New evidence for preservation of contemporary marine organic carbon by iron in Arctic shelf sediments
New evidence for preservation of contemporary marine organic carbon by iron in Arctic shelf sediments
复制标题
DOI：
10.1088/1748-9326/aca780
复制
发表时间：
2022-11
影响因子：
6.7
通讯作者：
J. Faust;P. Ascough;R. Hilton;Mark Stevenson;K. Hendry;C. März
中科院分区：
文献类型：
--
作者：
J. Faust;P. Ascough;R. Hilton;Mark Stevenson;K. Hendry;C. März
通过与铁矿物（FeR）结合来保护有机碳是其在海洋沉积物中稳定、长期储存和埋藏效率的重要因素。然而，大的不确定性仍然存在有关的来源，不稳定性，年龄和组成的有机质与天然沉积物中的铁。因此，碳-铁结合过程的时机和环境设置仍然难以捉摸。本文利用沉积有机质、底栖有孔虫的放射性碳（Δ 14 C）和稳定同位素（δ 13 C）以及与FeR结合的有机碳组分，探讨了北极海洋沉积物中与FeR结合的有机碳库的来源和年龄。在巴伦支海，我们发现，与铁相关的有机碳是年轻的整体比散装有机物质，可能是海洋衍生的。与其他OC-FeR来源调查的比较表明，在北极大陆架区域的大部分地区，FeR相关的有机碳是放射性碳富集的，并且与散装沉积物相比具有更高的δ 13 Corg值，而与沉积物深度/年龄无关。我们的研究结果表明，快速和优先绑定的新鲜和海洋有机物与铁。因此，易分解的不稳定有机物得到保护和稳定，强调了有机碳-铁缔合作为有效碳埋藏机制的潜力。
The protection of organic carbon through association with iron minerals (FeR) is an important factor in its stabilisation, long-term storage, and burial efficiency in marine sediments. However, large uncertainties still exist concerning the sources, lability, age, and composition of the organic matter associated with FeR in natural sediments. Therefore, the timing and environmental setting of the carbon-iron bonding process remain elusive. Here we use radiocarbon (Δ14C) and stable isotopes (δ13C) of downcore bulk sedimentary organic matter, benthic foraminifera and the organic carbon fraction bound to FeR to interrogate the source and age of the organic carbon pool associated with FeR in Arctic marine sediments. In the Barents Sea, we find that the organic carbon associated with FeR is younger overall than the bulk organic matter and is probably marine derived. The comparison to other investigations of OC-FeR origins reveals that in large parts of Arctic shelf regions FeR associated organic carbon is radiocarbon enriched and has a higher δ13Corg value compared to the bulk sediment, irrespective of sediment depth/age. Our findings suggest a rapid and preferential binding of fresh and marine organic matter with FeR. Hence, labile organic matter prone to decomposition is protected and stabilised, underlining the potential of the organic carbon–iron association as an efficient carbon burial mechanism.