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.

Automated summary

The study revealed that PCBs in the South China Sea are mainly influenced by air mass origins and monsoon winds, with PCBs primarily entering seawater through air-water gas exchange deposition. PCBs also show strong bioaccumulation in coral tissues. Compared to previous research, PCBs in corals from the South China Sea may pose potential risks by reducing zooxanthellae density and chlorophyll levels.