Origin and mobility of adsorbed sulfate in Andosol subsoils as revealed by stable isotope analysis

来源于火山灰的安多索底土通常含有大量被吸附的硫酸盐。为了阐明吸附硫酸盐的来源和迁移性，测量了土壤剖面中硫酸盐含量的垂直分布和不同深度土壤中硫酸盐- s的稳定同位素比值，以及吸附硫酸盐的解吸/洗脱特征和同位素交换性质。结果表明，农业土壤中积累的硫酸盐来源于肥料，其来源与未开垦土壤不同，并且肥料来源的硫酸盐在土壤剖面中具有较大的流动性，导致先前吸附的其他阴离子（如硝酸盐）的解吸和向下位移。

Andosol subsoils derived from volcanic ash often contain large amounts of adsorbed sulfate. To elucidate the origin and mobility of the adsorbed sulfate, measurements were made on the vertical distribution of sulfate content in soil profiles and the stable isotope ratio of sulfate-S in soils sampled at different depths, together with desorption/elution characteristics and isotopic exchange properties of the adsorbed sulfate. The results demonstrate that sulfates accumulated in agricultural soils have been derived from fertilizers and have origins distinct from those in uncultivated soils, and that the fertilizer-derived sulfate has a relatively large mobility in soil profile, causing desorption and downward displacement of antecedently adsorbed other anions such as nitrate.