Carbon cycling within the upper methanogenic zone of continental rise sediments: An example from the methane-rich sediments overlying the Blake Ridge gas hydrate deposits
Carbon cycling within the upper methanogenic zone of continental rise sediments: An example from the methane-rich sediments overlying the Blake Ridge gas hydrate deposits
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DOI：
10.1016/s0304-4203(97)00019-4
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发表时间：
1997-07-01
期刊：
影响因子：
3
通讯作者：
Ussler, W
中科院分区：
文献类型：
--
作者：
Borowski, WS;Paull, CK;Ussler, W
从卡罗莱纳上升和布莱克岭，并从许多DSDP/ODP网站收集的活塞岩心的数据表明，极端的C-13-枯竭的甲烷和西格玛CO2发生在大陆上升沉积物的最高产甲烷带。我们推断，C-13-贫化甲烷产生的产甲烷区的顶部附近时，碳的C-13-贫化西格玛CO2，微生物介导的厌氧甲烷氧化产生的，通过CO2还原循环回甲烷。在27个活塞岩心中收集了间隙水和气体样品，其中16个穿过硫酸盐还原带进入卡罗莱纳隆起和布莱克岭的含甲烷沉积物。同位素测量（δ（13）C（CH 4）），δ（13）C（CO2），来自两个不同同位素池的甲烷样本。(1)来自海底渗漏现场的甲烷显示出平均δ（13）C（CH 4）值为-69 +/- 2千分之一，反映了附近DSDP现场大于或等于160 mbsf的值。(2)20个区域分离的站点（样本深度为10至25 mbsf）的δ（13）C（CH 4）值范围为-85至-103 ppm，δ（13）C（CO2）为负，为-48 ppm。甲烷和CO2池中非常低的三角洲（13）C值突出了硫酸盐-甲烷边界处和附近大陆隆起沉积物中碳循环的重要性。(C)1997年Elsevier Science B.V.
Data from piston cores collected from Carolina Rise and Blake Ridge, and from many DSDP/ODP sites indicate that extreme C-13-depletion of methane and Sigma CO2 occurs within the uppermost methanogenic zone of continental rise sediments. We infer that C-13-depleted methane is generated near the top of the methanogenic zone when carbon of C-13-depleted Sigma CO2, produced by microbially-mediated anaerobic methane oxidation, is recycled back to methane through CO2 reduction. Interstitial water and gas samples were collected in 27 piston cores, 16 of which penetrated through the sulfate reduction zone into methane-bearing sediments of the Carolina Rise and Blake Ridge. Isotopic measurements (delta(13)C(CH4)), delta(13)C(CO2), Methane samples from two distinct isotopic pools. (1) Methane from a seafloor seep site shows a mean delta(13)C(CH4) value of -69 +/- 2 parts per thousand, mirroring values found at greater than or equal to 160 mbsf from a nearby DSDP site. (2) Twenty, areally-separated sites (sample depth, 10 to 25 mbsf) have delta(13)C(CH4) values ranging from -85 to -103 parts per thousand, and delta(13)C(CO2) as negative as -48 parts per thousand. The very low delta(13)C values from the methane and CO2 pools highlight the importance of carbon cycling within continental rise sediments at and near the sulfate-methane boundary. (C) 1997 Elsevier Science B.V.