Distribution characteristics and environmental risk assessment of bisphenol analogues in the lower reaches of the Yangtze River.

To investigate the distribution patterns and environmental risks of emerging pollutants-bisphenols (BPs)-in the lower reaches of the Yangtze River, water samples were collected from an 850 kilometer stretch of the river in September 2022, 2023, and 2024. Nine BPs were analyzed using solid-phase extraction (SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). This study systematically evaluated the occurrence, space distribution, annual comparison, environmental risks, and potential sources of BPs. The results revealed that eight BPs were consistently detected, and the average ∑BPs concentrations for the three years, in chronological order, were 67.2 ng L^-1, 28.0 ng L^-1 and 46.8 ng L^-1, showing a "decline-rise" pattern. The dominant substances bisphenol A (BPA), bisphenol S (BPS), and bisphenol F (BPF) remained consistent over the three years. A historic severe drought in 2022 led to elevated BP concentrations in Tongling-Changzhou section while there is no obvious spatial distribution pattern in September 2023 and 2024. Spearman correlation analysis indicated similar sources for BPA, BPF, bisphenol E (BPE), and bisphenol AP (BPAP), likely originating from wastewater discharge and surface runoff. Ecological risk assessment utilizing risk quotients (RQ) identified BPS as posing medium-to-high risks (RQ: 0.102-7.57) at all sampling sites, highlighting the need for urgent mitigation measures. Despite having the highest concentration, BPA exhibited low ecological risks at some sites. However, estimated daily intake (EDI) values for BPA via drinking water exceeded the European Food Safety Authority's provisional tolerable daily intake (t-TDI) of 0.2 ng·(kg d)^-1, suggesting its potential health risks for all age groups.