Meso- and microplastic contamination in mulching cultivated soil at a national scale, China

The contamination of soil by meso- and microplastics (MMPs) has been drawing increasing attention. However, the pollution characteristics of MMPs in mulching cultivated soil across China remain unclear. This study investigated the distribution of MMPs in long-term mulched soils in 29 provinces of China. MPs were found in all soil samples, while mesoplastics were found in only 29.6% of soil samples. The abundance of MPs in soil was 20.00–640.0 items·kg−1, and the average abundance was 213.0 items·kg−1. The average abundance of mesoplastics in the soil was 10.00 items·kg−1. MMPs were found to be primarily film-shaped (37.2%), blue in color (23.4%), and less than 1000 μm in size (39.7%), and the primary polymer was polyethylene (PE, 37.2%). Mulching times and crop types were important factors affecting MMP abundance in soil. These findings reveal the nationwide pollution pattern of MMPs in mulching cultivated soil over the long term, provide basic data for MMP pollution at the national scale, and provide a scientific basis for the rational use and management of plastic films and the treatment of soil MMP pollution.