《塑膠圍港 2018香港海域塑膠分佈》報告 Greenpeace 綠色和平｜香港辦公室 by 綠色和平東亞分部 Greenpeace East Asia

塑膠圍港香港海域塑膠分佈

｜ 2O18

Microplastics and large plastic debris in Hong Kong waters

霍年亨博士、林詠玲、吳嘉洛、李憲杰、楊令衠、賈柊楠 Dr. FOK Lincoln, LAM Wing Ling, NG Ka Lok, LI Hin Kit, YEUNG Ling Chun, JIA Zhong Nan

摘要本報告記錄了綠色和平船艦「彩虹勇士號」於2018 年1月在香港水域採樣調查海洋垃圾的結果。此調查利用採樣工具網Manta net在香港水域沿岸共20 個採樣點，在海面收集樣本，再抽取塑膠垃圾並分析其大小、形態、類別、聚合物。結果顯示，全部採樣點均收集到微塑膠（0.355至4.75毫米）及較大塑膠碎片（>4.75毫米），濃度平均值（±標準誤差，SEM）分別

為每立方米2.936顆（n/m3）及0.202 顆（n/m3）。當

目錄 Table of contents

中微塑膠的聚合物主要屬聚苯乙烯（PS）及聚乙烯（PE）；並以聚苯乙烯泡沫（俗稱「發泡膠」）及透明薄膜等類型為主。有關結果與香港社會慣常使用

摘要 Abstract

P.2

引言 Introduction

P.3-4

研究方法 Methodology

P.5-6

於香港西部水域，反映出大量漂浮在香港水域的塑

分析結果 Result

P.7-10

膠垃圾有部分是由本地產生的。

結論及討論 Conclusion and Discussion

P.11-12

綠色和平倡議 Greenpeace recommendations

P.13-14

嗚謝 Acknowledgement

P.14

英文版 English version

P.15-24

附錄 Appendix

P.25

參考文獻 References

P.25-26

發泡膠容器及塑膠包裝的狀況吻合。研究結果顯示香港吐露港及東部水域錄得的微塑膠濃度，明顯高

引言

隨著需求日益增長，塑膠早已投入大規模生產，應用

香港是一個人口達740萬的大都會（香港特別行政區

範圍亦日益廣泛，例如護膚產品中的微膠珠（Masura

政府統計處，2018）。種種證據指出，香港已成為微塑

et al., 2015）及製衣業的合成纖維（Thompson et

膠污染熱點（Fok & Cheung, 2015）。本地社會廣泛

al., 2004; Browne et al., 2007）。過去數十年，全球

使用即棄塑膠產品，包括食品包裝及發泡膠食物容器

塑膠物料產量急劇增長，至 2017年已達到3.4 8億噸

（Fok & Cheung, 2015）。2017年，香港的都市固體

（PlasticsEurope, 2018）。近期有研究指出，超過

廢物達到392萬噸，當中20%為塑膠廢物（香港環境保

9 5%的人為海洋垃圾是塑膠碎片（G a l g a n i et a l.,

護署，2019）。雖然香港設有妥善的廢物管理系統，但

2015）。據估計，每年有多達115萬至241萬噸的陸上

香港全年降雨量高（2018年雨量為2163毫米，香港天

塑膠碎片，經由河流進入全球海洋（Jambeck et al.,

文台，2019b）加上颱風等驟起的風暴，或會引致一些

2015; Lebreton et al., 2017）。

未經妥善管理的塑膠垃圾流入海洋環境。除本地污染源頭外，珠江亦是香港水域塑膠污染的來源之一。珠江是中國其中一個最大型的流域，面積達 453,700平方公里（珠江水利委員會，2018）。在2016 年，中國的塑膠年產量達到8,300萬噸（中國國家統計局，2018）。其中廣東省生產了670萬噸塑膠原料。然而，Gu et al.（2017）指出，中國農村地區的廢物管理發展落後。管理不善的塑膠廢物經由地表徑流進入河 © Greenpeace

流，最終落入南中國海（Cheung et al., 2018）。

颱風「山竹」過後，大批塑膠垃圾隨着海水湧上岸。

微塑膠是直徑小於5毫米的塑膠微粒（Ar thur et al., 2009; Kershaw et al., 2015）。它們或由於工業及商業應用而被直接製造出來（原始微塑膠），亦可能是大型塑膠經由海浪沖刷、水解，微生物降解及光降解等在環境中分裂（次生微塑膠；Wright et al., 2013）。現行污水處理系統無法完全隔除污水中的微塑膠（Brown et al., 2007），部分塑膠碎片，特別是體積細小的微塑膠，因而流入海洋環境。由於微塑膠的大小及外觀與沉積物

