Pollution of Microplastics in Coastal Plain of the Huangshui River Basin

Abstract Marine microplastic pollution is one of the hot spots in current marine environment research. The coastal zone has unique micro-plastic pollution characteristics at the junction of land and sea, and the micro-plastic pollution in the coastal zone soil is still unclear. In this study, Huangshui river basin was selected as the research area in Laizhou Bay, China. Soil samples were collected from the depth of 0-3, 3-6 and 6-9 cm at each location. Microplastics were separated by flotation. Microplastic characteristics were investigated and analyzed by Nile red staining and Fourier infrared spectrometer. The results showed that there was slight microplastic pollution in the coastal plain. 92.9% of the detected microplastics were granular, 6.1% were fibers, and only 1.0% were films. Microplastics with a particle size of 20-100 μm accounted for 57.9% of the total, particles with the size of 100-1000 μm accounted for 38.6%, and particles with the size of 1000-5000 μm accounted for 3.5%. The presence of film-like PE was detected, indicating that microplastic contamination in the soil was likely to come from the utilization and mulching of agricultural mulch. The amount of microplastics in soil was related to the size of microplastics. Abundance of microplastics in soil increased with decreasing of the size of soil. In addition, the microplastic content in soil decreased, and particles with a smaller size occupied a larger proportion, with the increasing of the depth of soil.