水化学对中国黄土砷解吸的影响

Effects of Hydrochemistry on the Desorption of Arsenic from Chinese Loess

本文采用提取法研究了我国黄土中砷的形态,并通过批量实验研究了砷脱附中的水化学功能。结果表明,黄土的砷含量较高且稳定,总砷含量为27.73 mg/kg,标准偏差为3.02 mg/kg;砷主要以特定吸附,其中,以与碳酸盐结合(38.69%)、与铁(氢)氧化物结合(36.63%)的形式存在,很少以水交换(0.19%)的形式存在;阴离子HPO_(4)^(2-)、HCO_(3)^(-)和SO_(4)^(2-)在pH值为7~9时具有不同程度的促进As释放的能力;在HPO_(4)^(2-)的质量浓度为10 mg/L时的砷释放量,比无磷酸盐时的砷释放量,大一个数量级。

In this paper,the speciation of arsenic in Chinese loess were investigated by sequential extraction method,and the hydrochemical function of arsenic desorption was studied by batch experiments.The results show that the arsenic content of loess is high and stable,the total arsenic content is 27.73 mg/kg,and the standard deviation is 3.02 mg/kg;arsenic mainly exists in the form of specific adsorption,in which it exists in the form of binding with carbonate(38.69%),binding with iron(hydrogen)oxide(36.63%),and rarely exists in the form of water exchange(0.19%);anions HPO_(4)^(2-),HCO_(3)^(-) and SO_(4)^(2-) have the ability to promote as release to varying degrees at pH 7~9;when the mass concentration of HPO_(4)^(2-) is 10 mg/L,the arsenic release is one order of magnitude larger than that without phosphate.