和浮游生物相似，有多項研究發現，多種生物曾誤食微塑膠（Blight & Burger, 1997; Gregory, 2009; Cole et

為調查香港沿岸水域塑膠污染的嚴重程度，本研究旨

al., 2013）。生物誤食微塑膠不僅可導致內傷及阻塞腸

在研究吐露港、香港東部及西部水域中，水面上的塑

道，亦可導致生育率及逃避捕食者的能力下降（Laist,

膠垃圾濃度及分佈。另亦會研究在香港水域發現的

1997; Derraik, 2002; Gregory, 2009）。此外，微塑膠

塑膠之大小、形態、類別、聚合物。由於本研究在旱季

會吸附化學物質或有毒物質，並作為傳輸污染物的載體

（2018年1月）進行，故所得數據並不代表香港水域中

（Andrady, 2011; Frias et al., 2010）。

微塑膠和較大塑膠碎片的全年平均濃度。

研究方法

2.1

採樣

使用兩個拖網同步採樣，並以2節的船速在水面拖

毫米（Cheung et al., 2018）（圖2）。本研究根據

行20分鐘，然後將網拉回船上徹底沖洗，而各囊網

Hanvey et al.（2017），將前4個級別的塑膠定義為

本研究在香港沿岸水域共選取了20個採樣點（圖1），

的內容物隨後保存在密封塑膠袋中，再送交實驗室

「微塑膠」，第5級別則為「較大塑膠碎片」。

其中3個位於吐露港（採樣點T1至T3）、6個位於東部

分析。

水域（採樣點E1至E6），其餘屬西部水域（採樣點 W1至W11）。採樣工作於2018年1月進行（1月5日至

研究人員使用放大率最高達45倍的立體顯微鏡進行 2.2

樣本處理

8日及12日至15日）。按照Cheung et al.（2018）採用的方法，利用採樣工具網Manta net收集漂浮海

塑膠微粒的分類及計量。塑膠微粒按形態被劃分為五類，包括（1）聚苯乙烯泡沫（polystyrenefoam,PF）、

在實驗室內，研究人員使用經過濾的去離子水沖

（2）纖維（fibre,FB）、（3）薄膜（film,FL）、（4）碎片

面的碎片樣本，其矩形開口為0.87x 0.16平方米，並

洗樣本，並放入燒杯中。去除有機物質後進行大

（fragment,FM）及（5）顆粒（pellet,PL）。此外，塑

附以一個網眼為333微米的網，及一個可拆式囊網

小分級。塑膠碎片分為5個大小級別：（1）0.355 -

膠碎片亦會按顏色分為四類：（1）白色、（2）透明、

（cod-end）。此外，網口中央安裝了一個流量計，

0.499毫米；（2）0.500 - 0.709毫米；（3）0.710 -

（3）有色及（4）黑色。塑膠碎片經分類後，會被烘乾

以測量每次拖行時所過濾的水量。每個採樣點均會

2.749毫米；（4）2.800 - 4.749毫米及（5）≥4.750

再測量重量，精確至0.0001克。

W8 W7

2.3

分析結果

由於各採樣點均使用兩個拖網同步採樣，故會計算兩者的塑膠碎片平均濃度，並以平均數值作統計分析之用。數量及重量的數值均以每立方米（m3）表示，

圖1 香港水域的採樣點（T1至T 3位於吐露港；E1至E6位於香港東部水域；W1至W11位於香港西部水域。各採樣點的名稱及座標，請參閱英文版附錄）

FTIR）光譜儀分析。

即分別為「每立方米海水的塑膠物數量」（n/m3）及

擇碎片並使用衰減全反射傅立葉紅外線（AT R -

T2 T3

W10

為確定經分選的塑膠碎片之聚合物成分，隨機選

W11

「每立方米海水的塑膠物淨重量」（mg/m 3）。有關統計檢定方法詳情，請參閱英文版。 2.4

實驗質量控制（請參閱英文版）

分析結果

3.1

整體塑膠碎片濃度

所有採樣點合共收集到18,123件塑膠碎片，其中94.0%為微塑膠（0.355-4.749毫米）。較大塑膠碎片僅分別為不同聚合物

5 大類塑膠類型

佔6.0%。微塑膠中，濃度介乎0.191至20.8 n/m3，濃度總平均值（±SEM）為2.936 ± 1.211n/m3；淨重平均濃度則為0.263 ± 0.126 mg/m3。較大塑膠碎片中，整體數量與淨重的總平均濃度（±SEM），分別為0.202

非塑膠

6.7 %

3.2 0

料

微塑膠（0.355 - 4.749 毫米）- 東部水域錄得的微塑膠平均濃度最高（7.637n/m3），其次為吐露港

件

7, 泡 4 膠 29

材

原

件

（2.344 n/m3）及西部水域（0.534 n/m3）。此外，濃度中位數以東部水域最高（5.355 n/m3），西部水

發

（

塑膠碎片在不同水域的比較

）膠 .2 粒 %

% 0

塑

膠

纖 6件維

7. 4

薄

膠

塑

18.1 %

8件膜

11.4 %

件

0.7 %

PP, PP/EPR

2.2 %

其他塑膠

± 0.082 n/m3 及 2.496 ± 0.925 mg/m3。

硬膠 78 碎 4 片

未能確定

域最低（0.414 n/m 3）。較大塑膠碎片（≥4.750毫米）- 東部水域錄得的較大塑膠碎片平均濃度最高（0.549n/m3），其次為

在吐露港、東部水域及西部水域採集的微塑膠濃度

吐露港（0.110 n/m 3）及西部水域（0.038 n/m 3）。

微塑膠（0.355 – 4.749 毫米） PS

表1a

60.9 %

在吐露港、東部水域及西部水域採集的微塑膠（0.355-4.749毫米）及較大塑膠碎片（≥4.750 毫米）之數量（n/m3）數據摘要微塑膠（0.355 - 4.749 毫米）

吐露港

2.344 件/立方米

東部

7.637 件/立方米

西部

0.534 件/立方米

數量（n/m ） 3

不同地區的微塑膠濃度濃度（件/立方米 ±標準誤差）

香港沿岸水域

2.936 ± 1.211

香港沿岸水域（2015）

0.256 ± 0.092

東部

西部

吐露港

東部

西部

平均值最低值最高值

2.344 0.512 5.089

7.637 0.639 20.843

0.110 0.009 0.262

0.549 0.021 1.165

0.038 0.003 0.098

p 值a a

南中國海

東海沿岸水域

葡萄牙沿岸水域

0.045 ± 0.093

0.167 ± 0.138

介乎 0.002 - 0.036

較大塑膠碎片（≥4.750 毫米）

吐露港

0.534 0.191 0.895

0.103

0.016

採用Kruskal-Wallis H 檢定法，以測試吐露港及香港東西水域錄得的濃度中位數是否相等。微塑膠濃度比較錄得有顯著差異（p < 0.05）（見粗體數字）。

表1b

吐露港與東西水域以及香港東西水域之間的微塑膠濃度（n/m3）配對比較微塑膠（0.355 - 4.749 毫米）吐露港

數量（n/m3）

東部水域

西部水域

平均值最低值最高值

2.344 0.512 5.089

3.041 0.191 20.843

7.637 0.639 20.843

0.534 0.191 0.895

p 值a a

東西水域

0.315

0.012

採用Mann-Whitney U 檢定法，以測試濃度中位數是否相等。顯著差異（見粗體數字）僅見於香港東西水域之間的配對比較（p = 0.012 < 0.05）。

分析結果

3.3

可辨認的塑膠碎片之特徵

大小介乎0.355-4.749毫米的塑膠顆粒（即微塑膠）佔所有塑膠碎片的94.0%。按塑膠形態表3

類別劃分，則微塑膠多屬聚苯乙烯泡沫（即發泡膠）（42.3%），其次為碎片（21.5%）及

按塑膠形態類別劃分的微塑膠及較大塑膠碎片的數量

纖維（18.7%）。較大塑膠碎片則主要是纖維（48.8%），其次為聚苯乙烯泡沫（19.8%）及薄膜（19.6%）。顏色方面，白色的塑膠碎片佔最多（55.3%），黑色則最少（5.1%）。其

塑膠類型

中，微塑膠以白色為主（56.9%），塑膠碎片則多屬有色的（40.9%）。

聚苯乙烯泡沫（PF）纖維（FB）薄膜（FL）碎片（FM）顆粒（PL）

7951個經目測分類的物品中，選取905個（11.4%）以ATR-FTIR進一步分析其聚合物成分。結果合共鑑別出16種聚合物，當中以聚苯乙烯（PS）佔最多（60.9%），其次為聚乙烯（PE, LDPE, MDPE: 18.1%）及聚丙烯／乙丙橡膠（PP/EPR: 7.0%）。其他鑑別出的聚合物尚有聚

