The adsorption characteristics of chromate and phosphate in basalt-derived soils with different ages in Hainan were investigated.The results indicated that free iron oxides and positive surface charge of the soils increased with the increase of soil age or soil development degree,thus the amount of chromate and phosphate adsorbed by soils changed in the same trends. Desorption rate of chromate adsorbed ranged from 19.8％ to 39.6％, which suggested that both specific and eleetrostatic adsorption were involved in chromate adsorption. However phosphate was mainly adsorbed through non-electrostatic adsorption mechanisms. The amount of phosphate desorbed from soil surfaces was very low and less than 6％. The desorption of phosphate in deionized water was greater than that in 0.1 mol/L NaNO3 and QNO3. Desorption of phosphate in 0.1 mol/L KNO3 was lower than that in 0.1 mol/L NaNO3. Electrolyte affected the dosorption of phosphate through the change of electric potential in adsorption plane on soil surfaces.%选择海南岛北部3个不同年代喷发的玄武岩发育的土壤研究了其对铬酸根(CrO42-)和磷酸根(PO43-)的吸附特征,结果表明随着母岩年龄的增加,土壤发育程度提高,土壤游离氧化铁和表面正电荷数量增加,对2种阴离子的吸附量增加.土壤CrO42-的解吸率在19.8%～39.6%之间,表明土壤对CrO42-的吸附涉及静电吸附和专性吸附2种机制,且随着土壤发育程度增加,CrO42-静电吸附所占比例增加.土壤对PO43-的吸附以非静电吸附为主,吸附的PO43-的解吸量非常低,其解吸率不超过6%.吸附PO43-在去离子水中的解吸量高于在0.1mol/L NaNO3和KNO3中的解析量,KNO3体系中的解吸量低于NaNO3体系中的,电解质主要通过改变胶体表面离子吸附面上的静电电位影响PO43-的解吸.
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