【摘要】 用连续提取方法分析了石灰土总硫、SO₄^2–、总还原态硫（TRS）和有机硫的硫同位素组成,探讨了石灰土中硫的迁移转化过程及其环境效应。有机硫是石灰土主要的硫形态,随剖面加深总硫和有机硫的δ34S值逐渐增大,其含量降低,这与有机硫持续矿化有关。SO₄^2–和TRS的δ34S值随剖面加深平行地增大指示了石灰土中存在SO₄^2–异化还原过程,并且TRS是主要产物。高pH值和较低的黏粒含量不利于SO₄^2–吸附,生物滞留后剩余的SO₄^2–主要通过淋溶迁移出石灰土剖面。当前酸沉降对石灰土的影响并不严重,SO₄^2–的淋溶迁移并没有引起石灰土pH值的显著降低。但值得关注的是,有机硫形态是酸沉降输入的SO₄^2–在石灰土中主要的硫滞留方式,SO₄^2–吸附基本可以忽略,则在硫的年沉降速率显著降低之后,在较长时期内,石灰土中有机硫的矿化可能释放大量的SO₄^2–进入地表和地下水体,与之相关的土壤理化性质变化和水体化学组成改变等方面的环境效应值得关注。更多还原

【Abstract】 The sequential extraction method for soil sulfur was used to determine the δ34S values of total sulfur, SO₄^2–, total reduced sulfur（TRS） and organic sulfur in limestone soil, with an attempt to discuss the transportation and transformation of sulfur and its environmental implications in limestone soil. Organic sulfur was the major sulfur form in limestone soil. Mineralization of organic sulfur explained the increasing δ34S values and decreasing sulfur contents of total sulfur and organic sulfur with increasing depth in soil profiles. The parallel increasing δ34S values of TRS and SO₄^2– indicate the occurrence of a bacterial reduction process of sulfate with TRS as the main product in limestone soil. The high pH values and low clay contents prevented SO₄^2– adsorption in limestone soil. Therefore, the residual SO₄^2– after biological S retention was lost by way of leaching in limestone soil profiles. At present, the effect of acid deposition on limestone soil appeared not so serious, because SO₄^2– transport did not lead to a decrease in the pH values of limestone soil. It is noted that the deposited SO₄^2– was retained as organic sulfur in limestone soil, and SO₄^2– adsorption can be negligible in limestone soil, then limestone soil may release more S into rivers by way of organic sulfur mineralization in a long period after a large decrease in annual sulfur deposition rate. The environmental implications such as changes in soil properties and chemical compositions of river water in Southwest China should be investigated in the future.更多还原