總數

整體

微塑膠（0.355-4.749 毫米）

較大塑膠碎片（≥4.750毫米）

數量

7,429 3,716 3,158 3,784 36

41.0 20.5 17.4 20.9 0.2

7,213 3,185 2,944 3,659 33

42.3 18.7 17.3 21.5 0.2

216 531 214 125 3

19.8 48.8 19.6 11.5 0.3

18,123

100

17,034

100

1,089

100

丙烯（PP: 4.4%）、三元乙丙橡膠（EPDM: 0.6%）、乙烯—醋酸乙烯酯（EVA:0.1%）（表4）。 A

圖 3 立體顯微鏡下鑑別出的微塑膠：(a)聚苯乙烯泡沫、(b)纖維、(c)薄膜、(d)碎片及(e)顆粒。比例尺代表1毫米。

表4

ATR-FTIR鑑別得出的聚合物

微塑膠是指直徑或長度少於5毫米的塑膠碎片，它們有不同的形態類別，例如碎片、纖維或薄膜等。

整體（樣本分類前）

表2

香港水域收集到的塑膠碎片的大小分布整體

吐露港

東部水域

西部水域

大小範圍（毫米）

數量

0.355 - 0.499 0.500 - 0.709 0.710 - 2.799 2.800 - 4.749 ≥ 4.750

5,325 4,847 5,224 1,638 1,089

29.4 26.8 28.8 9.0 6.0

816 594 702 167 106

34.2 24.9 29.4 7.0 4.5

3,735 3,502 4,342 1,357 850

27.1 25.4 31.5 9.8 6.2

774 751 180 114 133

39.7 38.5 9.2 5.8 6.8

總數

18,123

100

2,385

100

13,786

100

1,952

100

聚合物

數量

經檢測分析塑膠

905 824

100 91.1

1 聚乙烯 (PE), 低密度聚乙烯 (LDPE), 中密度聚乙烯 (MDPE) 2 聚丙烯 (PP), 聚丙烯／乙丙橡膠 (PP/EPR) 3 聚苯乙烯 (PS) 4 其他塑膠未能確定非塑膠

164 103 551 6 20 61

18.1 11.4 60.9 0.7 2.2 6.7

討論及結論

本研究顯示香港水域已受到塑膠污染。我們的研究發現，2018 年旱季的平均微塑膠濃度為2.936 ± 1.211 n/m3，數字大致高於2015年旱季進行的同類研究（Cheung et al., 2018），當時錄得的平均微塑膠濃度為0.256 ± 0.092 n/m3。

行，在一個月間錄得的結果並不能反映全年平均值，故或需要作進一步的調查，以顧及季節性的影響，才能更準確了解香港水域中微塑膠在不同時節及天氣之分佈。

其他研究提及不同地區的微塑膠濃度，與之比較，本研究錄得的微塑膠濃度水平亦高於其他受塑膠污染地區，包括南中國海（Cai et al., 2018）及東海沿岸水域（Zhao et al., 2014；

東部水域較西部水域錄得較高的微塑膠濃度。在全部20個採樣點中，錄得微塑膠濃度最高

表 5）。

的3個採樣點為E1、E4及E5，西部水域錄得的微塑膠濃度則介乎0.191至0.895 n/m3。這顯

表5

本研究與其他研究提及不同地區的微塑膠濃度之比較。本研究的資料以粗體表示。濃度研究地點香港沿岸水域

（n/m3 ± SEM） 2.936 ± 1.211

網眼尺寸 (微米)

季節

參考

Manta trawl

333

旱季

本研究

研究方法

示香港水域的塑膠碎片主要來自香港市內，例如市民亂拋垃圾、污水渠排放、海上運輸和工業活動（Tsang et al., 2017）。在3個調查區域中，吐露港錄得的微塑膠平均濃度為第二高，即2.344 ± 1.398 n/m3。吐露港為一個半封閉的淺水水體，目前已因運輸、廢物處理、拖網捕撈、養魚等人類活動而面臨

香港沿岸水域（2015）

0.256 ± 0.092

Manta trawl

333

旱季

Cheung et al., 2018

各種環境威脅（Owen & Sabdhu, 2000）。曾有研究指出，在封閉及半封閉區域會錄得較

南中國海

0.045 ± 0.093

Bongo trawl

333

旱季

Cai et al., 2018

東海沿岸水域

0.167 ± 0.138

Neuston net trawl

333

雨季

Zhao et al., 2014

高的微塑膠濃度（Barnes et al., 2009）。由於吐露港在旱季時需要長達38天時間沖刷淨

葡萄牙沿岸水域

介乎0.002 - 0.036

Neuston net trawl

280

未有提供

Frias et al., 2014

化，港口被陸地圍繞的情況經常導致水體天然分層現象（香港環境保護署，2016）。吐露港沖刷淨化需時，代表降雨帶來的碎片更容易囤積（香港環境保護署，2009），引致港內塑膠碎片濃度相對較高。

是次研究看到的微塑膠分佈，或是由於採樣工作首星期間曾降雨所致。降雨量對海洋環境中的塑膠碎片分佈起著重要作用（Ivar do Sul et al., 2013），因為風雨可以加劇陸地塑膠碎片轉移到海洋環境的情況。已有多項研究表明，微塑膠濃度在雨季時或暴雨後較高。Cheung et al.（2018）的一項研究發現，香港海面的平均微塑膠濃度在雨季時（6.124 ± 2.121 n/m3）高於旱季時（0.256 ± 0.092 n/m3）逾23倍。Moore et al（2002）亦曾發表研究報告指，美國加州南部沿岸水域錄得的塑膠碎片數量，在暴風雨後增加了6倍。上述研究證明，降雨量是影響微塑膠濃度的關鍵因素。本研究在2018年1月7日至8日採樣期間（即於東部水域取樣期間），分別錄得16.2毫米及11.6毫米的雨量。根據香港天文台（2018a）資料，2018年1月的月降雨量為62.2毫米，而在東部水域的取樣點一帶，1月7日

在本研究中，聚苯乙烯泡沫（發泡膠）（PF）為最主要的微塑膠類別（42.3%），並佔白色微塑膠的73.9%。香港兩項研究亦曾有類似發現，分別指出聚苯乙烯泡沫（發泡膠）為2014 年雨季在沙灘（40.7%）及2015年旱季在海面（92%）發現到的最主要微塑膠類別（Fok & Cheung, 2015; Cheung et al., 2018）。聚苯乙烯泡沫（發泡膠）廣泛應用於食品包裝及易碎物品保護包裝，因其容器價格廉宜、輕巧、防水及耐熱（Cheung et al., 2018）。此外，透明微塑膠（21.2%）是在香港水域發現的微塑膠中第二最多的顏色類別，其中分別有 55.8%及28.5%的透明微塑膠為薄膜及碎片。這與透明塑膠製品的常見用途相關，例如食品包裝（Zhao et al., 2014）。

錄得的降雨量介乎20至30毫米。西部水域的採樣工作在2018年1月12日至15日進行時，則未有錄得降雨量。這或許解釋了東部水域的平均微塑膠濃度，為何會明顯高於西部水域及高於Cheung et al.（2018）在2015年旱季錄得的水平。儘管如此，由於本研究於旱季進

綠色和平倡議

香港水域已遍佈主要來自香港的市內塑膠垃圾。綠色和平在香港沿岸水域共20個地點取

企業

樣，全部均採集到微塑膠和較大塑膠碎片，大部份屬聚苯乙烯(PS)及聚乙烯(PE)兩種主要用在即棄食品包裝的塑膠複合物，研究結果反映生產商和零售商過度包裝食品的問題，正正就是解決「塑膠圍港」的下一個主要戰場，而企業和政府亦必須立即行動作出改革。

