Occurrence, Distribution, And Fate Of Polychlorinated Biphenyls (Pcbs) In Multiple Coral Reef Regions From The South China Sea: A Case Study In Spring-Summer

Concentrations of 24 PCBs were simultaneously determined in air, seawater, and corals from the South China Sea (SCS) in spring-summer for understanding their distribution and fate in multiple coral reef regions. The Sigma(24)PCBs (6.8-294 pg m(-3)) were mainly influenced by air mass origins in air samples. Southeast monsoon caused higher Sigma(24)PCBs (mean: 61 pg m(-3)) than the southwest (mean: 19 pg m(-3)). Sigma(24)PCBs in seawater (2.8-7.7 pg L-1) was equally distributed from the nearshore to offshore regions under low flow velocity and swirling state of the ocean current. Significantly higher air-water gas exchange deposition fluxes (3.5-29 ng m(-2) d(-1)) than dry deposition (0.14-2.0 ng m(-2) d(-1)) indicated that diffusion of PCBs from the atmosphere into seawater was the governing process in the SCS. PCBs in corals are strong bioaccumulative (Log BAFs: 2.49-7.86). The distribution of Sigma(24)PCBs in coral tissues (nd -42.9 ng g(-1) dw) was significantly correlated with that in air samples, suggesting PCBs may have a migration pattern of atmosphere-ocean-corals in the SCS. Compared to a previous risk assessment study, the Sigma(24)PCBs in corals from the SCS may cause potential risks to corals by reducing zooxanthellae density, chlorophyll-a (Chl-a) and chlorophyll-C-2 (Chl-C-2) in corals. (C) 2021 Elsevier B.V. All rights reserved.