Plant Uptake and Distribution of Endosulfan and Its Sulfate Metabolite Persisted in Soil

The distributions of endosulfan (ED) residues (α-, β-isomers, and sulfate-metabolite) in cucumbers grown in soils treated with ED at concentrations of 20 and 40 mg kg-1 were assessed using indoor and outdoor experiments. In all treatments, degradation rates of the α-isomer in soils were higher than that of the β-isomer. In the indoor tests, uptake amounts of total ED by cucumbers, after 15 d of growth, were 7.8 and 14.5 mg kg-1 in 20 and 40 mg kg-1-treated pots, respectively. For growth time from 15 to 30 d, uptake amounts in 20 and 40 mg kg-1-treated pots were 3.8 and 7.9 mg kg-1, respectively. Outdoor tests resulted in smaller ED residues in cucumbers than those in indoor tests. In both indoor and outdoor tests, ED residues absorbed were highest in roots, and the α-isomer was the more frequently absorbed isomer. These results will be useful for determining management criteria for soil persistent pesticides.本研究通过室内与大田试验，评估了在施加浓度为20 mg·kg⁻¹和40 mg·kg⁻¹硫丹（Endosulfan, ED）的土壤中种植的黄瓜体内硫丹残留（包括α-、β-异构体及其硫酸酯代谢物）的分布特征。所有处理组中，土壤内α-异构体的降解速率均高于β-异构体。室内试验中，黄瓜生长15天后，20 mg·kg⁻¹和40 mg·kg⁻¹处理盆栽组的黄瓜总硫丹吸收量分别为7.8 mg·kg⁻¹和14.5 mg·kg⁻¹；当黄瓜生长至15~30天阶段时，两组处理盆栽的总硫丹吸收量分别为3.8 mg·kg⁻¹和7.9 mg·kg⁻¹。室外大田试验中黄瓜体内的硫丹残留量低于室内盆栽试验。无论是室内还是室外试验，黄瓜根部的硫丹残留量均为最高，且α-异构体是更易被吸收的异构体类型。本研究结果可为土壤持久性农药的管理标准制定提供科学依据。