綠色和平建議企業以減少使用塑膠為原則，改革產品包裝及銷售方式：訂立減塑目標及時間表，並承諾以減量而非回收作為解決方法，阻止塑膠圍港發生。

政府

減少不必要的產品包裝及提供無包裝銷售形式：不少預先包裝的食品使綠色和平建議，政府應趕上國際步伐，盡快訂立減塑目標、時間表及具體的行動方案：

用多層塑膠，常見於生果、蔬菜或禮盒裝的糖果零食。生產商及零售商應立刻從產品設計及銷售方面著手改革，減少甚至完全淘汰即棄塑膠包裝，並轉向以可重用或無包裝的形式販售。

首先立法管制使用難以回收的即棄塑膠，如即棄塑膠餐具、即棄發泡膠餐盒，長遠應全面禁止使用。針對市面的過度包裝塑膠，政府應盡快規管，如落實生產者責任制，要求生產商減少使用及回收其產品的包裝物料等。 © Greenpeace

定期檢驗香港海域、河流及飲用水中微塑膠含量，監控塑膠污染情況，並

過度包裝也是污染海洋元凶之一。

不少超市也會使用大量即棄塑膠來包裝新鮮蔬果。

公開檢測數據。

參考外國已經實行的例子，不少食品企業已經訂立3 -5年的減塑目標，而且重新設計產品包裝，儘量以其他物料取代即棄塑膠。在零售方面，更可設立無包裝的銷售區域，讓顧客按份量自備器皿購買，或是以可退

成立跨界別合作平台，與民間團體、商界及其他持份者定期交換意見，在

回的器皿售賣貨品。

各自範疇多推廣減用塑膠、善用資源，並且攜手加強公民教育，鼓勵市民針對即棄餐具，連鎖快餐企業須針對外賣的塑膠問題對症下藥，邁向走

在日常生活盡量少用即棄塑膠。

塑。例如提供外賣走塑優惠或不主動提供非必要的塑膠餐具。

鳴謝

特此鳴謝綠色和平船艦「彩虹勇士號」支持採樣工作，並感謝香港教育大學環境科學系的呂靜宜小姐、吳泳楠小姐、徐家美小姐、周藹銓小姐協助採樣及分析。

Abstract This report documents the results of a marine debris survey in Hong Kong waters carried out onboard the Greenpeace Rainbow Warrior vessel in January 2018. Water surface samples were collected by manta nets at 20 coastal locations in Hong Kong. Both microplastics (0.355 – 4.75mm) and large plastic debris (>4.75 mm) were detected from all sites with mean (± SEM) abundances of 2.936 ± 1.211 n/m3 and 0.202 ± 0.082 n/m3, respectively. Microplastics comprised 94.0% of the debris by number. Microplastic abundance was significantly higher in the Eastern waters than in the Tolo Harbour and the Western waters. Microplastics were predominately composed of

similarities in size and appearance to sediment and plankton species,

polystyrene (PS) and polyethylene (PE). White polystyrene foam and transparent film were the major microplastic

microplastic ingestion is common (Setälä et al., 2014; Farrel & Nelson,

types found in Hong Kong waters. This result correlates with the prevalent use of foam containers and plastic

2013; Lusher et al., 2013; Wright et al., 2013). Previous studies have

packaging in Hong Kong.

reported the ingestion of microplastics by a wide range of organisms (Blight & Burger, 1997; Gregory, 2009; Cole et al., 2013). The uptake of microplastics may lead not only to internal injuries and intestinal

Introduction

blockage, but also reduced fertility and predator avoidance (Laist, 1987; Derraik, 2002; Gregory, 2009). Furthermore, microplastics are prone to adsorb chemicals or toxic substances and therefore work as a vector for transporting pollutants in the environment and into the biota (Andrady,

Plastics are durable, corrosion and chemical resistant, cheap and

2011; Frias et al., 2010).

lightweight when compared to traditional materials, such as wood and metals (Laist, 1987). With a rising demand, plastics have been mass produced and increasingly used in a growing variety of applications, for

Hong Kong is a metropolitan city with a population of 7.4 million (Census

example, microbeads in skin care products (Masura et al., 2015) and

and Statistics Department of HKSAR, 2018). Evidence suggests the city

synthetic fabrics used for garment manufacturing (Thompson et al.,

is a hotspot of microplastic pollution (Fok & Cheung, 2015). Single-use

2004; Browne et al., 2007). Over the past few decades, the annual world

plastic products, including food packaging and foam food containers, are

production of plastic materials has increased dramatically and has reached

widely used locally (Fok & Cheung, 2015). In 2017, the annual amount of

348 million tonnes in 2017 (PlasticsEurope, 2018). Due to a culture of

municipal solid waste generated was 3.92 million tonnes, of which 20% was

disposability and inefficient waste management, disposal of plastic waste

plastics (HKEPD, 2019). Although Hong Kong has a state-of-the-art waste

becomes ordinary. Recent studies have shown that plastic debris made

management system, the high annual rainfall (2018 annual total rainfall:

up over 95% of anthropogenic litter in the oceans (Galgani et al., 2015). It

2163 mm; Hong Kong Observatory, 2019b) coupled with occasional flash

was estimated that between 1.15 and 2.41 million tonnes of land-based

flood-inducing storms such as typhoons, may deliver mismanaged plastic

plastic debris enters the world’s oceans every year from rivers (Lebreton et

waste into the marine environment. Apart from local sources, the Pearl

al., 2017). The end result is the ubiquitous presence of plastic debris in the

River is known to be one of the sources of plastic pollution in Hong Kong

world's oceans, amounting to over 5.25 trillion pieces floating on the sea

waters. The Pearl River is one of the largest catchments in China with an

surface (Eriksen et al., 2014). Owing to the rampant proliferation of plastic

area of 453,700 km2 (Pearl River Water Resources Commission, 2018).

debris in the marine environment, public and scientific awareness on the

In 2016, annual production of plastic materials in China amounted to

issue has been increasing.

83 million tonnes (National Bureau of Statistics of China, 2018). Among which, 6.7 million tonnes of plastic materials were produced in Guangdong

Microplastics are tiny plastic particles of less than 5 mm in diameter

Province. Nonetheless, Gu et al. (2017) indicated that waste management

(Arthur et al., 2009; Kershaw, 2015). They are either directly manufactured

in rural areas in China is under-developed. Carried by surface runoff,

for industrial and commercial applications (primary microplastics) or

mismanaged plastic waste enters rivers and eventually into the South

fragmented from larger debris through mechanical (including wave action

China Sea (Cheung et al., 2018).

and hydrolysis), microbial and photo-degradation in the environment (secondary microplastics; Wright et al., 2013). As above-mentioned, a

To investigate the severity of plastic pollution in the coastal waters of Hong

portion of plastic debris entered the marine environment due to leakages

Kong, this study aimed to examine the spatial variations in the abundance

in waste management systems. Microplastics can leak easily due to

of floating plastic debris in the Tolo Harbor, Eastern and Western waters

their size. The current water treatment systems are unable to remove

of Hong Kong. Moreover, the abundance, sizes, colors and compositions of

microplastics in sewage completely (Brown et al., 2007). Due to their

plastic debris found in Hong Kong waters were analysed.

Methodology

and ‘large plastic debris’, respectively, according to the terminology of microplastic quantification proposed by Hanvey et al. (2017).

