Occurrence and sources of micro-plastics in various water bodies, sediments, and fishes in Ansan, South Korea.

In this study, the Pearson correlation coefficients were determined to derive correlations between micro-plastics (MPs) in carp and river crabs. MPs were detected for various water sources, including four rivers and four main waterways, sediments, and fish, using Fourier transform infrared spectrometry (FTIR), microscopic analysis, and image mapping. Carp and river crabs had coefficients of 0.888 and 0.724, respectively, which showed a high positive correlation. In water samples, the MPs detected in rivers were higher than those in the main waterway. However, in sediment samples, the MPs detected in the main waterway were higher than those in the rivers. It is believed that MPs are carried toward shore by ocean tide. The size of most of the sediment MPs was 20-49 µm, representing 64.1% of the entire population. The plastics detected in this study were polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE), which originate from synthetic fibers, scrubs, and packing material. MP pollution by non-point pollution sources was investigated, with the abundance of MPs increasing by 2 to 3 times between the dry and wet seasons in water and sediment, respectively. It was determined that the inflow of MPs into rivers could have been due to non-point source pollutants from household items, roads, plants, and soil around the water sources.