Occurrence, Distribution, and Risk Assessment of Phenolic Endocrine-Disrupting Chemicals in Surface Waters of the World's Longest Water Diversion Project: The Non-Negligible Impact of Local Wastewater Emissions.

Water contamination by phenolic endocrine-disrupting chemicals (EDCs) is a global environmental concern. Yet, the occurrence of phenolic EDCs in artificial water diversion systems remains poorly understood. Thus, the Eastern Route of the South-to-North Water Diversion Project, the world's longest water diversion project, was chosen as the study area to investigate the spatiotemporal distribution of alkylphenols (APs) and bisphenol A (BPA), typical phenolic EDCs, and to evaluate their risks. During the diversion operation, higher mean ΣAP concentrations were observed in lakes of Nansi and Dongping relative to the Luoma Lake-Dongping Lake and Yangtze-Luoma Lake diversion channels. The AP composition in the two lakes was also different from that in the two channels. These findings demonstrated that the canal water was not a key source of AP contamination in the lakes, highlighting the importance of local wastewater inputs. The spatial distribution of ΣAP and BPA concentrations in the lakes was mainly affected by the riverine inputs. For ecological risks, 4-n-nonylphenol (4-n-NP) exhibited moderate ecological risks at 81.3% of sampling sites in Dongping Lake and 68.8% of those in Luoma Lake, highlighting the need for heightened attention in future studies. Even under the high exposure scenario, 4-n-NP and BPA would not produce health risks to residents through water intakes. Overall, surface water resources of the Eastern Route Project were confirmed to be safe for human consumption.