Reduce the speed of Rainbow Warrior to 2 knots

2.1

Record sampling time, location, seawater salinity, and weather conditions

Deploy two Manta nets on the sides of Rainbow Warrior and trawl for 20 minutes to sample microplastic from the sea surface

Digestion and size fractionation of samples

In the laboratory, samples were rinsed with filtered deionized water and place into beakers. To remove

Examine and categorise samples into 5 types of microplastics in the laboratory

Sampling

In this study, a total of 20 sites were selected in the coastal waters of Hong Kong. Three of them are located in the Tolo Harbor (site T1 to T3), six in the Eastern waters (site E1 to E6), while the rest in the Western waters (site W1 to W11). Sampling was conducted on January 5th to 15th, 2018 with a break between January 9th and 11th. Following the method adopted by Cheung et al. (2018), floatable marine debris samples were collected by manta nets (Ocean Instruments Inc., San Diego, USA) which have a rectangular opening of 0.87 x 0.16 m2. The net frame was attached to a net and a detachable cod-end with a mesh size of 333μm. A flowmeter (General Oceanics Inc., Model: 2030R) was also mounted in the center of the net mouth for measuring the volume of water filtered in each tow. At each sampling site, two trawls were carried out in parallel. To avoid the collection of non-representative samples affected by ship wakes, the nets were deployed out of and faced away from the ship’s wake zone. The nets were towed at the air-sea interface for 20 minutes at a speed of 2 knots. The nets were then lifted onboard and thoroughly rinsed with seawater from the outside, with a direction starting from the net mouth downward to the cod-end. Contents retained in each cod-end were transferred to a labelled, sealable plastic bag with deionized water, mixed with 30% formalin and stored for laboratory analysis. 2.2

Use FTIR spectrometer to analyse the composition of microplastics

T2 T3

W11

W10 W4

W9 W8 W7

Fig. 1. Sampling sites in Hong Kong waters. Sites T1 – T3 are located in the Tolo Harbor; sites E1–E6 are located in the eastern coastal waters of Hong Kong; sites W1–W11 are located in the western coastal waters of Hong Kong. See Appendix for the geographical coordinates of sampling sites.

organic materials, the samples were placed on a hotplate stirrer and treated with 30% hydrogen peroxide (H2O2) solution at 60 to 65°C for 24 to 72 hours. Digestion is considered as completed when the solution turns clear or yellow, and there is no visible particulate organic matter (Davidson & Dudas, 2016). Size fractionation was carried out after the completion of digestion. Each of the samples was poured through a stack of stainless steel wire mesh sieves (aperture size: 0.355, 0.5, 0.71, 2.8 and 4.75 mm), enabling plastic debris to be fractionated into five size classes: (1) 0.355 – 0.499 mm; (2) 0.500 – 0.709 mm; (3) 0.710 – 2.749 mm; (4) 2.800 – 4.749 mm and (5) ≥4.750 mm (Cheung et al., 2018). In this study, plastic items in the first four classes and the last class are regarded as ‘microplastic’

2.3

Density separation and visual sorting

All floating particles were separated from the saturated saline solution via floatation. Samples within the first two classes (i.e. 0.355–0.499 and 0.500–0.709 mm) were subsampled using a Folsom plankton sample splitter (Aquatic Research Instruments, USA) and vacuum filtered through a mixed cellulose ester filter (Advantec, Japan, diameter: 47 mm, pore size: 0.45 μm). The filters were sealed in petri dishes with lids and oven dried at 60°C for 24 hours. Classification and numeration of particles were carried out under a stereo-microscope at up to 45X magnification (Olympus, Tokyo, Japan, Model: SZ61). Plastic particles were classified and counted into five categories, including (1) polystyrene foam (PF), (2) fibre (FB), (3) film (FL), (4) fragment (FM) and (5) pellet (PL), based on the visual identification criteria suggested by Hidalgo–Ruz et al. (2012) and Cheung et al. (2016). Aside from this, plastic debris was characterized by color and divided into four groups: (1) white, (2) transparent, (3) colored and (4) black. Moreover, samples in the remaining classes (i.e. 0.710–2.749, 2.800–4.749, and ≥4.750 mm) were rinsed from the sieves and re-suspended in tap water for visual identification. Items were visually sorted into the above mentioned categories and counted by naked eyes. The sorted plastic items were then oven-dried at 60°C for 24 hours and weighted to the nearest 0.0001g.

2.4

Verification of plastic items using ATR-FTIR

To determine the polymer composition of sorted plastic debris, debris was randomly selected and analyzed using an attenuated total reflection Fourier

Transformed Infrared (ATR–FTIR) Spectrometer (PerkinElmer Frontier, Schwerzenbach, Switzerland). All analyses were performed with 8 co-added scans in transmission mode in the spectra range from 4000 to 550 cm-1. Items with a search score ≥0.7 were accepted as a correct identification; items with a score <0.7 but ≥0.6 were classified as undefined; items with a score <0.6 were rejected and classified as non-plastic, following the method adopted by Yang et al. (2015). 2.5

Statistical analysis

As samples at each sampling site were collected by parallel trawling, the average concentration of two duplicates was calculated and used for statistical analysis. Values were expressed in cubic meter (m3), by number and weight using the concentration units of “the number of plastic items per cubic meter of sea water” (n/m3) and “the dry weight of plastic items per cubic meter of sea water” (mg/m3), respectively. Statistical tests were performed using IBM SPSS software (version 25). As the data did not approach a normal distribution (Shapiro-Wilk test: p-value < 0.05), non-parametric tests were performed. Differences among multiple groups were analyzed by the Kruskal– Wallis H Test (Kruskal & Wallis, 1952). If the test showed a statistically significant difference (p-value < 0.05), paired–comparisons were then conducted with the Mann-Whitney U Test (Mann & Whitney, 1947). 2.6

Quality control of experiments

To prevent aerial microplastic contamination during sample processing, the following measures were adopted. A cotton lab coat and nitrile gloves were worn at all times. All work surfaces and equipment, including laboratory glassware and sieves, were previously rinsed with filtered deionized water before use and thoroughly cleaned after each use. Equipment and samples were immediately covered with aluminum foil when they were not in use. In addition, H2O2 was filtered through a hardened ashless filter paper (Chmlab Group, Spain, Model: F2142-090, diameter: 90 mm, pore size: 20 μm) prior to use to remove particulates. Filter papers soaked with deionized water were placed in uncovered petri dishes and put in the work area to detect airborne contamination. The filter papers were then observed under a stereomicroscope. No plastic particles were found on any of the filters.

Results

3.1

Polymer composition

Overall plastic debris concentrations

A total of 18,123 plastic debris were collected from all sampling sites, of which 94.0% were microplastics (0.355 – 4.749 mm). Large plastic debris only accounted for 6.0%. In terms of microplastics, the concentrations by number ranged from 0.191 to 20.8 n/m3, with an overall mean (±SEM, standard error of the mean) concentration of 2.936 ± 1.211 n/m3, while the mean concentration by dry weight was 0.263 ± 0.126 mg/m3. In terms of large plastic debris, the overall mean (±SEM) density by number and dry weight were 0.202 ± 0.082 n/m3 and 2.496 ± 0.925 mg/m3, respectively (Table 1).

