Abstract：
Pesticide residues and microplastics (MPs) in agricultural soils are two major concerns for soil health and food safety. The degradation of chlorpyrifos (CPF), an organophosphorus pesticide, releases phosphates. This process may be affected by the presence of MPs in the soil. The combination of CPF and MPs presence in the soil may thus produce interaction effects that alter the soil phosphorus (P) balance. This study explores the degradation pathways of CPF (6 mg kg-1, 12 mg kg-1 of CPF addition) in soils with different levels of polylactic acid MPs (PLA-MPs) (0.0 %, 0.1 %, 0.5 %, 1.0 % w/w), and analyzes soil P fractions and phosphatase enzyme activities to investigate soil P bioavailability under different treatments. Results show that the degradation of CPF fits to a first-order decay model, with half-lives (DT50) ranging from 11.0 to 14.8 d depending on PLA-MPs treatment. The concentration of its metabolite 3, 5, 6-trichloropyridine 2-phenol (TCP) reached a peak of 0.93-1.67 mg kg-1 within 7-14 days. Similarly, the degradation of CPF led to a significant transient increase in P bioavailability within 3-7 days (p < 0.05), with a peak range of 22.55-26.01 mg kg-1 for Olsen-P content and a peak range of 4.63-6.76 % for the proportions of available P fractions (H2O-P+NaHCO3-P+NaOH-P), before returning to prior levels (Olsen-P: 11.28-19.52 mg kg-1; available soil P fractions: 4.15-5.61 %). CPF degradation (6 mg kg-1) was significantly inhibited in soil with 1.0 % PLA-MPs addition. The effects of MPs and CPF on soil P fractions occur at different time frames, implying that their modes of action and interactions with soil microbes differ.
摘要：
农业土壤中的农药残留和微塑料（MPs）是土壤健康和食品安全的两个主要问题。毒死蜱（CPF）的降解，有机磷杀虫剂,释放磷酸盐。该过程可能受到土壤中MP存在的影响。土壤中CPF和MPs的结合可能会产生相互作用，从而改变土壤磷（P）平衡。本研究探讨了不同聚乳酸MPs(PLA-MPs)水平(0.0%,0.1%,0.5%,1.0%w/w)，并分析了土壤P组分和磷酸酶活性，以研究不同处理下土壤P的生物有效性。结果表明，CPF的退化符合一阶衰减模型，半衰期（DT50）为11.0至14.8d，具体取决于PLA-MPs治疗。其代谢物3，5，6-三氯吡啶2-苯酚（TCP）的浓度在7-14天内达到0.93-1.67mgkg-1的峰值。同样，CPF的降解导致P生物利用度在3-7天内显著短暂增加(p<0.05)，Olsen-P含量的峰范围为22.55-26.01mgkg-1，有效P馏分（H2O-PNaHCO3-PNaOH-P）的峰范围为4.63-6.76％，在恢复到以前的水平之前（Olsen-P：11.28-19.52mgkg-1；有效土壤P分数：4.15-5.61％）。添加1.0％PLA-MPs可显著抑制土壤中CPF降解（6mgkg-1）。MPs和CPF对土壤磷组分的影响发生在不同的时间框架，这意味着它们的作用方式和与土壤微生物的相互作用不同。
