboratory.

Larger samples were required for resource estimation and so mechanised drilling was undertaken in the 1950s and 1960s. Several large ironsand deposits were discovered and mining operations were established at the three largest: Waikato North Head in 1969, Waipipi in 1971 and Taharoa in 1972. The Waikato North Head and Taharoa mines continue today, but Waipipi closed in 1987.

Mining and production Mining at Waikato North Head (see Figures 5 and 6) and Taharoa processes sand with approximately 1825% titanomagnetite. This is concentrated by gravity and magnetic methods to produce a product with

Figure 3: Taranaki has four andesite volcanoes: Egmont (active from 127,000 years ago â&#x20AC;&#x201C; recent), Pouakai (active approximately 250,000 years ago), Kaitake (active about 500,000 years ago) and Paritutu (Sugar Loaf Islands; active about 1.75 million years ago). Pouakai, Kaitake and Paritutu were each a similar shape and size to Egmont, but are now mostly eroded (see Figure 4).

Photograph courtesy of Lloyd Homer.

approximately 80% titanomagnetite. This material has a chemical composition of approximately 57% iron, 7.7% titanium dioxide and 0.4% vanadium oxide. Resources of the deposits are generally quoted in terms of this ironsand concentrate rather than raw sand.

New Zealand produces approximately two million tonnes of ironsand concentrate annually. Production from Waikato North Head is used for making steel at the Glenbrook Steel Mill, whereas ironsand from Taharoa is exported to steel mills in Asia.

Developing a New Zealand iron and steel industry There were various attempts to smelt the ironsands from 1849, but the high titanium content and fine grain size defeated traditional blast furnace technology. In the 1950s, new iron and steel making technologies in the form of the direct reduction kiln and electric arc furnace were applied to the ironsands by the Department of Scientific and Industrial Research and others. This led to the setting up by the government in 1959, of the New Zealand Steel Investigating Company, with the objective of determining the technical and economic feasibility of manufacturing steel using ironsand. Successful trials of the newly developed direct reduction technology led to its adoption in 1964. A steel mill was commissioned

by New Zealand Steel Ltd at Glenbrook in 1970, to use ironsand from the Waikato North Head mine.

Figure 4: The erosion of Kaitake cone has been modelled in 3D using Geographic Information System software. Most of the cone has been eroded (yellow) leaving remnants of the cone (blue).

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Figure 5: Waikato North Head produces approximately one million tonnes per year of concentrate that is piped as a slurry 18km to the steel mill at Glenbrook.

Figure 6: Mining titanomagnetite-bearing dune sand at Waikato North Head with a bucket wheel excavator.

Photograph courtesy of NZ Steel.

Photograph courtesy of Lloyd Homer.

The ironsand concentrate is blended with subbituminous Huntly coal for reducing the iron oxide, and Te Kuiti limestone which acts as a flux (substance that promotes melting). The mixture is reduced in rotary kilns to sponge iron containing 70% metallic iron. This is then melted in an electric arc furnace to produce molten pig iron containing about 93% iron. The pig iron is poured into a steel-making vessel, along with scrap steel, for steel production.

with modern exploration. Titanomagnetite is slightly magnetic and experiments with aeromagnetic surveys, using a magnetometer in an aeroplane, in the 1970s proved very successful in showing the extent of the ironsand deposits at Taharoa. Modern exploration typically uses aeromagnetic surveys as a reconnaissance exploration method to pinpoint concentrations of ironsand for sampling by drilling. One company has recently used ground penetrating radar to determine the thickness and makeup of the sand bodies.

Modern exploration The exploration drilling in the 1950s-1960s was generally of a reconnaissance nature for many of the ironsand deposits with only a few, widely spaced holes, so there is potential for improving the resource estimates

Why explore offshore?

During the 1960s and 1970s, sampling of seabed sediments showed concentrations of ironsand offshore from the Waikato River, the Mokau River, New Plymouth and Patea (see Figure 1). This has encouraged mineral

Figure 7: Magnetic anomalies in offshore airborne surveys are interpreted to represent concentrations of ironsands in paleo-shorelines and paleo-river channels formed when sea level was lower than at present, particularly associated with the 9 ka paleo-shoreline (or 9,000 years before present). The Aeromagnetic survey was flown for petroleum exploration in 1996 by World Geoscience Corporation Ltd. 26 New Zealand Association of Science Educators

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explorers to investigate offshore. Aeromagnetic surveys show magnetic ribbons that are interpreted as concentrations of titanomagnetite deposits in former rivers and beaches when sea level was much lower than at present, during glacial periods (see Figure 7).

For example, magnetic anomalies form patterns along a zone corresponding to the interpreted shoreline of nine thousand years ago.

The huge demand for resources to build infrastructure in expanding economies such as China and India has resulted in high demand and prices for iron ore. This has encouraged several mining and exploration companies to explore for iron ore on the west coast, both onshore and offshore. A strip of the offshore coast from near North Cape to Whanganui is currently under mineral permits for prospecting and exploration (see Figure 8), but it will take several years of exploration to determine if there are sufficient resources for mining to be possible.

For further information contact: t.christie@gns.cri.nz

Acknowledgements This article has been prepared with funding from the Foundation for Research Science and Technology, and assistance of Trans-Tasman Resources (www.ttr.co.nz).

Dave Heron assembled the GIS model of Kaitake, Bryan Davy processed the magnetic data and Carolyn Hume drafted the figures.

Resources

Figure 8: Minerals permits for ironsand exploration, March 2010 (source: www.crownminerals.govt.nz).

Carter, L. (1980). Ironsand in continental shelf sediments off western New Zealand - a synopsis. New Zealand Journal of Geology and Geophysics, 23, 455 468. http://www.royalsociety.org.nz/site/publish/journals/nzjgg/notable/default.aspx Christie, A.B. & Brathwaite, R.L. (1997). Mineral commodity report 15 - iron. New Zealand Mining, 22, 22-37. http://www.crownminerals.govt.nz/cms/pdf-library/minerals/minerals-overviewpdfs-1/report15_iron.pdf http://www.teara.govt.nz/en/iron-and-steel/ http://www.nzsteel.co.nz/about-new-zealand-steel

Where was the largest known meteorite found?

Katherine Eastall, Ridgeway School Duncan Steel, an astronomer and the author of the book Rogue Asteroids and Doomsday Comets responded: The largest meteorite known is a nickel-iron specimen of mass over 60 tonnes, which was found near Grootfontein in Namibia in 1920. The second most massive is a 34 tonne nickel-iron body found in the Antarctic, and which now stands in the American Museum of Natural History in New York.

Although nickel-iron meteorites consist of only a small proportion of incoming meteoroids, they represent a large fraction of recovered meteorites â&#x20AC;&#x201C; especially of the larger sizes â&#x20AC;&#x201C; due to their strength and also greater likelihood of being recognized. Stony meteorites tend to fragment in the atmosphere, and are thus less likely to reach the ground intact. The largest known stony meteorite is a 2 tonne specimen which fell in China in 1976. However, in 1908 an object thought to have been a small stony asteroid with a mass of about 200,000 tons (diameter about 50 metres) blew up high above Siberia. No large meteorite reached the ground, but the shock wave caused devastation of the forest below.

If one considers even larger rocks from space, these are not significantly impeded by the atmosphere, and so hit the

ground with their original speed (typically 100,000km per hour). At such a speed these objects have more energy than a hundred times their own mass of TNT, and so can cause great devastation and large craters. The best-known impact crater on Earth is the 1.3km wide Meteor Crater in Arizona, formed 49,000 years ago. There are over 150 known craters on the Earth, some of them hundreds of kilometres across.

There are no known impact craters in New Zealand, but there are 23 in Australia: in fact four of the Australian craters are less than 6,000 years old. In 1990 it was recognized that a heavily eroded crater on the Yucatan Peninsula of Mexico is likely to be linked to the extinction of the dinosaurs 65 million years ago. The crater is over 180 kilometres in diameter, and was formed by an asteroid or comet about 20 kilometres in size. Astronomers believe that there are at least 2,000 asteroids, and many comets, on orbits that could lead to massive impacts on the Earth, and thus environmental catastrophes that could end civilization as we know it.

Moves are now afoot to start an international search programme to discover these and determine whether an impact is due in the foreseeable future, in which case it would be possible to divert the offending projectile so that it misses our planet.

Send questions to: questions@ask-a-scientist.net.

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iron fertilisation Is ocean iron addition part of the solution to climate change? Cliff Law, NIWA explains: Introduction Climate change, resulting from carbon dioxide (CO2) emissions by human activities, is one of the issues facing future global stability. Despite this awareness, current actions to reduce CO2 emissions appear to be having minimal impact on the atmospheric trend, and consequently governments and organisations are considering alternative approaches. Many of these are geoengineering techniques that require alteration of natural cycles or processes to either reduce the amount of solar radiation reaching the Earth’s surface or increase the amount of CO2 removed from the atmosphere. The oceans are an important natural sink for CO2, that have accounted for ~40% of all CO2 released since the start of the Industrial Revolution, thereby providing a buffer against climate change. About half of this CO2 uptake has been by the ‘biological pump’, in which photosynthesis by billions of floating phytoplankton cells in the surface waters of the ocean converts dissolved CO2 to organic matter. Upon dying the cells sink, and the carbon is exported into the deep ocean where it may be retained for hundreds of years.

Plant growth in our gardens is determined by the availability of light and nutrients, and the same is true for phytoplankton in the surface ocean. Whereas light is generally available, a seasonal trend exists for nutrients such as nitrate and phosphate which are supplied to the surface from deep water during winter but then are rapidly removed in spring. However, in certain regions these ‘macronutrients’ remain perennially high in surface waters throughout spring and summer, whereas phytoplankton biomass, as indicated by the pigment chlorophyll, remains

relatively low. These High-Nutrient Low-Chlorophyll (HNLC) regions include the Southern Ocean, the Equatorial Pacific and the Sub-Arctic North Pacific, and account for ~30% of the global ocean (see Figure1). This excess of macronutrients in surface waters suggests that something else is limiting phytoplankton growth in these regions.

Are parts of the open ocean anaemic?

Initially this anomaly was thought to be due to low light in these regions, but improvements in marine analytical chemistry in the 1980s led to a novel idea that lack of iron was the reason. As with many living organisms, phytoplankton also require micronutrients such as iron in trace amounts as essential components of enzyme systems.

Yet, despite being one of the most abundant elements in the Earth’s crust, dissolved iron is only found in low concentrations in surface waters in the open ocean. This is because the oxidised form of iron is particulate and tends to sink out. Consequently sufficient dissolved iron is only found in coastal regions and in open ocean waters that receive high dust input or upwelling. The surface waters in the HNLC regions, which are some distance from land, have perennially high macronutrients (see Figure1) and conversely extremely low dissolved iron.

The iron limitation hypothesis was championed by John Martin, a marine biogeochemist at Moss Landing Marine Laboratory, California. He supported this with evidence from bottle experiments in which the addition of dissolved iron to water from HNLC regions caused phytoplankton to grow.

He also used data from ice cores, which show an inverse relationship between atmospheric CO2 and iron over the last 160,000 years. This was interpreted as indicating that during the periods in Earth’s history of low iron availability, the removal of CO2 by phytoplankton photosynthesis was

Figure 1: Distribution of nitrate in the surface ocean, showing elevated concentrations in the three HNLC regions of the Southern Ocean, Equatorial Pacific and Sub-Arctic Pacific. Overlain are white crosses that indicate the locations of the in situ addition experiments with iron (white), iron and phosphate (green), and natural iron supply studies (red).

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Experiments in the open ocean However, the evidence from the bottle incubations was not conclusive, and so the next step was to directly release dissolved iron into the surface waters of HNLC regions to determine whether phytoplankton growth would be stimulated in situ. Initiating an in situ experiment is not as simple as it may initially seem, due to the dynamic nature of the ocean. For example, it is easier to test whether fertiliser causes a crop to grow on an area of agricultural land, than in a patch of surface ocean water that is moving, spreading and mixing with surrounding water. To account for this during the in situ iron experiments, the dissolved iron is released along an expanding track around a central drifting buoy, so that a coherent patch of fertilised water of ~50100km2 results (see Figure 2).

Whereas the approach in these experiments has often been incorrectly described as ‘dumping iron filings’, most experiments have instead used single or repeat additions of 0.5-3 tonnes of dissolved iron sulphate. Although this may sound a large volume, when distributed over 50km2 it only raises the background dissolved iron by 20-40 fold.

