Occurrence, distribution, and fate of polychlorinated biphenyls (PCBs) in multiple coral reef regions from the South China Sea: A case study in spring-summer

摘要

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 ∑_(24)PCBs (6.8-294 pg m~3) were mainly influenced by air mass origins in air samples. Southeast monsoon caused higher ∑_(24)PCBs (mean: 61 pg m~3) than the southwest (mean: 19pg m~3). ∑_(24)PCBs in seawater (2.8-7.7 pgL~(-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 224PCBS 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 ∑_(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.