Plastic type

Table 1. Summary statistics of the densities of microplastics (0.355–4.749 mm) and large plastic debris (≥4.750 mm) by number (n/m3) and weight (mg/m3).

Non-plastic items

6.7 %

60.9 % 2.344 n/m

Eastern Water 3

7.637 n/m

Western Water 3

0.534

n/m3

Overall 20

2.936 1.211 0.761 0.897 0.191 20.844

0.202 0.082 0.049 0.116 0.003 1.165

Weight a (mg/m3)

Mean SEM Median IQR Minimum Maximum

0.263 0.126 0.041 0.206 0.005 2.356

2.496 0.925 0.565 4.410 0.001 16.884

The weight data of microplastics only includes those in the range of 0.710 – 4.749 mm.

3.2 Tolo Harbour

Large plastic debris (≥4.750 mm)

Overall 20

Mean SEM Median IQR Minimum Maximum

Microplastic densities in different regions

Microplastics (0.355 – 4.749 mm) Number (n/m3)

0 es ec

P 3 6 elle t

|1 3 , br 71 e 6

ec pi

F 3 , ilm 15 8

18.1 %

% 7. 4

F 3 , ra g 78 m 4 e

0.7 %

11.4 %

other plastics

|0 P .2 7, oly % 4 st 2 9 yr en pi e ec fo es | 4 am 1. 0 %

PP, PP/EPR

2.2 %

Undefined items

Spatial comparison of plastic debris concentrations

3.2.1. Microplastics (0.355 – 4.749 mm)

The highest mean density of microplastics by number was found in the

Eastern waters (7.637 n/m3), followed by the Tolo Harbour (2.344 n/m3) and the Western waters (0.534 n/m3; Table 2a). The median concentration was the highest in the Eastern waters (5.355 n/m3), while the lowest concentration was found in the Western waters (0.414 n/m3). The distribution of median concentration were significantly different among three investigated areas (p = 0.016). Specifically, a significant difference (p = 0.012) was observed in the distribution of median concentration for the

HK compared to other region

Density （n/m3 ± SEM）

Western and Eastern waters of Hong Kong (Table 2b). However, there was no statistically significant difference (p = 0.315 > 0.05)

Hong Kong coastal waters

Hong Kong coastal waters (2015)

South China Sea

Coastal waters of East China Sea

Portuguese coastal waters

2.936 ± 1.211

0.256 ± 0.092

0.045 ± 0.093

0.167 ± 0.138

0.002 - 0.036

between the Tolo Harbour (1.430 n/m3) and the combined dataset of the Eastern and Western waters (0.743 n/m3) with respect to their median concentrations (Table 2b). The comparisons of the mean and median concentrations by weight were similar to those by number. In general, the mean and median concentrations in the Eastern waters were higher than those in the Tolo Harbour and the Western waters. However, the comparison between three investigated areas did not show a significant difference (p = 0.239; Table 2a). 3.2.2. Large plastic debris (≥4.750 mm)

The highest mean concentration of large plastic debris by number was found

in the Eastern waters (0.549 n/m3), followed by the Tolo Harbour (0.110 n/m3) and the Western waters (0.038 n/m3; Table 2a). Similarly, the mean concentration by weight was the highest in the Eastern waters (4.984 mg/m3), followed by the Tolo Harbour (2.111 mg/m3) and the Western waters (1.245 mg/m3; Table 2a). Their median densities also followed the same pattern. Despite the fact that there were noticeable differences in the median densities by number and by weight, they were not significant.

Table 2a. Summary statistics of microplastic (0.355 – 4.749 mm) and large plastic debris (≥4.750 mm) densities in the Tolo Harbour, Eastern waters and Western waters of Hong Kong by number (n/m3) and weight (mg/m3). Microplastics (0.355 – 4.749 mm) N

cotton and animal wax, while the others were rejected items with a search score lower than 0.6. There was a total of 16 polymer types identified, polystyrene (PS) was the predominant type (60.9%), followed by polyethylene (PE, LDPE, MDPE: 18.1%) and polypropylene/ethylene propylene rubber (PP/EPR: 7.0%). Furthermore, other polymer types, including polypropylene (PP: 4.4%), ethylene propylene diene monomer (EPDM: 0.6%) and ethylene-vinyl acetate (EVA: 0.1%), were identified (Table 6).

Table 3.

Large plastic debris (≥4.750 mm)

Tolo

East

West

Tolo

East

West

Number (n/m3)

Mean SEM Median IQR Minimum Maximum pb

2.344 1.398 1.430 0.512 5.089

7.637 3.406 5.355 14.160 0.639 20.843 0.016

0.534 0.075 0.414 0.479 0.191 0.895

0.110 0.772 0.059 0.009 0.262

0.549 0.219 0.487 1.066 0.021 1.165 0.103

0.038 0.009 0.027 0.052 0.003 0.098

Weight a (mg/m3)

Mean SEM Median IQR Minimum Maximum pb

0.177 0.146 0.039 0.023 0.469

0.677 0.379 0.283 1.408 0.010 2.356 0.239

0.061 0.023 0.029 0.093 0.005 0.229

2.111 1.343 1.669 0.038 4.626

4.984 2.680 2.319 9.800 0.022 16.884 0.365

1.245 0.632 0.264 1.194 0.001 6.128

Size distribution of plastic debris collected from Hong Kong waters. Overall

Size range (mm)

0.355 – 0.499 0.500 – 0.709 0.710 – 2.799 2.800 – 4.749 ≥ 4.750

5,325 4,847 5,224 1,638 1,089

29.4 26.8 28.8 9.0 6.0

816 594 702 167 106

34.2 24.9 29.4 7.0 4.5

3,735 3,502 4,342 1,357 850

27.1 25.4 31.5 9.8 6.2

774 751 180 114 133

39.7 38.5 9.2 5.8 6.8

Total

18,123

100

2385

100

13,786

100

1,952

100

Type composition of microplastics and large plastic debris by number of items. Overall

Polystyrene foam (PF) Fibre (FB) Film (FL) Fragment (FM) Pellet (PL)

The weight data of microplastics only includes those in the range of 0.710–4.749 mm. Kruskal-Wallis H Test is used to test whether the median densities of the Tolo Harbor, Eastern waters and Western waters of Hong Kong are equal. A significant difference ( p < 0.05) (highlighted in bold) was found in the comparison of microplastic concentration by number.

Total

Table 2b. Paired-comparisons of microplastic concentrations by number (n/m ) between the Tolo Harbour and the combined dataset (Eastern and Western waters), as well as the Eastern and Western waters of Hong Kong. 3

Table 5.

Number (n/m3)

Combined dataset

East

7,429 3,716 3,158 3,784 36

41.0 20.5 17.4 20.9 0.2

7,213 3,185 2,944 3,659 33

42.3 18.7 17.3 21.5 0.2

216 531 214 125 3

19.8 48.8 19.6 11.5 0.3

18,123

100

17,034

100

1089

100

Color composition of microplastics and large plastic debris by number of items.

Mean SEM Median IQR Minimum Maximum pa

2.344 1.398 1.430 0.512 5.089

3.041 1.415 0.743 0.530 0.191 20.843

7.637 3.406 5.355 14.160 0.639 20.843

0.534 0.075 0.414 0.479 0.191 0.895

0.315

Transparent White Colored Black

West

Total

Table 6.

