江汉平原旱地和水田土壤镉的吸附与解吸特征及影响因素

Adsorption and Desorption Characteristics of Cd in Upland and Paddy Soil of Jianghan Plain

为揭示旱地和水田土壤镉的吸附解吸特征,以江汉平原黄豆地、棉花地以及水稻田土壤为研究对象,开展土壤镉的吸附动力学实验、等温吸附-解吸实验以及有机质的影响实验.结果表明:江汉平原土壤对镉的吸附是一个较为复杂的吸附动力学过程且以化学吸附为主,研究区土壤镉的初始吸附速率总体上表现为水田土壤大于旱地土壤;旱地土壤对Cd^(2+)具有较低的吸附能力和较高的解吸能力,水田土壤对Cd^(2+)具有较高的吸附能力和较低的解吸能力,这与土壤有机质含量、土壤粘粒含量等因素有关;去除有机质后旱地、水田土壤对镉的吸附量均明显下降,且旱地土壤降幅更为明显,水田土壤去除有机质后对Cd^(2+)的吸附能力依然高于旱地土壤.研究结果可为不同类型农田土壤的镉污染修复提供理论依据.

In order to reveal the adsorption and desorption characteristics of Cd^(2+) in upland and paddy soil,the soil of soybean field,cotton field and rice field in Jianghan Plain were taken as the research objects to carry out the adsorption kinetics experiment,isothermal adsorption desorption experiment and influence experiment of organic matter on soil Cd^(2+).The results showed that:the adsorption of Cd^(2+) by soil in Jianghan Plain was a complex adsorption kinetic process,and was dominated by chemisorption.The initial adsorption rate of Cd^(2+) in paddy soil was higher than that in dryland soil;while dryland soil had lower adsorption capacity and higher desorption capacity for Cd^(2+),paddy soil had higher adsorption capacity and lower desorption energy for Cd^(2+).This is related to soil properties such as organic matter content,Cd^(2+) background content and soil clay content.After removing organic matter,the adsorption capacity of Cd^(2+) in upland and paddy soil decreased significantly.The adsorption capacity of Cd^(2+) in paddy soil was still higher than that in upland soil after the removal of organic matter.The research in this paper can provide a theoretical basis for the remediation of Cd^(2+) pollution in different types of farmland soils.