Understanding Healthy Waterways. Part 4: Salinity.

How can we help keep our waterways healthy?

Part 4: Salinity How does salinity affect the health of our waterways?

Suitable for grades 5 and 6 Written by: Jill Reade

CONTENTS LIST

PAGE

PAGE PAGE

OVERVIEW Introduction and Teacher Background

Graphic Design: Lisa Eastman

2

ENGAGE Lesson 1 - What is that taste?

6 Lesson 2 - What has happened here? 7

EXPLORE Lesson 3 - What a limp spud!

9

Lesson 4 - Is the salt still there?

11

Lesson 5a - How saline is that?

12 Lesson 5b - The Liquorice/Salinity Game 14 (optional) EXPLAIN Lesson 6 - Why does salinity matter?

17

ELABORATE Lesson 7 - How does salt affect seed germination?

18

EVALUATE Lesson 8 - This is the problem 19 - what do we do now?

www.waterwatch.org.au

OVERVIEW

OVERVIEW ENGAGE Facts

EXPLORE

Introduction and Teacher Background Information Lesson 1 What I Want to know What is that taste?

How willwater I findsamples out I have Learnt Taste with increasing What amounts of salt in them. Compare the amount of salt in the samples to the amount of salt in sea water.

Lesson 2 What has happened here?

What is the history of salinity in Australia?

Lesson 3 What a limp spud!

Examine the effect of salt on potato cells or animal tissue.

Lesson 4 Is the salt still there?

Lesson 5 a - How saline is that? b - The Liquorice/Salinity Game (optional)

How does salt get into the upper levels of the soil?

Use a conductivity meter to measure salinity and make the connection between conductivity and salinity.

“The Liquorice Salinity Game”

EXPLAIN

Lesson 6 Why does salinity matter?

Research the problem of salinity and reflect on its effects.

ELABORATE

Lesson 7 How does salt affect seed germination?

Design an experiment to investigate the effect of salt on seedlings or on seeds.

EVALUATE

Lesson 8 This is the problem - what do we do now?

Construct a cartoon or story book about the history of salinity and its effects in Tasmania.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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OVERVIEW INTRODUCTION This series of learning activities is part of a wider learning sequence based around the guiding question - How can we help keep our waterways healthy?

The entire unit consists of five parts – an introduction to water, then sections on turbidity, temperature, salinity and a final section on water life and habitat.

The sequence uses the 5Es model for teaching and learning in Science.

SCIENCE OUTCOMES Students will be able to: • Identify a possible source of salinity in their local catchment area.

• Measure salinity using a conductivity meter.

• Identify a way that salinity would affect the health of a waterway.

• Follow directions to conduct simple investigations about salinity.

• Explain their understanding of the effects of salinity.

How does salinity affect Teacher Background Information the health of a waterway?

Salinity is the presence of soluble salts in water or soils. The salt that most people are familiar with is table salt, known chemically as sodium chloride, which people use to help flavour food. It is also, in small amounts, an important chemical which is necessary for the body’s nervous system to work properly.

Sodium chloride is, however, only one of the many different chemicals which are chemically speaking correctly known as

What causes salinity?

Salt is, of course, a major component of ocean water, but we do not normally think of salt as being in ‘fresh water’ waterways.

The history of the problem starts in our past. Australian soils are naturally rich in salts (think about Lake Eyre) because over millennia salt has blown in from the ocean and parts of Australia were also covered by sea in the past. Movement of water through the soil leaches the salt from the soil, and then washes it into our waterways. Normally the amount of salt coming from this source is not enough to affect plants and animals or to influence most

“salts”. Magnesium chloride, magnesium sulphate and calcium bicarbonate are three other salts which are found in sea water which is a common source of salt.

The presence of any of these substances and many other such chemicals in waterways or soils can contribute to the problem of salinity.

Note Soluble indicates that the chemical dissolves in water.

waterways. However salt is distributed throughout the soil profile so if more salt is brought up to the surface of the soil by a rise in the underground water table, and is concentrated at ground level, the soil and surrounding waterways can become contaminated with the excess salt.

Why would the groundwater in the water table rise? The two main causes of a rise in the water table are known as dryland salinity and irrigation salinity.

Continues on next page!

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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OVERVIEW Salinity - Continuing from previous page.

CONNECTIONS TO THE STATEMENT OF LEARNING Year 3 Science as a Human Endeavour • Students share responsibility for the quality of their immediate environments.

Year 3 Science as a Way to Know • Students begin asking questions and make predictions.

• Students plan and conduct simple investigations. They collect, record and present data.

• Students share findings, discuss how an investigation could be changed and consider fairness of tests.

Year 5 Science as a Human Endeavour • Students consider appropriate ethical issues and consequences of human activity. They investigate how their actions contribute to sustainability of local environments.

Dryland salinity Dryland salinity is caused by removal of deep rooted plants and shrubs from an area and their replacement with annual pasture crops that do not use as much water. This allows more water from rainfall to pass through the topsoil into the water table so that the level of the water table rises, bringing along with it the salts from the soil and rocks deep in the ground. Runoff from the pastures subsequently carries these salts with it into waterways.

RAIN OR EXCESSIVE IRRIGATION RAIN

RAIN

Some water is taken up by the roots.

Year 5 Science as a Way to Know • Students derive questions and predictions for testing. They plan an investigation, collect data, checking and repeating observations.

• Students present data in appropriate ways and then identify patterns. They compare results with predictions and draw conclusions.

Note These statements have been summarised.

Curriculum Connections to other learning areas Numeracy – measurement, reading scales, using informal and formal measurement.

Literacy –students maintain a journal of their activities, thoughts and ideas as they proceed through the unit. Teachers use a word wall.

Irrigation salinity Irrigation salinity occurs when irrigation water soaks past the soil area, where the plant roots grow, adding more water to the watertable.

This in turn, causes the watertable to rise, bringing salts with it which dissolve in the groundwater. When the irrigation water dries out and the underground water drops again it leaves the salt that has come up with the watertable on the surface.

Very little water is taken up by plants.

Most of the water trickles through the Intermediate Layer.

Some water trickles through the Intermediate Layer.

GROUNDWATER LEVEL REMAINS CONSTANT

BEDROCK

Rate of water entering Groundwater Layer equals rate of water lost from Groundwater Layer.

No plants or plants with shallow roots

GROUNDWATER LEVEL RISES

BEDROCK

Salinity in waterways is also increased by stormwater runoff and runoff from pasture areas treated with fertilisers, herbicides and pesticides.

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HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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OVERVIEW Salinity - Continuing from previous page.

When did salinity become a problem?

In the past, before European settlement, the land was occupied by aboriginal people and only small areas were cleared at any one time. Fire was the main method used to stimulate new plant growth bringing the animals to the area.

The population was small, the people moved around a great deal, and although, over time, the type of plants present would have been affected there was still a mix of trees, shrubs and grasses in the landscape.

When European settlement began white people settled in one area and cleared the land to plant pasture for grazing animals and eventually crops for human and stock feed.

Over time as more areas were cleared the mix of plant types in the landscape changed considerably and the effects mentioned above started to be seen.