Mann-Whitney U Test is used to test whether the median densities are equal. A significant difference (highlighted in bold) only exists in the pairedcomparison of the Eastern and Western waters of Hong Kong ( p = 0.012 < 0.05). a

3.3

Characterization of identified plastic debris

Plastic particles (i.e. microplastics) in the size range 0.355 – 4.749 mm accounted for 94.0% of the total plastic debris. The majority of microplastics identified in the Tolo Harbour and the Western waters was smaller than 0.71 mm, representing 59.1% and 78.2% of the samples respectively. However, microplastics in size range 0.5 – 2.799 mm were the most abundant in the Eastern waters (56.9%; Table 3). Regarding the plastic type, polystyrene foam (42.3%) was the predominant type of microplastic, followed by fragment (21.5%) and fibre (18.7%). Fibre (48.8%) was the most abundant type of large plastic debris, followed by polystyrene foam (19.8%) and film (19.6%). Among the microplastics and large plastic debris, pellet was the least dominant type, accounting for 0.2% and 0.3%, respectively (Table 4). As to the colors, white plastic debris accounted

Microplastics (0.355–4.749 mm)

Large plastic debris (≥4.750 mm)

3,870 10,014 3,305 934

21.4 55.3 18.2 5.1

3,613 9,683 2,860 877

21.2 56.9 16.8 5.1

257 330 445 57

23.6 30.3 40.9 5.2

18,123

100

17,034

100

1089

100

Types of polymer identified by the ATR-FTIR. Overall

Polymer composition

0.012

Large plastic debris (≥4.750 mm)

Overall

Microplastics (0.355 – 4.749 mm)

Microplastics (0.355–4.749 mm)

Color Tolo

Western Waters

Plastic type

Eastern Waters

Table 4.

Tolo Channel

Items scanned Plastic itemsa

905 824

100 91.1

(1) Polyethylene (PE) (2) Low-density polyethylene (LDPE) (3) Medium-density polyethylene (MDPE) (4) Polypropylene (PP) (5) Polypropylene/ethylene propylene rubber (PP/EPR) (6) Polystyrene (PS) (7) Ethylene-vinyl acetate (EVA) (8) Ethylene propylene diene monomer (EPDM) Undefined itemsb Non-plastic itemsc

132 29 3 40 63 551 1 5 20 61

14.6 3.2 0.3 4.4 7.0 60.9 0.1 0.6 2.2 6.7

Items with a search score ≥0.7.

Items with a search score <0.7 but ≥0.6.

Items with a search score <0.6 and items made of non-synthetic materials.

for the majority (55.3%) of plastic debris, with black being the least dominant color (5.1%). Specifically, the predominant color of microplastics and large plastic debris was white (56.9%) and colored (40.9%; Table 5). Out of 7951 visually sorted items, 905 items (11.4%) were selected and analyzed by the ATR–FTIR for their polymer compositions. Among the selected items, 91.1% were identified as polymers (i.e. items with search score ≥0.7) and 2.2% were undefined items (i.e. items with search score <0.7 but ≥0.6). Only 6.7% of the selected items were non-plastic, most of them consisted of paper,

Fig. 3. Stereomicroscope images of identified microplastics: (a) polystyrene foam, (b) fibre, (c) film, (d) fragment and (e) pellet. Scale bars represent 1 mm.

Discussion and conclusion

This study revealed that Hong Kong waters are polluted by plastics. Our findings reported a mean microplastic concentration of 2.936 ± 1.211 n/m3 in 2018 dry season, which was an order of magnitude higher than a study conducted in Hong Kong waters in 2015 dry season (Cheung et al., 2018) and they reported a mean microplastic abundance of 0.256 ± 0.092 n/m3. Compared with the microplastic abundance in different regions reported in other studies, the level of microplastic concentration is also higher than other polluted regions, including the South China Sea (Cai et al., 2018) and the coastal waters of East China Sea (Zhao et al., 2014; Table 7).

Table 7. Comparison of microplastic concentrations between this study and other regions. Data of this study is highlighted in bold. Study Area Hong Kong coastal waters Hong Kong coastal waters (2015) South China Sea Coastal waters of East China Sea Portuguese coastal waters

Density (n/m 3 ± SEM)

Method

Mesh size (μm)

2.936 ± 1.211 0.256 ± 0.092 0.045 ± 0.093 0.167 ± 0.138 Range: 0.002–0.036

Manta trawl Manta trawl Bongo Trawl Neuston net trawl Neuston net trawl

333 333 333 333 280

Season

Reference

Dry season This study Dry season Cheung et al., 2018 Dry season Cai et al., 2018 Rainy season Zhao et al., 2014 Not stated Frias et al., 2014

fragile items. Containers made with polystyrene foam are

microplastics were films and fragments, respectively.

cheap, lightweight and water and thermal resistant (Cheung

This correlates with the common use of clear plastics in

et al., 2018). In addition, transparent microplastics (21.2%)

plastic production, such as food packaging (Zhao et al.,

were the second most abundant type found in Hong Kong

2014). More importantly, a regular monitoring program is

waters. Specifically, 55.8% and 28.5% of the transparent

needed to see what actions should be taken in the future.

Greenpeace Recommendations

Hong Kong waters are surrounded by plastic waste that is mostly generated by the city itself. Taking into account the high percentage of polystyrene (PS) and polyethylene (PE) in the samples, this research reveals the severity of plastic pollution originating from over-packaging. Government and Corporate action is needed immediately to tackle this issue.

Government Greenpeace calls on the government to develop a comprehensive action plan to reduce the use of single-use plastics with ambitious targets and a clear timeline for implementation. Specifically, the government should implement the following: Limit and in the long run ban the use of single-use plastic, particularly those that are difficult to recycle, such as disposable plastic tableware and disposable styrofoam containers. Implement a producer responsibility

The spatial difference observed for microplastic concentrations could be the result of rainfall during the first week of sampling .Precipitation plays an important role on the distribution of plastic debris in the marine environment (Ivar do Sul et al., 2013) because the translocation of land-based plastic debris to the marine environment can be accelerated by rain and wind (Zhou et al., 2015). Previous studies have shown that microplastic densities were higher in the rainy season or after heavy rainfall. A previous study by Cheung et al. (2018) found that the mean microplastic concentration recorded in the rainy

and spatial distribution of microplastics in Hong Kong waters.

scheme in order to reduce the single-use packaging materials directly from the source.

Microplastics were more abundant in the Eastern waters than in the Western waters. The concentrations of

Regularly monitor the microplastic concentration and distribution in Hong Kong waters, rivers and drinking

microplastics found in E1, E4 and E5 were the top three highest

water. Disclose the results publicly and make all test data available for public discussion.

among all 20 sampling sites, while microplastic concentrations in the Western waters ranged between 0.191 and 0.895 n/ m3. This finding suggests that plastic debris in Hong Kong

Establish a cross-sectoral collaboration platform to exchange views with community groups, the business

waters could mainly come from terrestrial sources, such as

sector and other relevant stakeholders on a regular basis to promote the reduction of plastics.

illegal dumping, sewage discharge, maritime transport and industrial activities (Tsang et al., 2017).