Although usually acidified to pH 2 to maintain it in a soluble form, the iron is still rapidly oxidised and lost from surface waters, so in order to follow the fertilised patch of water a tracer is also added. Sulphur hexafluoride, a dissolved gas that is detectable at incredibly low concentrations, is used as it permits tracking even when a patch covers an area exceeding 1000km2. During a typical experiment, the patch position and boundaries are determined by mapping sulphur hexafluoride in surface water (see Figure 2), and the water at the centre of the patch (the ‘IN station’) is then compared with water outside the patch (the ‘OUT station’) to determine if the added iron has had an effect.

Iron grows phytoplankton The first in situ iron addition experiments took place in the Equatorial Pacific during October 1993, and have subsequently been followed by twelve further experiments in this and other regions (see Figure 1). Most experiments have shown consistent increases in phytoplankton biomass, albeit of different magnitudes, with chlorophyll increasing 2-14 fold at the patch centre. The resulting patches, which often exceed 1000km2 in surface area, have been observed in satellite images of ocean colour (see Figure 3a).

In most experiments phytoplankton cell size has generally increased due to a shift in the type of phytoplankton, with the smaller phytoplankton that dominate in HNLC regions giving way to larger phytoplankton. The latter are often diatoms, a group of phytoplankton with silicate shells that are important in the transport of organic carbon to the deep ocean (see Figure 3).

This increase in phytoplankton growth in the iron fertilised patch stimulates drawdown of dissolved CO2 (see Figure 4), which in some experiments has decreased at the patch centre by 40%. This coincides with increased uptake of macronutrients, with nitrate, phosphate and silicate declining at the centre of the iron patch, often to levels that begin to limit phytoplankton growth. The phytoplankton response has varied in different in situ iron experiments due to differences in light availability, patch mixing and dilution, and grazing by zooplankton. Nevertheless, these in situ experiments have confirmed the first part of the iron hypothesis: that iron availability limits phytoplankton in HNLC waters.

Photosynthesis does not equal carbon export However, few of the in situ experiments have measured the export of the carbon fixed by the phytoplankton into the sub-surface ocean. This reflects that the motivation behind the in situ iron experiments was to understand what controls phytoplankton growth and how marine ecosystems respond to change in nutrient supply, rather than whether iron addition can increase ocean carbon uptake.

The in situ experiments that have measured carbon export have identified that only 2-20% of the carbon fixed by phytoplankton in the iron fertilised patch is subsequently transferred to sub-surface waters. This is consistent due to non-fertilisation studies, and is due to the majority of sinking phytoplankton being broken down by grazing and bacterial activity and converted back into inorganic nutrients and CO2 before reaching deep water. Consequently although iron addition stimulates phytoplankton growth, it remains unclear whether it increases the transfer of carbon from atmosphere to the deep ocean.

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correspondingly low, and so atmospheric CO2 was elevated.

Consequently, the iron hypothesis not only linked iron availability to phytoplankton growth, but also to oceanic carbon uptake and atmospheric CO2 concentration.

Geoengineering interest Nevertheless, from the outset there has been interest in using this approach at larger scales to increase phytoplankton growth and enhance the ocean carbon sink.

This can be partly attributed to John Martins’ attentioncapturing quote: “Give me half a tanker of iron, and I’ll give you the next ice age”. The subsequent in situ iron experiments further reinforced the potential, particularly with the unambiguous visual demonstration of iron-induced phytoplankton growth in satellite ocean colour images (see Figure 3a).

Furthermore, initial laboratory studies indicated that as phytoplankton require iron in very low quantities, iron addition represented a potentially cheap approach to removing carbon. With the development of an active carbon trading market over the last 5-10 years, commercial organisations are now promoting large-scale ocean iron fertilisation, with the claim that it offers the greatest potential for carbon sequestration of all available techniques.

Is it effective?

Evidence indicates that large-scale iron fertilisation may not be such an effective approach to lowering atmospheric CO2.

One of the main attractants for the commercial sector is the apparent large ‘bang-for-buck’ of iron addition. The early laboratory studies of phytoplankton cultures suggested a ratio of carbon fixed to iron added on the order of 110000, with an estimated cost of a few dollars per tonne of carbon fixed. However, subsequent in situ experiments have shown a lower ratio of carbon exported to iron added, of 100030000, and so a higher cost per tonne of carbon of >$300 making it considerably less attractive.

The lower carbon:iron ratio estimated from the in situ iron experiments results in part from the rapid loss of added iron, which could possibly be minimised in future releases by addition of iron in an organic form. However, estimates of carbon uptake by large-scale iron fertilisation using ocean models have also decreased, as a result of improvements in both the models and baseline information on processes and fluxes. Current estimates now suggest that large-scale (global ocean) long-term (100-year) fertilisation with iron would draw down atmospheric CO2 by 33µatm, which is <9% of current atmospheric CO2 levels. So although ocean iron addition isn’t the answer to climate change, could it be part of the solution? It has been suggested that iron fertilisation could be just one of a portfolio of technological New Zealand Association of Science Educators

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approaches to lowering atmospheric CO2. However, recent re-analysis of ice core data suggests that the rate of CO2 drawdown resulting from iron addition may be too slow to be of use.

Verification is difficult There are also other criteria that must be considered in addition to effectiveness. The carbon regulatory market requires further standards for carbon sinks, which include verification of carbon storage, and permanence, by which carbon must be retained for 100 years or greater. Again, using the previous analogy of crops on agricultural land, it is easier to follow the transfer and storage of carbon in a terrestrial system than in the more dynamic ocean. Not only will the carbon fixed by phytoplankton sink 1000s of metres through the water column, but it is also transported laterally over 1000s of kilometres by ocean currents. Determining the permanence of carbon sequestration in the ocean is therefore highly challenging, expensive and currently not considered viable with existing technology. Yet this is essential, particularly as the 100-year time horizon, which is generally considered to be depths greater than 500m, is only reached in certain

regions, with sub-surface water returning to the surface within decades in other regions.

Potential side effects A further criterion of the carbon trading market is no side effects, and yet there are a number of potential effects of iron fertilisation both locally and at distance from the fertilisation site. For example, the in situ iron experiments have demonstrated that iron addition causes an increase in large phytoplankton groups, and so a change in biodiversity that may impact further up the food chain. At present this is viewed as positive, as increased phytoplankton biomass may lead to an increase in consumers and fish stocks. However, there is concern that fertilisation may also stimulate the development of toxic algal blooms. Although this has not been observed in any in situ iron experiments, recent evidence indicates that the diatom species that respond to iron addition also increase their production of neurotoxin.

Concern has also been raised regarding the â&#x20AC;&#x2DC;far-fieldâ&#x20AC;&#x2122; effects of ocean fertilisation. As phytoplankton decompose and decompose dissolved oxygen is consumed, which may cause expansion of low oxygen zones in the mid-water

Figure 2: a) Initiating an in situ iron experiment by releasing dissolved iron along an expanding track (blue line) around a central drifting buoy (red line). b) Adding iron sulphate to a tank of acidified seawater. c) Surface mapping using concentration of the dissolved tracer sulphur hexafluoride in surface waters. The shipâ&#x20AC;&#x2122;s track is indicated by the black dots overlying the contour plot of sulphur hexafluoride concentration.

Figure 3: A NASA ocean colour image over the Southern Ocean south of Australia showing a patch of elevated chlorophyll 150km long covering ~1000km2 at 40 days after iron-fertilisation during the New Zealand SOIREE iron experiment in January 1999. b) A microscope image of the diatom Fragilariopsis kergulensis, the diatom species that bloomed during the SOIREE iron experiment.

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Figure 4: Dissolved CO2 concentration anomaly in surface waters, showing maximum CO2 drawdown at the centre of the iron patch on Day 25 of the SERIES iron addition experiment in the Gulf of Alaska. The pink dots represent nominal locations of the IN and OUT stations for comparing the response to iron addition with unperturbed conditions.

column, as indicated by ocean models. The spatial extent of ‘dead zones’ of very low oxygen content has increased particularly in upwelling regions, and this could be further exacerbated by large-scale iron fertilisation.

Associated with oxygen removal is the increased production of other gases during microbial decomposition.

This includes nitrous oxide, another greenhouse gas that has a global warming potential 300 times that of CO2 on a molecular basis. An increase in nitrous oxide production in the mid-water column and subsequent ventilation to the atmosphere may negate any benefits gained from the CO2 drawdown stimulated by iron-induced phytoplankton growth. To date there has been no evidence of this from the in situ iron experiments, although ocean models suggest that this offsetting effect of nitrous oxide production may be significant dependent upon the location of iron addition. Conversely increased production of sulphurcontaining gases has been observed in some in situ iron experiments, which on larger scales could increase cloud formation and potentially enhance cooling of the planet.

A further concern is that of ‘nutrient-robbing’ by which enhanced macronutrient uptake by phytoplankton due to iron addition in one region may deprive another region downstream of nutrients and thereby reduce productivity.

Legislation These potential side effects are just one of the reasons why large-scale iron fertilisation remains a contentious issue.

Other uncertainties, such as the sourcing and transport of the huge volumes of iron required for large-scale addition over periods of 10-100 years, and the use of large areas of the ocean commons for which no relevant regulations or jurisdiction exist also represent major sticking points.

The current interest in large-scale iron fertilisation by commercial organisations, combined with these uncertainties, has led to statements of concern by leading environmental organisations. This in turn has stimulated recent activity in the development of international legislation.

A statement issued by the International Maritime Organisation which administers the London Convention, the main legal instrument for controlling marine pollution, has decreed that ocean fertilisation activities other than legitimate scientific research are prohibited. An assessment framework for establishing the legitimacy of future scientific in situ iron experiments is currently under development.

Currently there are no firm plans to undertake large-scale iron addition experiments; however, the continuing increase in atmospheric CO2 and development of the global carbon trading market will undoubtedly see further activity and research on ocean iron fertilisation at larger scales.

For further information contact: c.law@niwa.co.nz

Further reading Bertram C. (2010) Ocean iron fertilization in the context of the Kyoto protocol and the post-Kyoto process. Energy Policy 38, 1130-9.

Boyd P.W. et al (2007) Mesoscale iron enrichment experiments 1993-2005: synthesis and future directions. Science 315, 5812, 612-7.

Buesseler K.O. et al (2008) Ocean iron fertilization – moving forward in a sea of uncertainty. Science 319, 162.

Royal Society (2009) Geoengineering the climate: science, governance and uncertainty. RS Policy Document 10/09.

Strong A.L., Cullen J.J., & Chisholm S.W., (2009) Ocean fertilization. Science, policy and commerce. Oceanography 22, 236-61.

12 Papers in the Theme Section on Implications of large-scale iron fertilization of the oceans, Marine Ecology Progress Series (2008); vol 364, 213-309.

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ripping yarns: science in Asia Written by Miles Barker,Waikato University In three previous articles in New Zealand Science Teacher1 I have told a number of stories from the history of science – stories that are intended to illuminate the nature of science itself. Unashamedly to catch the eye, I chose to call them collectively ‘ripping yarns’, a label that has strong connotations from a bygone age of blissful imperialism.

Actually, bubbling through the three new science stories in this article can be found one of the dominant features of the age of imperialism: uneasy race relations. The scientist in the first story, Austrian-American botanist Joseph Rock (1884–1962), who worked in China, has been described as “an egomaniac at best, a racist at worst.”2 Then there is science and technology historian Joseph Needham (1900–1995) who, initially through his research assistant and lover at Cambridge University, Lu Gwei-djen, ultimately came to be described as “the man who loved China”3 and who, controversially, became an apologist for the newly constituted People’s Republic of China. The final story features Indian J.C. Bose (1858–1937), physicist and botanist, who for decades contended heroically with the lofty and patronising attitudes of the British Raj science establishment.

However, each story also has its own particular purpose – to illuminate an important proposition about the nature of science. These propositions feature in the classic catalogue4 of the features of science (Table 1) that I used in the three earlier articles. Since I wrote those fourteen stories, however, the need to explore the Nature of Science in classrooms, proclaimed in the banner headline across each page of our science curriculum of 2007, has taken on a greater urgency.

I address this after I have told these three new stories.

Rhododendrons, yak butter and brigands Botanist-explorer Joseph Rock’s idea of ‘dinner in the field’ was more elaborate and less communal than that of most scientists. Wherever he found himself in the great northsouth corridor of the China-Tibet borderlands – in a steamy jungle, a forest of fir trees beside a rushing torrent, on a grassy plain beneath snow-clad mountains – Rock’s evening expectations would be the same. The clean linen cloth would be spread on the folding table, the bottle of good wine would appear, and his cook (from the Naxi ethnic minority people) would serve, on a gold dinner service, dishes similar to those that Rock recalled from his boyhood in the twilight of the Hapsburg era in Vienna.

