Microplastics in Chinese coastal waters: A mini-review of occurrence characteristics, sources and driving mechanisms

The oceans are facing global and irreversible pollution from microplastics, and China is not immune. In this mini-review, information on microplastics in four coastal waters of China and the natural and social environment of key basins were compiled. The results showed that microplastics were ubiquitous in the coastal waters, and the abundance and spatial distribution of microplastics varied significantly under different sampling methods. For trawl samples, microplastic abundance ranged from 0.045 to 1170.8 items m-3, among which the coastal waters of the East China Sea were the most polluted. For filtered samples, microplastic abundance ranged from 46 to 63,600 items m-3, and the coastal waters of the Yellow Sea were the most polluted. Meanwhile, human activities in basin were the key factors affecting microplastic pollution in coastal waters. The main terrestrial source in the coastal waters of the South China Sea was express packaging loss, whereas the main source in the other coastal waters was tyres and road markings wear from vehicle trip. The decoupling results of analytic hierarchy process showed that there was spatial heterogeneity in the impact of socio-economic and natural environmental factors in the basin on the distribution of microplastics in coastal waters. Among the five major basins, the impact weights of the latter were 20.00%, 83.34%, 66.66%, 50.00% and 25.00%, respectively. This study provides the first perspective of land-sea linkage to summarize the characteristics, sources and influencing factors of microplastics in Chinese coastal waters, providing ideas for reducing marine microplastic pollution from the source.