Ecological Risk Assessment of Pesticide Residues' Chronic Impacts in Taihu Lake

Taihu Lake is an important ecosystem in east China, and also an ecologically vulnerable region. Pesticide residues can be detected in Taihu Lake. Although the environmental concentrations are not high enough to harm the ecosystem acutely, the residues can pose potential risk to the ecosystem and human health because of their chronic impacts. It is necessary to assess the ecological risk induced by pesticide residues' chronic impacts. Based on the integration of risk quotient method and probabilistic risk assessment method, this paper proposes a methodology of ecological risk assessment of pesticide residues' chronic impacts. It indicates that dichlorvos posed quite high chronic risk to the ecosystem, while risks posed by other pesticides are acceptable. Whereas combined ecological risk posed by the mixture is 24.08% in average, which exceeds the acceptable 5% level. Temporal variations of each pesticide's contribution to the total ecological risk are also presented. This analysis shows that risk alleviation actions should be made taking account of the pesticide residues' chronic impacts in Taihu Lake.