水溶性有机质对土壤中镉吸附行为的影响

水溶性有机质 (DOM)是陆地生态系统和水生生态系统中的一种很活跃的组分 .本文以赤红壤、水稻土和褐土作为供试土壤 ,研究了来源于稻秆和底泥的DOM对土壤中Cd吸附行为的影响 .DOM对土壤中Cd的吸附行为具有明显的抑制作用 .这种抑制作用与土壤类型和DOM种类有关 .在 3种供试土壤中 ,无论添加稻秆DOM还是底泥DOM ,都会使Cd的最大吸附容量和吸附率明显降低 ,其下降幅度为17 3%～ 93 9%.在添加同一种DOM的前提下 ,DOM对Cd吸附的抑制作用均为 :赤红壤 >水稻土 >褐土 .如果不添加DOM ,则土壤对Cd的最大吸附容量主要取决于土壤固相的吸附特性 ,添加DOM后土壤对Cd的最大吸附容量则主要取决于液相中的DOM .由此推断 ,传统的看法 ,通过施用有机肥来固定土壤中的Cd并达到治理重金属污染土壤的观点值得商榷 .

Cadmium adsorption in soil influenced by dissolved organic matter derived from rice straw and sediment.

Dissolved organic matter (DOM) is an active component in territorial ecosystems.Effects of two types of DOMs extracted from sediment(DOM-{sed}) and rice straw(DOM-{rs}) on isotherm adsorption of Cd in latosol red soil (acidic soil),paddy soil and drab soil(alkaline soil)were studied using batch equilibrium studies.The maximum adsorption of Cd in all the 3 soils used was reduced by the additions of both of DOM-{sed} and DOM-{rs}.The range of the maximum adsorption of Cd decreased from 17^3% to 93^9% from all the 3 soils when DOMs were added.It was found that the decreaseds in the maximum adsorption of Cd was in order of latosol red soil>paddy soil>drab soil when the same DOM(DOM-{sed} or DOM-{rs}) was added.Effects of DOM-{sed} or DOM-{rs} on Cd adsorption were positively related with the soil pH.The maximum adsorption of Cd in the soils was dependent on the characteristics of soil solid when no DOM was added,and decided by the DOMs in soil solutiom when DOM was added.The results imply that the proposed technology using organic manure to stablize Cd in soils is not suitable for remediation of contaminated soil.