Aquatic life water quality criteria and ecological risks of herbicides and insecticides in waters across China

Excessive pesticide application and subsequent environmental losses increasingly threaten aquatic ecosystems, yet the ecological risk posed by these pesticides in China has not been explored at the national level. Therefore, this study derived water quality criteria (WQCs) for 36 widely used pesticides in China based on a toxicity dataset of native aquatic species. The ecological risks were evaluated using a multi-level assessment approach. The results showed that insecticides posed higher risks than herbicides and that high-risk pesticide areas were concentrated in eastern and southern China. Based on the tiered risk assessment methods (namely, risk quotient, margin of safety, and joint probability curve), the sulfonylurea herbicide nicosulfuron and the insecticides deltamethrin, chlorpyrifos, cyfluthrin, avermectin, parathion, and imidacloprid were found to be the main contributors to high risks in water bodies in both cropland and urban regions of China. These results provide a scientific reference for the formulation and revision of pesticide WQCs and water quality standards, as well as for pesticide pollution control and management in China.