Later, after dining alone, and while his party of up to two hundred settled in for the night, Rock would relax his travelweary body in steamy water in his Abercrombie and Fitch collapsible bathtub. Meanwhile, in the shadows around him, the servants attended to Rock’s personal comfort; the porters unloaded the plant presses, cameras, and so on, thus releasing the yaks or mules for feeding and watering by the muleteers; and the mercenaries took up lookout stations, guarding against the ever-present possibility of brigands emerging from the anarchical countryside to attack the expedition.

In the first half of the twentieth century, other botanists, each with their carefully-guarded territory, worked on the resplendent and, at that time, little-known flora of the China-Tibet borderlands. However, Rock’s flamboyant expeditions and his colourful personality have become an 32 New Zealand Association of Science Educators

enduring part of the history of China’s south-west. Much of this is due to the enigmatic and eccentric character of this stocky, 1.72m tall, habitually pith-helmeted scientist. It was not just that his temperament was volatile; it was that his personality was deeply contradictory.

Often charming in European company, he was privately perpetually lonely. He was both self-aggrandising and deeply insecure. He was frequently dismissive of Han Chinese culture and surprisingly obtuse about the Tibetan world, but he was nevertheless invariably affectionate, if somewhat patronising, towards the Naxi minority people who inhabit the area of the south-western province of Yunnan where Rock made his base near the town of Lijiang.

After a wearisome time in the remote country of the borderlands, he would long to be rid of China, but once back even in Shanghai (let alone Boston or Vienna) he would be decrying ‘civilisation’ and longing for the solitude and the grandeur of the China-Tibet borderlands. And all of these erratic foibles spilled over into his science. While his meticulous and pioneering botany was internationally greatly respected, his contributions to ethnography were generally seen by specialists as flawed because of his fascination with the macabre and the sensational. It was impossible to identify where Rock the scientist and Rock the idiosyncratic citizen of the world began and ended. Indeed, his life is a good example of the proposition that scientists participate in public affairs both as specialists and as citizens.

Rock, by a combination of opportunism and bluff, suddenly became a botanist in his early twenties. Born into the lower classes in status-conscious Vienna, he had experienced an impoverished childhood, made more bitter by the contrast with his father’s workplace – Franz Rock was a steward in the luxurious home of a wealthy Polish count.

At eighteen years of age, Joseph Rock left Vienna with no academic qualifications but having demonstrated a formidable memory and a gift for languages. (Ultimately, he taught himself eight languages, including Sanskrit; he began learning Chinese in Vienna at the age of thirteen.)

Drifting his way to the United States and, out of work in Honolulu, he successfully persuaded the Division of Forestry that he was needed as an herbarium collector. That day he blustered and charmed his way into a successful lifelong career, made possible by his orderly, systematic mind, his prodigious memory, his relentless energy for writing and exploring, his love of natural beauty and solitude, and his willingness to go where few trained botanists had ever penetrated. During his subsequent travels in India, Burma and mainly China over the next thirty years, he shipped more than 80,000 plant specimens back to institutions as prestigious as the Arnold Arboretum at Harvard University, Kew Gardens in London, and the Smithsonian Institution in Washington. He specialised in rhododendrons, had two new species named after him, and his numerous but irregular journeys back to London, Edinburgh, Berlin and Boston kept him well informed, and also enhanced his international prestige. Curiously, however, Rock never actually published any works on the botany of China.

Early in his time in China, Rock’s attention was diverted towards another discipline – ethnography. In 1924 Rock,

home of twenty-seven years near Lijiang. For the next eleven years he was a perpetual emigrant, always travelling, nowhere at home. He gave up ethnography and returned to his two early interests, botany and languages. Rock died of a heart attack in Honolulu in 1962, just prior to the publishing of the second volume of a monumental and still widely revered dictionary of the language of the Naxi people.

Joseph Rock’s story reminds us that scientists are citizens too.

Sometimes this becomes apparent when scientists become involved in public action-taking: Nobel Prize winners British crystallographer Dorothy Hodgkin, and New Zealander Maurice Wilkins, of DNA renown, also devoted much of their energies towards international peace and understanding8; and many climate scientists “are going out of their way as private citizens to say,‘Wake up! This is not a good thing to be doing.’ ”9 And sometimes scientists’ lives as private citizens spill over and, unintended, influence their specialist activities in science: there is evidence that the private religious views of scientists as eminent as Sir Isaac Newton and Charles Darwin inevitably affected their professional lives.10 So, too, did Joseph Rock’s private inner world impinge dramatically and erratically on his public work in science.

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now an American citizen, secured a lucrative contract with National Geographic Magazine and over the next ten years “our man in China”5 became known internationally to millions of readers through the nine articles he wrote. His achievements in this area are uneven. The articles contained stunning photography; amazingly, Rock was taking and developing in the field the first colour photographic plates in the 1920s. For example, such photos flamboyantly illustrated Rock’s account of the production and display of the sculptured and tinted yak butter deities which formed the backdrop to the festive devil dancing at the Choni lamasery up in Gansu province.6 However, his frequent claims to be “the first white man” to view aspects of indigenous life, or to explore a snowy peak or a river gorge betray (certainly to our ears today) at best a Eurocentric bias. With readership and funding no doubt in mind, his attention was frequently transfixed by macabre and sensational details; even the titles of his articles spoke of “weird ceremonies”,“strange kingdoms”,“brigand-infested central China”,“holy mountain of the outlaws”.7 And he can be rightly accused of dismissively treating everyday people and customs with a high-mindedness that contrasted with the avid attention he paid the indigenous, so-called, kings and princes of the region. Approaching a settlement, Rock would often require his entourage to carry him into the town in a sedan chair, in order to impress the population, and especially its rulers, of his importance. It is hard to escape the conclusion that his attitude towards people in power was an outcome of the way he forever begrudged his own lowly beginnings in Vienna.

Rock’s time in China finally came to an end in 1949 as Mao Zedong’s newly constituted People’s Republic of China required Westerners to vacate Yunnan province. Worn out by years of travel, by the perpetual threats to his physical safety, and now by indifferent health, Rock fled from his

Joseph Needham’s great labour of love Cambridge University historian Joseph Needham’s long life (1900–1995) is remarkable for one titanic enterprise that he came passionately to embrace: the documenting of China’s entire history of science and technology, and its contribution to world civilisation generally.

Needham’s clearest purpose was to promote cross-cultural understanding; in attacking Western complacency, he aimed to show just how many crucial scientific advances, in fact, originated in China – the invention of printing, gunpowder and the magnetic compass are three of hundreds of examples.

Needham’s monumental labour of love comprised 18 hefty

Table 1: Thirteen propositions about the nature of science (from Rutherford and Ahlgren, 1990), and seventeen stories from science that illuminate the propositions. The stories are either in the present article, or in three earlier editions of New Zealand Science Teacher.

Propositions about the Nature of Science The Scientific World View • The world is understandable • Science ideas are subject to change • Science knowledge is durable • Science cannot provide complete answers to all questions

Scientific Enquiry • Science demands evidence • Science is a blend of logic and imagination • Science explains and predicts • Scientists try to identify and avoid bias • Science is not authoritarian

The Scientific Enterprise • Science is a complex social activity • Science is organized into content disciplines and is conducted in various institutions • There are generally accepted ethical principles in the conduct of science • Scientists participate in public affairs both as specialists and as citizens

Stories from Science (and sources in NZST) ‘All knowledge is my province’-Frances Bacon’s big claim (#113) The spirals of life (#106) Joseph Needham’s great labour of love (#124) ‘A plant is an animal standing on its head’ (#113) Harold Wellman-honest to a fault (#113) The case of the midwife toad (#113) Why the Kaingaroa forest isn’t grassland (#101) What transpires in heartless vegetables? (#106) Radio waves and brain waves (#124) The shameful case of sex in plants (#106) Knowing ourselves-bias in anthropology (#113) Joan Wiffen, dinosaur woman (#101) Maize, mysticism and jumping genes (#113) Facial eczema day at Ruakura (#106) Andreas Reischek-the collector (#101) Romanov DNA-from Siberia to sainthood (#106) Rhododenrons, yak butter and brigands (#124)

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tomes when he died, and it is proposed that his appointees will conclude a 25-volume programme. With some disagreement, these volumes are revered as a supremely important contribution to humankind. Needham’s story, one of passionate single-mindedness, rigorous scholarship, and political activism, tells us much about the proposition that science ideas are subject to change.

Yes, we can all think of instances where the great ideas in science are successively replaced (for example, Newtonian physics by Einsteinium physics), but Needham’s story brings another meaning to this proposition about the nature of science – that our constructions of science history themselves are subject to change by hindsight.

Historians of science are quite often drawn from the ranks of scientists themselves,11 and so it was with Needham.

After an intellectually stimulating but solitary boyhood in London, he embarked on courses at Cambridge University that led him into biochemistry and then embryology.12 By 1935 he was working with the famous C.H. Waddington on one of the greatest scientific puzzles of the time: the identity of the ‘organizer’ responsible for inducing embryological differentiation. Needham’s private interests were many – this tall, rangy, bespectacled, tousle-haired man, with a wicked grin and a piercing gaze, was also a nudist, a morris dancer, an accordion player and a chainsmoking churchgoer with a strong bent for philosophy and exploring the origins of cultures.

But Needham’s world was to take a new direction late one summer day in 1937, when Lu Gwei-djen knocked softly and unexpectedly on his office door. A talented biochemist herself, who was fleeing from the Japanese invasion of China, the 33-year-old was offering to work with Needham and his biochemist wife of 13 years, Dorothy.

Soon, fascinated by the forms and mysteries of Chinese characters, Needham was begging Gwei-djen to teach him the language. In little time, Needham’s systematic and wide-ranging foray into Mandarin was causing him to fall in love, not only with the language, but also with China itself.

And, inevitably, he found his admiration growing rapidly for the people who, over the last 3,000 years, had made this language their cultural continuum.

Needham’s newfound love of China was no passing phase, and World War II provided an opportunity to pursue this passion – he was seen as the ideal person to fulfil the role of Director of the Sino-British Science Co-operation Office, in Chongqing.13 So it came about that Needham’s plane touched down in June 1943, in what is today the world’s largest city, but what was then a place of war-ravaged chaos. Located in west-central China, Chongqing had been bombed more than 200 times in the previous three years, as the invading Japanese sought to destroy the city to which Chiang Kai-shek had moved his Nationalist government from Nanjing,14 far to the east.

Needham set about his task with vigour – rebuilding scientific life in China by boosting morale and providing equipment and, more politically, waving the flag for Britain and establishing relations with the Chinese communists. By the end of the war he had carried out eleven expeditions (four of them major) and had covered 30,000 miles; he had visited nearly 300 scientific institutions and he had delivered thousands of tons of equipment.

But during his time in China, Needham also had a personal agenda. In 1942 in New York, he had confided a sudden idea to Gwei-djen: why not, one day, write a book that would explain to the Western world just how profound and enormous was China’s contribution to science? His mission in China was an ideal chance to pursue that thought and, typically systematic, he had collected thousands of

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documents for this purpose by the time the War was over.

One very early, massively difficult expedition typifies his goal. In August 1943, Needham and a party set out from Chongqing in a converted Chevrolet ambulance for the far northern province of Gansu. Needham’s objective was to visit Cave 17, one of the 400 man-made Mogao Grottos near the far western town of Dunhuang on the famous dry and dusty Silk Road. It was here in 1907, that an immense ancient Chinese library had been discovered, including a printed scroll that was now recognised as the oldest dated printed book in history. It is the ‘Diamond Sutra’, printed in AD 868. In other words, printers had been at work in China six centuries before either Gutenburg or Caxton set their own first books in type in Europe. As Needham’s biographer Simon Winchester puts it,15 “If any one thing in all creation gave the lie to the Western notion that China was a backward country, this was it”.

Returning to Europe, Needham was called on to assist in the setting up of the United Nations Educational, Scientific and Cultural Organization – it is said16 that “he was famously instrumental in putting the S in UNESCO” – but by 1948 it was time for his book to be born. Installed back in room K-I at Cambridge University (a room he occupied for six decades), Needham began writing Science and Civilisation in China.

Once started each day, he would work non-stop until long after dark, typing everything himself. The task was massive, and its completion ever-receding. Volume I appeared in 1954. By the time he died in 1995 there were 18 volumes; and by 2008 the faithful inheritors of the task had completed 24 volumes, comprising 15,000 pages and three million words.17 It covers everything from the evolution of the most theoretical of mental models in astronomy and the nature of materials, across to things as pragmatic as the invention of the toothbrush (9th century AD) and toilet paper (AD 589). Beginning with what today would be called the pure sciences, it ranges into engineering, papermaking, ceramics, navigation, mining, metallurgy, architecture and painting. It ventures into areas where the very titles may to us seem “lost in translation”: ‘glyphomancy’, ‘ataraxy’ and ‘scapulamancy and milfoil lots’.

