Isotope evidence for secondary sulfide precipitation along the Marsyandi River, Nepal, Himalayas
Isotope evidence for secondary sulfide precipitation along the Marsyandi River, Nepal, Himalayas
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DOI：
10.1016/j.epsl.2013.04.033
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发表时间：
2013-07-15
影响因子：
5.3
通讯作者：
Bickle, Mike J.
中科院分区：
文献类型：
--
作者：
Turchyn, Alexandra V.;Tipper, Edward T.;Bickle, Mike J.
我们目前的硫和氧同位素数据从41个样品溶解的河流硫酸盐从沿着65公里的Marsyandi河在北方喜马拉雅山。河流硫酸盐的硫和氧同位素组成（分别为δ S-34（SO 4）和δ O-18（SO 4））对河流系统的硫来源产生了独特的限制。Marsyandi河的源头有轻微的S-34（SO 4）和O-18（SO 4）三角洲，这就要求河流的硫酸盐来源是通过黄铁矿的缺氧风化（可能通过Fe 3+）。Marsyandi支流中硫酸盐的δ S-34（SO 4）和δ O-18（SO 4）在下游增加，这可能是由于在温暖和潮湿的集水区中，来自碳酸盐岩的输入或细菌硫酸盐还原以及随后的硫化物沉淀造成的;这些过程中的任何一个都可能导致残留河流硫酸盐的δ S-34（SO 4）和δ O-18（SO 4）。元素比，如Sr/Ca和Ca/SO 4表明，如以前的研究也得出结论，蒸发岩风化是不重要的Marsyandi河。我们的结论是，同位素数据是最一致的发病细菌硫酸盐还原和次生硫化物沉淀在土壤中的温暖和潮湿的下游集水区。我们的研究结果有影响，了解硫酸盐的来源，海洋以及氧化还原和酸度预算内迅速侵蚀集水区。(C)2013爱思唯尔有限公司版权所有。
We present sulfur and oxygen isotope data from 41 samples of dissolved riverine sulfate from along 65 km of the Marsyandi River in the Northern Himalayas. Coupled sulfur and oxygen isotopic composition of riverine sulfate (delta S-34(SO4) and delta O-18(SO4) respectively) yield unique constraints on the source of sulfur to the river system. The headwaters of the Marsyandi River have light delta S-34(SO4) and delta O-18(SO4), which requires that the source of sulfate to the river is through the anoxic weathering of pyrite (likely via Fe3+). The delta S-34(SO4) and delta O-18(SO4) of sulfate in tributaries to the Marsyandi increase downstream, which could result either from inputs from evaporites or bacterial sulfate reduction with subsequent sulfide precipitation in warmer and wetter catchments; either of these processes could result in heavy delta S-34(SO4) and delta O-18(SO4) of the residual river sulfate. Elemental ratios such as Sr/Ca and Ca/SO4 suggest, as previous studies have also concluded, that evaporite weathering is not important in the Marsyandi River. We conclude that the isotope data is most consistent with the onset of bacterial sulfate reduction and secondary sulfide precipitation in the soils in the warmer and wetter downstream catchments. Our results have implications for understanding the source of sulfate to the ocean as well as the redox and acidity budget within rapidly eroding catchments. (C) 2013 Elsevier B.V. All rights reserved.