Corporates

season (6.124 ± 2.121 n/m3) was more than 23 times the dry

Among the three investigated areas, Tolo Harbour has the

season (0.256 ± 0.092 n/m3) in Hong Kong surface waters.

second highest mean density of microplastics as 2.344 ± 1.398

Greenpeace urges corporations to take immediate action to reduce unnecessary single-use plastics, including

Moore et al (2002) also reported a six-fold increase in the

n/m3. Tolo Harbour is a shallow semi-enclosed water body which

packaging and to provide alternative delivery systems to customers without reliance on wasteful packaging.

number of plastic debris after a storm in the coastal waters of

is currently under local environmental threats from a wide range

Specifically, corporates should implement the following:

southern California. These results indicate that precipitation

of human activities, such as shipping, waste disposal, trawling

is a critical control on microplastic abundances. During the

and fish farming (Owen & Sabdhu, 2000), and previous studies

Establish ambitious targets with a clear timeline for reducing single-use plastics, going for ’reduction’ rather

sampling period of 7th and 8th January 2018 (i.e. when samples

have reported a higher microplastic densities in enclosed and

than ‘recycling’ as the real solution to the issue.

were obtained from the Eastern waters), 16.2 and 11.6 mm

semi-enclosed areas (Barnes et al., 2009). Since Tolo Harbour

of daily rainfall was recorded respectively. According to the

has long flushing time of 38 days in the dry season, the harbour’s

Hong Kong Observatory (2018a), the monthly rainfall was

landlocked situation often leads to the natural stratification of the

62.2 mm in January 2018, and sampling sites located in the

water column. The long flushing time of Tolo Harbor means that

Eastern waters received precipitation with the range 20 to

debris generated by rainfall events will easily be trapped (HKEPD,

30 mm on the 7th January 2018. However, sampling in the

2009), which in turn cause a relatively higher concentration of

Western waters was conducted from 12th to 15th January

plastic debris within the harbour.

2018, when no precipitation was recorded. This can perhaps

In this study polystyrene foam was the dominant type

explain why the mean microplastic concentration was

of microplastic (42.3%), and it accounted for 73.9%

significantly higher in the Eastern waters than in the Western

of the white microplastics. Similarly, previous studies

waters, and why it was higher than the result recorded in the

conducted in Hong Kong also reported that polystyrene

2015 dry season by Cheung et al. (2018). Nonetheless, this

foam was the predominant form of microplastic in the

study was conducted during the dry season and microplastic

surface waters (40.7%) during the 2015 dry season and on

densities recorded in one month cannot represent the annual

beaches (92%) during the 2014 rainy season (Fok & Cheung,

average. Therefore, a further survey accounting for the effect

2015; Cheung et al., 2018). Polystyrene foam is widely used

of seasonality might be needed for a more accurate temporal

locally in food packaging and as protective packaging for

Reduce unnecessary packaging and invest in alternatives to single-use plastics: Many pre-packaged foods use multilayer plastic packaging, which is commonly found in fruit, vegetables or gift boxes. Manufacturers and retailers should immediately initiate reforms in product design and sales methods to reduce single-use plastics, while putting in place plans to completely eliminate these and move to reusable or unpackaged forms. With reference to examples already implemented in foreign countries, many food companies have set a 3-5 year target to reduce the use of single-use plastics, and have redesigned product packaging to replace disposable plastics with other materials. In the retail sector, it is also possible to set up a plastic-free area where customers can purchase with their own containers or by using containers provided by retailers that can be returned. Single-use plastic tableware should be eliminated but in the meantime, the fast food industry should adopt policies to incentivise the use of reusable tableware, for example by providing discounts to customers who request plastic-free take-away meals. Acknowledgement We acknowledge the support by the Greenpeace fleet Rainbow Warrior for sample collection. We are thankful to Ms. Lui Ching Yee, Ms. Ng Wing Nam, Ms. Tsui Ka Mei, and Ms Chow Oi Chuen from The Education University of Hong Kong, Department of Science & Environmental studies for their kind assistance in sample collection and analysis.

附錄 Appendix

Region Tolo Harbor

Eastern waters

Western waters

•

Farrell, P. & Nelson, K. (2013). Trophic level transfer of microplastic: Mytilus edulis(L.) to Carcinus maenas(L.). Environmental Pollution, 177, 1-3.

•

Fok, L., & Cheung, P. K. (2015). Hong Kong at the Pearl River Estuary: A hotspot of microplastic pollution. Marine Pollution Bulletin, 99(1-2), 112-118.

Coordinate Latitude (°E) Longitude (°N)

•

Frias, J. P. G. L., Sobral, P. & Ferreira, A. M. (2010). Organic pollutants in microplastics from two beaches of the Portuguese coast. Marine Pollution

22.453056 22.453444 22.469111 22.530250 22.521444 22.526333 22.401194 22.288306 22.216917 22.203139 22.185250 22.169833 22.205417 22.173278 22.171861 22.170806 22.188667 22.204028 22.243333 22.260944

•

Locations and names of all sampling sites in Hong Kong.

Site

Name

Sampling date

T1 T2 T3 E1 E2 E3 E4 E5 E6 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11

Tolo Channel Tolo Channel Tolo Channel Chek Chau North Chek Chau Northeast Tung Ping Chau West Cheung Tsui Chau South North Ninepin Island Northeast South Ninepin Island Southeast Chung Hom Kok Southwest Lamma Island Southeast Lamma Island Southwest Cheung Chau South Soko Island East Soko Island East Soko Islands West Fan Lau Southeast Fan Lau Northwest Tai O Southwest Tai O Northwest

6 January 2018 13th January 2018 6th January 2018 6th January 2018 7th January 2018 7th January 2018 8th January 2018 8th January 2018 8th January 2018 13th January 2018 13th January 2018 13th January 2018 12 th January 2018 12 th January 2018 12 th January 2018 12 th January 2018 14th January 2018 14th January 2018 14th January 2018 14th January 2018 th

114.245972 114.276639 114.300028 114.353389 114.390944 114.422944 114.407333 114.367528 114.435528 114.211167 114.172639 114.094083 114.017694 113.953083 113.951389 113.886944 113.873361 113.844222 113.834694 113.846944

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香港教育大學環境科學系：霍年亨博士、林詠玲、吳嘉洛、李憲杰、呂靜宜、吳泳楠、徐家美、周藹銓綠色和平東亞分部：楊令衠、賈柊楠 Department of Science & Environmental Studies, The Education University of Hong Kong: Dr. FOK Lincoln, LAM Wing Ling, NG Ka Lok, LI Hin Kit, LUI Ching Yee, NG Wing Nam, TSUI Ka Mei, and CHOW Oi Chuen Greenpeace East Asia: YEUNG Ling Chun and JIA Zhong Nan

2O18 綠色和平是一個全球環保組織，致力於以實際行動推動積極改變，保護地球環境與世界和平。 Greenpeace is a global, independent campaigning organization that uses peaceful protest and creative communication to expose global environmental problems and promote solutions that are essential to a green and peaceful future.

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