Microplastics (MPs) and heavy metals widely coexist in agricultural soils, posing significant risks to soil-plant ecosystems. This study explores the effects of five common MPs—polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polylactic acid (PLA)—and environmental-simulating microplastics (EMPs), composed based on the composition of local MPs in agricultural soils, on the bioavailability and phytotoxicity of Cd and Cr in soils. Pot experiments demonstrated that MPs, particularly PE and EMPs at a 5% dosage, markedly decreased soil pH, water-holding capacity, and soil organic carbon content. This decrease in pH led to enhanced Cd and Cr mobility and bioavailability, especially with PE and EMPs increasing Cr bioavailability in 15 cm depth soil by up to 43.9% and 37.8%, respectively. In soils with 2.1 mg/kg of Cd and 390 mg/kg of Cr, both 1% and 5% doses of MPs inhibited wheat growth while enhancing the uptake and translocation of Cd and Cr in wheat. Notably, PE, PS, PLA, and EMPs exposure significantly elevated levels of oxidative stress markers (SOD, POD, CAT, and MDA) in wheat. These findings highlight the importance of further research on the combined impacts of MPs and heavy metals on soil health and plant safety.

中文翻译：

---

微塑料诱导的农业土壤-小麦系统中 Cd 和 Cr 行为的变化：金属生物利用度和植物毒性的见解


微塑料 （MP） 和重金属在农业土壤中广泛共存，对土壤植物生态系统构成重大风险。本研究探讨了五种常见 MP——聚乙烯 （PE）、聚丙烯 （PP）、聚氯乙烯 （PVC）、聚苯乙烯 （PS） 和聚乳酸 （PLA）——以及基于农业土壤中当地 MP 成分组成的环境模拟微塑料 （EMP） 对土壤中 Cd 和 Cr 的生物利用度和植物毒性的影响。盆栽实验表明，MPs，特别是 5% 剂量的 PE 和 EMP，显着降低了土壤 pH 值、持水能力和土壤有机碳含量。pH 值的降低导致 Cd 和 Cr 迁移率和生物利用度增强，尤其是 PE 和 EMP 将 15 厘米深土壤中的 Cr 生物利用度分别提高了 43.9% 和 37.8%。在 Cd 含量为 2.1mg/kg 和 Cr 含量为 390mg/kg 的土壤中，1% 和 5% 剂量的 MPs 抑制小麦生长，同时增强小麦对 Cd 和 Cr 的吸收和转运。值得注意的是，PE、PS、PLA 和 EMPs 暴露显着提高了小麦氧化应激标志物（SOD、POD、CAT 和 MDA）的水平。这些发现强调了进一步研究 MP 和重金属对土壤健康和植物安全的综合影响的重要性。