Kinetics of microplastic generation from different types of mulch films in agricultural soil.
Kinetics of microplastic generation from different types of mulch films in agricultural soil.
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DOI：
10.1016/j.scitotenv.2021.152572
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
Yang Yang-Yang;Zhen Li;Changrong Yan;D. Chadwick;Dave Jones;E. Liu;Qin Liu;Runhao Bai;W. He
中科院分区：
文献类型：
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作者：
Yang Yang-Yang;Zhen Li;Changrong Yan;D. Chadwick;Dave Jones;E. Liu;Qin Liu;Runhao Bai;W. He
塑料材料在环境风化后会形成较小尺寸的微塑料，其在农业领域的污染具有重要意义，并日益受到社会关注。塑料地膜被认为是农业土壤微塑料污染的主要来源。然而，塑料地膜微塑料形成的机理和动力学很少被理解。在这项研究中，从典型的地膜，如氧化降解，生物降解，和传统的非降解（聚乙烯，PE）地膜，微塑料的产生率进行了量化，在模拟紫外线照射下的土壤。结果表明，生物降解地膜的微塑料形成最快，氧化降解地膜次之，白色PE地膜和黑色PE地膜最差。微塑料生成的动力学严格遵循Schwarzchild定律，在微塑料生成模型中，指数在1.6309和2.0502之间呈指数增长。在2.1 MJ/m2的累积紫外线照射下，可生物降解、氧化降解、白色和黑色不可降解地膜中微塑料的平均释放量分别为475、266、163、147个颗粒/cm 2;粒径主要分布在0.02-0.10 mm范围内。紫外线照射后，观察到地膜的结晶度和表面侵蚀同时增加，这进一步决定了材料对光氧化的可及性和活性（反映为HI指数），因此对微塑料碎片的数量和尺寸范围起着关键作用。
Upon environmental weathering, plastic materials form smaller sized microplastics, of which the contamination in agricultural fields is of significant importance and increasing social concern. Plastic mulch films are considered a major source of agricultural soil microplastic pollution. However, the mechanism and kinetics of microplastic formation from plastic mulch films were rarely understood. In this study, the rate of microplastic generation from typical mulch films, such as oxodegradable, biodegradable, and conventional non-degradable (polyethylene, PE) mulch films, were quantified in soil under simulated UV irradiation. Results showed that microplastic formation was more rapid from biodegradable mulch film, followed sequentially by oxodegradable mulch film, white PE mulch film, and black PE mulch film. The kinetics of microplastic generation strictly followed the Schwarzchild's law, with exponential growth at indexes between 1.6309 and 2.0502 in the microplastic generation model. At a cumulative UV irradiation of 2.1 MJ/m2, the average quantity of microplastics released from biodegradable, oxodegradable, and white and black non-degradable mulch films were 475, 266, 163, 147 particles/cm2, respectively; with particle sizes largely distributed within 0.02–0.10 mm range. Concurrent increase in crystallinity and surface erosion of the mulch films were observed upon UV irradiation, which further determined the accessibility and activity of the materials to photo-oxidation (reflected as HI indexes), therefore played a critical role on the quantity and size ranges of microplastic debris.