Identification of long-range transported polycyclic aromatic hydrocarbons in snow at Mt. Tateyama, Japan

Snow layers, L-I to-III, collected from the wall of a snow pit at Murododaira on Mt. Tateyama, Japan, were melted and filtered into soluble (S) and particulate (P) fractions by a glass filter (pore size: 0.5 µm). The total concentration of the polycyclic aromatic hydrocarbons (PAHs) was highest in L-I. In this layer, PAHs with 5–6 rings, which exist mainly in particulate matter (PM) in the atmosphere, were almost completely in the P-fraction. PAHs with 4 rings, which exist in both the particle and the gas phase in the atmosphere, exhibited higher or equal concentrations in the S-fraction. Finally, non-sea salt SO₄ ²⁻, which exists as sulfur oxides in the atmosphere, was filtered into the S-fraction. The air mass for L-I, traced via back trajectory, passed through northeastern and central China. These results suggest that PAHs transported from China to Japan precipitated in snow at Mt. Tateyama. In the melted snow, PM-associated PAHs were primarily in the P-fraction, but lower molecular-weight PAHs were partly in the S-fraction. Gas-phase PAHs were also found in the S-fraction. Furthermore, the high concentration of non-sea salt Ca²⁺ in the S-fraction of L-I implies the presence of Asian Dust.