A study of microplastic pollution in the tidal flats along the west coast of Korea

Abstract

Microplastics (MPs) widely distributed in marine ecosystems globally, with coastal sediments as important sinks of microplastic contamination. However, few research has been conducted on microplastics in the tidal flats, west coast of South Korea. The surface sediments (0–5 cm) were collected from seven stations, and sediment cores (0–40 cm) were also collected from three stations with lower-than-expected, the highest, and lowest microplastic abundance in surface sediments. MPs were isolated from the sediment through the density separation method then identified using Fourier transform infrared microspectroscopy. The lowest and highest microplastic concentrations in surface sediments were found in Hampyeong Bay (20.2 ± 9.9 particles per 50 g dry weight) and Geum River Estuary (324.9 ± 34.2 particles per 50 g dry weight), respectively. The mean abundance of MPs in core sediments ranged from 25.1 to 302.3 particles per 50 g dry weight, and the quantity of MPs in core sediments tended to decrease with depth. Overall, fragments of <1 mm were dominant, with polyethylene and polypropylene being the most frequent types of polymers. Analysis of sediment cores has shown that increasing trends in core MPs well corresponds to the recent economic growth in Korea. In conclusion, the present study would be the first report of the horizontal and vertical distribution and characteristics of MPs in tidal flats along the west coast of Korea which has been influenced by chronological anthropogenic activities.