Intensive land-based activities increase the potential risk of benzo[α]pyrene (BaP) to aquatic ecosystems and human health in coastal areas of China

Industrial expansion and overpopulation in cities experiencing economic growth, especially in coastal cities, continuously expose aquatic ecosystems to contaminant loading from land-based activities. This study employed a Berkeley-Trent (BETR) model to simulate benzo[α]pyrene (BaP) exposure levels in aquatic ecosystems of coastal regions during 1985–2050 while considering five shared socio-economic scenarios (SSP1, SSP2, SSP3, SSP4, and SSP5). The highest BaP concentrations were estimated for Shanghai and Tianjin, corresponding to the two areas that exhibited the highest potential human health risk. Risk quotient (RQ) analysis indicated that aquatic ecosystems in 80% of coastal areas were potentially affected by BaP contamination, while higher RQ values were observed for Shanghai, Tianjin, and Guangdong. Crustaceans in aquatic ecosystems were estimated to be more sensitive to BaP exposure compared to amphibians, fish, and mollusks, with the former exhibiting potentially affected fraction (PAF) values of 0.19%–20.26%. Further, PAFs of crustacean for Shanghai and Tianjin were 9.73% and 6.57%, respectively, both exceeding 5% and suggesting that crustaceans within these two areas would likely considerably suffer from greater BaP exposure threats. BaP exposure levels and corresponding risks continuously increased from 1985 to 2035 with ongoing intensive land-based activities, followed by slight decreases during 2035–2050. The SSP1 scenario represented a sustainable development strategy that led to lower emissions compared to the SSP2, SSP3, SSP4, and SSP5 scenarios. Employing strategies like those in the SSP1 scenario will thus help reduce BaP exposure levels and risks to environments and humans. Thus, SSP1 is the optimal scenario to help control future contamination and potential ecological risks to aquatic ecosystems and human health in coastal areas.