Huang Guanxing, Chen Zongyu, Sun Jichao, Liu Fan, Wang Jia, Zhang Ying
Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China,
Environ Sci Pollut Res Int. 2015 Jun;22(11):8367-74. doi: 10.1007/s11356-014-3958-5. Epub 2014 Dec 24.
Using by sequential extraction procedures to obtain the chemical forms of arsenic in soils can provide useful information for the assessment of arsenic mobility and bioavailability in soils. However, sample pretreatments before the extraction probably have some effects on the fractionation of arsenic in soils. Impact of sample pretreatments (freeze-drying, oven-drying, air-drying, and the fresh soil) on the fractionation of arsenic in anoxic soils was investigated in this study. The results show that there are some differences for arsenic fractions in soils between by drying pretreatments and by the fresh soil, indicating that the redistribution among arsenic fractions in anoxic soils occurs after drying pretreatments. The redistribution of arsenic fractions in anoxic soils is ascribed to the oxidation of organic matter and sulfides, the crystallization of iron (hydr)oxides, the ageing process, and the diffusion of arsenic into micropores. The freeze-drying is the best drying method to minimize the effect on the fractionation of arsenic in anoxic soils, while air-drying is the worst one. Drying pretreatments are not recommended for the fractionation of arsenic in anoxic soils with high concentration of iron.
采用连续提取程序获取土壤中砷的化学形态可为评估土壤中砷的迁移性和生物有效性提供有用信息。然而，提取前的样品预处理可能会对土壤中砷的分级产生一些影响。本研究考察了样品预处理（冷冻干燥、烘干、风干和新鲜土壤）对缺氧土壤中砷分级的影响。结果表明，干燥预处理土壤与新鲜土壤中砷的形态存在差异，这表明缺氧土壤中砷形态在干燥预处理后会发生重新分布。缺氧土壤中砷形态的重新分布归因于有机质和硫化物的氧化、铁（氢）氧化物的结晶、老化过程以及砷向微孔的扩散。冷冻干燥是将对缺氧土壤中砷形态分级影响降至最低的最佳干燥方法，而风干是最差的方法。对于铁含量高的缺氧土壤，不建议采用干燥预处理来进行砷的分级。
