Persistent organic pollutants versus their alternatives in the eastern Pearl River Estuary, South China: Distribution, ongoing transition, and risk prioritization

With the global restriction and phase-out of Persistent Organic Pollutants (POPs), environmental occurrence, fate, and risks of the widespread-use alternatives to POPs are gaining increasing global concern. This study provides a systematic assessment of three major groups of POPs and their alternatives, including 45 per- and polyfluoroalkyl substances (PFAS), 29 halogenated flame retardants (HFRs), and three classes of chlorinated paraffins (CPs, including short-chain CPs, medium-chain CPs, and long-chain CPs), in seawater and sediment from the coastal environment of the Hong Kong Special Administrative Region of China, a densely populated metropolis in the eastern Pearl River Estuary receiving substantial anthropogenic inputs. Concentrations of PFAS, HFRs, and CPs in seawater ranged 2.56–174, 1.29–81.4, and 39.2–361 ng/L, respectively, while those in sediment ranged 0.248–1.86, below the method quantification limit (