Estimation of the Origin of Marine Litter Accumulated on the Coast: Morphological, Elemental, and Compositional Analysis of Debris Samples Collected on the Western Coast of Kyushu, Japan

The surface morphology, element, and composition analysis of marine litter samples taken from 19 coasts in Hakata Bay, Tsushima Island, and Goto Islands were carried out in September 2021 and June 2022 to examine the composition and origins of marine debris. The samples were collected at the shoreline, the junction of coastal plant communities and sandy areas, and within communities where debris accumulates. Our findings indicated that the most prevalent type of marine litter was plastic debris, but that the abundance and composition of the litter samples varied between the coast near the mouth and within Hakata Bay. The islands and the bay’s marine debris also have a distinct composition. We used SEM/EDS and FT/IR to evaluate the debris’ surface morphology and element composition to establish its anthropogenic and geographic origin. The most common types of debris were polypropylene and high-density polyethylene. However, the most abundant types of foam debris appeared to be more likely to be the product of fishing industry waste. More effective treatment options are urgently required due to the difficulty in resolving the negative effects of both locally and internationally created litter and the effects of the Tsushima current flow and inefficient waste management.