溶解性有机质对重金属在土壤中吸附和迁移的影响

溶解性有机质(DOM)是土壤中最具有活性的组分,可以与重金属发生吸附、解吸、络合等一系列作用,对重金属的迁移转化、生物有效性等产生一系列重要影响。通过实验研究溶解性有机质对重金属吸附和迁移的影响。吸附实验表明,重金属Cu、Pb、Cr、Cd在土壤中吸附能力是不同的,土壤对重金属吸附能力的大小顺序为PbCuCrCd。土柱实验表明,重金属Cu、Pb、Cd、Cr在土壤中的迁移规律相似,均为前期淋出液重金属含量较低,后期随时间的增大而增大,当达到吸附饱和后浓度趋于稳定。但不同重金属迁移速率各不相同,这与吸附实验结果相符。溶解性有机质的存在对重金属迁移的影响主要体现在迁移速率上,其穿透时间比去除有机质的情况短,有机质的存在有利于重金属离子向下迁移,但当达到饱和后对重金属迁移浓度影响不显著。

Effects of Dissolved Organic Matter on Adsorption And Migration of Heavy Metals in Soil

Dissolved organic matter (DOM) was the most active component in soil. DOM in soil may conduct a series of important influences on the bioavailability of heavy metals through the reaction as adsorption, desorption and complexation. The effect of dissolved organic matter on the adsorption and migration of heavy metals Cu, Pb, Cd, Cr have been determined by the soil column experiment. The adsorption experiments shows that the adsorption capacity of heavy metals Cu, Pb, Cr , Cd in soil are different, and the range of the soil adsorption capacity is Pb>Cu>Cr>Cd. By comparing the presence of DOM of isothermal adsorption experiments, it is found that DOM has inhibition on adsorption of soil to heavy metals. The soil column experiment results shows that the heavy metal Cu, Pb, Cd, Cr has the same migration patterns in soil, which all previous leaching liquid low heavy metal content, and then increases with time, the stable after reaching the adsorption saturation concentration. But migration ratesfor different heavy metal are different. At the presence of DOM, to the migration rate of heavy metal is increased, and the penetration time become shorter . While, when saturated, the effect is not significant.