毒死蜱在不同土壤腐殖酸上的吸附/解吸特征

通过平衡振荡法研究毒死蜱在不同来源土壤腐殖酸(Has)上的吸附/解吸行为.结果表明,毒死蜱在Has上的等温吸附行为用Freundlich模型描述相对更合理;它们的吸附等温线在实验范围内基本呈直线,且吸附能力很强,顺序为:紫色潮土Has＞黄壤Has＞中性紫色土Has＞酸性紫色土Has＞腐殖土Has;但毒死蜱的解吸率较小,其值均小于26.70%,有明显的滞后现象,尤其是腐殖土Has和紫色潮土Has,固定能力顺序为:紫色潮土Has＞腐殖土Has＞中性紫色土Has＞酸性紫色土Has＞黄壤Has.由于不同来源土壤中Has的组成结构差异明显,它们对毒死蜱的吸附/解吸规律表现出不同的特征.土壤Has对毒死蜱的吸附/解吸行为的影响是多种因素综合作用的结果,具体作用机理尚待进一步研究.

Adsorption of chlorpyrifos on humic acids in soil samples

Batch isotherm experiments were performed to study the phenomena of adsorption of chlorpyrifos on humic acids (HAs) obtained from several types of soil samples. The adsorptive capacity and equilibrium chlorpyrifos concentration relationships were well represented by the Freundlich adsorption model. Chlorpyrifos was strongly adsorbed in all HAs that only a small fraction (<26.7%) of the adsorbed chlorpyrifos was desorbed in the desorption runs. The absorbability in decreasing order was: purple alluvium>yellow soil>neutral purple soil>acid purple soil>humus soil, while the chlorpyrifos retention rate in decreasing order was: purple alluvium>humus soil>neutral purple soil>acid purple soil>yellow soil. Both composition and structure of HAs affected the observed adsorption and desorption characteristics. HAs from different soils are significantly different from each other; therefore, a series of adsorption/desorption experiments should be performed for every case of interest.