Distribution, fate and sources of polycyclic aromatic hydrocarbons (PAHs) in atmosphere and surface water of multiple coral reef regions from the South China Sea: A case study in spring-summer

Highlights: • PAHs' level and sources were studied in air and water of coral reef regions (CRR). • Ocean current and wind fields were key factors affecting the distribution of PAHs. • Net atmospheric deposition of PAHs occurred in CRRs, South China Sea (SCS). • Global warming may retard atmospheric deposition of PAHs in coral reef regions. • PAHs may have a migration pattern of atmosphere-ocean-corals in SCS. Our previous study revealed PAHs' wide occurrence in corals from multiple coral reef regions (CRRs) in the South China Sea. However, little is known about their occurrence, distribution, fate, and sources in the ambient environment of these CRRs. This study aimed to resolve these research gaps. The results showed ∑₁₅PAHs (total concentrations of 15 US EPA priority controlled PAHs exclude naphthalene) in the atmosphere (gas-phase: 0.31–49.6 ng m⁻³; particle-phase: 2.6–649 pg m⁻³) were mainly influenced by air mass origins. Southwesterly wind caused higher ∑₁₅PAHs than the southeasterly wind. The ∑₁₅PAHs in seawater from the nearshore (462 ± 244 ng L⁻¹) was higher than that from offshore Zhongsha Islands (80.5 ± 72.1 ng L⁻¹) because of the effect of terrigenous pollution and ocean current. Source apportionment indicated that the mixed sources of spilled oil and combustion from neighboring countries were the main contributors to PAHs in these CRRs. The total deposition fluxes showed that PAHs tended to migrate from the atmosphere to seawater. Global warming may inhibit this process, but PAHs still have a migration pattern of atmosphere-ocean-corals, which will further increase the environmental pressure on coral reef ecology.