In addition, from a human viewpoint: • Salt contaminated water becomes unsuitable for irrigation as most crops have a low salt tolerance.

• Salt contaminated water may become too saline for humans and livestock to drink.

• Water with a high salt content is known to cause corrosion (rusting) of pipes and equipment.

• Water with extra salt becomes “hard”, which causes a problem for people washing clothes as hard water requires more detergent to make suds.

How does salinity affect our waterways?

• Trees and shrubs along the waterway may die because of the salt level in the soil which then means that the problem of run-off, erosion and a rising water table is aggravated.

• Most freshwater animals cannot live in salt water so they lose their habitat.

Note An explanation of the nature of ions is beyond the requirements of this material.

Briefly, ions have an electric charge and because of the presence of the charged particles in the water the liquid is able to transmit current.

What is conductivity?

Conductivity is the ability of a liquid (or solid) to carry an electrical current. Water containing salt can do that because it contains ions such as sodium ions and chloride ions.

Photograher: David Armstrong

A note about salinity The effects of salinity on plants Salinity is a very serious and widespread problem in Australia because excess salt is contaminating a number of major waterways, and in addition it is decimating large tracts of agricultural land particularly in the Murray Darling Basin and areas of Western Australia.

As an example of the scale of the problem, more than $130 million of agricultural production is lost annually due to salinity.

In Tasmania, salinity is a much lesser problem than it is on the mainland. Only about 1% of the agricultural land is salt affected, however the problem is worse in some areas than others, so in some places up to 5 - 8% of land can be salt affected. The main areas affected in Tasmania are in irrigated areas in the Cressy area of the Northern Midlands, King Island and in the Cole River Valley in south east Tasmania.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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ENGAGE Lesson 1 OVERVIEW To show that a small amount of salt in water does not have a noticeable taste, but as the concentration increases it is unpalatable.

To connect the salt that we use in food with salinity in water.

Students: • Mix salt solutions with different amounts of salt in them.

• Taste the salty water and agree on its palatability.

• Link the amount of salt in the water they have prepared to how much is in sea water.

EQUIPMENT • 4 plastic cups for mixing the salt water • a plastic cup for each child • salt - about 50g for the class • teaspoons to measure the salt • 4 x 3 teaspoons for tasting • black texta • digital kitchen scales • a pop stick stirrer for each cup

HELPFUL HINTS • Seawater has around 3½ grams of salt for 100mls of water which is about the quantity in a generous “measuring” teaspoon.

• Freshwater has less than ½ gram of salt.

• Salt does not dissolve as easily as sugar so it may take a bit of stirring.

SAFETY NOTE Make sure all containers are clean as students will taste the water in this activity.

What is that taste?

Lesson steps 1.

Who has taken a gulp of sea water while swimming in the sea? What is it like – okay or yuk?

2.

This lesson is about finding out how much salt it takes to make tap water taste like sea water.

3.

Work in groups to prepare cups and stir in salt.

4.

Transfer a little liquid from each cup, one at a time, into your cup for tasting.

5.

Start with cup 1 and work up to 4. Rinse out your cup with tap water after each taste.

6.

Record what you taste in your journal.

Cup number

Amount of salt

1

No salt

2

3 grains

3 4

1/4 tspn 1 big tspn

CUP 1

CUP 2

No salt

3 grains

CUP 3

CUP 4

1/4 tspn

1 tspn

Don’t forget to clean up!

Taste

? ? ? ? ? ? ??

on soluti saline y salinit ve l o s s i d n ntratio conce

some thin nkin ng questions 1. In whi

ch cup did you st art to taste the sa lt?

2. Which cup ta sted like saltwat er fr om the sea?

3. Was the salty water pleasant or un pl ea sant?

4. Would you no tice a little bit of sa lt in w at er?

5. Would you no tice a lot of salt in water?

Suggestion

to the word wall as you ! Add go through the lessons.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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ENGAGE Lesson 2 OVERVIEW Share current knowledge about salinity and begin to construct a flowchart to show how salinity has become such a problem.

Students: • Review the information they have heard about salinity.

• Discuss their understanding and examine ideas about how the problem started.

WHATS COMING? In the next sections of the unit the students will see why salinity is a problem for us and other living things and how it comes about in some more detail.

What has happened here?

- the history of salinity in Australia Lesson steps 1.

Brainstorm all the ideas and information that students have about salinity.

2.

Ask questions such as: • Have you heard the term salinity?

• Where have you heard it?

• Why do people seem concerned about salinity?

• When did salinity start to be a problem in Australia?

3.

If no-one has heard of salinity or is aware of how salinity started to be a problem say that salinity is a problem caused by too much salt in waterways and on land and that one of the reasons we are having such a problem with salinity now is because of things that happened long ago in the past and more recently after European settlement. (Check that they understand what is meant by European settlement.)

4.

This outline of the events that have led to salinity may be turned into a story but it is important that students understand that even though these things happened in the past they are real.

Thirlstane Photographer: David Armstrong

Continues on next page!

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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ENGAGE

Lesson 2 - Continuing from previous page.

The Story of Salinity

Click h er printa e for ble ver sion!

Long ago, a long time before people came to live in Australia, because it is an island and surrounded by the ocean, our land had lots of salt blown onto it. This happened over many millennia.

The salt was absorbed into the soil where it remained, mostly contained deep under the surface. Lots of trees and plants grew everywhere; they were used to the salt and were not affected by it. The trees were also thirsty and soaked up almost every drop of rain that fell on the land. The underground water table which might have brought the salt to the surface remained deep down and the system was in balance.

About 40,000 years ago the Aboriginal people arrived in Australia. They lived in harmony with the country, moving around to find food as they needed new sources of meat. They did not clear the land although they set fires occasionally to bring on new plant growth. The system was still in balance.

Then around 200 years ago European settlers arrived in Australia. European people were used to living in just one place and building houses to live in, so they settled in one area rather than moving around. They were also used to a different land so they did not understand the new land very well.

They still needed food for themselves and their animals, so they cleared the land for pasture by chopping down the trees. Sometimes they burnt the land at the wrong time of the year.

Some people brought new plants which became weeds, and other crop plants to grow instead of the native plants.

As more and more people lived on the land they needed to grow more crops so they used fertilisers, which helped the crops grow, but added salt to the soil. As the land is dry they also used irrigation to help the crops grow.

More people needed jobs, and factories were built to make things and to provide jobs.

Sometimes the factories discharged material into the waterways.

All these factors combined and the land started to change, perhaps forever, and the problem we call salinity started to make its effects felt.

tth hinking questio

ns

Use the in nffo orrm mattiio on in n the ou uttlliine to conssttrru uct a simple timeline of ho h w thingss ha h ve change ed d on our land o the last millio over i n or so yea ars and wha at t h ha s ha ppened to make salinity a pr oblem.

STEP 1 Prehistory (more than a mill ion years ago) STEP 2 40,000 ye ars ago STEP 3 200 year s ago STEP 4 20 years ago

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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EXPLORE Lesson 3 OVERVIEW How does salt affect plant tissue?

Students: • Prepare a saline solution.

