Atmospheric wet deposition of PAHs to the sea-surface microlayer

Sea-surface microlayer (SML) and subsurface seawater samples (SSW) collected from Singapore’s coastal environment were analyzed for 14 polycyclic aromatic hydrocarbons (PAHs) in the dissolved (DP) and suspended particulate phase (SPM). Samples were collected prior to and after rainfall events to ascertain the contribution of wet atmospheric deposition of PAH enrichment to the SML. The concentration ranges of ∑PAHs in the SML before rain and after wet deposition were 2.6–46.2 ng L−1 and 4.3–278.0 ng L−1, respectively, for the DP and 3.8–31.4 ng L−1 and 12.8–1280 ng L−1, respectively, for the SPM. Load factors (i.e. concentration after wet deposition relative to before wet deposition) of the atmospheric wet deposition for DP and SPM ranged from 1.4 to 42.9 and 1.2 to 337, respectively. This study provides the first data on PAH concentration, enrichment (i.e. concentration of PAHs in SML relative to subsurface water) and load factors in the SML before and after wet deposition to the ocean surface.