Science and Civilisation in China has had its critics, both in terms of its scholarship and its politics. Sometimes Needham has been accused of mistranslation; ambiguous writings in the ancient Chinese manuscripts, it is suggested, have been massaged into exaggerated claims for innovation in China. Other criticisms have been made about deep-seated assumptions: is ‘science’ universal, as Needham suggests, and can comparisons be meaningfully made, at all, between Eastern and Western science? Needham has been accused of being politically naïve – he lent his voice to calls for an international investigation into communist accusations that American forces were using biological weapons in the Korean War, and he was consequently denounced in the British press as a traitor and a stooge.18 This has spilled over into hostility towards the Marxist framework he adopted in Science and Civilisation in China.

Needham’s final years were marked by huge worldwide acclaim which, however, did nothing to distract him from the task. When Dorothy died, in 1987, he was briefly married to Lu Gwei-djen, whom he once tenderly described as “the explainer, the antithesis, the manifestation, the assurance of a link no separation can break.”19 Continuing to write to the end, Needham passed away in March 1995.

The notion of “re-writing history” is interesting. If someone tells you that you are “re-writing history”, it is usually not a compliment. Instead, it is often an accusation that you are trying to persuade people (probably for your own dubious

Radio waves and brain waves In a lecture room in the huge old colonial-style Town Hall in Calcutta,21 the ‘City of Palaces’, a large audience had gathered that day in 189522 and all eyes were on the short, portly, dapper figure of the Bengali scientist Jagadis Chunder Bose (pronounced ‘Berzah’) as he made the final meticulous preparations for the demonstration. At the appointed time there was no failure; to the crowd’s wonderment and delight, at the flick of a finger, Bose activated the transmitter and caused the mysterious invisible waves to apparently hurtle right through the body of the chairman, Lieutenant-Governor Sir William Mckenzie, through three solid walls, and to activate a receiver 75 feet away in an adjacent room. In the words of Bose’s 1920 biographer, Patrick Geddes, “the receiver … which curiously anticipated the antenna of modern wireless … at this distance still had energy enough to make a contact, which set a bell ringing, discharged a pistol and exploded a miniature mine.”23 Radio waves had now been demonstrated in public in Asia.

But this was no cheap trick turned on, circus-style, for mass entertainment; nor was it an all-or-nothing experiment designed to prove, one way or the other, whether radio waves existed. It was simply a sober demonstration of Bose’s hard-won powers of logic and imagination. J.C. Bose24 (1858–1937), often described as India’s first modern scientist, was not a man to leave anything to chance, and his habitually authoritative exterior that day, as he drew his audience into advances at the very frontier of science, revealed how utterly confident he was in what he was doing.

Schooled in East Bengal (now Bangladesh), and having obtained his BA in Calcutta, Bose had travelled to England, where he first studied medicine in London, and was then awarded a scholarship to Christ’s College, Cambridge University, where he took up physics. Bose immersed himself in James Clerk Maxwell’s epic theorising about electromagnetic waves of various lengths, and also in the practical demonstration of their existence by Heinrich Herz.

Bose’s teachers included Lord Rayleigh and James Dewar, and his work – both theoretical and practical, especially his capacity to devise the most sensitive and robust of instruments – was later to win high praise from the great Lord Kelvin. But the decades following Bose’s return to India in 1885 would show that there was even more to Bose’s life in science than being at the world forefront of the invention of radio.

Later, Bose would turn to plant physiology and achieve distinction there; and, in the stultifying context of science

in British colonial India, his grappling with an attempt to define, create and amplify a uniquely ‘Indian’ science was a brave, if initially doomed, enterprise. In an utterly astonishing way, Bose infused three careers – physicist, botanist and activist in the culture of science – with the notion that science is a blend of logic and imagination.

Mention radio waves and, of course, the name of Guglielmo Marconi, the Italian scientist-engineer and businessman comes to mind. The research of Bose and Marconi has interesting parallels. During the 1890s, both were strenuously seeking to reduce the wave length of radio waves to a matter of millimetres (needed for effective transmission), and both were labouring to perfect a ‘coherer’, that is, a radio wave receiver.25 Around the time of Bose’s demonstration in the Calcutta Town Hall, Marconi was gradually extending the range of his transmission, first over about a mile on his father’s estate in Italy in the autumn of 1895, then in England across a distance of nine miles on the Salisbury Plain in 1896, and then, most dramatically, across the Atlantic Ocean, a distance of 1800 miles on December 12th 1901. But there were also important differences: Marconi had no academic qualifications in physics, Bose did; Marconi usually never lacked supportive working facilities and funding for his projects, Bose often did; Marconi had a great eye for global marketing, Bose’s ultimate concern, as we shall see, was for the fortunes of science itself in Colonial India; Marconi was quick to patent his discoveries, Bose never did. And although both were acclaimed for their work, somehow Marconi received very much the major share – along with Karl Braun, he was awarded the Nobel Prize in Physics in 1909. Bose was nominated for a Nobel by his friend, the Bengali poet Rabindranath Tagore, but missed out, although he did receive a share of honours from the Western science establishment: he was knighted by the British government in 1916, and he was elected a Fellow of the Royal Society of London in 1928.

However, by the time these awards were made, Bose had dramatically switched his attention from heartland physics to heartland botany and, even wider, to the relationships between the living and the nonliving worlds. His capacity to monitor tiny electrical currents was the connecting factor in this stunning leap of the imagination, but there were also deep-seated philosophical reasons for his switch. Bose’s work in physics had been entirely within the framework of mainstream or Western science26 but now, around the year 1901, his research clearly began to show the influences of certain aspects of the Indian philosophical tradition, notably the doctrine of ‘monism’ – the notion that reality is in some sense one, that is, unchanging or indivisible or undifferentiated.

His views culminated in the publication of Response in the Living and Nonliving in 1902. The book’s main theoretical importance was the propounding of the so-called Bosian thesis, namely that there is no discontinuity between the living and the nonliving. His strongest claim, that “inorganic matter possessed a specific property, electrical responsiveness, that was the fundamental property of life itself”,27 was in any literal sense, not one that the course of biological science has since sustained. However, in a number of more general ways (for example, ecological systems’ thinking) Bose’s insistence on the fundamental inter-relatedness of the living and nonliving worlds is not so controversial today.

Plant physiology emerged as the main thrust of Bose’s research in his later years. Using instruments like his ‘Crescograph’, which was said to be able to record plant growth as small as 1/100,000 inch per second28, Bose

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purposes) that past events took a different course from what is generally accepted. But, actually, there is a sense in which all history is perpetually and properly being re-written; the events of the past are forever being reinterpreted, not only as new evidence comes to hand, but also in the light of the set of ideas and theories which we hold precious today. In Russia, they sum this up with the pithy saying, “Russian history is unpredictable”. So it also is with the history of science.

To expand the point made at the beginning of this story: science ideas are undoubtedly subject to change; many people can cite science theories that have been discarded and replaced – for example, in astronomy (the crystalline spheres of the ancient Greeks), in chemistry (phlogisten), in physics (the optical ether), in biology (spontaneous generation) and in Earth science (catastrophist geology).20 However, the Joseph Needham story also tells us that science ideas are frequently perceived to change because our account of them changes, by hindsight.

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made contributions to studies in what we would call chronobiology, translocation, photosynthesis, and plant growth and responsiveness. Bose’s plant physiology was in many ways the opposite of his physics; it was “eccentric, idiosyncratic, overwhelmingly prolific, surprising …” and “… it drew a mix of intense admiration and intense dislike among scientists in the West in a way his physics never did.”29

The lack of acceptance was due to such things as the absence of any research tradition in which the work could be placed (no one else was measuring electrical responses across plant tissues, and it fell in a gap between physicists and physiologists); some regarded it as a work of philosophical rather than scientific interest; and, very significantly, the work was based on Bose’s idiosyncratic

Table 2: Connections between seventeen stories from science published in four editions of New Zealand Science Teacher and the ‘Understanding about science’ statements in The New Zealand Curriculum. Key connecting words are in italics. The curriculum statements are treated cumulatively rather than sequentially replacing. The five stories with a New Zealand context are asterisked.

Science curriculum statements: Understanding about science

Stories from science

Connections

LEVEL ONE AND TWO • Appreciate that scientists ask questions about our world that lead to investigations and that openmindedness is important because there may be more than one explanation.

- ‘All knowledge is my province’ – Francis Bacon’s big claim (#113) - Knowing ourselves – bias in anthropology (#113) - Rhododendrons, yak butter and brigands (#124) - The spirals of life (#106)

LEVEL THREE AND FOUR • Appreciate that science is a way of explaining the world and that science knowledge changes over time.

• Identify ways in which scientists work together and provide evidence to support their ideas.

- The shameful case of sex in plants - Applying models for plant sexual life (#106) cycles allows us to explain and predict botanical mysteries.

- Joseph Needham’s great labour of love (#124) - He rewrote the changes over time that have occurred in Chinese science and - Maize, mysticism and jumping genes hence changed Western perceptions. (#113) - Barbara McClintock and other - Facial eczema day at Ruakura* (#106) geneticists worked together - Joan Wiffen, dinosaur woman* (#101) respectfully but from very different assumptions.

- Toxicologists, soil scientists, botanists and mycologists worked together.

- The scientific community initially worked together with her very unevenly.

LEVEL FIVE AND SIX • Understanding that scientists’ investigations are informed by current scientific theories and aim to collect evidence that will be interpreted through processes of logical argument.

- ‘A plant is an animal standing on its head’ (#113) - Why the Kaingaroa forest isn’t grassland* (#101) - What transpires in heartless vegetables? (#106) - Radio waves and brain waves (#124)

- Aristotle’s erroneous idea that plants get their food from the ground guided current scientific theory for 2000 years.

- The cobalt-‘bush sickness’ link was discovered by dogged logic and inspired interpretation of evidence.

- The fruitless search for plant/animal analogies was contradicted by logical interpretation of Hales’s experiments.

- J. C. Bose’s extraordinary powers of logic and imaginative interpretation were applied to physics, botany and living/nonliving relationships.

LEVEL SEVEN AND EIGHT • Understand that scientists have an obligation to connect their new ideas to current and historical scientific knowledge and to present their findings for peer review and debate.

- Harold Wellman – honest to a fault* (#113) - The case of the midwife toad (#113) - Andreas Reischek – the collector* (#101) - Romanov DNA – from Siberia to sainthood (#106)

- He connected his new ideas about the South Island’s alpine fault to a thenminority theory: plate tectonics.

- Lamarckian Paul Kammerer’s difficulties in submitting to peer review culminated in his suicide.

- His activities would spark huge peer debate today, on conservation grounds.

- The atmosphere of fear and suspicion in the final Soviet years retarded processes of peer review and open debate in the use of DNA fingerprinting.

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- His ‘scientific method’ was supposedly a way of responding to whatever questions were asked.

- Open-mindedness has been difficult because our approaches have been dominated by current values in society.

- Joseph Rock’s open-mindedness was clouded by his temperament and the expectations of his reading audience.

- More than one explanation (nucleic acids versus nucleoproteins) competed in the DNA story.

Stories and the NZ Curriculum Table 2 shows how the seventeen stories in four issues of New Zealand Science Teacher illuminate the thirteen

propositions about the nature of science suggested by Rutherford and Ahlgren. Now – and not forgetting that all the stories actually comprise many rich cross-currents and issues about how science works – I have identified from each story one dominant aspect which aligns with key words in the ‘Understanding about science’ statements in The New Zealand Curriculum (see Table 2). I would stress that I have interpreted the statements cumulatively, that is, I assume that each contains a wealth of meaning that can be explored in greater and greater depth across each successive level of schooling. The stories are therefore to be selected and used in whatever way is most productive, appropriate and purposeful. Even better, they might inspire storytelling and story writing in others.39 Overall, it is my hope that they will humanize, de-mythologise and enliven our science teaching.

