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（包括大尺寸塑料（macro-plastics）、微塑料（microplastics, MPs）以及纳米塑料（nanoplastics））作为一类新兴污染物，已被证实会显著影响土壤生态系统功能。因此，亟需稳健量化土壤中塑料的污染现状与潜在来源。本研究以全球农用塑料生产与消费第一大国中国作为典型研究案例，阐明我国农田中大尺寸塑料与微塑料的污染现状。本研究首次基于收录728个采样点信息的163篇学术文献，系统梳理了我国农田土壤中大尺寸塑料与微塑料的赋存状态与丰度水平。研究结果显示，我国农田中大尺寸塑料的平均浓度与微塑料的丰度分别为103 kg·公顷⁻¹与4537 件·千克⁻¹（干土重）。此外，本研究整合了当前关于农田土壤中大尺寸塑料与微塑料来源的最新科研证据。农用塑料地膜与有机废弃物是被报道最多的污染来源，表明二者对农业土壤中的塑料碎屑贡献显著。进一步而言，本研究还梳理了用于量化土壤中大尺寸塑料与微塑料、以及估算农业系统内塑料物料存量与通量的各类建模方法。