A decade-long meta-analysis of risks posed by pesticides in Chinese surface waters.

Despite their global benefits to agriculture, pesticides pose potential risks to wildlife as well as to the structure and function of ecological communities. A comprehensive meta-analysis was conducted to assess the occurrence, toxicity effects, and ecological risks of pesticides in the surface water of major river basins of China from 2012 to 2023. Using a multi-tier risk assessment, exposure and ecotoxicity data were analyzed and compared for 58 priority pesticides, revealing widespread contamination across major river basins. Among the 46 frequently detected pesticides, concentrations ranged from non-detectable to 12,100 ng/L, with hazard quotients (HQ) ranging from a maximum of 21,764.71 for deltamethrin to a minimum of 0.01 for carbaryl. The Pearl, Huai, and Yangtze River basins exhibited the greatest concentrations of pesticides, particularly in regions with intensive agricultural activity. Base on HQ screening, the hierarchical risk assessment identified 20 "high-risk" pesticides, while semi-probabilistic analysis further prioritized 13 compounds out of 28 pesticides with prioritization index (PI) > 1.0. Notably, probabilistic risk assessment revealed that, over the decade, bifenthrin and λ-cyhalothrin posed the greatest threats, with maximum risk products (the product of exceedance probability and magnitude of effect) of 81.24 % and 76.96 %, respectively. These findings demonstrate that pyrethroid insecticides present the greatest risks to aquatic organisms in Chinese surface waters. This systematic evaluation provides critical insights for evidence-based environmental management strategies and underscores the urgent need for enhanced monitoring of greater-risk pesticides to protect aquatic biodiversity.