吡虫啉在棉土中的吸附-解吸、消解与淋溶特性  

Adsorption/Desorption,Dissipation and Leaching Behavior of Imidacloprid in Typical Soil of Cotton-field

作　　者：杨凤 郑露奇 曾雯琪 节梦蕾 杨亚磊 景伟文 YANG Feng;ZHENG Luqi;ZENG Wenqi;JIE Menglei;YANG Yalei;JING Weiwen(College of Chemical Engineering,Xinjiang Agricultural University,Urumqi 830052,China)

机构地区：[1]新疆农业大学化学化工学院,新疆乌鲁木齐830052

出　　处：《环境科学与技术》2025年第3期67-75,共9页Environmental Science & Technology

基　　金：国家重点研发计划项目(2016YFD0200207-3);新疆农业大学大学生创新基金项目。

摘　　要：该研究通过实验室和田间试验评估了吡虫啉农药在新疆地区棉花种植土壤中的吸附-解吸、消解特性和浸出潜力。吸附-解吸试验(采用振荡平衡法)的结果表明,Freundlich等温模型能较好地描述其吸附-解吸特性,测得K_(f)值为2.318,吸附系数(1/n_(ads))>1,吸附等温线属于S型,吡虫啉在供试土壤内部的吸附为非线性分配过程,吸附自由能(ΔG)小于40 kJ/mol,说明吡虫啉以自发的物理吸附机理为主。随着吡虫啉浓度的增加,吸附量逐渐增加。计算有机碳吸附常数(K_(oc))为421 mL/g(200<K_(oc)≤1000,Ⅳ级),证明吡虫啉在该土壤中属于较难吸附,具有“中等移动性”。解吸动力学与吸附动力学趋势相似,测得的K_(f)值为0.543,说明吡虫啉易被该土壤解吸,且解吸呈负滞后性。室内土柱淋溶试验的结果表明,吡虫啉的最大含量分段在5~15 cm,依据《化学农药环境安全评价试验准则》中农药移动性等级划分标准,吡虫啉在供试土壤中属于难淋溶性农药。相比于室内试验,田间试验的结果表明吡虫啉在田间各土层中的迁移速度较慢,但最终随时间的推移从土壤表层运动到深层,且在田间浅层土壤中的移动速率较深层土壤快。吡虫啉在各土层中的半衰期较短(2.81~8.41 d),按照《农作物中农药残留试验准则》(NY/T 788-2018)标准划分,吡虫啉属于易消解农药。利用GUS指数法,结合田间试验的结果进行验证,认为吡虫啉的淋溶性与其易消解性有关。吡虫啉施用量越高,淋溶量越大,随着吡虫啉初始淋溶量的增加,淋溶强度会增强。腐殖酸对土壤中的吡虫啉具有截留作用。总体上看,吡虫啉施用后在供试土壤中属于难吸附、易解吸,易于消解而难淋溶,虽环境风险不高,但仍应控制用量,科学施用。This paper elaborates on the evaluation of adsorption/desorption,dissipation characteristics and leaching potential of imidacloprid pesticide in cotton-planting soil collected from Xinjiang region by both laboratory and field experiments.As a result of the adsorption/desorption test(using oscillating equilibrium method),the Freundlich isotherm model could better describe the adsorption/desorption characteristics of imidacloprid.K_(f) value measured is 2.318,the adsorption coefficient(1/n_(ads))>1;the adsorption isotherm is categorized as S type,the adsorption of imidacloprid onto the test soil is a nonlinear process and the adsorption free energy(ΔG)is less than 40 kJ/mol,indicating that imidacloprid adsorption is mainly in line with spontaneous physical adsorption mechanism,and with the increase of imidacloprid concentration,the adsorption amount gradually increased as well.The organic carbon adsorption constant K_(oc) being calculated is equal to 421 mL/g(200<K_(oc)≤1000,GradeⅣ),which means that imidaclopr is relatively difficult to be adsorbed on the test soil,having“medium mobility”,and the desorption kinetics is similar to adsorption kinetics;and K_(f) value measured is 0.543,indicating that the desorption of imida⁃cloprid is relatively easy,and the desorption midacloprid has a trait of negative hysteresis.Further,results of the laboratory soil-column leaching test show that the maximum content of imidacloprid appeared in the range 5~15 cm of soil layer,so according to the mobility classification standard of pesticides in the Guidelines for Environmental Safety Evaluation of Chemical Pesticides,imidacloprid belongs to non-leachable pesticide,which is also proved by the results of the field experiment.Compared with the results of the laboratory soil-column leaching test,the results of field experiment show that the migration rate of imidacloprid in each of the soil layers in the field is slow,but eventually,imidacloprid moves gradually from the surface layer to the deep layer,and the travel rate of

关 键 词：吡虫啉 吸附 解吸 消解 淋溶 

分 类 号：X53[环境科学与工程—环境工程] X592