Distribution of PAHs in the northwestern part of the Japan Sea

Surface water samples were collected at 13 stations in the Japan Sea and filtered through a glass fiber membrane (pore size 0.5 μm). The vertical distribution of PAHs (nine points from depths between 2 m and 3300 m) were measured at one station. Thirteen PAHs having 3–6 rings in the dissolved and particulate phases were determined by HPLC with fluorescence detection. The mean concentration of total PAHs on the seawater surface was 8.5 ng/L. The mean concentrations in the dissolved and particulate phases for surface seawater were 5.6 ng/L and 2.7 ng/L, respectively. In the dissolved phase, 3-ring PAHs were the largest contributor, and 5-ring or more PAHs were in low ratio. Also, concentrations of PAHs in the particulate phase were dominated by 3-ring and 4-ring PAHs, but ratio of 3-ring PAHs was lower than in dissolved phase. Maximum of concentrations of PAHs in the dissolved (6.5 ng/L) and particulate (10.6 ng/L) phases were found for a depth 300 m. The possible source of PAHs is the atmosphere.