Dynamics and Mass Balance of Polycyclic Aromatic Hydrocarbons in and around the Seto Inland Sea, Japan
Abstract Polycyclic aromatic hydrocarbons (PAHs) were analyzed to elucidate the distribution, ecological risk, pathways, and fluxes of these pollutants in and around the Seto Inland Sea, Japan. High molecular weight PAHs (5–6 rings) were primarily found in regions close to the bay estuaries, and their proportions decreased at distances further from the estuaries (offshore areas), where low molecular weight PAHs (2–4 rings) were more ubiquitous. Ecological risk assessments revealed that the PAHs found in the sediments should have no adverse effects on benthic communities, with the exception of fluorene, which was detected in high levels in the sediment from Beppu Bay. A mass balance for PAHs in the Seto Inland Sea, calculated based on data collected in the field and published literature findings, showed the PAH flux into the Seto Inland Sea from atmospheric deposition were ca. 5 times higher than that from riverine inflows. Comparison of the amount of the PAH flux between the Seto Inland Sea and other seas suggested that the Seto Inland Sea is less polluted than the Gulf of Lion and the Bohai Sea, and more polluted than the Yellow Sea.