Bioaccumulation of Diverse Organic Contaminants in Oysters from Highly Dynamic Estuary: Physicochemical Properties and Season-Dependent Characteristics

Conventional chemical monitoring using grab samples can hardly reflect the highly dynamic trends in the pollution in estuaries. Here, we examined the bioaccumulation characteristics of organic contaminants based on a 6-year (2015–2020) oyster biomonitoring campaign in the Pearl River Estuary. Using target and suspect analyses, 198 out of ∼1000 organic contaminants were detected with sum concentrations reaching 37,912 ng/g dry wt. By examining diverse contaminants with logK_ow ranging from −0.22 to 15 and half-life ranging from 2.6 to 379 d, distinct season-dependent bioaccumulation was recognized across chemical hydrophobicity and persistence. Approximately twice more contaminants with high hydrophobicity (logK_ow > 6) and half-life >10 d exhibited higher bioaccumulation during the wet season. Geographically, about two-fold more contaminants with moderate and high hydrophobicity exhibited higher levels in oysters from the more urbanized eastern coast than the western coast. The inclusion of diverse suspect analytes in biomonitoring helped to reveal chemical- and season-dependent bioaccumulation characteristics of organic contaminants in highly dynamic estuaries.