For further information contact: mbarker@waikato.ac.nz

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ideas about what constitutes the ‘sign of life’. In a sense, this was a tussle between Bose’s powers of logic and his imagination. As one commentator puts it, “On the one hand, he was an experimentalist and instrument designer par excellence; on the other, his monistic metaphysics exceeded what his data could deliver.”30 Bose’s third career, as an activist in the culture of science, developed relentlessly as his life went on. When, as a young man, Bose was advancing into science in Calcutta in the late nineteenth century he had found himself in a profoundly discouraging environment. Western science had been very slow to establish itself in India over the previous three hundred years, and the prevailing view of the British colonial administration was that Indians were incapable of engaging in fundamental scientific research and that, instead, they should concentrate on applied technology.31 This assumption impacted on Bose when – now impressively qualified from Cambridge University – he arrived back in Calcutta in 1885. He was offered a post at India’s best-known college, Presidency College in Calcutta, as a junior professor of physics but only if, being Indian, he agreed to receive two-thirds of the regular salary. Bose famously protested by foregoing his pay and by relentlessly appealing to the authorities. Three years later he achieved pay parity.32 This incident cannot help but have propelled Bose’s thinking along a pattern common in the development of science in European-colonised countries: from the initial sciences which accompany early colonial penetration (zoology, geology, geography), to a science which draws on established European practices and institutions, and then to a third stage – a somewhat independent science tradition, invented by scientists who are natives of, and culturally tied to, the colonised country. 33 Bose’s mind clearly began taking into account how, as one of his biographers puts it, “for centuries the Indian imagination had used nondualist thought to impose order on diversities, contradictions and oppositions, and a unified worldview on a fragmented society.”34 As we have seen, this awareness spilled over into the underpinnings of Bose’s own research. However, Bose’s imagination also caused him to question the very structure of organised science in India, and in 1917 he inaugurated an advanced research centre in Calcutta: the Bose Institute. Its purpose, according to Bose’s dedication speech, was to defy the excessive specialisation in modern science and to capitalise on India’s unique strengths: “Through her habit of mind (India) is peculiarly fitted to realise the idea of unity, and to see in the phenomenal world an orderly universe.”35 If Bose’s imagination had taken a leap which was difficult for some Western scientists to accommodate at that time, assessments now are more forgiving; for example, “Today, when biophysics is a generally recognised discipline and comparative physiology rests on a more scientific basis, the idea that animal and plant tissues exhibit similar responses seems less controversial and may even be taken as foreshadowing Norbert Wiener’s cybernetics.”36 These days, there is a widespread acceptance that Eurocentric views of science and technology have “primarily de-developed the vast majority of the peoples who were supposed to benefit from such science and technology transfers.”37 A final thought: it is important that the developers of school science curricula do not perpetuate the myth that science is an exclusively Western, post-Renaissance activity.38

Acknowledgements I am grateful to Elizabeth Barker and to Dr Ajitha Nayar for pointing me towards the Needham and Bose stories respectively, to Li Jinrui for her comments on an earlier draft of this article, and to many other friends and colleagues in China and India.

Footnotes

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Barker, M. (2002). Ripping yarns – science stories with a point, 101, 31-36; Barker, M. (2004). Spirals, shame and sainthood – more ripping yarns from science, 106, 6-14. Barker, M. (2006). Ripping yarns – a pedagogy for learning about the nature of science, 113, 27-37.

Mayhew, B., & Huhti, T. (1998). Lonely planet: South-west China, p. 378.

Hawthorne, Aust: Lonely Planet Publishing.

Winchester (2008). See below, has been published under this alternative title in the United States.

Rutherford, J., & Ahlgren, A. (1990). Science for all Americans. New York: Oxford University Press.

Edwards, M. (1997). Our man in China. National Geographic Magazine, 191(1), 62-81.

Rock, J. (1928). Life among the lamas of Choni: Describing the mystery plays and butter festival in the monastery of an almost unknown Tibetan principality in Kansu province. National Geographic Magazine, 54, 569-619.

National Geographic Magazine 1924, #46, 473-499; 1925, #47, 447-491; 1925, #48, 331-347; 1931, #60, 1-65.

Ferry, D. (1998). Dorothy Hodgkin: A life. London: Granta. Wilkins, M. (2003). The third man of the double helix: The autobiography of Maurice Wilkins. Oxford: Oxford University Press.

Kolbert, E. (2006). Field notes from a catastrophe – man, nature and climate change, p. 131. New York: Bloomsbury.

Manuel, F. E. (1974). The religion of Isaac Newton. Oxford: Clarendon Press.

Quammen, D. (2006). The reluctant Mr. Darwin. New York: Norton.

The philosopher Thomas Kuhn is an obvious example.

Many of these biographical details are sourced from Simon Winchester’s (2008) superbly readable account.

Formerly Chungking.

Formerly Nanking.

Winchester (2008), p. 102.

Hessenbruch (1999), p. 868.

Winchester (2008), p. 9. It is published by Cambridge University Press.

Blue (2004).

Needham (1969), frontispiece.

French, S. (2007). Science: key concepts in philosophy, p. 95. London: Continuum.

That is, modern-day Kolkata.

Accounts differ as to the exact date. This is a sensitive point for those who would claim that Bose’s initial transmission preceded Marconi’s.

Quoted in Habib and Raina (2007), p. 314.

This is how he is usually referred to.

Bose’s innovative coherer comprised a tube containing iron in the form of fine wire spiral springs with a layer of mercury between; radiation caused the system to switch to a conducting state, detected by a very sensitive galvanometer in the circuit.

Habib and Raina (2007), p. 328.

Ibid. p. 335. http://www.vigyanprasar.gov.in/scientists/JCBOSE.htm, 07.04.09 Habib and Raina (2007), p. 345 Ibid, p. 338.

Ibid, p. 139 Kumar (2006), p. 218.

Habib and Raina (2007), p. 326.

Nandy (1995), p. 62.

Ibid, p. 60.

continued on page 38

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CoRes and PaP-eRs CoRes and PaP-eRs can be used as tools for promoting the pedagogical content knowledge (PCK) of novice (and not so novice) science teachers, writes Anne Hume, School of Education, University of Waikato.

Introduction There has been increasing discussion around pedagogical content knowledge (PCK) as a useful idea for promoting teacher learning. PCK was first introduced by the America writer Lee Shulman (1987) in recognition of the very specialized professional knowledge expert teachers in particular subjects possess, e.g. the knowledge that an expert science teacher has that sets him/her apart from any scientist expert in that field. Shulman credited these expert teachers with the ability to carry out teaching as a complex and challenging activity that required ongoing and informed decision making in response to individual student’s learning needs, rather than just the simple transmission of information from teacher to students. He maintained that they possess a special blend of science content knowledge and pedagogical knowledge for teaching particular science topics to particular groups of students, which is built up over time and experience and which he termed PCK. PCK is topic specific, unique to each science teacher, and can only be gained through teaching practice. However, it is a very difficult form of knowledge to describe and exemplify because experienced teachers very rarely discuss or share it with fellow teachers − often because there are few opportunities in busy professional lives to do this, and also because of its fluid nature, constantly changing and evolving as classroom circumstances dictate. Thus PCK tends to remain hidden as tacit rather than explicit knowledge.

Since Shulman first introduced this notion of PCK, other writers have begun to explore, debate, and expand upon its nature. Magnusson et al., (1999) identified five components of a science teacher’s PCK that there is some agreement on in the science education field. These components include his/her: • orientations towards science teaching (the teacher’s knowledge of science and the nature of science, and beliefs about science and how to teach it) • knowledge of curriculum (what concepts and skills to teach and when to teach)

• knowledge of assessment (what to assess, why and how); • knowledge of students’ understanding of science (including their prior knowledge and misconceptions and potential misconceptions) • knowledge of instructional strategies (proven appropriate and effective).

The specific PCKs that teachers will need to develop during their teaching careers require a great deal of professional learning. Classroom teaching experience is essential for building this knowledge; but imagine the value to novice science teachers of having access to such knowledge that already exists! Not to mention those teachers already in the profession who lack expertise in particular science content areas, such as the physics specialist who is asked to teach biology in junior science programmes. Until recently there have been few concrete examples that are applicable to science teaching.

Developing PCK exemplars About six years ago a group of science education researchers at Monash University, began investigating if they could ‘capture’ the PCK of some expert science teachers for use in initial teacher education. Loughran et al. (2004, 2006) identified a number of expert science teachers in their local area, and invited them to participate in a research project to see if their aim of capturing expert PCK was feasible. To help the teachers recognize and depict components of their PCK, Loughran et al. created strategies known as Content Representations (CoRes) and Pedagogical and Professionalexperience Repertoires (PaP-eRs).

The CoRes are templates which attempt to portray collective overviews of expert teachers’ PCK related to the teaching of a particular science topic and are accompanied

by PaP-eRs, which are narratives about how specific aspects of the topic aligned to the CoRe have been taught by the expert teachers − each CoRe has a set of related PaP-eRs (see Figure 1 over page).

Use of CoRes and PaP-eRs in science teacher education The CoRes and PaP-eRs developed by the expert science teachers in the Loughran et al. study are presented in the 2006 publication Understanding and developing science teachers’ pedagogical content knowledge by J. Loughran, A. Berry and P. Mullhall.

continued from page 37 Susskind (1980), p. 325.

Harding, S. 1998). Is science multicultural? Postcolonialisms, feminisms and epistemologies. Bloomington: Indiana University Press, p. 7 38 Hodson, D. (1998). Science fiction: The continuing misrepresentation of science in the school curriculum. Curriculum Studies, 6(2), 191-216.

39 See New Zealand Science Teacher, #113, p. 27.

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Main sources about Joseph Rock Aris, M. (1992). Lamas, princes, and brigands: Joseph Rock’s photographs of the Tibetan Borderlands of China. New York: China House Gallery.

Goodman, J. (2006). Joseph F. Rock and his Shangri-La. Hong Kong: Caravan Press.

Sutton, S.B. (1974). In China’s border provinces: The turbulent career of Joseph Rock. New York: Hastings House.

Winchester, S. (1996). The river at the centre of the world: A journey up the Yangze, and back in Chinese time. New York: Henry Holt.

Main sources about Joseph Needham Blue, G. (2004). Joseph Needham. In H. C.G. Matthew & B. Harrison (Eds.) Oxford Dictionary of Biography. Oxford: Oxford University Press (electronic source).

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Hessenbruch, A. (1999). Joseph Needham. In Kelly Boyd (Ed.), Encyclopedia of historians and historical writing. London: Fitzroy Dearborn.

Needham, J. (1969). The grand titration: science and society in east and west.

London: Allen and Unwin.

Teich, M., & Young, R. (eds.) (1973). Changing perspectives in the history of science: Essays in honour of Joseph Needham. London: Heinemann.

Temple. R. (1998). The genius of China: 3,000 years of science, discovery, and invention. London: Prion.

Winchester, S. (2008). Bomb, book and compass: Joseph Needham and the great secrets of China. London: Viking.

Main sources about J. C. Bose Habib, S. I., & Raina, D. (Eds.) (2007). Social history of science in India. Oxford: Oxford University Press.

Kumar, D. (2006). Science and the Raj – A study of British India (2nd ed.) Oxford: Oxford University Press.

Nandy, A. (1995). Alternative sciences: creativity and authenticity in two Indian scientists. Delhi: Oxford University Press (2nd ed.).

Susskind, C. (1980). Bose, Jagadis Chunder. In C.C. Gillespie (Ed.), Dictionary of scientific biography, v.2, p.325. New York: Charles Scribner.

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Figure 1. CoRe (Content Representation) and associated PaP-eRs (Pedagogical and Professional experience Repertoires); lines from the PaP-eRs represent the links to particular aspects of the CoRe. Ref: Loughran et al., 2004, p. 376

They are now being used in pre-service science teacher education to introduce and help novice teachers understand what PCK might involve. For example, in another Loughran et al. (2008) study, student teachers examined the existing CoRes and PaP-eRs and then created some of their own. These strategies helped student teachers to frame their thinking about the links between science content and pedagogy. CoRe construction, in particular, appeared to provide student teachers with a more sophisticated view about learning to teach science, and how to teach for understanding.

I have also introduced the CoRes and PaP-eRs developed

by Loughran et al. (2006) into my science and chemistry education courses at the University of Waikato through a series of reflective and discussion tasks in the workshops.

They have proved to be very effective in raising the student teachers’ awareness and understanding of PCK, and the students appreciated the insights working with CoRes and PaP-eRs gave them about teaching science. … it brought up some ideas that I did not know about and problems that we could face as teachers … when we are teaching we need to be more aware that it is not necessarily the content that is of most importance but it is how we are teaching and why… I really like how CoRes break down a topic into what is intended to be taught, why it is important, what the teacher should know, difficulties that could arise, assessing the level of the students, how to teach each concept … it helps me identify what I need to work on and be aware of how I can work around complications that arise as I teach each concept.

