摘要
用土壤硫形态连续提取方法分离测定了喀斯特坡地土壤总硫、有机硫、SO24-和FeS2的硫同位素组成及其含量.总体来看,土壤剖面表层各形态硫δ34S值FeS2最低,介于-6.86‰^-4.22‰,其次为SO24-(-2.64‰^-1.34‰),第三为总硫(-3.25‰^-1.03‰),最高为有机硫(-1.63‰~0.50‰),随土壤剖面加深各形态硫δ34S值均有增大的趋势.SO24-和FeS2的δ34S值深度分布具有共变性,这与SO24-异化还原有关;而总硫和有机硫的δ34S值随剖面加深而平行增大,则与有机硫循环有关.硫同位素组成可鉴别土壤硫源,同时SO24-异化还原和有机硫矿化有明显的硫同位素分馏,而硫化物氧化及SO24-同化基本不产生同位素分馏,则土壤各形态硫的硫同位素组成的垂直变化可以很好地记录与深度相关的硫循环过程.并且,通过对比各形态硫含量及其硫同位素组成的深度分布特征,也可以很好地判别土壤内部的SO24-和有机硫组分的迁移过程.
Sequential extraction methods for soil sulfur were used to determine δ^34S ratios and sulfur contents of total sulfur, organic sulfur, SO4^2- and FeS2 in slope soils of karst areas. In general, FeS2 has the lowest δ^34S ratios, ranging from -6.86‰ to -4.22‰, followed in ascending order by SO4^2- （ -2.64‰- 1.34‰） , total sulfur （ -3.25‰- 1.03‰） and organic sulfur （ - 1.63‰- 0. 50‰） in surface soils of profiles, and δ^34S ratios in different sulfur forms all show increasing trend with profiles deepening. Covariations of δ^34S ratios of SO4^2- and FeS2 with increasing depth are related to SO4^2-dissimilatory reduction, while the increase in parallel of δ^34S ratios of total sulfur and organic sulfur could be resulted from organic sulfur cycling. δ^34S ratios have been extensively used to indicate sulfur sources, moreover, SO4^2- dissimilatory reduction and organic sulfur mineralization result in significant sulfur isotopic fractionation, and sulfides oxidation and SO4^2- assimilation have no isotopic fractionation occurred, the vertical variations of δ^34S ratios in different sulfur forms can therefore be good records for depth-dependant sulfur cycling processes. Furthermore, by comparing depth distributions of sulfur contents and δ^34S ratios in different sulfur forms, it is easily to discuss the migration of SO4^2- and organic sulfur fractions in soil profiles.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2010年第2期415-422,共8页
Environmental Science
基金
中国科学院西部行动计划项目(KZCX2-XB2-08)
国家重点基础研究发展规划(973)项目(2006CB403205)
天津市科技发展计划项目(06YFSZSF05100)
关键词
喀斯特
黄色石灰土
黄壤
硫同位素
硫循环
karst
yellow limestone soils
yellow soils
sulfur isotopes
sulfur cycling
