土壤中镉的吸附解吸研究进展

Advance in studies of cadmium sorption and desorption in soils

首先概述了国内外关于土壤对镉的吸附解吸的基本研究方法与实验条件。用于吸附解吸实验的土样以通过20目筛为宜,而不同形式的支持电解质及其离子浓度的选择对实验结果有很大影响,应由实验的具体目的和要求确定合适的实验条件。位于土壤颗粒表面的各吸附点位与镉的结合能的能量高低不一,可将土壤对镉的吸附作用区分为专性吸附和非专性吸附。可用传统的或融入新参数的吸附等温线表达土壤对镉的吸附过程,土壤对镉的吸附性能可用综合因子来形容,如吸附势、吸持率、平均分配系数、Langmuir方程的常数k和Freundlich方程的系数k等表达方式,同时寻找这些综合因子与土壤基本理化性质之间的关系。文章最后讨论了影响吸附过程的主要环境因子,并就土壤pH和水分条件的影响机制进行了分析。

This paper summarizes the primary way to investigate cadmium sorption and desorption in soils at home and abroad. Soils for experiment should be ground and passed through a 1 mm sieve, and both electrolyte composition and ionic strength affect results of experiments. Detailed experimental conditions should be determined from the objective. Soil particle surface is heterogeneous and has different affinity sorption sites, and process of sorption is differentiated into specific sorption and nonspecific sorption. Sorption process may be expressed by traditional or new-parameter-included sorption isotherms, and sorption capability can be described by one parameter, such as sorption potential, sorption rate, and average distribute rate. Many researches studied the relationship between the parameter and soil characteristics. Finally some factors affecting the sorption and the influencing mechanisms of soil pH and moisture are discussed.