Analysis of eutrophication and measures for ecological restoration in Dianshan Lake

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.