• Place slices of potato in saline solution and in fresh water.

• Compare the two slices of potato and record observations.

• Identify reasons why salinity might be a problem.

EQUIPMENT • a fresh medium sized potato • 2 dishes • a tablespoon • a knife • salty water HELPFUL HINTS Slice the potato yourself, but slice it so that students can see what you do and are assured that you have not done anything to the potato before hand.

What a limp spud!

Lesson steps 1.

Slice a potato lengthwise into several pieces around ½ cm in thickness and so that each piece has two flat sides.

2.

Place some of the potato pieces in one dish and the rest in another and fill both dishes with water.

3.

Add two tablespoons of salt to one of the dishes, and label it "salty water."

Stir the salt to dissolve it.

4.

Let the potatoes soak for 15 minutes.

5.

OBSERVE: Compare the potatoes.

What do they look like and feel like?

Is there a difference in firmness?

6.

INFER: What might have happened to cause the difference?

7.

PREDICT: What might happen if the potato in salt water was put back into fresh water. Will it make the potato firm again? Try doing this.

8.

Salted water

Don’t forget to clean up!

Fresh water

Record in your science journal what you have observed and what you think the salt does to the plant tissue.

Continues on next page!

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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EXPLORE Lesson 3 - Continuing from previous page.

A DEFINITION OF OSMOSIS “Osmosis is the net movement of water across a selectively permeable membrane driven by a difference in solute concentrations on the two sides of the membrane. ” www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/ osmosis.html

The above definition of osmosis is a scientific one.

Now in simple language: What happens is that through the process called osmosis, water moves from areas of low salt concentrations to areas of high salt concentrations.

Adding salt to the potato water creates a higher salt concentration in the dish than in the potato. This means water from the cells of the potato slice that is soaking in salt water moves out, leaving behind a limp spud!

Some extra background information for teachers All living things are made up of cells, however not all cells are exactly the same. Plant cells are generally rectangular in shape and have a firm structure known as a cell wall encasing them which makes the cell look like a box. (See the picture.)

Plant cells also have a lot of water present in them.

The combination of the cell wall and water in the cell provides the plant with rigidity. When a plant starts to dry out the cells lose their water and the plant becomes floppy because there is not enough water to keep the cells rigid. The plant cell wall will still support the plant to some extent and hold it together, but it will not provide rigidity.

Water is also pulled out of plant cells by salt coming in contact with the cells. This process is known as osmosis.

(See the definition of osmosis.)

This is one of the reasons that salt has a negative effect on plants. It stops water and nutrients moving effectively into the plant cells so that the plant’s growth is affected.

Some types of salts are also toxic to plants.

http://www.steve.gb.com/images/science/plant_cell.png (Retrieved 17/06/07)

An optional class demonstration Dissolve the shell from an egg using an acid (e.g. vinegar) and then placing the shell-less egg into salty water.

See what happens to the egg membrane over the next day or two.

Put a second egg which has had its shell removed into fresh water and compare the two eggs after twenty four and forty eight hours.

Note This demonstration should be started about a week before the potato experiment so that the two experiments can be completed at about the same time.

Hint for the demonstration Vinegar takes from several days to a week to dissolve eggshell so put the eggs in the fridge while the shell is dissolving, or get a stronger acid from a secondary school to speed things up.

If you decide to use vinegar, which is the safer choice with younger children, then change the vinegar several times over the week to keep the acidity level high.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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EXPLORE Lesson 4 OVERVIEW How can salt be dissolved from soil by the leaching effect of water?

Students • Prepare some salty soil.

• Wash the soil with water to remove as much salt as possible by dissolving.

• Evaporate the water from the solution.

• Observe that the salt remains after the water has evaporated.

Is the salt still there?

Lesson steps

Step 3 Don’t forget to clean up!

1.

How does salt that is in soil get into groundwater? What happens to salt when it dissolves in water? Is it still there and how can we see it?

2.

Each group should have a cup of soil.

3.

Sprinkle a dessert spoon of salt over the soil Step 6

EQUIPMENT • Soil – potting mix SAFETY NOTE Be careful not to breathe in potting mix.

• A large sieve • Chux super wipe to line the sieve • Saucepan • Hotplate • Salt • A cup or container to collect water

SAFETY NOTE Children are asked to evaporate water in this investigation – as water is heated on a hot plate it will spit steam. Children should wear safety glasses if they are available, or keep well back from the saucepan.

You may also leave the water they have produced to sit in a sunny place where evaporation is slower (up to two or more days) but safer.

4.

Mix the salt in thoroughly until it cannot be seen.

5.

Now line a sieve with a double layer of Chux super wipe.

6.

Place the cup of soil into the sieve and wash the soil with about 2 cups of clean water from the tap or use distilled water.

(Do not use too much water as it will take too long to evaporate later).

7.

Collect the water as it filters through the soil.

8.

Now pour the same water back through the soil again (several times) to wash the soil thoroughly as this will help make sure the salt is dissolved out.

Note This process is similar to groundwater rising and falling several times through the soil layers leaching out more salt each time it goes up and down.

9.

Place the water on a shallow plate and leave it in a sunny window or if you want to be quicker use a saucepan on a hot plate and heat slowly until all the water has evaporated away.

10.

What is left? Make a record of your observations.

Numeracy Connection - weigh the salt before and after to see how much you can get back.

11.

Make a photographic record of this investigation to assist in reviewing the investigation later.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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EXPLORE Lesson 5a OVERVIEW How is salinity measured? How does the amount of salt affect the taste?

How saline is that?

1.

Students • Prepare solutions of different salinity levels.

• Learn the technique for measuring salinity using a salinity meter.

• Gain an appreciation of what concentration levels mean by tasting the solutions.

Step 1

Lesson steps Number four containers 1 – 4 and half fill them with fresh rain water or distilled water.

1 2.

Follow the instructions (below) to measure the salinity level of the water in container 1. Record the conductivity.

The reading should be less than 800 µs/cm.

3.

Add salt to container 2, ¼ of a teaspoon at a time, stirring between each spoon of salt added until the solution measures approximately 1500 µS/cm. Record how much salt was added.

4.

Add salt to container 3 until it measures approximately 7000 µS/cm. Record the amount of salt added.

5.

Add salt to container 4 until it measures >10000 µS/cm. Record the amount of salt added.

6.

Compare the amount of salt added to the amount you tasted in lesson 1 and record your comparison in your data table.

Note This activity can be done in small groups or as a whole class demonstration.

2

3

4

Salinity Meter Measurement Instructions EQUIPMENT • Salinity meter from a local high school or from Waterwatch • Table salt • Distilled water or rain water • 4 small, clean containers (plastic cups) • Instructions for measuring salinity • Teaspoons

• Remove cap and rinse end of probe in the water to be tested.

• Switch unit on (on/off button).

• Dip the end of the probe into the water to be tested.

• Gently swirl the probe until the numbers stop changing on the screen.

• Multiply your reading by 1000 (e.g. 1.73x1000 = 1730 µS/cm).

• Record your result.

• Rinse the end of the probe with tap water and measure a second solution or turn off.

Ask students why the probe should be rinsed after each measurement is recorded.

