College of Plant Science and Technology, Department of Plant Protection, Huazhong Agricultural University, Wuhan, 430070, China.
College of Plant Science and Technology, Department of Plant Protection, Huazhong Agricultural University, Wuhan, 430070, China.
Chemosphere. 2022 Dec;308(Pt 2):136280. doi: 10.1016/j.chemosphere.2022.136280. Epub 2022 Sep 6.
Agricultural plastic films and triazole fungicides are widely used in agricultural production process. Exposure to natural environment, agricultural plastic films will degrade into micron plastic particles, which will adsorb pesticide molecules and may affect their toxicity, biological activity and persistence. The long-term coexistence of microplastics (MPs) and triazole fungicides will bring potential harms to the agricultural ecological environment. Therefore, two kinds of triazole fungicides flusilazole (FLU) and epoxiconazole (EPO) were selected as cases and the adsorption behaviors of them on polystyrene and polyethylene were investigated. A series of factors which could affect the adsorption behavior were evaluated. Specifically, the particle size of MPs could affect its adsorption capacity, and the smaller the particle size, the stronger the adsorption capacity. Moreover, with the increase of pH value from 6.0 to 9.0, the adsorption capacity of MPs to target compounds gradually increased. The effect of ionic strength was evaluated by NaCl, and 0.05% of NaCl was beneficial to the adsorption process, while the continuous increase of NaCl concentration inhibited the adsorption. Oxalic acid and humic acid decreased the adsorption capacity of flusilazole on PE by 15.99-32.00% and PS by 35.02-48.67%, respectively. In addition, compared with the single pesticide system, the adsorption capacity of MPs for flusilazole and epoxiconazole in the binary pesticides system decreased by 36.13-37.93% and 44.36-51.35%, respectively, indicating that competitive adsorption occurred between the two pesticides. Meanwhile, the adsorption process was evaluated by adsorption kinetics and adsorption isotherms and were consistent with pseudo-second-order kinetic model and Freundlich isotherm model, respectively. Finally, several characterization analyses were conducted to investigated the adsorption mechanism, and hydrogen, halogen bonding and hydrophobic interaction proved to play an important role. The study on the adsorption behavior and mechanism of pesticide on MPs was the basis of assessing the risk of joint exposure.
农用塑料薄膜和三唑类杀菌剂在农业生产过程中被广泛使用。暴露在自然环境中，农用塑料薄膜会降解为微米级塑料颗粒，这些颗粒会吸附农药分子，可能会影响其毒性、生物活性和持久性。长期共存的微塑料（MPs）和三唑类杀菌剂可能会对农业生态环境带来潜在危害。因此，选择了两种三唑类杀菌剂氟硅唑（FLU）和环唑醇（EPO）作为案例，研究了它们在聚苯乙烯和聚乙烯上的吸附行为。评估了一系列可能影响吸附行为的因素。具体来说，MPs 的粒径会影响其吸附能力，粒径越小，吸附能力越强。此外，随着 pH 值从 6.0 增加到 9.0，MPs 对目标化合物的吸附能力逐渐增强。通过 NaCl 评估离子强度的影响，0.05%的 NaCl 有利于吸附过程，而 NaCl 浓度的不断增加则抑制了吸附。草酸和腐殖酸分别使氟硅唑在 PE 和 PS 上的吸附量降低了 15.99-32.00%和 35.02-48.67%。此外，与单一农药体系相比，MPs 对二元农药体系中氟硅唑和环唑醇的吸附能力分别降低了 36.13-37.93%和 44.36-51.35%，表明两种农药之间存在竞争吸附。同时，通过吸附动力学和吸附等温线对吸附过程进行评价，结果与准二级动力学模型和 Freundlich 等温线模型一致。最后，进行了几种特征分析来研究吸附机制，结果表明氢键、卤键和疏水相互作用发挥了重要作用。研究农药在 MPs 上的吸附行为和机制是评估联合暴露风险的基础。
