南海东沙海域浅表层柱状沉积物孔隙水地球化学特征及对冷泉流体活动的指示

发布时间：2018-03-21 09:45

本文选题：甲烷缺氧氧化(AOM)　切入点：孔隙水　出处：《地球化学》2017年04期 　论文类型：期刊论文

【摘要】：海底沉积物孔隙水地球化学特征能够快速响应有机质硫酸盐还原作用(OSR)和甲烷缺氧氧化作用(AOM)引起的变化,并记录冷泉渗漏活动的特征。本文对采集自南海东沙海域天然气水合物发育区的重力柱状沉积物孔隙水样品(D17-2015)进行了阴阳离子(SO_4~(2-)、Ca~(2+)、Mg~(2+))、微量元素(Sr~(2+)、Ba~(2+))、溶解无机碳(DIC)及其δ~(13)C_(DIC)等地球化学分析。在深度剖面上硫酸根离子浓度呈直线降低,确定的硫酸盐-甲烷转换带(SMTZ)约为海底下7.0 m,在紧邻SMTZ界面之下的溶解Ba~(2+)浓度突然增加,同时δ~(13)C_(DIC)(-38.8‰)值极端负偏,说明此站位存在强烈的AOM作用。利用反应-运移模型模拟计算获得的硫酸根向下通量为35.3 mmol/(m~2·a)、甲烷向上的通量为30.0 mmol/(m~2·a)、OSR和AOM消耗硫酸盐的相对比例分别约为15%和85%。这些结果表明AOM作用是占主导作用的生物地球化学过程。
[Abstract]:The geochemical characteristics of pore water in seabed sediments can quickly respond to the changes caused by the reduction of organic matter sulfate (OSRs) and the anoxic oxidation of methane (AOM). The percolation characteristics of cold springs were recorded. The gravity columnar sediment pore water samples collected from the natural gas hydrate development area in Dongsha area of the South China Sea were collected from D17-2015). Geochemical analysis such as DICand 未 ~ (13) C _ (+) DIC. The concentration of sulfate ion decreases linearly in depth profile. The determined sulphate-methane transition zone (SMTZ) is about 7.0 m below the sea floor. The concentration of dissolved Ba~(2 under the interface of SMTZ increases suddenly, and the value of 未 ~ (13) C ~ (13) C ~ (-1) C ~ (-1) C ~ (-1) C ~ (-1) C ~ (-1) C ~ (-1) C ~ (-1) C ~ (-1) is extremely negative. The downward flux of sulfate is 35.3 mmol/(m~2 路a ~ (-1), the flux of methane up is 30.0 mmol/(m~2 路a ~ (-1) and the ratio of consumption of sulfate to AOM is about 15% and 85, respectively. These results indicate that AOM is a dominant biogeochemical process.
【作者单位】：中国科学院广州地球化学研究所边缘海地质重点实验室;中国科学院大学;中国地质调查局广州海洋地质调查局;上海海洋大学海洋科学学院上海深渊科学工程技术研究中心;
【基金】：国家自然科学基金(41606048) 中国地质调查局水合物专项(GZH201100311,GZH201100305-06-07,DD20160217)
【分类号】：P618.13

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