Potential sources and occurrence of macro-plastics and microplastics pollution in farmland soils: A typical case of China

Plastic debris (including macro-plastics, microplastics (MPs), and nanoplastics), defined as an emerging contaminant, has been proven to significantly affect soil ecosystem functioning. Accordingly, there is an urgent need to robustly quantify the pollution situation and potential sources of plastics in soils. China as the leading producer and user of agricultural plastics is analyzed as a typical case study to highlight the current situation of farmland macro-plastics and MPs. Our study summarized information on the occurrence and abundance of macro-plastics and MPs in Chinese farmland soils for the first time based on 163 publications with 728 sample sites. The results showed that the average concentration of macro-plastics, and the abundance of MPs in Chinese farmlands were 103 kg ha−1 and 4537 items kg−1 (dry soil), respectively. In addition, this study synthesized the latest scientific evidence on sources of macro-plastics and MPs in farmland soils. Agricultural plastic films and organic wastes are the most reported sources, indicating that they contribute significantly to plastic debris in agricultural soils. Furthermore, the modeling methods for quantifying macro-plastics and MPs in soils and estimating the stock and flow of plastic materials within agricultural systems were also summarized.

塑料碎屑（包括大塑料（macro-plastics）、微塑料（microplastics, MPs）和纳米塑料（nanoplastics））作为一类新兴污染物，已被证实可显著干扰土壤生态系统功能。因此，亟需精准且可靠地量化土壤中塑料污染的现状及其潜在来源。本研究以全球农用塑料生产与使用大国中国为典型案例，聚焦农田土壤中大塑料与微塑料的污染现状。本研究首次基于涵盖728个采样点的163篇公开发表文献，系统梳理了中国农田土壤中大塑料与微塑料的赋存特征与丰度水平。研究结果显示，中国农田中大塑料的平均含量为103千克/公顷，微塑料的平均丰度为4537件/千克干土。此外，本研究整合了农田土壤中大塑料与微塑料来源的最新科研证据，其中农用塑料地膜与有机废弃物是当前报道最多的塑料来源，表明二者对农业土壤中的塑料碎屑贡献显著。同时，本研究还梳理了用于量化土壤中大塑料与微塑料、以及估算农业系统内塑料物质储量与通量的模型方法。