An inorganic geochemical argument for coupled anaerobic oxidation of methane and iron reduction in marine sediments
An inorganic geochemical argument for coupled anaerobic oxidation of methane and iron reduction in marine sediments
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DOI：
10.1111/gbi.12077
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发表时间：
2014-03-01
期刊：
影响因子：
3.7
通讯作者：
Kasten, S.
中科院分区：
文献类型：
--
作者：
Riedinger, N.;Formolo, M. J.;Kasten, S.
在这里，我们展示了在阿根廷盆地收集的沉积物的结果，阿根廷盆地是一个非稳态沉积海洋系统，其特征是由于沉积物改造随后快速沉积，富甲烷层中含有丰富的氧化铁。我们全面的无机数据集表明，铁还原在这些硫酸盐和硫化物耗尽的沉积物是最好的解释微生物介导的processessimplifying甲烷厌氧氧化耦合铁还原（Fe-AOM）作为最有可能的主要机制。虽然在许多现代海洋环境中很重要，但铁驱动的AOM与硫酸盐依赖的AOM相比可能不会消耗类似数量的甲烷。然而，它可能对深层生物圈产生广泛影响，并在硫酸盐贫乏的海洋环境中主导铁和甲烷循环。铁-AOM可能在> 25亿年前的太古代海洋中特别相关，以其在生物圈中产生和积累氧化铁（在铁地层中）而闻名，生物圈可能充满甲烷但硫酸盐含量低。当时甲烷是一种关键的温室气体，能够在相对较低的太阳光度下维持适宜居住的气候，与铁循环的关系可能会影响生物圈中的甲烷损失。
Here, we present results from sediments collected in the Argentine Basin, a non-steady state depositional marine system characterized by abundant oxidized iron within methane-rich layers due to sediment reworking followed by rapid deposition. Our comprehensive inorganic data set shows that iron reduction in these sulfate and sulfide-depleted sediments is best explained by a microbially mediated processimplicating anaerobic oxidation of methane coupled to iron reduction (Fe-AOM) as the most likely major mechanism. Although important in many modern marine environments, iron-driven AOM may not consume similar amounts of methane compared with sulfate-dependent AOM. Nevertheless, it may have broad impact on the deep biosphere and dominate both iron and methane cycling in sulfate-lean marine settings. Fe-AOM might have been particularly relevant in the Archean ocean, >2.5billion years ago, known for its production and accumulation of iron oxides (in iron formations) in a biosphere likely replete with methane but low in sulfate. Methane at that time was a critical greenhouse gas capable of sustaining a habitable climate under relatively low solar luminosity, and relationships to iron cycling may have impacted if not dominated methane loss from the biosphere.