Jackie (pseudonym), journal notes

CoRe design As an extension of CoRe use in my chemistry course, the student teachers were given the opportunity to create a form of hypothetical PCK (since they had little/no prior experience of teaching the topic) by designing their own CoRes for topics such as Year 12 Redox Reactions and Quantitative Chemistry. They found the task of creating theoretical PCK very challenging, especially the format of the CoRe, but did concede that there may be long-term benefits to their learning.

Because I was unsure of the content myself … it was such a new way to look at it I struggled. I jumped all over the place.

Tammy (pseudonym), interview

But maybe that will come with practice if we keep slogging at it?

Gina (pseudonym), interview Yes, I think it would be good to use it as planning a unit and then base the lessons on it.

Emma (pseudonym), interview I have since taken a much more planned approach to the use of CoRe design in the chemistry course with careful scaffolding of learning experiences leading up to their introduction. My pedagogy focused on helping student teachers develop a set of generic strategies for accumulating relevant knowledge and skills prior to constructing CoRes. Group activities included: • tasks that introduced and engaged the students in critical analysis and reflection on the purposes of science education, the nature of science, the national science curriculum statement (MoE, 2007), learning theories and misconceptions in science, pedagogy and teacher beliefs about teaching and learning, assessment including national qualifications, and the worth of various science education websites • preliminary exercises introducing PCK and CoRes and PaP-eRs • determination of what pre-existing concepts and skills Year 11 students might have for the topic Atomic structure and bonding (these ideas were also to include some common misconceptions) using sources like the NZ science curriculum statements (1993, 2007); text commonly used in schools; and reputable Internet sites such as BESTCHOICE, CHEMSOURCE and the Royal Society of Chemistry. This was followed by brainstorming and selection of relevant and appropriate concepts and skills that school students might be expected to learn for Atomic structure and bonding at Years 11, 12 or 13 (including reference to NCEA standards; exam papers and accompanying marking schedules and examiners’ reports), to gain an overall picture of how the sequence of concepts and skills evolved over the three years • identification of concepts and skills that a Year 12 class studying Redox Reactions would be likely to cover and development of 5–8 key ideas or enduring understandings that formed the basis upon which they designed a CoRe on Redox Reactions New Zealand Association of Science Educators

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• exploration of available resources and location, trialling and recording of potential teaching and learning experiences for the Redox Reactions topic.

This search also included the identification of common misconceptions (both pre-existing and potential) and areas of learning difficulty related to their key Redox Reactions ideas and any appropriate pedagogical strategies for addressing them.

Later on the student teachers were given the opportunity to try designing another CoRe for Year 12 chemistry on Quantitative Chemistry.

CoRe design and emerging PCK The students this year tackled the CoRe design tasks with more confidence and purpose, and the content of their CoRes contained aspects that can be clearly linked to the components of PCK possessed by expert chemistry teachers such as: • the enduring understandings that students need to develop, e.g., Oxidation numbers are a tool for keeping track of electrons • keener awareness of issues around students’ understandings e.g., an awareness that chemists view the world of materials on three levels (micro, macro, and symbolic) and that students need to be able to move between levels in their thinking in order to understand chemical ideas • a greater repertoire of potentially useful instructional strategies for promoting learning and monitoring the nature of science understanding, e.g., use of the analogy of the concentration of boys in the class − girls are the solvent to help learners make links between concrete examples and abstract ideas like concentration in quantitative chemistry.

In the interviews, the student teachers also indicated awareness of how CoRe design was heightening their awareness of the components of PCK, like knowledge of curriculum, instructional strategies, and students’ understandings.

And I know before I did this I just popped into the class and you went ahead, but with this now, it gives you the sort of foundation of what you should be looking at, as I said before, to make sure … you’ve got to know what the kids have done before … according to the curriculum what they should be doing and how you’re going to do it… And once you start looking into the websites and that, there’s a lot of information out there and a lot of misconceptions as well … trying to make sure that you cover misconceptions because, even in our classes, there are quite a few misconceptions and … wow! … get those ironed up first, yeah.

Malcolm, (pseudonym), post-interview They were very appreciative of the preparatory work done in workshops and valued the step-by-step collaborative approach to gathering relevant materials and developing a CoRe as a pre-cursor to teaching.

So she’s been really helpful in giving us lots of different things to go to, to look for information, just almost building up a conscious list of where you can source what you need to know … And we did a separate part each and then brought it back the next time, we had class and went through every part.

Carol (pseudonym), post-interview … I think it’s trying to get you to think, to pre-reflect, as such, to make sure you think about those things before it happens.

Malcolm, (pseudonym), post-interview

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Their work with existing CoRes and PaP-eRs and CoRe design has shown me that such approaches offer novice teachers the opportunity to access some of the knowledge and thinking of expert science teachers before, during and after their first teaching experiences. Their lack of classroom experience and experimentation at this stage of their professional careers is a limiting factor in their PCK development, but CoRes and PaP-eRs offer a good start.

CoRes design, for example, has allowed my student teachers to construct a hypothetical form of PCK for particular topics that they can now take into their first classroom teaching experiences and trial. Hopefully this emerging form of PCK should give them a strong basis upon which to learn how to teach specific chemistry content effectively.

Follow up on CoRe design My intention now is to follow up on these novice teachers to investigate how useful they find their chemistry CoRes (redox and quantitative) in planning and teaching these topics in their first year of teaching, and if they have carried on the practice of CoRe design for other science/chemistry areas. It would also be interesting to determine to what extent and in what way their PCK changes after classroom experience of teaching the topics.

In conclusion, one student interestingly speculated on the value of designing CoRes with her teaching colleagues once she began teaching.

Yeah, I think that would be really beneficial to do with teachers … say like, next year in my department or whatever… it would be quite useful if they are open to it and if there’s time and stuff to show them what it’s about … to tell them like how to get the big ideas. They probably would know the big ideas anyway, but that’s something that we’ve done quite a lot on … how to find the big ideas … but then the filling out of the boxes because they would have taught it a lot more. Then they’re going to know and I think it would be quite helpful for me … especially as a beginning teacher.

Carol (pseudonym), post-interview Her comments suggest that collaborative CoRe design involving associate and/or fellow teachers of beginning teachers could be a form of potential professional learning for all concerned. Such involvement would require experienced teachers to be convinced of the value of such exercises which can only begin to happen through exposure to and experience with CoRes as professional learning tools. I think professional learning tasks among science department staff that involve examination of available CoRes, and their PaP-eRs, like those in the Loughran et al. book Understanding and developing science teachers’ pedagogical content knowledge (2006), and CoRe and Pa-PeR design could be very valuable tools for the promotion of PCK development of all science teachers, experienced as well as novice!

For further information contact annehume@waikato.ac.nz

References Magnusson, S., Krajcik, J., & Borko, H. (1999). Nature, sources, and development of pedagogical content knowledge for science teaching. In J. Gess-Newsome N.G. Lederman (Eds.), Examining pedagogical content knowledge: The construct and its implications for science education (pp. 95-132). Boston:Kluwer.

Ministry of Education. (1993). Science in the New Zealand curriculum. Wellington, New Zealand: Learning Media.

Ministry of Education. (2007). The New Zealand Curriculum. Wellington: Learning Media.

Loughran, J., Berry, A., & Mullhall, P. (2006). Understanding and developing science teachers’ pedagogical content knowledge. Rotterdam The Netherlands: Sense Publishers.

Shulman, L. (1987). Knowledge and teaching: Foundations of the new reform.

Harvard Educational Review, 57(1), 1-22.

The following is a brief edited extract from Alpha 106 – Iron hypothesis by Dr Julie Hall, NIWA, Hamilton. It has been reproduced here with the kind permission of the RSNZ. The full version of this alpha (and other recent issues) is free and can be downloaded from: www.royalsociety.org. nz. Please note: teachers are advised to refer to Cliff Law’s article in this issue for an update on this experiment.

What is the iron hypothesis?

The Fe hypothesis suggests that: (i) the concentration of dissolved Fe limits phytoplankton (plant plankton) growth and biomass in a large proportion of the nutrient-rich regions of the world’s oceans, including the Southern Ocean; and (ii) an increased Fe concentration in the Southern Ocean in the last glacial maximum resulted in increased movement of carbon into the deep ocean.

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This hypothesis was first proposed by John Martin of the Moss Landing Laboratory in the USA in the late 1980s, after the development of technology which enabled the measurement of CO2 concentrations in ancient air trapped in ice cores. This allowed scientists to show that CO2 concentrations as low as 200 parts per million (ppm) occurred during the last glacial period. This should be compared to the interglacial period of 280ppm CO2. This represents a change of approximately 170 billion tonnes of carbon in the Earth’s atmosphere.

For a change of this magnitude to occur, it was suggested that changes in the CO2 in the ocean must have also occurred as there is approximately 60 times more CO2 in the ocean than in the atmosphere.

All recent issues of Alpha are now downloadable for free from the RSNZ website: www.royalsociety.org.nz

Why is the Earth like a magnet?

Nicole Collingwood, Balclutha School Gary Wilson, a geologist at Otago University and who specialises in palaeomagnetism, responded: Well, I’m sure you know already that magnets are made up of blocks of the metal called iron (or sometimes called steel).

In fact any block of iron is naturally magnetic. If you have a compass you can test this by taking a nail and bringing the point of the nail close to the compass. As you move the nail, the compass needle follows the direction you move the nail. When the nail is close to the compass it has much more effect than when the nail is far away from the compass.

Iron, itself, is a naturally occurring mineral. You can find it in various places on the surface of the Earth. If you’ve ever been to the beach on the west cost of the North Island of

New Zealand, you would find that it is black in colour, and this is because the sand grains that make up the beach are in fact made of iron (if you haven’t been there, you might be able to see a picture in a picture book of New Zealand).

This iron comes from the centre of the Earth. The centre of the Earth is, in fact, a solid core of iron. And, just like the nail that you put close to the compass, all that iron is magnetic. Now, the centre of the Earth is a long way away from Balclutha, but, there is more than a million times the amount of iron in the centre of the Earth than in your nail, so you can still feel the effect of the magnetism from the iron core of the Earth out at the surface of the Earth in Balclutha.

Send questions: questions@ask-a-scientist.net.

How do magnets work?

Jarrod Taylor, Balclutha Primary School John Campbell, a physicist at the University of Canterbury, responded: Magnets are a result of electrical currents. You can show this effect if you have a magnetic compass, some copper wire and a torch battery. To make an electromagnet, wind part of the wire into a coil of several turns of diameter about the same size as the compass. Place this on its edge near the compass and briefly touch the two ends of the wire on opposite ends of the battery.

You should see the compass needle move. (Don’t leave the wire connected to the battery too long or it will run out of energy.) By altering the orientation of the coil with respect tothe compass needle, you will soon learn that the orientation which gives the biggest effect is when the axis of the coil is at right angles to the end of the compass needle.

So there are many devices, such as electric motors, which use magnetic forces to operate. However, there are some materials which are permanently magentized such as an iron magnet. Where does their magnetism come from?

From the electrical currents of electrons orbiting the atom.

An atom is a tiny thing. It would take about five million side by side to cross a full stop on this page. Every atom consists of an even tinier nucleus – as first shown by our countryman Ernest Lord Rutherford – about which orbit very tiny electrical particles (electrons). So each orbiting electron is a little electromagnet. Because of the way electrons pair up in atomic orbits and chemical bonds, the magnetism of one electron cancels that of its pair.

They circle in opposite directions. So usually atoms don’t show strong magnetic effects.

Atoms with an odd number of electrons must behave like a little magnet. However, in almost all atoms, each atom’s magnet points in a different direction and overall they cancel out. There are a few materials, such as iron, colbalt, and gadolinium, for which the atoms all co-operate and point in the same direction. For these materials, often called ferromagnetic materials, each atom has a very tiny magnetic effect, but because there are so many atoms all co-operating (about 100,000,000,000,000,000,000 atoms in a pinhead) the resulting magnetism is very strong.

Send questions to: questions@ask-a-scientist.net.

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by Melva Jones Library news School Services loans’ are now issued for the whole term.

It is now even more important to get your requests in early, especially for the start of a new term when our staff workload will be at its peak.

However, our staff is still more than happy to issue books throughout the term, and would appreciate you returning resources as soon as you have finished with them to enable them to be reissued to another user.

For more information on the National Library’s to schools visit: http://www.natlib.govt.nz/schools

Books About Iron Iron and Steel by Greg Pyers (Echidna Books, 2003) Focusing on Australian industry, the book has useful information, with photos, about mining, production of steel and environmental impact. Level: primary, intermediate.

