杭州湾海洋垃圾污染的调查与分析

Investigation and analysis of marine litter pollution in Hangzhou Bay

海洋垃圾除了对海洋野生动物和生物多样性具有显著影响外,还会造成严重的环境和经济问题。为了解和缓解海洋垃圾问题,海洋垃圾调查是必要的。2023年4月,利用专业海洋环境调查船对杭州湾海域开展了海面漂浮垃圾和海底垃圾同步调查,2022年7月-10月完成了杭州湾口4个断面的海滩垃圾调查。调查结果显示:杭州湾海域大块、特大块海面漂浮垃圾的平均个数为414个/km^(2),中、小块海漂垃圾为8446个/km^(2),海底垃圾为10301个/km^(2);杭州湾中、小块海面漂浮垃圾的平均密度为0.56 kg/km^(2),海底垃圾为70.22 kg/km^(2)。杭州湾内各点位的海面漂浮垃圾个数和密度明显高于杭州湾外围点位;杭州湾外围点位海底垃圾个数和密度明显高于湾内点位。塑料类垃圾是杭州湾海洋垃圾中数量最多的垃圾类型,占总数的一半以上。杭州湾海面漂浮垃圾数量明显高于全国平均值,密度却远低于全国平均值,存在着“小块化、轻质化”特征。通过清洁海岸指数(clean-coast index,CCI)和塑料丰度指数(plastic abundance index,PAI)评估了调查海滩的清洁度和塑料垃圾污染程度,结果显示,4个调查海滩均属于非常清洁等级,PAI指数显示岱山县的九子沙滩和鹿栏晴沙属于塑料垃圾丰度非常低的等级,而舟山市的朱家尖沙滩、嵊泗县的基湖沙滩属于塑料垃圾丰度低的等级。

Besides having a significant impact on marine wildlife and biodiversity,marine litter can cause serious environmental and economic problems.To understand and alleviate marine litter problems,investigations on marine litter are essential.In April 2023,a simultaneous survey of floating litter and seabed litter was conducted in the waters of Hangzhou Bay using a professional marine environmental survey vessel,and during July to October 2022 a beach litter survey was conducted in four sections of the Hangzhou Bay.The results showed that the average abundance in the studied area was 414 items/km^(2) for large to extra large floating litter,8446 items/km^(2) for medium-size floating litter,and 10301 items/km^(2) for seabed litter.On average,the floating litter in Hangzhou Bay recorded 0.56 kg/km^(2),and 70.22 kg/km^(2) for seabed litter.The abundance and weight density of floating litter were higher in the inner part of Hangzhou Bay than those in the outer,while for seabed litter the result was reversed.Plastic debris was the most abundant type of marine litter in the area,accounting for more than half of the total abundance.In comparison,the abundance of floating litter in Hangzhou Bay was significantly higher than the national average,but the weight density was lower than the national average,which suggested an overall feature of“small pieces and light weighted”.Assessment for beach cleanliness and degree of plastic debris pollution based on the CCI and PAI indices showed that the four surveyed beaches all reached level“very clean”,Jiuzi beach and Lulanqingsha beach in Daishan county were classified under the category of“very low abundance of plastic debris”,and Zhujiajian beach in Zhoushan city and Jihu beach in Shengsi county under the category of“low abundance of plastic debris”according to the PAI index respectively.