Occurrence, ecological risk, and human health assessment of herbicide residues in Chaohu Lake, China

Herbicide is one of the most widely used pesticides in China, yet its spatiotemporal dynamics and associated risks in Chaohu Lake remain poorly understood. Here, we investigated the occurrence, partitioning behavior, and multi-tier risks of three amide herbicides (AHs) and two organophosphorus herbicides (OPHs) in Chaohu Lake, China, using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). All target herbicides were detected in surface water and sediments, showing significantly higher concentrations in summer than in winter and a pronounced spatial gradient, with higher levels in the western than in the eastern lake regions. The majority of the compound was butachlor (BUT), which was 14.950 µg/L in water and 21.909 µg/kg in sediment. The lowest concentration was gluconate-ammonium (GIU), which was 0.050 µg/L in water and 0.570 µg/g in sediment. Sediment-water partitioning coefficients ( K d ) correlated positively with octanol-water distribution coefficient (log k ow ) and total organic carbon (TOC), indicating strong sediment adsorption. Risk assessments revealed that AHs posed high acute ecological risks to aquatic organisms, whereas OPHs showed negligible effects. Human health risk models indicated no significant non-carcinogenic risks (NCR) from acetochlor (ACE), BUT, glyphosate (GLY), or GIU at current levels. This study reported the occurrence of HAs and OPHs in Chaohu Lake for the first time, which filled the data gap of typical herbicides in the ecosystem.