Year-round Behavior of Marine Litter Drifted on the Coast in the Seto Inland Sea

Abstract

The marine litter drifted on the coast is expected to affect coastal environment and ecosystem. However, its year-round behavior still remains poorly understood. In this paper, we examined the spatial distribution of the drifted litter from 23 rivers to the Seto Inland Sea and influence of the seasonal wind or river discharge on the drifting process of the litter in the Seto Inland Sea by semi 3-D FEM numerical simulation model. Moreover, we also carried out field observations in the Narugashima Island which is located at the southeastern part of Seto Inland Sea. It is clarified the source of most litter (golf ball or cigarette lighter) is the river basin in the Seto Inland Sea, however, some of them were reached from nearby Asian countries.