冻融作用对土壤吸附重金属的影响

以Pb²⁺和Cd²⁺为目标污染物研究冻融作用对土壤吸附重金属的影响, 推断了影响机制, 并分析了温度对冻融土壤吸附重金属的影响. 结果表明, 冻融作用降低了土壤对重金属的吸附量, 影响了吸附曲线的斜率, 但未改变吸附曲线形状, 这与冻融作用改变土壤理化性质有关: 冻融作用影响了土壤对Pb²⁺和Cd²⁺的吸附机制, 引起专性吸附向非专性吸附转变, 利于Pb²⁺和Cd²⁺向环境的解吸和释放. 冻融作用未影响土壤对Pb²⁺和Cd²⁺的吸附热力学性质, 随着温度的升高, 冻融土壤和未冻融土壤对Pb²⁺的吸附量逐渐升高, 属于吸热反应； 对Cd²⁺的吸附量降低, 属于放热反应.

Effect of Freeze-Thaw on the Adsorption of Heavy Metals by Soil

We used Pb2+ and Cd2+ as target pollutants to study the effect of freeze-thawing cycles on the adsorption of heavy metals by soil,decuced the effect mechanisms,and analyzed the effect of temperature on heavy metal adsorption on freeze-thaw soils.The results show that the freeze-thawing cycles reduced the Pb2+ and Cd2+ adsorption on soil,and changed the slope of Pb2+ and Cd2+ adsorption isotherms.Freeze-thawing cycles changed the adsorption mechanism of soil from specific adsorption to nonspecific adsorption,and it promotes soil to desorbe and release Pb2+ and Cd2+ to the environment.Freeze-thaw did not change the therm odynamic property of Pb2+,Cd2+ adsorption on soil,with the rise of temperature,Pb2+ adsorptions on freeze-thaw soil and untreated soil were increased,which belong to endothermic reaction;but the adsorption of Cd2+ reduced with temperature rise,which belongs to the exothermic reaction.Under the same pH conditions,the adsorption quantities of Pb2+ and Cd2+ on freeze-thaw soil were lower than those on untreated soil.