Tephra Deposition and Bonding With Reactive Oxides Enhances Burial of Organic Carbon in the Bering Sea
Tephra Deposition and Bonding With Reactive Oxides Enhances Burial of Organic Carbon in the Bering Sea
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DOI：
10.1029/2021gb007140
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发表时间：
2021-10
影响因子：
5.2
通讯作者：
Jack Longman;T. Gernon;Martin R Palmer;H. Manners
中科院分区：
文献类型：
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作者：
Jack Longman;T. Gernon;Martin R Palmer;H. Manners
海洋沉积物中有机碳（OC）的保存对地球系统中的碳循环发挥着重要的控制作用。在这些海洋环境中，在被称为火山灰的碎片火山物质沉积的地方发生的成岩反应可能会增强有机碳的保存。虽然这一过程发生的机制已被充分了解，但对该过程的特定地点研究仍然有限。在这里，我们报告了一项对白令海沉积物（IODP 站点 U1339D）的研究，以调查更新世和全新世期间海洋火山灰沉积对碳循环的影响。我们的结果表明，火山灰层是具有不同 δ13C 值的 OC 埋藏位点，并且该过程主要与 OC 与活性金属的键合有关，约占火山灰层内所有 OC 的 80%。此外，活性金属从火山灰分布到火山灰层上方和下方的非火山沉积物中，增强了这些沉积物中 OC 的保存，约 33% 的 OC 与活性相结合。重要的是，OC-Fe 耦合在超过 70 万年的沉积物中很明显。因此，这些相互作用可能有助于解释在古代海洋沉积物中观察到的有机碳的保存。
Preservation of organic carbon (OC) in marine sediments exerts a major control on the cycling of carbon in the Earth system. In these marine environments, OC preservation may be enhanced by diagenetic reactions in locations where deposition of fragmental volcanic material called tephra occurs. While the mechanisms by which this process occurs are well understood, site‐specific studies of this process are limited. Here, we report a study of sediments from the Bering Sea (IODP Site U1339D) to investigate the effects of marine tephra deposition on carbon cycling during the Pleistocene and Holocene. Our results suggest that tephra layers are loci of OC burial with distinct δ13C values, and that this process is primarily linked to bonding of OC with reactive metals, accounting for ∼80% of all OC within tephra layers. In addition, distribution of reactive metals from the tephra into non‐volcanic sediments above and below the tephra layers enhances OC preservation in these sediments, with ∼33% of OC bound to reactive phases. Importantly, OC‐Fe coupling is evident in sediments >700,000 years old. Thus, these interactions may help explain the observed preservation of OC in ancient marine sediments.