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利用2000年～2001年杭州湾交通通道工程海域环境调查与监测、大小洋山海域跨海大桥和码头建设以及宁波镇海炼化项目的环境影响评价资料,结合浙江省海洋污染基线调查的成果,分析了杭州湾丰水期主要污染因子的分布变化规律及其成因,结果表明:(1)杭州湾海域水质受陆源影响显著,面源和无组织排放的污染物以及沿岸径流携带入海的污染物,使水体处于严重的富营养化状态。(2)无机氮、活性磷酸盐是丰水期杭州湾海域水体的主要污染因子,其在水体中的含量从湾顶至湾口逐渐降低。无机氮在水体中的含量较高,均超过四类海水水质标准;活性磷酸盐在水体中的含量在湾顶和湾中段超过四类海水水质标准,在湾口段超过三类海水水质标准。(3)化学需氧量和石油类物质也是丰水期杭州湾海域水体重要的污染因子,湾顶段的化学需氧量、石油类物质平均含量超过二类海水水质标准。石油类污染物质含量呈现湾中段低,湾顶段和湾口段高的分布态势,表明石油类污染物质的含量除了受陆源排污的影响外,还与各类船舶及大型石化企业等长期排污有密切关系。(4)由于钱塘江潮汐的作用,杭州湾海域水体交换剧烈,湾内高含量的悬浮物质一定程度上促进了水体中污染物质的降解。
Based on the environmental impact assessment of sea environment survey and monitoring of Hangzhou Bay traffic channel project from 2000 to 2001, the construction of large and small Yangshan sea-crossing bridges and wharfs and the environmental impact assessment of Ningbo Zhenhai Refining and Chemical Industry Project, and the results of the baseline survey of marine pollution in Zhejiang Province The results showed as follows: (1) The water quality in the Hangzhou Bay was affected by the terrestrial sources significantly. The pollutants discharged from the surface and the unorganized areas as well as the pollutants carried by the coastal runoff into the sea, The water is in a serious eutrophication state. (2) Inorganic nitrogen and active phosphate are the main pollutants of Hangzhou Bay waters during the wet season, and their contents in the water body gradually decrease from the top to the mouth of Bay. The content of inorganic nitrogen in water body is higher than the four kinds of seawater quality standards. The content of active phosphate in the water body exceeds the four types of seawater quality standards in Baytop and Bay, and exceeds the three types of seawater quality standards in the Bayou section. (3) Chemical oxygen demand and petroleum substances are also important pollution factors of Hangzhou Bay waters during the wet season. The chemical oxygen demand and the average content of petroleum substances in Bay top exceed the second-class seawater quality standards. The content of petroleum pollutants showed a low distribution in the middle part of the bay, a high distribution in the bay top and the bayou section, indicating that the content of petroleum-based pollutants is not only affected by land-based pollutants, but also closely related to long-term sewage discharges of various types of ships and large-scale petrochemical enterprises relationship. (4) Due to the tidal effect of the Qiantang River, the exchange of water bodies in the sea of Hangzhou Bay was fierce. The high suspended matter in the bay promoted the degradation of pollutants in the water to a certain extent.