Control of sulfate pore-water profiles by sedimentary events and the significance of anaerobic oxidation of methane for the burial of sulfur in marine sediments
Control of sulfate pore-water profiles by sedimentary events and the significance of anaerobic oxidation of methane for the burial of sulfur in marine sediments
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DOI：
10.1016/s0016-7037(03)00199-6
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发表时间：
2003-07-01
影响因子：
5
通讯作者：
Boettius, A
中科院分区：
文献类型：
--
作者：
Hensen, C;Zabel, M;Boettius, A
沉积和数字回声测深仪数据证实的重力驱动的物质流沉积表明了阿根廷盆地西部沿着大陆边缘的主要动态沉积条件。在这项研究中，我们提出了地球化学数据，共23个重力岩心。孔隙水SO2通常在沉积物表面以下几米内通过甲烷的厌氧氧化（AOM）而耗尽。不同形状的SO，配置文件（凹，扭结和S型）可以一致地解释可能结合在CH，从下面的通量变化的沉积幻灯片，因此，主要代表瞬态孔隙水条件。由于幻灯片可以保持其原始的沉积签名，地球化学，物理性质和水声数据的综合分析和数值模拟可以应用于重建沉积历史。我们提出了一阶估计的沉积事件的一个地区，传统的地层学方法未能这一天。调查地点的结果表明，目前的条件是几十年至几千年前发生的事件的结果，并促进了从大陆架到深海的持续质量运输，沉积了大量的活性化合物。高丰度的活性铁相在这一地区保持低硫化氢水平的沉积物中的几乎定量沉淀的所有还原硫酸盐AOM。对于整个区域，我们估计每年进入AOM区的SO（4）（或CH（4））通量为6.6 × 10（10）摩尔。按全球大陆坡和海隆地区推算，这一数字可能达到每年约2.6x10（12）摩尔。如果硫完全固定在沉积物中，则其约为先前估计的最近全球海洋沉积物中硫埋藏量的全球值的两倍，即每年1.2x10（12）摩尔。因此，AOM显然对全球硫库的调节做出了非常重要的贡献，这一点迄今尚未得到充分认识。这一发现可能对全球地球化学模型产生影响，因为硫埋藏是随着时间的推移大气氧水平发展的重要控制因素。版权所有（C）2003 Elsevier Science Ltd.
Gravity driven mass-flow deposits proven by sedimentary and digital echosounder data are indicative for prevailing dynamic sedimentary conditions along the continental margin of the western Argentine Basin. In this study we present geochemical data from a total of 23 gravity cores. Pore-water SO, is generally depleted within a few meters below the sediment surface by anaerobic oxidation of methane (AOM). The different shapes of SO, profiles (concave, kink- and s-type) can be consistently explained by sedimentary slides possibly in combination with changes in the CH, flux from below, thus, mostly representing transient pore-water conditions. Since slides may keep their original sedimentary signature, a combined analysis and numerical modeling of geochemical, physical properties, and hydro acoustic data could be applied in order to reconstruct the sedimentary history. We present first order estimates of the dating of sedimentary events for an area where conventional stratigraphic methods failed to this day. The results of the investigated sites suggest that present day conditions are the result of events that occurred decades to thousands of years ago and promote a persisting mass transport from the shelf into the deep-sea, depositing high amounts of reactive compounds. The high abundance of reactive iron phases in this region maintains low hydrogen sulfide levels in the sediments by a nearly quantitative precipitation of all reduced sulfate by AOM. For the total region we estimate a SO(4) (or CH(4)) flux of 6.6 x 10(10) moles per year into the zone of AOM. Projected to the global continental slope and rise area, this may sum up to about 2.6 x 10(12) moles per year. Provided that the sulfur is completely fixed in the sediments it is about twice the global value of the recent global sulfur burial in marine sediments of 1.2 x 10(12) moles per year as previously estimated. Thus, AOM obviously contributes very significantly to the regulation of global sulfur reservoirs, which is hitherto not sufficiently recognized. This finding may have implications for global geochemical models, as sulfur burial is an important control factor in the development of atmospheric oxygen levels over time. Copyright (C) 2003 Elsevier Science Ltd.