Organophosphate esters in surface water across China: Occurrence, distribution, driving factors and ecological risk

As widely used flame retardants and plasticizers, organophosphate esters (OPEs) are emerging contaminants that pose significant risks to aquatic ecosystems and human health. However, quantitative assessments of OPE pollution at the national scale are lacking due to scarce monitoring data and the unclear relationships between OPE concentrations and their driving factors. This study provides the first national-scale assessment of OPEs in Chinese surface waters by compiling a dataset of 355 sampling sites from 2010 to 2024 and developing a random forest model to quantify their spatial distribution, driving factors, and ecological risks. The results showed that the spatial distribution is primarily influenced by anthropogenic activities and climatic factors. Ecological risk assessment reveals that tris(2-ethylhexyl) phosphate (TEHP) and 2-ethylhexyl diphenyl phosphate (EHDPP) posed potential ecological risks (RQ > 0.01) in surface waters of China, with high risk regions concentrated in Northeast China and Southeast China, as well as certain high-altitude inland areas. Particularly, the risk quotient of TEHP exceeded 1 in the Pearl River Basin, indicating high risk. Our findings provided predictive data and risk identification for OPE contamination in Chinese surface waters, offering valuable insights for future regulatory efforts.