Continues on next page!

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EXPLORE Lesson 5a - Continuing from previous page!

Water Quality Standards - Data Table µS/cm Use

Activity

0 - 800

Write a short of report of the investigation including a record of the data in your journal. Be sure to compare the amount of salt added in each of the containers to the amount needed to get a salty taste in lesson 1.

• • 800 - 2500

Container Level

Amount of Salt (tspn)

Reading on the Conductivity Meter Screen

Reading x1000

•

Salinity (µS/cm)

•

Taste •

•

2500 - 10 000

• •

Now look at the data table on the right to see how much salt causes water to become unusable for some of the ways we use water.

•

extension tension i exte extension ension i ion nsio If time permits prepare a poster, a model using toys etc or PowerPoint to show how water use changes with increasing salinity.

Over 10 000

• •

n •

Good drinking water for humans (provided there are no germs or chemicals that are invisible to our eyes) Generally good for irrigation Suitable for all livestock Can be drunk by humans (although most people would prefer not to drink this water) Not ideal for irrigation (can be used if the soil is suitable, there is good drainage and plants are salt tolerant) Suitable for all livestock

Not recommended for human consumption (you could drink a little if you needed to) Not normally suitable for irrigation (except on very salt-tolerant crops) Poultry and pigs can tolerate up to about 6000 µS/cm; most other livestock can drink water up to 10 000 µS/cm Not suitable for human consumption or irrigation Not suitable for poultry, pigs or any animals feeding young (beef cattle can use water to 17 000 µS/cm and adult sheep on dry feed can tolerate 23 000 µS/cm) Water up to 50 000 µS/cm (the salinity of the sea), can be used to flush toilets (provided rusting in the cistern can be prevented) and for making concrete (provided the steel rods used for reinforcement are protected)

Adapted from: ‘SALTWATCH Involve me and I’ll understand’ Dept. Primary Industries, Queensland, 1994

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EXPLORE Lesson 5b OVERVIEW To provide a realistic demonstration of the way in which all things in the environment are interdependent, and to consolidate the concept of salinity as a problem.

Students • Play a role in the liquorice /salinity game.

• Share observations and ideas.

• Identify some sources of salinity problems.

• Explain why some plants are more affected by salinity than others.

EQUIPMENT • 7 packets of normal sweet red liquorice • 1 normal sweet black liquorice (from the supermarket) • 1 packet of 'single salted' Dutch liquorice • 1 packet of 'double salted' Dutch liquorice • 1 packet of 'triple salted' Dutch liquorice (from confectionery shops) • some cups or a bucket to spit the liquorice out into • some water for rinsing out mouths • some jelly beans to give out after the exercise (the liquorice is very salty) • cards with pictures of local tree/shrub/flower species and their names if needed (see suggestions) • a long piece of blue material to represent a river ( if required)

SAFETY NOTE Be sure to check that no students will suffer adverse dietary effects from this activity.

The Liquorice/ Salinity Game (optional)

Click h er printa e for ble ver sion!

Lesson steps The sections which are to be read out are printed in blue.

1.

Introduce the lesson by telling the children that they are going to experience what it is like to be a plant beside a stream that is going to be influenced by salt pollution.

2.

Explain Each of you is to pretend that you are a tree next to a stream. Each of you is a different tree species.

(Optional Extra - give each student a random card selection with the name and picture of a local plant species. ) Before land clearing, all the trees with their big long root systems used roughly the same amount of rain water as entered the groundwater system each year, so the groundwater level was in balance, and remained at the same depth in the soil each year. You are all trees next to a stream in a natural bush setting, untouched by humans, so there are lots of trees everywhere using the groundwater.

The students are given a piece of normal sweet liquorice.

HELPFUL HINTS In this activity the students pretend they are trees near a stream. The pieces of liquorice are given to show the effects of increasing amounts of salt Those 'trees' that pull a face or spit out the liquorice at any stage ‘die' (due to their sensitivity to salt - i.e. `salt intolerance’) This exercise is ideal to do outside next to a stream, so that children can more readily visualize the situation This activity is optional because it is potentially expensive and obtaining the liquorice may be difficult. Teachers may use other materials to replace the salty liquorice e.g., small biscuits baked with salt instead of sugar.

Some students may literally associate their plant picture card with their own reaction to liquorice so in this case omit the use of the cards.

Check the list of local plants for the most suitable ones for your area (Lesson 5b Teacher’s Sheet).

Click h er this wo e to see rkshee t!

The Liquorice Game has been copied from Ribbons of Blue http://www.wrc.wa.gov.au/ribbons/index.html Continues on next page!

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

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EXPLORE Lesson 5b - Continuing from previous page The sections which are to be read out are printed in blue.

3.

Explain This liquorice represents the water that you, as trees, live off. The rain that you receive has some salt in it (because salty water gets blown in from the sea and there is some salt in the air near the coast) and, over millions of years this salt and the salt from rocks which dissolves in rainwater gets into the soil. This has built up a lot of salt in the soil, however it is not a problem for you when the system is in balance and there are lots of trees like you keeping the groundwater at the same depth.

When humans clear the land for farming it does become a problem because all the trees are removed, and the crops don't use even half as much water as a big tree. Also, the roots of the crops are very shallow and don't use the groundwater as their roots don't reach it. So each year it rains there is too much water for the crops to use and the groundwater level rises closer to the surface. The store of salt that normally sits just above the groundwater level starts to be dissolved by the groundwater and the groundwater becomes a little bit salty. This groundwater feeds into the streams, which end up in big rivers, so everything goes a bit salty.

4.

5.

Explain The water in the stream is starting to reduce in quality. (If any students “die”.) You who have died are very sensitive trees, and although beautiful, you can't handle changes in water quality.

(You may remove one or two trees as you go if none ”die" from the liquorice and, depending on the class size, to show that some have died over time.)

6.

Explain A few years have passed and you are the only trees left on the land. The farmer has noticed the level in his groundwater bore is only about 1m from the surface. It used to be about 4m below ground. The groundwater is getting quite salty, and the poor trees have to drink it everyday!

Give them the salted liquorice. A few should start to ”die" now.

7.

Explain You poor trees are not that salt tolerant. There are even fewer trees left now to use up the groundwater, so the levels just keep getting closer and closer to the surface bringing with it all the salt that has built up in the soil over thousands of years. In some low-lying areas the groundwater has reached the surface, full of salt. The sun evaporates the water and leaves the concentrated salt on the surface. This is called a saltpan.

Give the students the unsalted Dutch liquorice.

Give the surviving trees the double salt liquorice. Tell them not to swallow it whole, they have to chew it properly if they can!

Explain A person has just bought the bit of bush and the creek you live on. The person has started to clear the trees to make paddocks.

You are looking a bit weak now and the, insects are attacking you because you are weak. Imagine how it must be to only have salty water to drink.

Remove two of the trees to represent the clearing process.

(Ask them to remember what they thought salty water in the first activity tasted like.) Most trees will die with the double salt.

The Liquorice Game has been copied from Ribbons of Blue http://www.wrc.wa.gov.au/ribbons/index.html Continues on next page!

