棕壤及其各粒级微团聚体对Cu~(2+)吸附解吸特性的研究

采用室内分析的方法,研究了棕壤及其各粒级微团聚体对Cu2+的吸附解吸作用。结果表明:棕壤与其各粒级微团聚体相比,对Cu2+的吸附能力较弱,而三级微团聚体对Cu2+的吸附能力的大小顺序为:<10μm粒级微团聚体>10~50μm粒级微团聚体>50~250μm粒级微团聚体。同时,通过NH4OAc,EDTA对Cu2+的解吸情况的研究得出,棕壤及其不同粒级微团聚体对Cu2+的吸附机制是不同的,在棕壤和各粒级微团聚体中,<10μm粒级的微团聚体对Cu2+的吸附机制以专性吸附为主,固定Cu2+的能力最强,从而能降低Cu2+的活性,不易为植物吸收,其次为10~50μm粒级微团聚体和棕壤,而50~250μm粒级微团聚体对Cu2+的吸附以静电吸附机制为主,其吸附的Cu2+可以被交换,因此固定Cu2+的能力较差。

Analysis of Adsorption-Desorption of Cu2+ on Brown Earth and its Particle Fractions of Microaggregates

Effects of adsorption-desorption of Cu~(2+) on brown earth and several different particle fractions of microaggregates extracted from it was investigated based on the chemical analysis.The results showed that compared with brown earth different particle fractions of microaggregates presented tighter adsorption with Cu~(2+),the orders of adsorption ability was <10μm particle >10-50μm particle >50-250μm particle.Oppositely,in desorption research adding EDTA and NH_4OAc to release Cu~(2+),it could be draw that the main adsorption mechanism of Cu~(2+) on brown earth and microaggregates was not the same. Among them,the adsorption mechanism of Cu~(2+) on the <10μm particle was specific adsorption,so the ability of fixing Cu~(2+) was the strongest,therefore the activity of Cu~(2+) in soil can be restrained,thus hard to be absorbed by the plants.The second one was 10-50μm particle fraction,then was brown earth,the 50-250μm particle fraction was the last one.The mechanism of this particle fraction was ion-exchange,which meant the adsorbed Cu~(2+) could be exchanged,so as far as the other particle fractions of microaggregates and brown earth was concerned,the fixed ability of this particle fraction was poor.