Pollution Characteristics,Source And Ecological Risk Assessment Of Pesticides In Northwest Of Taihu Lake Basin

Pesticides play a prominent role in protecting plants from pathogens,fungi,insects and weeds.However,oversue of pesticides may cause water pollution and ecological toxicity,which has aroused widespread concern.Simultaneous analysis of 37 pesticides using solid phase extraction-liquid chromatography-mass spectrometry were established.This paper systematically studied the pollution characteristics of pesticides in rivers and lakes in the northwestern Taihu Basin.The occurrence characteristics of pesticides in fish ponds,livestock and poultry farms and sewage treatment plants were investigated,and the cluster analysis method was used to explore the potential sources of pesticides in surface water.The risk levels of pesticides were analyzed by calculating risk quotient in order to evaluate the risks of single pesticide and mixed pesticides in the water environment in the northwest of Taihu Lake Basin.The purpose of this paper is to provide data basis and scientific support for promoting the improvement of water environment quality,realizing the restoration of water ecology and the improvement of water ecological function in Taihu Lake Basin through scientific research methods.The main conclusions are as follows:(1)The results showed that 17 kinds of pesticides were detected in the surface water of northwestern Taihu Lake Basin in 2018.Carbendazim,isocarbophos and imidacloprid were the main pollutants.Water bodies with severe pesticide pollution in surface water include Gehu Lake,Zhushanhu Lake,Luhenghe River,Sanshangang River.The total order of pesticide concentration in surface water in different seasons were as follows: March > August > June > November.(2)There were 14 kinds of pesticides detected in 2019,imidacloprid,carbendazim,thiamethoxam and parathion were the main pesticides.In terms of seasonal variation,the detection levels of pesticides were in the order of: March > August > November > June.Pesticide pollution in 2019 was reduced compared to 2018: the average concentration of pesticides in March,June and August was reduced to varying degrees,indicating lake pollution was significantly improved.The differences in the spatial and temporal distribution of pesticides might be related to factors such as climate,crop types and growth conditions,human practices,and other factors.(3)A total of 11 pesticides were detected in potential sources.The concentrations of dichlorvos,parathion,acetamiprid,imidacloprid and thiamethoxam were relatively high.According to the results of cluster analysis,sewage treatment plants and livestock and poultry farms were the main potential sources of pesticides in surface water,such as Yong'anhe River,Wunanhe River and Wujingang River,Taige Canal,as well as in Gehu Lake and Zhushanhu Lake.(4)The results of the risk quotient calculation indicated that carbofuran,methomyl,carbendazim,dichlorvos,parathion,isocarbophos and phoxim in surface water have potential high risks to aquatic organisms.Dichlorvos,parathion and carbendazim showed high risk levels in the potential sources.The mixed risk of pesticides in most monitoring sections showed high risks.