Department of Environmental Science, The University of Arizona, Tucson, AZ, 85721, USA.
Environ Pollut. 2023 Apr 1;322:121235. doi: 10.1016/j.envpol.2023.121235. Epub 2023 Feb 6.
The detection of microplastics (MPs) in agricultural soils has raised alarms on their potential impacts on agricultural production, particularly in China where agriculture has great importance for domestic consumption and export. This review aims to present the abundance, sources and impacts of MPs in the agricultural soils of China. It has the novelty of synthesizing sustainable agronomic practices to reduce MPs pollution of agricultural soils based on the sources identified. According to the extant study, the abundance of MPs in the agricultural soils in China ranged from 4.94 items/kg in the lower reaches of Yangtze River to 40,800 items/kg in Yunnan Province. The MPs were predominantly ≤1 mm and were mainly composed of fragments, films and fibers. Polyethylene and polypropylene MPs were most reported. Plastic mulching films were the most significant source of MPs in agricultural soils, followed by abandoned greenhouses and the use of organic fertilizers containing fugitive MPs or whose sources were often MPs-polluted. MPs were found to alter soil physicochemical properties for instance, water flow, water-stable aggregates, soil aggregation, soil pH, bulk density and nutrient contents. MPs also affect soil biota through changing the richness and diversity of soil microbial community while retarding growth and disrupting physiological functions of soil macrofauna. The effects of MPs on crops vary and range from alteration of biomass, metabolism and nutrient demands to impacted photosynthesis. Sustainable solutions include the use of grass clippings - straw mix as organic mulches, the use of compost as soil amendment in conjunction with grass-straw mix and incorporation of weed-suppressing biomass into compost, the use of jute and biodegradable plastics for greenhouses, proper decommissioning of abandoned greenhouses as well as setting standards for allowable MPs contents in organic fertilizers and irrigation water.
微塑料（MPs）在农业土壤中的检测引起了人们对其对农业生产潜在影响的警惕，尤其是在中国，农业对国内消费和出口至关重要。本综述旨在介绍中国农业土壤中 MPs 的丰度、来源和影响。它的新颖之处在于根据确定的来源，综合了可持续的农业实践，以减少农业土壤中 MPs 的污染。根据现有研究，中国农业土壤中 MPs 的丰度范围从长江下游的 4.94 个/千克到云南省的 40800 个/千克。MPs 主要为≤1mm，主要由碎片、薄膜和纤维组成。聚乙烯和聚丙烯 MPs 是最常报道的。塑料覆盖薄膜是农业土壤中 MPs 的最重要来源，其次是废弃的温室大棚和使用含有逃逸 MPs 的有机肥，或者其来源通常是 MPs 污染的。MPs 改变了土壤物理化学性质，例如水流、水稳定团聚体、土壤团聚体、土壤 pH 值、容重和养分含量。MPs 还通过改变土壤微生物群落的丰富度和多样性来影响土壤生物区系，同时减缓土壤大型动物的生长并破坏其生理功能。MPs 对作物的影响各不相同，从改变生物量、代谢和养分需求到影响光合作用。可持续的解决方案包括使用草屑-秸秆混合物作为有机覆盖物、使用堆肥作为土壤改良剂与草-秸秆混合物结合使用以及将抑制杂草的生物质纳入堆肥中、使用黄麻和可生物降解塑料用于温室、妥善拆除废弃的温室以及为有机肥和灌溉水中允许的 MPs 含量制定标准。