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

15

EXPLORE

The sections which are to be read out are printed in blue.

8.

Explain Any remaining trees are fairly salt tolerant, and these trees are needed to plant in areas where it is a little bit salty and other flora won't grow. The salt problem is now affecting the whole farm as the groundwater table is virtually at the surface. The farm can no longer grow crops. It has white salt on the crusty, bare soil surface, and in winter, the whole farm turns into mushy mud because it is waterlogged.

The creek is so sick that nothing lives in it anymore, only a few trees are surviving, although they are also pretty sick. The problems are not going away.

Now give them the "triple salt" liquorice!

Explain to any trees still surviving You are the most salt tolerant 'trees' around and we should plant you all over the farms to help to reduce the groundwater levels. What was once a beautiful bit of natural bush has became a large area of salt. The creek is now virtually dead, along with the land.

1. Imagine that you are the farm er and see your tr gradually dying. ees What might you do to help the problem?

2. What do you think the commun ity should do now to help cont rol this problem before it becomes any worse?

3. What’s happen ing to the fauna relying on the tr (e.g. possums, bi ees rds, insects)?

4. Research whi ch trees in your lo cal area are actu the most and/or ally the least salt tole ra nt .

H ow could you use this know ledge?

5. Write a reflect ion in your journa l explaining wha you think about t what you saw.

Word W a

9.

thinking questio ns

ll

Lesson 5b - Continuing from previous page

salt salinity groundwater

saltpan tolerant

water cycle water table

The Liquorice Game has been copied from Ribbons of Blue http://www.wrc.wa.gov.au/ribbons/index.html

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

16

EXPLAIN Lesson 6 OVERVIEW Students research the science and then summarise, represent and explain their observations about salinity.

Students • Review their investigations and discussions.

• Work in pairs to summarise the way in which salinity becomes a problem.

• Recognise that salinity is a major form of land degradation.

Why does salinity matter?

Lesson steps Look carefully at the graphic of how tree clearing causes dryland salinity.

2.

Now work as pairs to write your own explanation to say what is happening to the land when it is affected by dryland salinity.

3.

Click h er printa e for ble ver sion!

BEFORE CLEARING

1.

!

Suggestion During this stage a visit to a salt affected area, a guest speaker such as a Waterwatch coordinator or a farmer who is affected by salinity will help children understand the problem from different perspectives.

How tree clearing may cause dryland salinity

RAIN

Water taken up from soil, evaporates from leaves.

Trees also acts as umbrellas.

Some water filters through to groundwater.

When ready share your ideas with two other groups. Change your ideas or combine them to decide on an explanation which you feel is the clearest and most accurate way to explain how dryland salinity works.

GROUNDWATER LEVEL

AFTER CLEARING

4.

Present your final explanation together with a labelled diagram to the class.

5.

The other cause of salinity (which is more common in Tasmania) is similar in many ways to dryland salinity. It is called irrigation salinity. Read the Salinity Fact Sheet Click he and research what else you can find this workres to see heet! out about it.

6.

SAME AMOUNT OF RAIN

More water filters through to groundwater.

Salty water emerges in low-lying areas.

GROUNDWATER LEVEL RISES AND DISSOLVES SALT IN SUBSOIL

As a group draw a diagram to show how irrigation salinity may become a problem.

These links are some possible sources of more information: http://dnr.nsw.gov.au/care/soil/landdeg/irrigationsalinity.pdf http://www.abc.net.au/learn/silentflood/ep1_story.htm http://www.informaction.org/cgi-bin/gPage.pl?menu=menua.txt&main=salinity_gen.txt&s=Salinity From the Catchment Environment Education Program Kit Source: PLEMING: Teacher Resource Kit, Soil Conservation Service of NSW.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

17

ELABORATE Lesson 7 OVERVIEW Design an experiment to show first hand some of the problems salinity causes to plants.

Students • Design an investigation.

• Carefully prepare and label dishes for the investigation.

• Carefully add salt solution and mung beans to the dish.

• Observe and record the process of plant germination and growth.

• Record observations using a table in their science journal.

• Infer if high concentrations of salt prevent seeds from germinating.

• Draw conclusions about the effect of salt on agricultural land.

How does salt affect seed germination?

Lesson steps 1.

2.

SUGGESTED EQUIPMENT • approx. 200 mung beans, dry (1X 500g pkt) • 12 round takeaway containers • 2 paper towels per container • 1 packet of salt • distilled water for salt solutions • 1 measuring jug • 1 plastic cup • 1 eyedropper for adding the salt • kitchen scales for measuring the salt • tweezers • magnifying glass

To design an experiment to investigate this problem think about questions such as: • “How could we find out how much salt mung beans can tolerate?”

• “How much salt should we use?”

• “Can we use plain old tap water?

Does it have any salt already in it?”

• “How many seeds should we use?”

Use the CREST planning proforma to help identify the variables and design the investigation statement. Discuss keeping the variables the same, e.g. same size containers, number of beans, etc.

If I change the ……………… then I will measure …………………. Click

her this wo e to see rkshee t!

C

Note See the associated teacher sheet thlick here to see is work sheet! for extra assistance with the design of this experiment and more background information.

In this work you have been finding out how the problem of salinity arises. You have been told that this is bad for plants and for waterways. Now you are going to see for yourselves if this is really true by seeing how much salt mung beans can tolerate before failing to germinate.

3.

Note When you have decided on what amounts of salt you should try help the teacher make up the solutions.

Don’t forget to clean up!

4.

Prepare the dishes ready for the experiment but before starting look at some dry and soaked mung beans with a magnifying glass to identify the parts of the seed. Draw a diagram in your journal to show what a mung bean seed looks like.

5.

Place the mung beans into the dishes and store them in a cool location.

6.

Observe each day (over 3 to 7 days)

7.

Record the number of beans that have sprouted and any other observations that can be made.

8.

Analyse and present the results using pictograms, tables, graphs or posters.

9.

Discuss the experiment and decide whether the method answered all of your questions. What changes could be made to make the experiment more satisfactory? What other questions could be asked? (If possible, follow up some or all of these questions.)

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

18

EVALUATE Lesson 8 OVERVIEW Students reflect on what they have found out about the effects of salinity on waterways, represent their understanding of the history of salinity and plan action in their local community.

This is the problem - what do we do now?

Lesson steps 1.

Reflect back on the work you have completed on salinity and its importance in the land and aquatic environment.

Think about • How salinity problems happen?

• How does salinity affect the land and the waterways?

• Why is salinity bad for plants and animals?

• How do the things that people do contribute to making salinity a problem?

Students • Review the information they have collected.

• Share and record their ideas.

• Create a timeline or flowchart to summarise the history of salinity in this country.

• Reflect on how they could help address this problem in their own catchment area.

TO COMPLETE YOUR WORK To complete your work write a reflection in your journal: • What new things did you learn during the unit?

• What activity did you enjoy most? Why? • Which activity would you like to change or add to? Why? • What did you learn about human impact on the environment and how the community could help look after it?

Consider also • Is salinity a problem in your catchment?

