烯啶虫胺在热带土壤中吸附解吸特征研究

为了解烯啶虫胺在热带地区风化程度较高的酸性土壤中的环境行为，根据叶化学农药环境安全评价试验准则曳中土壤吸附试验规定，采用振荡平衡法，研究了烯啶虫胺在3 种不同热带土壤上的吸附特性。结果表明，烯啶虫胺在3 种热带土壤上的吸附过程能用Freundlich 方程和Langmuir 方程进行较好的拟合，且吸附行为存在较大的差异，其Kf值分别为水稻土1.530 L/kg，铁质湿润雏形土3.153 L/kg，暗红湿润铁铝土2.724 L/kg。烯啶虫胺在3 种热带土壤上的吸附属于难吸附等级，解吸较为容易，易在热带土壤中移动，在施用的过程中容易造成地下水污染。此外，烯啶虫胺在3 种热带土壤上的吸附主要是分配作用，且吸附自由能驻G 均小于40 kJ/mol，属于物理吸附过程。

Study on adsorption and desorption ofnitenpyram in tropical soil

In order to understand the environmental behavior of nitenpyram in acid soil with higher degree ofweathering in tropical areas, according to experimental guideline for environmental safety evaluation of chemicalpesticides, this paper analyzed the adsorption processes of Nitenpyram in three types of tropical soil by batch equilibrationtechnique. Results showed that the adsorption isotherms of Nitenpyram in three types of tropical soil could be describedwell by Freundlich and Langmuir equations. Adsorption behavior of Nitenpyram varied in different types of tropical soil:adsorption coefficient (Kf) of nitenpyram in paddy soil, ferric-udic cambosols and udic ferralisols was 1.530, 93.153 and2.724 L/kg, respectively. Nitenpyram was hard to be adsorbed in these soils but was easy to desorb. Adsorption free energy(G) of nitenpyram in three types of tropical soil was lower than 40 kJ/mol, showing that the partition was predominant andthe adsorption process relied mainly on physical adsorption.