Geochemistry of deep sea sediments at cold seep sites in the Nankai Trough: Insights into the effect of anaerobic oxidation of methane
Geochemistry of deep sea sediments at cold seep sites in the Nankai Trough: Insights into the effect of anaerobic oxidation of methane
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DOI：
10.1016/j.margeo.2012.07.013
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发表时间：
2012-09
期刊：
影响因子：
2.9
通讯作者：
H. Sato;Ken‐ichiro Hayashi;Y. Ogawa;K. Kawamura
中科院分区：
文献类型：
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作者：
H. Sato;Ken‐ichiro Hayashi;Y. Ogawa;K. Kawamura
从南海海槽的“甲烷渗漏”地点回收了两种类型的沉积物：受甲烷厌氧氧化（AOM）影响的“冷渗”沉积物和未受影响的“典型含氧海洋沉积物”，对这些沉积物中的碳、硫、铁和痕量金属的浓度进行了分析。结果表明，“冷泉”沉积物的硫含量高于典型的含氧海洋沉积物，尽管两种沉积物的有机碳含量相同。渗流沉积物的高硫含量表明 AOM 是“冷渗”地点的主要过程； AOM 产生的 H2S 被固定为硫化铁等还原硫。在非渗漏地点的表层沉积物中发现了最高的锰浓度（约 1000ppm），而在“冷渗”沉积物中没有观察到锰的强烈富集。在含甲烷渗漏产生的还原环境中，锰可能以可溶性 Mn2+ 离子的形式从沉积物中释放出来。 “冷泉”沉积物中的钼含量（高达28.3ppm）比典型的含氧海洋沉积物高出约30倍。然而，在我们的样品中没有观察到钼和有机碳含量之间的相关性，这是缺氧沉积物的特征。 “冷泉”沉积物是钼全球地球化学循环中的潜在汇。
Two types of sediment were recovered from “methane seep” sites in the Nankai Trough: “Cold seep” sediment affected by anaerobic oxidation of methane (AOM), and unaffected “Typical oxic marine sediment,” Concentrations of carbon, sulfur, iron, and trace metals were analyzed in these sediments. The results showed that the sulfur contents of “cold seep” sediments are higher than those of typical oxic marine sediments, although the organic carbon contents of the two types of sediment are identical. The high sulfur contents of seep sediments suggest that AOM was the dominant process at the “cold seep” sites; H2S produced as a result of AOM was fixed as reduced sulfur such as iron sulfide. The highest manganese concentrations (approx. 1000ppm) were found in surface sediments at non-seep sites, whereas a strong enrichment of Mn was not observed in the “cold seep” sediments. Manganese might be released from sediments as soluble Mn2+ion in the reduced environment produced by methane-bearing seepage. The molybdenum content in “cold seep” sediments (up to 28.3ppm) is about 30 times higher than that in the typical oxic marine sediments. However, a correlation between Mo and organic carbon contents, which is characteristic of anoxic sediment, was not observed in our samples. “Cold seep” sediments are a potential sink in the global geochemical cycle of Mo.