• Salinity is still a relatively minor problem in many parts of Tasmania compared to the remainder of Australia: does that mean that we can ignore it?

• How can you prevent salinity from becoming a problem in your catchment?

References: www.saltwatch.org.au/saltwatch/book/5_page.html Distribution of saline soils in Tasmania: http://soer.justice.tas.gov.au/2003/lan/2/issue/27/ataglance.php

Activity 1 Create a timeline, a flowchart or a photographic poster to show the history of salinity in Tasmania or Australia. (Use the timeline you started in Lesson 1 to help you get going.) Include as much of your understanding as possible. A starting point is shown below and on the student worksheet.

Way back in time:

Nature untouched.

Then the aboriginals came:

The aboriginals treated the land like this:

Only small areas of land were cleared and new growth stimulated.

When the white people came they cleared big areas for their crops.

Click h er this wo e to see rkshee t!

This resulted in:

Irrigation salinity because of land clearing for crops.

No stimulation for new growth.

And so on...

Activity 2 As a class discuss and then write: Why is it important for us in Tasmania to address the problem of salinity now?

Write a letter to your regional national resource management group to express your concern about the problem of salinity, ask what is happening

and propose some actions. (Remember to explain your understanding of the problem.)

Or map out an action plan to show how the community can stop salinity becoming a bigger problem in Tasmania.

HOW CAN WE HELP KEEP OUR WATERWAYS HEALTHY? Part 4: Salinity

19

FOR STUDENTS

ENGAGE

The Story of Salinity Long ago, a long time before people came to live in Australia, because it is an island, and surrounded by the ocean, our land had lots of salt blown onto it.

This happened over many millennia.

The salt was absorbed into the soil where it remained, mostly contained deep under the surface. Lots of trees and plants grew everywhere; they were used to the salt and were not affected by it. The trees were also thirsty and soaked up almost every drop of rain that fell on the land. The underground water table which might have brought the salt to the surface remained deep down and the system was in balance.

About 40,000 years ago the Aboriginal people arrived in Australia. They lived in harmony with the country, moving around to find food as they needed

new sources of meat. They did not clear the land although they set fires occasionally to bring on new plant growth. The system was still in balance.

Then around 200 years ago European settlers arrived in Australia. European people were used to living in just one place and building houses to live in, so they settled in one area rather than moving around. They were also used to a different land so they did not understand the new land very well.

They still needed food for themselves and their animals, so they cleared the land for pasture by chopping down the trees. Sometimes they burnt the land at the wrong time of the year.

Some people brought new plants which became weeds, and other crop plants to grow instead of the native plants.

Aboriginal people

As more and more people lived on the land they needed to grow more crops so they used fertilisers, which helped the crops grow, but added salt to the soil.

As the land is dry they also used irrigation to help the crops grow. More people needed jobs and factories were built, to make things, and to provide jobs.

Sometimes the factories discharged material into the waterways.

All these changes combined together and the land started to change, perhaps for ever and the problem we call salinity started to make its effects felt.

Return to: PART 4, Lesson 2 - What has happened here?

FOR STUDENTS

EXPLORE

The Liquorice/ Salinity Game 1. What is it like to be a plant beside a stream that is going to be influenced by salt pollution? Lets find out.

Each of you is to pretend that you are a tree next to a stream. Each of you is a different tree species.

Your teacher may give you the name and picture of a local plant species to help you get into the part but remember that your plant may not actually be one that is affected by salt when it is in the environment.

Before land clearing, all the trees with their big long root systems used roughly the same amount of rain water as entered the groundwater system each year, so the groundwater level was in balance, and remained at the same depth in the soil each year. You are all trees next to a stream in a natural bush setting, untouched by humans, so there are lots of trees everywhere using the groundwater.

First you may have a piece of, normal sweet liquorice.

2. This liquorice represents the water that you, as trees, live off. The rain that you receive has some salt in it (because salty water gets blown in from the sea and there is some salt in the air near the coast) and, over millions of years this salt and the salt from rocks which dissolves in rainwater gets into the soil.

This has built up a lot of salt in the soil.

However, it is not a problem for you when the system is in balance and there are lots of trees like you keeping the groundwater at the same depth.

3. When humans clear the land for farming it does become a problem because all the trees are removed; and the crops don't use even half as much water as a big tree. Also, the roots of the crops are very shallow and don't use the groundwater as their roots don't reach it. So each year it rains there is too much water for the crops to use and the groundwater level rises closer to the surface. The store of salt that normally sits just above the groundwater level starts to be dissolved by the groundwater and the groundwater becomes

a little bit salty. This groundwater feeds into the streams which end up in big rivers, so everything goes a bit salty.

Now try some unsalted Dutch liquorice.

4.

A person has just bought the bit of bush and the creek you live on. The person has started to clear the trees to make paddocks.

Two trees leave because of the clearing process.

5.

The water in the stream is starting to reduce in quality. (If any students “die”) You who have died are very sensitive trees, and although beautiful, you can't handle changes in water quality.

Two or more trees “die” because they do not like the change in water quality, or , because they get old and die.)

6.

A few years have passed and you are the only trees left on the land. The farmer has noticed the level in his groundwater bore is only about 1m from the surface.

It used to be about 4m below ground.

Continues on next page!

Return to: PART 4, Lesson 5b - The Liquorice/Salinity Game

page 1/2

FOR STUDENTS

EXPLORE - The Liquorice/ Salinity Game Continuing from previous page The groundwater is getting quite salty, and the poor trees have to drink it everyday!

Now try the salted liquorice. Some trees will probably ‘die’.

7. You poor trees are not that salt tolerant.

There are even fewer trees left now to use up the groundwater, so the levels just keep getting closer and closer to the surface bringing with it all the salt that has built up in the soil over thousands of years. In some low-lying areas the groundwater has reached the surface, full of salt. The sun evaporates the water and leaves the concentrated salt on the surface. This is called a saltpan.

Now try the double salt liquorice. Don’t swallow it whole, chew it properly!'

8. You are looking a bit weak now and the insects are attacking you because you are weak. Imagine how it must be to only have salty water to drink.

Remember what salty water tastes like.

Most trees will die with the double salt.

9. Any remaining trees are fairly salt tolerant, and these trees are needed to plant in areas where it is a little bit salty and other flora won't grow. The salt problem is now affecting the whole farm, as the groundwater table is virtually at the surface. The farm can no longer grow crops. It has white salt on the crusty, bare soil surface, and in winter, the whole farm turns into mushy mud because it is waterlogged.

The creek is so sick that nothing lives in it anymore, only a few trees are surviving, although they are also pretty sick.

The problems are not going away.

Now try the “triple salt" liquorice!

10. You are the most salt tolerant 'trees' around and we should plant you all over the farms to help to reduce the groundwater levels. What was once a beautiful bit of natural bush has became a large area of salt. The creek is now virtually dead, along with the land.

Photograher: David Armstrong

? ? ? ? ? ?? ? some thin nkin ng questions 1. Imagin

e that you are th e farmer and see your tree s gradually dieing what mig ht you do to help the problem?

