Study on the water environmental quality and algal bloom risk after heavy metal pollution accident in the Xiannv Lake
In recent years,more and more water bodies have been subjected to the dual stress of eutrophication and heavy metal pollution,which has become an important problem for water environment management.Taking the Xiannv Lake in Jiangxi Province as an example,based on the environmental accident happened in 2016,the eutrophication,heavy metal pollution characteristics and phytoplankton community structure of the lake and the rivers were studied,the sources of heavy metal pollution in the basin was analyzed,and the risk of algal bloom in the water was assessed.The results showed as follows:(1)The total nitrogen pollution in Xiannv lake was serious,and the average concentration of total nitrogen was 1.88 mg·L-1,the ammonia nitrogen and total phosphorus reached the Class Ⅱ-Ⅲ standard of surface water,and the overall water body was at the level of mild eutrophication.(2)The characteristic pollutants Cd,TI and As,showed light pollution in the lake area and moderate or severe pollution in the river area.The water quality was not affected by the characteristic pollutants in wet and dry seasons after the event,However,the concentration of heavy metals Fe and Mn is higher in the basin,which was related to environmental background pollution.(3)Bacillariophyta and Pyrrophyta were dominant in the river of the Xiannv Lake,while Cyanophyta and Cryptophyta were dominant in the lake.Cyanophyta was overwhelmingly dominant in the lake during the wet season(summer),and the cell density of Cyanophyta was maintained in 107cells·L-1,which indicated a high risk of cyanobacterial bloom.(4)CCA showed that the density of phytoplankton was significantly affected by the characteristic pollutants of the event in the short term,but the influence of heavy metals was weakened with the passage of time,nitrogen and phosphorus were still the main influencing factors.(5)Strengthening environmental protection and management in the mining area of Xiannv Lake basin,controlling the input of exogenous nutrient load and developing scientific ecological breeding were effective measures to prevent and control the deterioration of the water environment and restore the balance of ecosystem in Xiannv Lake.
万方数据
维普
