【摘要】 三种可变电荷土壤对砷的吸附实验结果表明,在pH3~7范围内,As(Ⅲ)的吸附量随pH的升高而增加,三种土壤对As(Ⅲ)吸附能力的大小顺序为砖红壤>黄壤>红壤。红壤和砖红壤对As(Ⅴ)的吸附量随pH的升高而降低,黄壤中呈相反的变化趋势,三种土壤对As(Ⅴ)吸附能力的大小顺序是黄壤>砖红壤>红壤。三种可变电荷土壤对As(Ⅴ)的吸附能力较对As(Ⅲ)大得多,砷的吸附量既与土壤游离氧化铁的含量有关,又与氧化铁的结晶形态密切联系,由于黄壤中水化氧化铁在游离铁中所占比例较高,其对As(Ⅴ)吸附能力较砖红壤和红壤大。As(Ⅲ)与As(Ⅴ)共存体系的研究结果表明,两种形态的砷可以竞争可变电荷土壤表面的吸附位,但在酸性条件下As(Ⅴ)较As(Ⅲ)有更强的竞争能力,因为As(Ⅴ)使土壤对As(Ⅲ)的吸附量显著减小,而As(Ⅲ)对红壤和砖红壤吸附As(Ⅴ)有一定的影响,对黄壤中As(Ⅴ)的吸附几乎没有影响。更多还原

【Abstract】 Data from the experiment on arsenic adsorption by three variable charge soils show that As(Ⅲ) adsorption increased with pH rising from 3 to 7,and the three soils followed the order: latosol>yellow soil>red soil.While,As(Ⅴ) adsorption decreased with rising pH in red soil and latosol,an opposite trend was observed in yellow soil,making the three soils in the order: yellow soil>latosol>red soil in As(Ⅴ) adsorption.These soils have greater adsorption capacity for As(Ⅴ) than for As(Ⅲ),and the adsorption of either As(Ⅴ) or As(Ⅲ) was related not only to content of the free iron oxides in the soils,but also to crystalline type of the oxides in the soils.The yellow soil showed larger adsorption capacity for As(Ⅴ) than latosol and red soil due to its high proportion of hydrated iron oxides.Results from the binary system of As(Ⅲ) and As(Ⅴ) indicated that the two species of arsenic competed with each other for adsorption sites on variable charge soils;and As(Ⅴ) was more competitive than As(Ⅲ) under acidic condition,because the presence of As(Ⅴ) depressed the adsorption of As(Ⅲ) to a larger extent,and vice versa in red soil and latosol to a certain extent,but almost no effect of the presence of As(Ⅲ) on As(Ⅴ) adsorption by yellow soil was observed except with a high pH.更多还原