2. What do you think the commun ity should do now to help control this problem befo re it becomes any worse?

3. What’s happen ing to the fauna relying on the tr ees (e.g. possum s, birds, insects)?

4. Research whi ch trees in your local area are ac tually the most and/or the least salt tolerant.

How could you us e this knowledge?

5. Record your ideas in your science journal.

Return to: PART 4, Lesson 5b - The Liquorice/Salinity Game

page 2/2

FOR TEACHERS

EXPLORE

Riparian Plant Species Weed Plants • Crack Willow - Salix alba X fragila • Gorse - Ulex europaeus • Ragwort - Senecio jacobea • Boneseed - Chrysanthemoides monilifera • Blackberry - Rubus fruticosus • Bracken Fern - Pteridium esculentum NOTE: Many of the plant species listed here are more common in the wetter parts of Tasmania and may not occur in low rainfall areas such as the Midlands.

Native Plants - although not all are endemic.

Ferns and grasses • Alpine waterfern - Blechnum penna-marina • Fishbone waterfern - Blechnum nudum • Sagg - Lomandra longifolia • Cutting grass - Gahnia sp.

• Tall Sedge - Carex appressa var. virgata Shrubs and ground covers • Box micrantheum - Micrantheum hexandrum • Pink swamp heath - Sprengelia incarnata • Bauera - Bauera rubioides • Mint bush - Prostanthera sp.

• Dogwoods - e.g. Pomaderris apetala and elliptica • Musk - Olearia argophylla • Stinkwood - Zieria arborescens

Small trees • Blanket Leaf - Bedfordia salicina • Cheesewood - Pittosporum bicolor • Dogwood - Pomaderris apetala • Yellow bottlebrush - Callistemon pallidus • Woolly tea tree - Leptospermum lanigerum • Swamp melaleuca - Melaleuca sp.

Larger Trees • Blackwood - Acacia melanoxylon • Myrtle - Nothofagus cunninghamii • Mountain Ash - Eucalyptus regnans • Swamp Gum - Eucalyptus ovata Reference Tasmanian Streambank Plants; Rae Glazik, Michael Askey–Doran, 2004 Guide to Flowers and Plants in Tasmania; Launceston Field Naturalists Club, 1981 Tamar Valley Weeds Strategy Group; www.weeds.asn.au/weeds/weeds_fr.htm

Willow Photographer: Jill Reade

Return to: PART 4, Lesson 5b - The Liquorice/Salinity Game

FOR STUDENTS

EXPLAIN

How tree clearing may cause dryland salinity BEFORE CLEARING

RAIN

Water taken up from soil, evaporates from leaves.

Trees also act as umbrellas.

AFTER CLEARING

Some water filters through to groundwater.

SAME AMOUNT OF RAIN GROUNDWATER LEVEL

More water filters through to groundwater.

Salty water emerges in low-lying areas.

GROUNDWATER LEVEL RISES AND DISSOLVES SALT IN SUBSOIL

Return to: PART 4, Lesson 6 - Why does salinity matter?

FOR STUDENTS

EXPLAIN

You don’t have to g et

wet but it’s more fu n

if you do!

Salt Watch (South Australia) Salinity Fact Sheet The two main causes of salinity problems in Australia are dryland salinity and irrigation salinity: in nity? tion of salts a tr n What is sali e c n o c r or rs to the vel of a rive Salinity refe le y it n li a s ad il. The water or so of the salt lo re u s a e m a t table is know abou water body s u f o t s o is ater. M owever, this h , l) C carried in w a (N e e total m chlorid refers to th y it salt or sodiu n li a S . . lt pe of sa ed salts e.g lv o s is d f only one ty o e on of a rang nate. concentrati and bicarbo m iu s s ta o p , magnesium y linity occur? ith naturall w How does sa t n e n ti n o a dry c lly not in Australia is at are usua th s it s o p e nd alt d ffect plant a a occurring s to s n o ti e a ncentr t is excessiv n te n o c sufficient co lt a vity. ival. When s nd producti la d n animal surv a ty li a ace, water qu the soil surf r it degrades a e n r o t a ases el of Salinity incre ed by a rise in the lev rally s u ca ringing natu b are usually s le b ta s rd wate concentrate is h T . e undergroun c a rf ent alt to the su ent depend m occurring s n o ir v n e ects the salt and aff and water. on that soil

Dryiand salinity is caused when the rising water-table brings natural salts in the soil to the surface. The salt remains in the soil and becomes progressively concentrated as the water evaporates or is used by plants.

One of the main causes for rising water-tables is the removal of deep rooted plants, perennial trees, shrubs and grasses and their replacement by annual crops and pastures that do not use as much water, allowing more water to pass through the soil profile to the water-table.

Both dryland and irrigation salinity can increase the amounts of dissolved salt entering adjoining rivers and streams.

The manipulation of rivers, dams and lakes can also increase waterway salinity by changing natural surface water and groundwater flows.

Irrigation salinity occurs when irrigation water soaks past the soil area where the plant roots grow, adding to the existing water-table.

The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries and the underground water-table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated.

Continues on next page!

Return to: PART 4, Lesson 6 - Why does salinity matter?

page 1/3

FOR STUDENTS

EXPLAIN - Salt Watch (South Australia) Salinity Fact Sheet Continuing from previous page

The main causes of salinity Land Use • Clearing of native vegetation for farming and housing.

• Deep-rooted perennial species such as mallee trees have been replaced with crops and pastures with shallower roots and different seasonal growth patterns.

• Irrigation practices, which use water inefficiently (such as overhead irrigation, flood irrigation and irrigating for long periods infrequently), allows large quantities of water to seep into the groundwater.

The water table rises bringing with it dissolved salts from the soil.

• Run-off, erosion and stormwater pollution can wash salts into the river system.

• The use of fertilisers, herbicides and pesticides.

Geomorphology • Australia is a dry continent with naturally occurring salt deposits.

• The River Murray system was once part of an inland sea.

• Weathering and erosion of rock.

• Wind-blown top soil, salt lakes and sea spray.

The imp ac

t of h

igh sali High sa nity linity ca n result environ in a me includin ntal, economic number of g: and soc • Loss ial impa • River of habit cts water b at for freshwa ecomes affectin ter flora native fauna (m too salt g local & y to drin and os adapted regiona for hum k, to live in fauna are not t l a w n • a s t e a Salt des r suppli nd • Wate troys co salt water). es r becom livestock. ncrete a w e hich can s unsuit as salty nd able for a f w f e a c t t e roads, b bitumen, r stunts and brid irrigatio • Trees uildings the gro n and • Corro ges. compou shrubs along th wth of plants. sion and nding th e river d • Wate b ie e erosion r becom lockage of pip and risin problems of ru , elines. es hard for wash er, whic n-off, g water in g h is a pr tables. clothe faster an o d requir s as it wears the blem es more m out (Deterg ent is le deterge ss effec tive in s nt. alty wat er.)

Continues on next page!

Return to: PART 4, Lesson 6 - Why does salinity matter?

page 2/3

FOR STUDENTS

EXPLAIN - Salt Watch (South Australia) Salinity Fact Sheet Continuing from previous page

How is salinity affecting Australia?

