Occurrence, distribution and affecting factors of microplastics in agricultural soils along the lower reaches of Yangtze River, China

Microplastics become one of the serious persistent pollutants in terrestrial environments, and thus may represent a threat to the quality of soil and inhabiting organisms. It is imperative to understand occurrence and distribution of microplastics in soils. In this study, a large-scale field survey encompassing 85 locations along the lower reaches of Yangtze River and estuary was performed to investigate the microplastics abundance in agricultural soils. Microplastics were isolated from all the samples and all depths (0-80 cm). The microplastics abundance in soils ranged from 4.94 items/kg to 252.70 items/kg, with an average of 37.32 items/kg. The most common microplastic type detected was Polypropylene (PP) occurring as white fragments with sizes ranging from 0.1 mm to 0.5 mm. Abiotic parameters such as soil pH and texture were the general factors being associated with microplastic abundance. Meantime, traffic was indicated as one important factor to affect the microplastic abundance. Overall, the road input seems to be the main source of microplastic pollution in agricultural areas along the Yangtze River and estuary. Further studies should elucidate the original of the plastic fragments in order to establish a baseline for regulative initiatives securing environmental protection.