Baseline study on microplastics distribution, polymer composition, size, and shape in the Korean Southwest Sea

The microplastics in the surface seawater at 23 fixed points in the southwestern waters of Jeju Island were analyzed to conduct a study on the distribution characteristics of microplastics. The abundance of microplastics was shown to be 0.17 ~ 1.37 (average 0.46) n/L, the materials were mainly PP and PE, and the shape of fragments was dominant in the 0.02–0.3 mm group in terms of sizes and shapes. Alkyd and polyester were dominant in the shape of fibers in the 1.0–5.0 mm group. The correlations between the abundance of microplastics, water temperatures, and salinity were compared and as a result, water temperatures, PE, and the 0.02–0.3 mm size group, and the shape of fragments showed negative correlations. Therefore, it is judged that the for PE, which are in the form of 0.02 ~ 0.3 mm fragments to flow into the study area through the Yellow Sea coastal current and the Korean coastal current that show tendencies of relatively low water temperatures. However, since salinity and PP and polyester showed positive correlations, it is judged the possibility for polyester, which are in the form of 1.0 ~ 5.0 mm fibers, to flow into the study area through the Taiwan warm current and Tsushima warm current. In conclusion, it could be judged that in the complex open waters where continental and oceanic waters intersect, the sources of inflow may be different depending on the components of microplastics.