Enrichment of adsorbed methane in authigenic carbonate concretions of the Japan Trench
Enrichment of adsorbed methane in authigenic carbonate concretions of the Japan Trench
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DOI：
10.1007/s00367-009-0143-9
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发表时间：
2009-10-01
影响因子：
2.1
通讯作者：
Saito, Saneatsu
中科院分区：
文献类型：
--
作者：
Ijiri, Akira;Tsunogai, Urumu;Saito, Saneatsu
在大洋钻探计划第186航次至日本海沟深海阶地ODP第1150和1151号站点期间，从海底以下245米至1 108米深处的沉积层中回收的自生碳酸盐结核中检测到大量吸附甲烷。结核中的甲烷含量（291- 4，528纳摩尔/克湿重）几乎比周围的大块沉积物（5-93纳摩尔/克湿重）高两个数量级，而甲烷/乙烷比率和稳定碳同位素组成非常相似。周围块状沉积物的碳酸盐含量（0.02-3.2湿重%）和周围块状沉积物的甲烷含量呈正相关。大量沉积物的碳酸盐含量外推表明，100wt%碳酸盐相当于每克大量沉积物1，886 +/- 732 nmol甲烷，这与碳酸盐结核中观察到的平均值（1，321 +/-1，067 nmol/g湿重，n = 13）。这些数据支持的假设，在沉积物中，吸附的烃类气体与自生碳酸盐强烈相关。
Substantial amounts of adsorbed methane were detected in authigenic carbonate concretions recovered from sedimentary layers from depths between 245 and 1,108 m below seafloor during Ocean Drilling Program Leg 186 to ODP sites 1150 and 1151 on the deep-sea terrace of the Japan Trench. Methane contents were almost two orders of magnitude higher in the concretions (291-4,528 nmol/g wet wt) than in the surrounding bulk sediments (5-93 nmol/g wet wt), whereas methane/ethane ratios and stable carbon isotopic compositions were very similar. Carbonate content of surrounding bulk sediments (0.02-3.2 wet wt%) and methane content of the surrounding bulk sediments correlated positively. Extrapolation of the carbonate contents of bulk sediments suggests that 100 wt% carbonate would correspond to 1,886 +/- 732 nmol methane per g bulk sediment, which is similar to the average value observed in the carbonate concretions (1,321 +/- 1,067 nmol/g wet wt, n = 13). These data support the hypothesis that, in sediments, adsorbed hydrocarbon gases are strongly associated with authigenic carbonates.