The Carbon-Sulfur Link in the Remineralization of Organic Carbon in Surface Sediments
The Carbon-Sulfur Link in the Remineralization of Organic Carbon in Surface Sediments
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DOI：
10.3389/feart.2021.652960
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发表时间：
2021-04
期刊：
影响因子：
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通讯作者：
H. Bradbury;A. Turchyn;A. Bateson;G. Antler;A. Fotherby;J. Druhan;M. Greaves;D. Sevilgen;D. Hodell
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文献类型：
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作者：
H. Bradbury;A. Turchyn;A. Bateson;G. Antler;A. Fotherby;J. Druhan;M. Greaves;D. Sevilgen;D. Hodell
在这里，我们提出了溶解无机碳（DIC）的碳同位素组成和硫酸盐的硫同位素组成，沿着硫酸盐浓度的变化，孔隙流体收集的一系列沉积物岩心位于沿着一个深度断面的伊比利亚边缘。我们使用这些数据来探索耦合微生物硫酸盐还原（MSR）有机碳氧化在最上层（高达9米）沉积物。我们认为，结合使用的碳和硫同位素组成，DIC和硫酸盐，分别在沉积孔隙流体中，通过δ 13 CDIC与δ 34 SSO 4交会图，揭示了重要的洞察力的性质，在海洋沉积孔隙流体中的碳-硫耦合在大陆边缘。我们的数据显示DIC和硫酸盐（分别）的碳和硫同位素组成的系统性变化，在所有站点，DIC的碳同位素组成减少之前，硫酸盐的硫同位素组成增加。我们将我们的研究结果与全球数据进行比较，结果表明，这种行为在一系列沉积物类型、位置和水深中持续存在。我们使用一个反应传输模型，以显示在海水中的DIC的量的变化，有机质的碳同位素组成，有机碳氧化量的早期成岩反应，以及甲烷的存在和来源的影响沉积孔隙流体的碳和硫同位素组成和形状的δ 13 CDIC与δ 34 SSO 4交叉图。硫酸盐还原和硫酸盐驱动的甲烷厌氧氧化过程中释放的DIC的δ 13 C是δ 13 CDIC与δ 34 SSO 4交会图中最小δ 13 CDIC值的主要控制因素，其中有机碳的δ 13 C在MSR和硫酸盐还原、硫酸盐驱动的AOM和甲烷生成的组合过程中都很重要。
Here we present the carbon isotopic composition of dissolved inorganic carbon (DIC) and the sulfur isotopic composition of sulfate, along with changes in sulfate concentrations, of the pore fluid collected from a series of sediment cores located along a depth transect on the Iberian Margin. We use these data to explore the coupling of microbial sulfate reduction (MSR) to organic carbon oxidation in the uppermost (up to nine meters) sediment. We argue that the combined use of the carbon and sulfur isotopic composition, of DIC and sulfate respectively, in sedimentary pore fluids, viewed through a δ13CDIC vs. δ34SSO4 cross plot, reveals significant insight into the nature of carbon-sulfur coupling in marine sedimentary pore fluids on continental margins. Our data show systemic changes in the carbon and sulfur isotopic composition of DIC and sulfate (respectively) where, at all sites, the carbon isotopic composition of the DIC decreases before the sulfur isotopic composition of sulfate increases. We compare our results to global data and show that this behavior persists over a range of sediment types, locations and water depths. We use a reactive-transport model to show how changes in the amount of DIC in seawater, the carbon isotopic composition of organic matter, the amount of organic carbon oxidation by early diagenetic reactions, and the presence and source of methane influence the carbon and sulfur isotopic composition of sedimentary pore fluids and the shape of the δ13CDIC vs. δ34SSO4 cross plot. The δ13C of the DIC released during sulfate reduction and sulfate-driven anaerobic oxidation of methane is a major control on the minimum δ13CDIC value in the δ13CDIC vs. δ34SSO4 cross plot, with the δ13C of the organic carbon being important during both MSR and combined sulfate reduction, sulfate-driven AOM and methanogenesis.