Insights into the occurrence of ten bisphenol analogues in tidal flat and deepwater sediments in the Pearl River Basin.

Bisphenol analogues (BPs), known endocrine disruptors, have raised increasing concerns due to their widespread use and potential ecological risks. Despite this, limited studies have focused on BPs in river sediments. In this study, we investigated ten BPs in different sediment types, including tidal flat and deepwater, across the Pearl River Basin. Sediment samples from the 0-15 cm depth at seven sites were also analyzed to investigate the vertical profile of BPs. In tidal flat sediments, no significant seasonal variation was observed in the total concentration of BPs (Σ10BPs), with values ranging from 20.8 to 148.1 ng/g in the dry season and 18.1-112.5 ng/g in the wet season. Spatially, the average concentration of BPs was lowest in estuarine sediments, while higher pollution levels were found in urban basin sediments. Deepwater sediments showed a higher BP concentration (average: 72.9 ng/g) compared to the corresponding tidal flat sediments (average: 65.5 ng/g), likely due to more favorable biodegradation conditions in tidal flat environments. The BP concentrations in sediment columns ranged from 12.2 to 93.8 ng/g. The vertical profile revealed that mid-layer sediments (5-10 cm) generally exhibited higher BP levels than ‌those in‌ the top (0-5 cm) and deeper (10-15 cm) layers. BPA showed significant positive correlations with total organic carbon (TOC) in tidal flat sediments. Environmental risk assessments based on the risk quotient (RQ) indicated that BP mixtures in Pearl River sediments posed low to medium risks to fish, algae, and crustaceans, with crustaceans being the most sensitive. To our knowledge, this is the first study to report the occurrence of BPs in tidal and deepwater sediments of a river.