The eutrophication trend of Dianshan Lake was evaluated, according to water quality monitoring data from the lake, which were obtained by the Shanghai Water Environmental Monitoring Center from 2008 to 2010. The results show that eutrophication in Dianshan Lake has been alleviated since 2008, and there exist regional and temporal variations in eutrophication, which can be described as follows: (1) the concentrations of TN, TP, SS, and Chl-a, which are the main eutrophication indices of the lake, decreased from 2008 to 2010; (2) the concentrations of TN and TP and the overall trophic state index in the water intake area upstream of Dianshan Lake were higher than those in the outflow area downstream of the lake; and (3) the area of the blue-green algal bloom in Dianshan Lake has decreased every summer. The results show that eutrophication is least significant in the southeastern area of Dianshan Lake due to water purification and ecosystem recovery by aquatic plants in this area, the ecosystem in Dianshan Lake is gradually recovering, and some effects need to be eliminated in order to achieve stability and positive cycling of the ecosystem.%根据2008-2010年淀山湖水质监测数据,评价该湖富营养化趋势.结果显示,2008年后,淀山湖的富营养化程度呈改善趋势,但水体富营养化存在区域差异.主要表现在:①2008-2010年的整个湖区水体中主要的富营养化指标TN、TP、SS、Chl-a质量浓度均呈下降趋势；②淀山湖上游来水区水体中TN、TP质量浓度比下游出水区高,综合营养状态指数同样也高；③淀山湖每年夏季暴发蓝藻水华的水域面积在不断减小.结果表明,淀山湖东南区域富营养化程度最轻,水生植物对水体净化、生态系统恢复具有重要价值；淀山湖的生态系统在逐步恢复.为使生态系统能巩固并形成良性循环,一些影响因素亟待解决.
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