Distribution, ecological risks and priority of pharmaceuticals in the coastal water of Qinhuangdao, China

Although there has been a surge of interest in research focused on the presence of pharmaceuticals in the marine environment, study on the distribution and risks of pharmaceuticals in coastal waters remains inadequately documented due to the specific features of the marine environment, such as strong dilution, high salinity, and complex hydrodynamics. In this study, thirty pharmaceuticals with diverse physicochemical properties were analyzed in a coastal sea with low hydrodynamic energy caused by various artificial structures. The results indicate that 14 compounds were detected in seawater, with concentrations ranging from <1 to 201.4 ng L-1, among which caffeine, metoprolol, and atenolol were detected at high levels. Statistical analysis reveals the prevalence of the most target pharmaceuticals with downward trends in concentrations from estuary to offshore region, demonstrating the significant impacts of riverine inputs on the coastal water. Nevertheless, the distribution patterns of caffeine and atenolol were intricate, suggesting that they may have also originated from other unknown sources. A newly-developed method combining risk quotient (RQ) and species sensitivity distribution (SSD) models was used in ecological risk assessment. The results indicate generally higher risks of target pharmaceuticals in the estuary compared to the offshore region, with caffeine, carbamazepine, and norfloxacin identified as the top three priority pollutants.