长江口主要污染因子研究及富营养化状况评价

A Study on Main Pollution Factors and Evaluation of Eutrophic State of Yangtze Estuary

采用主成分分析法对2004年2、5、8、11月长江口海域的水质污染分别进行了分析，从10项水质污染指标因子中提取出水质污染的3～4个主要因子。研究结果表明，提取出的主成分因子累计可解释总方差的70％以上。主成分F1中，化学需氧量、无机氮和活性磷酸盐具有较高的荷载值，可认为是农业污染和生活污水污染的综合;主成分F2中，重金属，油类具有较高的荷载值，代表了石化废水和重金属污染；主成分F3和F4中，铜、铅等具有较高的荷载值，代表了重金属污染。长江口海域营养质量指数均值为3.548，海域营养水平总体上属于Ⅲ级富营养水平，说明长江13海域大部分水体己达到富营养化水平。

Principal component analysis （PCA） was used to analyze the water pollution status of Yangtze estuary in 2004, and 3～4 principal components were extracted from 10 pollution indices. The results showed that those main components cumulatively accounted for over 70% of the total variance explainable. In the component matrix, COD, active phosphate and inorganic nitrogen had high loads in principal component F1 that may be considered as contamination from agricultural activities and household sewage; heavy metals and oil had high loads in principal component F2 that may be regarded as pollution of petrochemical effluents; Cu, Pb and etc. had high loads in principal components F3 and F4 that represented the contamination of heavy metals. Besides, an average value 3.548 of nutritional quality index （NQI） indicated that the most waters of Yangtze estuary have been over-nutritive. In brief, the eutrophication and heavy metal pollution of Yangtze estuary have to be controlled strictly.