192 / 2024-09-11 09:54:53

Distribution control and environmental fate of PFAS in the offshore region adjacent to the Yangtze River Estuary-a study combing multiple phases analysis

Per- and polyfluoroalkyl substances; Spatial distribution; Environmental fate; Phase partition; Vertical settling

The Yangtze River Estuary is the terminal sink of terrestrial per- and polyfluoroalkyl substances (PFAS) from the Yangtze River, while the environmental fate characteristics of legacy and emerging PFAS around this region were rarely discussed. Here, 24 targeted PFAS in seawater, sediments, suspended particulate matter (SPM) and plankton in the offshore region adjacent to this estuary were investigated. The three dominant PFAS in all phases were perfluorooctanoic acid (PFOA, 23.8-61.9%), perfluorobutanoic acid (PFBA, 23.6-42.8%) and perfluoro(2-methyl-3-oxahexanoic) acid (HFPO-DA, 6.1-12.1%), and perfluoro-1-butane sulfonamide (FBSA, 0.1-7.3%) was firstly detected. The horizontal distributions of PFAS were dependent on salinity and disturbed by multiple water masses, while the vertical variations could be explained by their different partitioning characteristics in the water-SPM-sediment system (partition coefficients, Log K_d and Log K_oc) and plankton (bioaccumulation factors, Log BAF). Although physical mixing was the major driver for PFAS settling (>83.7%), the absolute settling amount caused by the biological pump was still high (150.00-41994.65 ng m⁻²d⁻¹). More importantly, we found unexpected high Log K_d values of PFBA (2.24-4.55) and HFPO-DA (2.26-4.67), equaling to PFOA (2.28-4.72), which brought concerns about their environmental persistence. Considering the increased detection of short-chain and emerging PFAS, more comprehensive environmental behaviors analysis is required urgently.