NZ Websites About Iron Te Ara, Encyclopedia of New Zealand where you can read about the source of iron, extraction processes and the steel industry: http://www.teara.govt.nz/en/iron-and-steel NZ Steel has an informative website with a detailed explanation of the iron-making process: http://www.nzsteel.co.nz/ Another useful site is this one from NZMIA (NZ Minerals Industry Association): http://tinyurl.com/y4b55lg

New Science Book

Iron (Understanding the Elements of the Periodic Table)

by Heather Hasan (Rosen, 2005) One of a series, this title explains the source, characteristics and uses of iron, as well as explaining its relationship to other elements in the periodic table. Other titles are Carbon, Hydrogen, Nitrogen, Oxygen and Sodium. Level: intermediate, junior secondary.

Iron and Steel by Christine Mulvany (Macmillan, 2002) This is one of a series on Australian industries, and covers the uses and properties of iron, processing, and environmental impacts.

Level: primary, junior secondary.

The Elements: A Visual Exploration of Every Known Atom in the Universe by Theodore Gray (Black Dog & Leventhal, 2009) A double page spread for each element follows an overview of the periodic table. Information is given on the properties and uses of the element along with essential scientific data.

Photographs are provided where appropriate.

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Iron by Irene M. Franck, David M. Brownstone (Grolier, 2003) One of a series on ‘Riches of the Earth’, which explores the importance of iron in everyday life, both past and present. Level: primary to junior secondary.

Jacquie Bay and Fiona Anderson

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biology

doing science in NZ schools

science teacher

The New Zealand curriculum (MoE 2007) describes science as “a way of investigating, understanding and explaining our natural, physical world and the wider universe”. The curriculum statement goes on to describe science as an activity that students will do, supporting the concept that in order to understand science, students need to engage in investigating, modelling, communicating and debating. It is in doing that we learn.

There are many wonderful examples of New Zealand schools that are creating opportunities for students to engage in science in ways that link to the lives of the students, their whanau, and their communities. These activities facilitate development of understanding of science, and demonstrate to students that science is something that is used by people in their daily lives, has value and contributes to the economic and social well-being of our society. Over the next year, the Biology Educators’ Association of New Zealand would like to develop a catalogue of examples of activities that schools are undertaking where students are doing science, and contributing to the well-being of their communities. The stories will be shared on the BEANZ website, enabling teachers throughout New Zealand to link with, and learn from the experiences of colleagues.

Fiona Anderson, BEANZ Waikato regional co-ordinator and HOD Biology at St Peter’s School in Cambridge, has contributed the first of these which we share with you here. If you have examples of activities in your school where students are engaging in science related to the living world, through which they are contributing to the community, please send a summary of your activity with at least one photo to: biologyNZ@gmail.com

St Peter’s School Kahikatea Stand In 2003, the stand of about approximately two acres consisted of mature 150-year-old kahikateas. Several large titoki and one rimu made up a sparse sub canopy.

The floor of the bush was pasture and weeds with occasional plantings of regenerating native shrubs.

In 2004, St Peter’s School become involved in the Enviroschools’ program. Through Environment Waikato grants, enthusiastic teachers, students, parents, past pupils and a tireless Envirogroup a five-year restoration planting plan, outdoor classroom and metal walkway has been established.

Science provides opportunities for exploring the key dimensions of environmental education; in, for, and about the environment. The kahikatea stand is used as a context for senior biology and junior science, particularly Diversity at Year 9 and Ecology at Year 10. The Year 9 students investigate the diversity of life in the stand, while Year 10 students and teachers actively monitor

the stand using pitfall traps for invertebrates and simple transects to monitor the changes and development of the native plantings. St Peter’s has an active Envirogroup, and throughout their time at St Peter’s, students are encouraged to act on their learning in ways that maintain and improve the quality of the kahikatea stand; for example students take responsibility for cleaning up, weeding and planting native vegetation according to a professional restoration plan developed by Gerry Kessel.

The skills and attitudes developed contribute to the main aims of environmental education: developing “attitudes and values that reflect feelings of concern for the environment”, as well as developing the “skills involved in identifying, investigating, and problem solving associated with environmental issues”, and additionally developing “a sense of responsibility through participation and action as individuals, or members of a group, in addressing environmental issues”.

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chemistry

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having fun with nanoputians

by Suzanne Boniface Line structures are commonly used in organic chemistry to simplify the carbon chains and emphasise the functional groups. Although these are not introduced in senior school organic chemistry, students are usually familiar with the shorthand notation for cylcoalkanes and cycloalkenes and, possibly benzene rings. Using line structures can give rise to some remarkable shapes, and these have sometimes been the inspiration for the synthesis of interesting organic molecules. For example, the molecules cubane (C8H8), basketane (C10H12) and basketene (C10H20) have all been synthesised.

Cubane

Basketane

Basketene

In 2003, a series of molecules called ‘Nanoputians’ was synthesised by a team from Rice University in the US1,2.

These molecules, when drawn as line structures, resemble human forms and were named after the Lilliputians in Gulliver’s Travels.

Examples include:

Nanokid

Nanoballet dancer

Software for drawing titration curves A great piece of software for drawing a wide range of titration curves is AcidBaseLab. This program allows you to choose a solution and a titrant from the comprehensive range provided or according to pKa. When the curve is plotted using the smallest possible titrant intervals, the resulting graph can be used in worksheets and tests.

The software can be downloaded from: http://www. chemometrix.ua.ac.be/dl/acidbase/ Begin the titration by first choosing the solution for the burette by clicking on the ‘titrant’ button in the menu bar.

The solution to be titrated is chosen using the ‘solution’ button. Then the titration curve is plotted using the ‘titrate’ button. Here, there is the option of choosing the volume and increment of titrant to add as well as an indicator. To copy the curve into a word document it is necessary to ‘print’ the curve to the clipboard. Curves can also be saved as ‘txt’ files.

Nanotoddler

International Year of Chemistry 2011

An AB polymer configuration of a Nanoputian chain.

Some alternative heads to convert Nanokid to Nanoprofessionals include:

NanoAthlete (14)

NanoPilgrim (15)

NanoMonarch NanoTexan (18) (19)

NanoGreenBeret (16) NanoJester(17)

NanoScholar (20)

NanoBaker (21)

NanoChef (22)

While most of the chemistry is outside of the experience of Year 12 and 13 students, there are some interesting teaching ideas that can be introduced through these fun molecules.

1 2

Journal of Organic Chemistry. (2003). 68, 8750.

J Chem Ed. (2002). 80, 395

44 New Zealand Association of Science Educators

The International Year of Chemistry 2011 (IYC 2011) is a worldwide celebration of the achievements of chemistry and its contributions to the well-being of humankind.

Under the unifying theme Chemistry − our life, our future, IYC 2011 will offer a range of interactive, entertaining, and educational activities for all ages. The Year of Chemistry is intended to reach across the globe, with opportunities for public participation at the local, regional, and national level.

The goals of IYC 2011 are to increase the public appreciation of chemistry in meeting world needs, to encourage interest in chemistry among young people, and to generate enthusiasm for the creative future of chemistry.

The year 2011 will coincide with the 100th anniversary of the Nobel Prize awarded to Madame Marie Curie − an opportunity to celebrate the contributions of women to science.

IYC 2011 events will emphasise that chemistry is a creative science essential for sustainability and improvements to our way of life. Activities, such as lectures, exhibits, and hands-on experiments, will explore how chemical research is critical for solving our most vexing global problems involving food, water, health, energy, transportation, and more.

The NZ Institute of Chemistry is currently planning events that will include a national secondary schools’ quiz and a photo competition that will be open to school students. For further information about the international programmes visit: http://www.chemistry2011.org/

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physics

neodymium magnets are great for demonstrations byPaulKing

science teacher

There are some great demonstrations and experiments that can be done using neodymium magnets (Nd2Fe14B), some of which were demonstrated by Gorazd Planinsic at the Physicos in June 2009.

Water is diamagnetic Water is diamagnetic. Any magnetic field will slightly repel water, and by bringing a powerful magnet close to the point of incidence, the tiny (and definitely invisible) dimple created on the water surface can make the spot on the screen jerk.

The set-up, as shown in Figure 1, will enable you to produce an ‘optical lever’ for the visualisation of tiny effects. The arrangement is quite delicate, so you will need to ensure that you have adequate draught exclusion to avoid stray ripples, and also fine control of the magnet to be able to get it close enough to the water to create an observable change at the screen without contacting the water or getting in the way of the beam.

Figure 2: Demonstrating that the diamagnetic effect is variable in its intensity.

It is quite easy to replace the water with other materials, to show that the diamagnetic effect is variable in its intensity (see Figure 2). This variation in the effect is the key to MRI (Magnetic Resonance Imaging) scans.

Graphite and diamagnetic effect Graphite experiences the strongest diamagnetic effect.

Using the neodymium magnets and a pencil suspended from a single strand of cotton will produce a repulsion that is almost dramatic (Figure 3).

Figure 1: Neodymium magnet demonstration set up for an ‘optical lever’.

The students’ own scepticism should lead them to use controls (an ordinary iron magnet and a finger) in order to convince them that water does indeed have magnetic properties.

By reducing friction and mass, the repulsive diamagnetic effect can be shown by patient students. You probably wouldn’t want to demonstrate this to a class. It is very stately.

Senior students could make an estimate of the acceleration in an attempt to calculate the size of the force. This fits in beautifully with stories people tell of those who exert their puny force on massive objects, such as the one recently reported in a letter to the New Scientist whereby a bored but thoughtful conscript spent ten minutes shoving the side of a 3000 tonne destroyer moving it (all of ) 80cm. He was only stopped by the growing gap between the wharf and the ship!

POGIL workshop Earlier this year Rick Moog, the director of the POGIL project in the UK, was invited by the NZ Institute of Chemistry to visit NZ. He spoke to tertiary and secondary teachers in Auckland, Wellington and Christchurch. POGIL stands for Process Orientated Guided Inquiry Learning, and while the content of most of the POGIL material currently available is written for university courses, much of it is relevant for our senior chemistry programmes.

However, material is currently being developed for high school courses in chemistry and biology. NZ teachers who attended the two-hour workshop with Rick and would like to be part of the trialling of the new material

Figure 3: Graphite and diamagnetic effect.

Have the students investigate which type of pencil has the greater diamagnetic effect.

Try different materials but keep the aluminium rod for last!

They should find that aluminium is attracted to a strong magnet because aluminium is paramagnetic.

For further information contact: dhousden@xtra.co.nz For these and other demonstrations visit: http://www.youtube.com/watch?v=jyqOTJOJSoU&featu re=PlayList&p=663F664BFAF5BC7F&playnext_from=PL &playnext=1&index=33

are welcome to apply, online at: http://www.pogil.org/ high-school/hspi/classroom-tester NZIC will be looking for opportunities to further develop resources using this process. POGIL worksheets follow a learning cycle that helps students construct new knowledge through carefully crafted questions. POGIL philosophy is centred around the premise that ‘learning is not a solitary task’ and well-organised group work is essential to the process. Many of the ideas in POGIL will not be new to teachers, but the way they are packaged into the learning cycle has been shown to make significant difference to the learning experiences of students in chemistry.

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NZASE Primary Science Support Groups Report for SciCon 2010

By Ian Milne It seems very appropriate for the writer that this report will be presented at SciCon’s 2010 Journey to Discovery.

It has certainly been a journey of discovery for primary science educators in New Zealand since our meeting two years ago in Wellington.

At that time, primary science education in New Zealand was about to hear the contents of the damming 2007 National Education Monitoring Project (NEMP) report that featured the negative performance and attitude trends in the primary students’ learning and engagement towards the science they were doing at school.

The NEMP findings should have set the scene for some substantial intervention from the Ministry of Education into the professional development and support for primary teachers. The timing seemed ideal as the new Government had been very vocal in its support of the science community for generating the knowledge and wealth required to lift the aspirations of New Zealanders as a whole.

Unfortunately, the newly elected Government’s strong belief in the importance of promoting the National Standards in reading, writing and mathematics saw a dramatic reduction in professional development opportunities in primary science education. This lack of support has resulted in there being no primary science advisers within the state funded school support network.

All has not been lost for those who support primary science education. The education wing of the Royal Society of New Zealand (RSNZ) has accepted the challenge to overturn the negative trends. They intend to develop support networks within the wider education and science communities that will, in time, lead towards the development of primary science education programmes to inspire our children to become further involved in science activity.

The RSNZ has instigated ‘Advancing Primary Science’, a project that aims to lift teachers’ and childrens’ achievements in, and attitudes towards science. The NZASE strongly supports this RSNZ initiative, and the primary support group of NZASE has worked closely with the Royal Society as the project has developed.

