长三角和珠三角农业土壤对Pb、Cu、Cd的吸附解吸特性

研究了长江三角州和珠江三角州10种代表性农业土壤对重金属Pb、Cu和Cd的吸附与解吸特性。结果表明:大多数土壤对重金属有较强吸附能力,土壤性质对重金属吸附与解吸行为有很大影响。其中,pH值是影响土壤对重金属吸附与解吸的最重要因素,土壤重金属吸附量随pH值增加而增加。土壤pH值和有机质或粘粒含量较高的土壤(如乌栅土、青紫泥田、黄斑田),其对重金属吸附能力高于pH值和有机质或粘粒含量较低的土壤(如黄筋泥、粉泥田)。重金属解吸量随重金属吸附量和土壤重金属饱和度增加呈指数增加趋势;土壤对重金属的吸附能力从强至弱依次为Pb、Cu、Cd;当3种重金属共存时,重金属之间竞争能力强弱顺序与吸附能力顺序相同。重金属之间竞争作用随土壤酸度和重金属污染程度的增加而增强。

Lead, Copper, and Cadmium Adsorption-Desorption Behaviors of Agricultural Soils of Changjiang and Zhujiang Deltas

Ten agricultural soils,collected from the Changjiang and Zhujiang Deltas,were analyzed to explore Pb,Cu and Cd adsorption-desorption behaviors of the soils.It was found that soil properties had much influence on heavy metal adsorption-desorption behavior of the soils,and pH was the most important factor controlling adsorption-desorption of the metals.The soils high in pH value,organic matter content and clay content were higher in heavy metal adsorption capacity than those lower in these aspects.Heavy metal desorption rate of the soils increased exponentially with heavy metal accumulation of the soils.In terms of soil adsorption ability for heavy metals,a decreasing order was observed as Pb>Cu>Cd,and the same order was found with the heavy metals in competitive adsorption.The competition between the metals for adsorption increased with soil acidity and heavy metal pollution level of the soils.