The role of iron in the diagenesis of organic carbon and nitrogen in sediments: A long-term incubation experiment
The role of iron in the diagenesis of organic carbon and nitrogen in sediments: A long-term incubation experiment
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DOI：
10.1016/j.marchem.2014.02.007
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发表时间：
2014-05-20
期刊：
影响因子：
3
通讯作者：
Gelinas, Yves
中科院分区：
文献类型：
--
作者：
Barber, Andrew;Lalonde, Karine;Gelinas, Yves
海洋沉积物中有机质的埋藏和保存与铁、锰的成岩旋回密切相关。最近，已经表明，大约20%的沉积有机碳（OC）可以与可还原的氧化铁结合（Lalonde等人，2012年）。这些强铁-OC复合物，形成于沉积物的好氧层内，通过沉积、物理改造和生物扰动转移到更深的缺氧沉积物层，并且在地质时间尺度上是亚稳定的。使用长期（250天）的各种氧化还原和修正条件下（Fe（II）和溶解OM（DOM）的补充）的孵育，我们研究了铁的早期成岩转化的OM在海洋沉积物中的影响。通过跟踪其稳定的碳同位素特征（δ C-13）来监测新鲜藻类来源的DOM的命运。我们证明了C-13耗尽示踪剂通过吸附（吸附和共沉淀）到沉积物中的掺入。在铁氧化物的存在下，我们观察到的溶解的藻类材料的固相转移增加，揭示了铁穿梭DOM从沉积物孔隙沃茨沉积物颗粒的作用。此外，我们表明，铁的存在下，OC和有机氮（ON）有不同的效果，优先保存OC和加速降解的ON在活性氧化铁表面的存在下。因此，我们建议，氧化还原敏感的金属可以调节全球氧化还原平衡，通过增加碳保存以及施加控制的浓度上的固定氮物种在海洋沉积物中。(C)2014爱思唯尔有限公司版权所有。
The burial and preservation of organic matter (OM) in marine sediments is tightly coupled to the diagenetic cycles of iron and manganese. Recently, it has been shown that approximately 20% of the sedimentary organic carbon (OC) may be bound to reducible iron oxides (Lalonde et al., 2012). These strong iron-OC complexes, formed within the oxic layer of the sediment, are transferred to the deeper anoxic sediment layers through sedimentation, physical reworking and bioturbation and are metastable over geological timescales. Using long-term (250-day) incubations under various redox and amendment conditions (Fe(II) and dissolved OM (DOM) additions), we examined the effect of iron on the early diagenetic transformations of OM in marine sediments. The fate of fresh, algal-derived DOM was monitored by tracking its stable carbon isotopic signature (delta C-13). We demonstrate the incorporation of the C-13-depleted tracer into the sediment through sorption (adsorption and co-precipitation). In the presence of iron oxides, we observed an increased transfer of the dissolved algal material to the solid phase, revealing the role of iron in shuttling DOM from sediment pore waters to sediment particles. Furthermore, we show that the presence of iron has a differential effect on OC and organic nitrogen (ON), with preferential preservation of OC and accelerated degradation of ON in the presence of reactive iron oxide surfaces. Hence, we propose that redox-sensitive metals may regulate the global redox balance through increased carbon preservation as well as exerting a control on the concentration of fixed nitrogen species in marine sediments. (C) 2014 Elsevier B.V. All rights reserved.