杭州湾表层沉积物重金属污染现状及近期变化

The Current Status and Recent Changes in Heavy Metals Pollution in Surface Sediments of Hangzhou Bay

摘要: 基于杭州湾海域表层沉积物测试资料，揭示了重金属Cr、Cu、Zn、Pb、Hg、As、Cd的最新含量和分布特征现状，采用多元统计方法分析了其影响因素和主要来源，应用地质累积指数法和潜在生态风险指数法进行了污染状况和生态风险评价，根据多期资料对比，探讨了研究区重金属污染状况的近期变化。结果表明：研究海域重金属含量总体上呈中部高东西两侧低的平面分布特征，Cr、Cu、Zn、Pb、Cd受控于沉积物类型和有机质分布，以陆源输入为主，Hg、As主要来源于人为污染。地累积指数评价结果表明杭州湾海域总体处于清洁状态，北岸近岸和南部局部海域站点Hg和Cd具有中等潜在生态风险。Cr、Cu、Zn、Pb和Cd含量平均值在2008至2023期间总体表现为先下降后保持稳定的变化趋势，分别与沿岸地区工程建设、经济发展以及海域海洋开发活动和国家和地方加强污染治理、减少陆源排放有关。Hg和As在2008~2023年期间没有明显的变化趋势，今后应加强对研究区Hg、As和Cd含量和分布及其变化趋势的监测。

Abstract: Based on the testing data of surface sediments in Hangzhou Bay, this study reveals the latest content and distribution characteristics of heavy metals such as Cr, Cu, Zn, Pb, Hg, As, and Cd. Multivariate statistical methods were used to analyze their influencing factors and main sources. Pollution status and ecological risk were assessed using the geo-accumulation index method and the potential ecological risk index method. By comparing multi-period data, the recent changes in heavy metal pollution in the study area were discussed. The results show that the overall distribution of heavy metals in the study area is high in the middle and low on both the east and west sides, controlled by sediment types and organic matter distribution, with terrestrial input being the primary source for Cr, Cu, Zn, Pb, and Cd, while Hg and As mainly come from anthropogenic pollution. The geo-accumulation index assessment indicates that the Hangzhou Bay area is generally in a clean state, but the north shore near the coast and some sites in the southern part of the bay have medium potential ecological risks for Hg and Cd. The average contents of Cr, Cu, Zn, Pb, and Cd showed a trend of first decreasing and then stabilizing from 2008 to 2023, which is related to coastal construction, economic development, maritime activities, and the enhanced pollution control efforts by national and local governments to reduce terrestrial discharges. No significant trend was observed for Hg and As during 2008~2023. Future efforts should focus on strengthening the monitoring of the content, distribution, and trends of Hg, As, and Cd in the study area.