Department of Geology and Earth Systems Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA ; Max-Planck Institute for Marine Microbiology, Department of Biogeochemistry, Celsiusstrasse 1, D-28359 Bremen, Germany ; Department of Geological and Environmental Sciences, The Faculty of Natural Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105, Israel.
Department of Earth Sciences, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA.
Geochem Trans. 2014 May 28;15:7. doi: 10.1186/1467-4866-15-7. eCollection 2014.
The paper presents a quantification of main (hydrogen sulfide and sulfate), as well as of intermediate sulfur species (zero-valent sulfur (ZVS), thiosulfate, sulfite, thiocyanate) in the Yellowstone National Park (YNP) hydrothermal springs and pools. We combined these measurements with the measurements of quadruple sulfur isotope composition of sulfate, hydrogen sulfide and zero-valent sulfur. The main goal of this research is to understand multiple sulfur isotope fractionation in the system, which is dominated by complex, mostly abiotic, sulfur cycling.
Water samples from six springs and pools in the Yellowstone National Park were characterized by pH, chloride to sulfate ratios, sulfide and intermediate sulfur species concentrations. Concentrations of sulfate in pools indicate either oxidation of sulfide by mixing of deep parent water with shallow oxic water, or surface oxidation of sulfide with atmospheric oxygen. Thiosulfate concentrations are low (<6 μmol L(-1)) in the pools with low pH due to fast disproportionation of thiosulfate. In the pools with higher pH, the concentration of thiosulfate varies, depending on different geochemical pathways of thiosulfate formation. The δ(34)S values of sulfate in four systems were close to those calculated using a mixing line of the model based on dilution and boiling of a deep hot parent water body. In two pools δ(34)S values of sulfate varied significantly from the values calculated from this model. Sulfur isotope fractionation between ZVS and hydrogen sulfide was close to zero at pH < 4. At higher pH zero-valent sulfur is slightly heavier than hydrogen sulfide due to equilibration in the rhombic sulfur-polysulfide - hydrogen sulfide system. Triple sulfur isotope ((32)S, (33)S, (34)S) fractionation patterns in waters of hydrothermal pools are more consistent with redox processes involving intermediate sulfur species than with bacterial sulfate reduction. Small but resolved differences in ∆(33)S among species and between pools are observed.
The variation of sulfate isotopic composition, the origin of differences in isotopic composition of sulfide and zero-valent sulfur, as well as differences in ∆(33)S of sulfide and sulfate are likely due to a complex network of abiotic redox reactions, including disproportionation pathways.
本文对黄石国家公园（YNP）温泉和池塘中的主要（硫化氢和硫酸盐）以及中间硫物种（零价硫（ZVS）、硫代硫酸盐、亚硫酸盐、硫氰酸盐）进行了定量分析。我们将这些测量结果与硫酸盐、硫化氢和零价硫的四重硫同位素组成的测量结果相结合。本研究的主要目的是了解该系统中多种硫同位素分馏，该系统主要由复杂的、主要是非生物的硫循环控制。
黄石国家公园六个温泉和池塘的水样具有 pH 值、氯离子与硫酸盐比值、硫化物和中间硫物种浓度等特征。池塘中的硫酸盐浓度表明，硫化物的氧化是由深部母体水与浅层含氧水混合引起的，或者是由于大气氧气的表面氧化引起的。由于硫代硫酸盐的快速歧化作用，在 pH 值较低的池塘中，硫代硫酸盐的浓度较低（<6 μmol L(-1)）。在 pH 值较高的池塘中，硫代硫酸盐的浓度取决于不同的硫代硫酸盐形成地球化学途径而变化。四个系统中硫酸盐的 δ(34)S 值接近基于深部热母体水稀释和沸腾的模型混合线计算得出的值。在两个池塘中，硫酸盐的 δ(34)S 值与该模型计算的值差异显著。在 pH<4 时，ZVS 和硫化氢之间的硫同位素分馏接近零。在较高的 pH 值下，由于菱形硫-多硫化物-硫化氢体系的平衡作用，零价硫比硫化氢略重。热液池水中的三硫同位素（(32)S、(33)S、(34)S）分馏模式与涉及中间硫物种的氧化还原过程更一致，而与细菌硫酸盐还原过程不一致。在物种之间和池塘之间观察到较小但可分辨的 ∆(33)S 差异。
硫酸盐同位素组成的变化、硫化物和零价硫同位素组成差异的来源以及硫化物和硫酸盐之间的 ∆(33)S 差异可能是由于包括歧化途径在内的复杂非生物氧化还原反应网络所致。
