有机氯农药在农田土壤中的吸附解吸特征

Sorption and Desorption Characteristics of Organochlorine Pesticides in Soils

选取3种不同深度的农田土壤作为吸附剂,采用批量实验方法,研究了有机氯农药p,p’-DDD和γ-HCH在等温条件下的吸附解吸行为。结果表明,p,p’-DDD和γ-HCH的吸附解吸曲线均可用Freundlich模型较好拟合,并且在表层土壤中表现为线性,而在深部土壤中表现为非线性,表明深部土壤的组成可能更加复杂和不均匀。3种土壤对p,p’-DDD的吸附容量参数Kf值与总有机碳(TOC)含量大小关系一致,而γ-HCH的吸附Kf值却与DOM含量显著正相关。p,p’-DDD和γ-HCH在所有样品中的解吸均有不同程度的滞后现象,其中p,p’-DDD的解吸主要受土壤中有机质含量的影响,TOC含量越低滞后性越不明显,而γ-HCH的解吸滞后性比较复杂。

The sorption and desorption behaviors of p,p＇-DDD and γ-HCH of organochlorine pesticides in three soils of different depths were studied in batch experiments. Results showed that the sorption and desorption isotherms of p,p＇-DDD and γ-HCH could be fitted well by Freundlich model,and they were linear in the surface soil and non-linear in deeper soils,which may indicate the heterogeneity of composition in the deeper soils. Adsorption capacity parameter（Kf）of p,p＇-DDD on three soils had significant positive correlation with TOC content. There was significant positive correlation between Kf of γ-HCH and DOM content. p,p＇-DDD and γ-HCH in all samples had various desorption hysteresis. Desorption of p,p＇-DDD was mainly controlled by TOC content,and hysteresis was not obvious with lower TOC content. However,desorption hysteresis of γ-HCH in soils was complex.