In Australia, up to 17 million hectares will be affected by dryland salinity by 2050, according to National Land and Water Resources Audit figures.

As well as the obvious impacts of dryland salinity on agricultural productivity and rural and urban infrastructure, stream salinisation also poses critical challenges for our irrigation systems, drinking water, rivers and related ecosystems Additional effects of salinity in Australia: • More than $130 million of agricultural production is lost annually from salinity.

• More than $6 million is spent every year on building maintenance related to salinity in South Australia.

• Salinity causes $9 million damage annually to roads and highways in south-west New South Wales.

• The area of salt affected land in Western Australia is increasing at a rate of one football field per hour.

• If salinity is not effectively managed within 20 years, the salt content in Adelaide's drinking water may exceed World Health Organisation standards for desirable drinking water in two out of every five days.

• Increased salinity could cause the extinction of approximately 450 species of native flora and 250 species of invertebrate water fauna in the Western Australian wheat belt.

How do you measure salinity?

Salinity meters measure electrical conductivity, which increases with the concentration of salt. The units used

by Waterwatch to measure salinity are microSiemens per centimetre (µS/cm).

What can y ou do to he lp control s • Revegeta alinity? te with deep rooted nativ • Protect n e vegetation ative vegeta . tion in your • Improve local area. irrigation in frastructure • Be waterw and techno ise (save wa logies. ter and use • Get invo it more effic lved locally iently). with Waterw atch.

Used with permission from Waterwatch South Australia www.sa.waterwatch.org.au/saltwatch.htm retrieved 1 Oct 2007

Return to: PART 4, Lesson 6 - Why does salinity matter?

page 3/3

FOR STUDENTS

ELABORATE

Salinity investigation student planning sheet CREST Investigation Planner (This planning sheet is used in several sections.)

My Investigation is:

Brainstorm - all the things that could affect this investigation

Choosing Variables I will change I will measure

Things I will keep the same

Return to: PART 4, Lesson 7 - How does salt affect seed germination?

FOR TEACHERS

ELABORATE

How does salt affect seed germination?

Teacher Background Information This investigation clearly shows the damaging effects of salinity (salt) on seed germination.

The process of germination is in itself a feature of this investigation. Before starting the investigation it would be useful to spend up to half a lesson looking at examples of dry and soaked mung beans (two each per student) to observe and discuss germination and the life cycle of seeds. Students can see a scar and tiny hole in the mung bean seed coat. Discuss the amazing fact that each mung bean seed contains all the energy and instructions required to create a whole new mung bean plant which, under the right conditions, will grow and produce more mung beans.

Preparation Purchase mung beans which are readily available from supermarkets or health food stores. Collect sufficient quantities of takeaway containers or plastic cups. Prepare salt solutions as a demonstration (it may be too time consuming and inaccurate for the children to prepare them) after they have decided on the amounts to be used.

Students will appreciate just how tiny are the quantities of salt the mung bean seeds can

tolerate, if they see the actual amount of salt being added to the water.

Grades 5 or 6 students can be involved in the calculations by writing them on the whiteboard or simply by discussing each step. Decide how you will allocate salt solutions to each student.

Making the salt solutions: 1. Perform this as a teacher demonstration for younger students or to save on time.

The table shows the amount of salt to add to demineralised water (ask a local secondary school laboratory technician or college for some demineralised water) to make various salt solutions.

2. Measure salt required into cup on scales.

Hint If the weight required is less than your scale’s smallest increment, measure out 2 or 4 times the amount, pour into a pile and use a knife to halve or quarter the pile.

3. Add salt to the measured volume of water and stir.

Choose the concentrations you want to use: Salt concentration (by weight*)

Grams of salt to add

Tap 0% 0.25% 0.5% 0.75% 1.0% 1.5% 3.5% (equiv. to seawater)

0g 0g 0.6g 1.3g 1.9g 2.5g 3.8g 9.1g

250ml

500ml 0g 0g 1.3g 2.5g 3.8g 5.0g 7.6g 18.2g

* Figures in this table have been rounded.

Example Salt to add = (concentration× weight of water) ÷ 100 e.g. for a salt solution of 0.25% concentration in 250 mls water = ( 0.25 x250) / 100 = 0.625g rounded down to 0.6g

Equipment • Demineralised or distilled water – i.e. water which has had any salts taken out of it.

• Table salt • Plastic cups or bottles • Accurate kitchen scales • Measuring cup (250ml or larger) • Small cup (for salt) • Teaspoon

Continues on next page!

Return to: PART 4, Lesson 7 - How does salt affect seed germination?

page 1/2

FOR TEACHERS

ELABORATE - How does salt affect seed germination?

Continuing from previous page.

Some other hints for the experiment itself 1. Each student can prepare a dish, add a label (see below) and salt solution. It is a good idea to check each dish before allowing students to add the salt solution to ensure labels match the solutions.

2. Fold two sheets of paper towel in half two times to produce a square eight sheets thick.

Use the (takeaway) container to mark a circle on the top sheet.

3. Cut paper towel into circle 4. Add label to dish (see below for suggested label details). Use an eyedropper or pipette to moisten paper towel – drain off any excess water.

Suggested label information: Mung Bean Germination Experiment Salt (NaCl) Concentration: ________________________________________________

Adding Mung Bean seeds and allocating solutions The table below suggests the number of dishes to allocate to each salt concentration for various numbers of students in your class.

You could allocate these randomly by drawing them from a box and giving one to each student.

Note The tap water and the very strong salt solutions are controls.

Salt concentration Number of dishes Class of 18 Class of 27 No water (dry) Tap water 0% 0.25% 0.5% 0.75% 1.0% 1.50% 3.5%

1 2 2 3 3 2 2 2 1

1 3 3 4 4 4 4 3 1

Class of 30 1 4 4 5 5 4 4 2 1

3. Space mung beans evenly apart on paper towel.

4. Store in a well lit area but away from direct sunlight to avoid the paper towel drying out – observe daily for next 4 to 7 days.

Note Move dishes carefully to ensure the beans do not roll around – separate any beans that have rolled into each other after moving the container.

Reference: Lesson 12 – Germination Experiment Page 5 © 2006 ABC Science Online www.abc.net.au/science/ Retrieved 28th July 2007

1. Use a flat surface and a playing card or piece of thin cardboard to count and separate beans quickly. Use container lids to collect and carry beans to desks .

Date: _________________________ Prepared by: ____________________

2. Carefully place mung beans on paper towel with tweezers.

Return to: PART 4, Lesson 7 - How does salt affect seed germination?

page 2/2

FOR STUDENTS

EVALUATE

This is the problem - what do we do now?

Create a cartoon or flow chart to show how salinity has become a problem in Tasmania

Way back in time:

Nature untouched.

Then the aboriginal people came:

When the white people came they cleared big areas for their crops.

The aboriginal people treated the land like this:

Only small areas of land were cleared and new growth stimulated.

This resulted in:

Irrigation salinity because of land clearing for crops.

No stimulation for new growth.

And so on...

Do drawings or find pictures explaining what salinity can look like.

Return to: PART 4, Lesson 8 - This is the problem - what do we do now?