近30a来长江口海域生态环境状况变化趋势分析

在过去近30a监测结果基础上,对长江口海域生态环境变化趋势进行了分析。结果表明,近30a来,长江口海域水体中无机氮和活性磷酸盐呈现上升的趋势,重金属(铜、铅、镉和总汞)在一定范围内波动;浮游生物的种类数年际变化较大,浮游植物中硅藻比例有所下降,甲藻所占比例有所上升,浮游动物中桡足类的比例下降。讨论了长江径流输沙量与环境因子之间的相关性,发现硅酸盐的含量与输沙量呈显著正相关,且硅酸盐的减少与海域硅藻比例的减少具有一定相关性。长江口及其邻近海域环境与生态状况有所下降,特别是本世纪以来,海域的主要污染物仍为无机氮和活性磷酸盐,生物状态基本稳定在一个较低的水平上,近年来虽偶有波动,但没有明显改善的趋势。

The environment variation trend in the Changjiang River Estuary in the past 30a

This paper analyzed the environment variations trend in the Changjiang River estuary based on the monitoring results during about 30a. It indicates that during the past 30a, the inorganic nitrogen (DIN) and inorganic phosphate (DIP) concentrations increased, and the heavy metal elements (copper, lead, cadmium and total mercury) fluctuationed. Plankton species changed largely, the diatoms proportion declined, and the pfiesterias proportion rose. The copepod proportion of the zooplankton declined, but the community structure kept stable. Analysis of the correlation between the environmental factors (DIN, DIP, DSi) and sediment discharge showed that the DSi concentration positively correlated with sediment discharge, and positively correlated with diatoms proportion. The quality of the ecological environment in Changjiang estuary declined, particularly in this century, and DIN and DIP were the main pollutants.