Spatiotemporal variations and risk assessment of estrogens in the water of the southern Bohai Sea: A comprehensive investigation spanning three years

The ubiquitous and adverse effects of estrogens have aroused global concerns. Natural and synthetic estrogens in 255 water samples from the southern Bohai Sea were analyzed over three years. Total estrogen concentrations were 11.0–268 ng/L in river water and 1.98–99.7 ng/L in seawater, with bisphenol A (BPA) and 17α-ethynylestradiol (EE2) being the predominant estrogens, respectively. Estrogen showed the highest concentrations in summer 2018, followed by spring 2021 and spring 2019, which was consistent with the higher estrogen flux from rivers during summer. Higher estrogen concentrations in 2021 than in 2019 were driven by the higher level of BPA, an additive used in personal protective equipment. Estrogen exhibited higher concentrations in the southern coast of the Yellow River Delta and the northeastern coast of Laizhou bay due to the riverine input and aquaculture. Estrogens could disturb the normal endocrine activities of organisms and edict high ecological risks (90th simulated RQT > 1.0) to aquatic organisms, especially to fish. EE2 was the main contributor of estrogenic potency and ecological risk, which requires special concern. This is the first comprehensive study of estrogen spatiotemporal variations and risks in the Bohai Sea, providing insights into the environmental behavior of estrogens in coastal regions. Estrogens in waters are receiving particular attention owing to their potential endocrine-disrupting risks. Information on the environmental behavior of estrogens in marine environment is scarce. A comprehensive discussion was conducted on the distribution and risks of estrogens in the water of the southern Bohai Sea with a time span of three years. The levels and predominant estrogens were determined, the temporal variation and spatial patterns of estrogens were mainly clarified. The potential estrogenic potency and ecological risks of estrogens were evaluated, and priority pollutant (EE2) were identified. Such information is critical to protect oceanic ecosystem and public health.