A feature of the Royal Society’s support has been the Primary Science Fellowships that were announced at SciCon 2008. The first of these fellowships have been completed, and the teachers involved have enthusiastically returned to their schools inspired to promote teaching and learning of science. The teachers

46 New Zealand Association of Science Educators

selected for these fellowships will need further support from NZASE and local science teachers’ associations to continue to build the momentum of change.

In 2009, the third series of primary science conferences was completed throughout New Zealand. More than 360 teachers attended one or more of the two-day conferences. All were inspired by the wonderful speakers— both teachers and science educators, local and international—who shared their ideas and expectations so enthusiastically. The new curriculum featured strongly in the 2009 primary science conference programmes, and will again be a focus of the programme in 2011.

The theme for the 2011 primary science conferences to be held in April 2011 will be: The roles literacy and numeracy play in students learning and engagement with the nature of science when doing science.

As in the past there will be a mixture of seminars and practical hands-on workshops, as well as displays of relevant resource materials and organisations. This will be the fourth series of primary science conferences organised by NZASE and for the first time there will be a special reduced fee for teachers attending whose schools are members of NZASE. Organising for these conferences has started, and there will an opportunity for teachers attending SciCon in Nelson to provide recommendations and support at the primary forum that will be lead by Jessie Mackenzie, a teaching and learning specialist at the RSNZ. Regretfully I will be absent as I will be attending the ICASE 2010 world conference in Estonia.

I will finish with some very positive news. There may be no government funding for extra support for primary science, but there is a ground swell for having a more practical hands-on approach to learning in science in primary schools. I have heard of a number of schools implementing whole school programmes of children doing science, experiencing the awe and wonder of science, and then sharing it with their parents and communities. One school had over 700 parents and other family members attend an after school science symposium that featured the children sharing their school science experiences with the visitors who attended.

For further information contact: i.milne@auckland.ac.nz

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Earth science big ideas A recent document funded by the National Science Foundation, in the USA, has gathered and identified essential Earth science ‘Big Ideas’ and supporting concepts.

Some of these are important for New Zealand students and teachers including: • Earth scientists use repeatable observations and testable ideas to understand and explain our planet • Earth is 4.6 billion years old • Earth is a complex system of interacting rock, water, air, and life • Earth is continuously changing • Earth is the water planet • life evolves on a dynamic Earth and continuously modifies Earth • humans depend on Earth for resources • natural hazards pose risks to humans • humans significantly alter the Earth.

Fifteen Earth Science concepts The documents contain some new, different, and definitely interesting concepts, some of which I now share with you as they are not always emphasised in our classrooms. And some of them may even get us thinking in new directions. I have only listed 15 of them here, but a full list is available at: http://www.earthscienceliteracy.org/ 1. The four major systems of Earth are the geosphere, hydrosphere, atmosphere, and biosphere. These systems interact over scales ranging from microscopic to global in size, and fractions of a second up to billions of years in time.

2. All Earth processes are the result of energy flowing and mass cycling within and between Earth’s systems.

Energy is derived from both the Sun and the Earth’s interior.

3. Changes in part of one system can cause new changes to that system or to other systems, in complex ways.

The changes may take the form of ‘feedbacks’ that can increase or decrease the original changes and can be unpredictable and/or irreversible.

4. Earth is unique in that water has existed at Earth’s surface in three phases (solid, liquid, and gas) for billions of years, allowing the development and continuous evolution of life. Important properties of water include the ability of water to absorb and release heat, to reflect sunlight, to expand upon freezing, and to dissolve many other materials.

5. Water also plays an important role in many of Earth’s deep internal processes. Water allows rock to melt more easily, generating much of the magma that erupts as lava from volcanoes. Water facilitates the metamorphic

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

alteration of rock and is integral to plate tectonic processes.

Earth’s water cycles among the reservoirs of the atmosphere, streams, lakes, ocean, glaciers, groundwater, and deep interior of the planet. The total amount of water at Earth’s surface has remained fairly constant over the Earth’s history, although its distribution among reservoirs has varied.

There is less than 3% fresh water at the Earth’s surface. Most of this fresh water is stored as glaciers in Antarctica and Greenland. Less than 1% of Earth’s nearsurface water is drinkable liquid fresh water, and about 99% of this water is in the form of groundwater in the pores and fractures within soil, sediment, and rock.

Water resources are essential for agriculture, manufacturing, energy production, and life. In many places, humans withdraw both surface water and groundwater faster than they are replenished. Once fresh water is contaminated, its quality is difficult to restore.

Life changes the physical and chemical properties of Earth’s geosphere, hydrosphere, and atmosphere. The fossil record provides a means for understanding the history of these changes.

The particular life forms that exist today, including humans, are a unique result of the history of Earth’s systems.

Microorganisms dominated Earth’s early biosphere and continue today to be the most widespread, abundant, and diverse group of organisms on the planet. They change the chemistry of Earth’s surface and play a critical role in nutrient cycling.

Natural resources are limited and are distributed unevenly around the planet. Earth’s natural resources provide the foundation for all of human society’s physical needs. Most are non-renewable on human time scales, and many will run critically low in the near future.

Soil, rocks, and minerals provide essential metals and other materials for agriculture, manufacturing, and building. Soil develops slowly from weathered rock, and the erosion of soil threatens agriculture. Minerals and metals are often concentrated in very specific ore deposits. Many electronic and mechanical devices have specific requirements for particular rare metals and minerals that are in short supply.

Natural hazards result from natural Earth processes.

Hazardous events can significantly alter the size of human populations and drive human migrations.

Risks from natural hazards increase as populations expand into vulnerable areas or concentrate in alreadyinhabited areas.

Hazardous events can be sudden or gradual. They range from sudden events such as earthquakes and explosive volcanic eruptions, to more gradual phenomena such as droughts, which may last decades or longer.

science/PEB

By Jenny Pollock, Chair of NZASE Standing Committee − SCIPEB Earth science literacy is essential for our students. There are many reasons for this including: Earth is the only planet we will live on; we are dependent upon it for our existence; and we are now facing challenges, such as dwindling energy and mineral resources, changing climates, ocean acidification and water shortages, directly relate to the Earth sciences. How well humans survive the twenty-first century will depend upon the success of governments and individuals in managing Earth’s scarce resources.

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Acknowledgement: With thanks to: http://www.earthscienceliteracy.org/ New Zealand Association of Science Educators

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technicians

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fair pay for school support staff

By Ian de Stigter

In 1996, NZASE acted on a remit from Canterbury teachers to investigate concerns related to the role and duties of school science technicians by preparing a report.

Remuneration was one issue recorded in the 1997 report.

In a prolonged period of educational sector pay restraint, the maximum hourly rate for highly-qualified state school science technicians had fallen to 32% below the NZ all sectors’ average hourly rate, compared with 21% less in 1989, so it was a particularly low point. (There has been some improvement since, with more required.)

Joanna Beresford observed in relation to the 1994-98 primary teachers’ pay parity campaign that: “If people are financially devalued, they feel socially devalued. The rest of the community tends to think the same way. Teachers are not exempt from anxiety about their status, especially if society appears to devalue their work.” Science technicians at the time were not feeling great, either.

Kay Memmott, long-serving science technician at Havelock North High, and contributor to the 1997 NZASE report, recorded earlier involvement from the 1970s with pay negotiations for “…teacher aides, library assistants and laboratory assistants [sic]... One of my first aims was to change the name of laboratory assistant to laboratory technician. I had learnt that appropriate wording is very important.”

Under the Tomorrow’s Schools reforms which commenced in 1989, support staff pay was bulk-funded through the school’s operations grant. However, a growing number of support staff was required by schools to cope with increasing requirements. In 1989 there were about 7000 support staff, but there are now more than 24 000.

Howard Fancy, former Secretary for Education, concluded that the reforms, “underestimated ... the kind of supports, information infrastructure and systems principals and teachers would need.” This conclusion was confirmed by NZCER surveys between 1989 and 1999 which showed 61% of principals wanting more support staff.

The NZCER surveys also showed an increasing inadequacy of government funding of the operations grant, and an increased reliance of schools on fundraising. The Ministry of Education never included the school requirement for support staff as part of its funding formula, so there was no mechanism to adjust funding for increased support staff employment.

With the increasing operational poverty of schools as a context, NZEI has found it difficult to negotiate improvements in support staff pay and conditions. During a 20-year period when there have been major advances in the employment status of other women, gains for this female-dominant group have been more modest. While nurses, primary teachers, kindergarten teachers and early childhood educators have all achieved a major step change in their employment rewards, support staff have not − because they are being paid from an empty purse.

An NZEI support staff funding working party report in 2004 found a classic situation of gender pay inequity for support staff: “The majority of support staff are women. As a group their employment is characterised by many of the hallmarks of inequity in employment. Many are paid at low rates, or at a rate that does not reflect the skills and responsibilities they

48 New Zealand Association of Science Educators

have, and they are often part-time and in precarious employment.

There is also no clearly defined career path for most occupational groups in this sector.”

(Science technicians fit the general pattern for support staff − most are mothers who have returned to the workforce after time off to have children; 92% are female, compared with 91% of support staff generally.)

Not only was there a need for increased operational funding, but also a change to the funding of support staff pay. A new funding model needed to be flexible for schools to respond to local needs, but also provide more certainty and consistency in support staff employment. Some of the aspects of this are: permanent employment of professional salaried employees, with professional development and career paths, and consistent compliance with the collective agreement in grades and rates of pay.

Feedback from support staff indicated frustration about their situation, but they were often reluctant to seek better pay and conditions, even those they were legally entitled to, in recognition of school budget constraints.

As part of the government’s 2004 Action Plan for New Zealand Women, the government-appointed Pay and Employment Equity Taskforce produced an equity plan.

This recognised: “the issue is not simply a matter of equal treatment and social justice. Without action, the education and skills of women will be wasted, and the wider economy does not reap the benefit of these assets.”

The Taskforce was focused first on addressing the gender pay gap in the public service, the public health sector, and the public education sector (including employees in state and integrated schools).

The Taskforce defined employment equity as:“the elimination of barriers to equality for women in employment. It involves implementing gender neutral policies and practices in access to employment opportunities, and in terms and conditions of employment, including pay. Pay equity means that women receive the same pay as men for the same work and for work which is different, but of equal value. “ The goal for 2008, the end of its five year equity plan period, sums up expected achievement: “By 2008, genuine and durable pay and employment equity for women will be a feature of the New Zealand Public Service and public health and education sectors, the gender pay gap in those sectors will have been significantly closed, and all practicable steps to close the gender pay gap will have been taken.”

This expectation has proved to be overly optimistic.

In 2007-8 the Ministry of Education equity review of schools made 17 recommendations, including a pay investigation for school support staff. It contained an extensive response plan, including recommendations to address the inequities; implementation strategies; and monitoring and evaluation processes; with time frames. In April 2010, the report remains suppressed.

The Government must at some point meet an obligation to pay science technicians and other school support staff fairly.

For further information contact: destigterfamily@gmail.com

4 -7 JULY 2010 NELSON, NZ

Journey toto Journey Discovery Discovery The NZASE flagship biennial conference will be held in beautiful Nelson.

Four days of professional development and inspiration.

Diary these dates now and put it in your budgetâ&#x20AC;Ś plan to be there!

Register online to win a case of wine

www.confer.co.nz/Scicon2010 Phone: 03 546 6022 Email: scicon@confer.co.nz Venue: Nelson College for Girls

How important is the sea to you?

How important is the sea to you?

How important is the sea to you?

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The Leigh Marine Laboratory at Goat Island is a place to develop your passion forIsland the sea.is a Thegreat Leigh Marine Laboratory at Goat

The Leigh Marine Laboratory at Goat Island is a great place to develop your passion the sea.

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To your career options, a skill base great place to develop your passion forgeology, the sea. in biology, chemistry, statistics, physics, To enhance enhance your career options, develop askill skill base To your career options, develop a base geography, environment, mathematics or computer To enhance your career options, develop a skill in biology, biology, chemistry,statistics, statistics,physics, physics,geology, geology,base in science. chemistry, in biology, chemistry, statistics, physics, geology, geography, environment, mathematics ororcomputer geography, environment, mathematics computer geography, environment, mathematics or computer science. science. science.

To download a marine science handbook, or for more information the redevelopments currentlyor for download aonmarine science handbook, To To download a marine science handbook, or for underway at the laboratory, visit more information on the redevelopments To download a marine science handbook, orcurrently for more information on the redevelopments currently www.marine.auckland.ac.nz more information on the redevelopments currently underway at the laboratory, underway at the laboratory, visitvisit underway at the laboratory, visit www.marine.auckland.ac.nz www.marine.auckland.ac.nz www.marine.auckland.ac.nz

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