Estimation of Amount of Air Pollutants Discharge from Ships Sailing in Osaka Bay

Abstract

As a case study regarding the actual situation of air pollutant discharge from ships, the paper investigates the discharge amounts of nitrogen oxides NOx and sulfur oxides SOx from all ships sailing in Osaka Bay. Marine traffic in Osaka Bay is very intensified because it is surrounded by the highly industrialized Hanshin-Megalopolis and also Osaka Bay situates at the point connecting Pacific Ocean and Seto inland sea. This is the reason why Osaka Bay was selected here as a case study area. The investigation is carried out by three stages. The first is to investigate the trip table, that is, the OD-table of all ships sailing in Osaka Bay. The second is to study the dischage rate of each ship of various kinds at various operating conditions and the third is to estimate the dischage amount from all ships. The estimation results reveal that total discharge amount from ships is unexpectedly large, and NOx is comparable with the amount from land and SOx is larger than the land. As for the dischage intensity per area, the marine is also larger than the land especially in the port zone near the coast. Thus the report indicates that the discharge from ships could not be ignored and its effect on the coastal environment should be investigated in order to search the proper procedures against air pollution.