Nickel as indicator of fresh organic matter in upwelling sediments
Nickel as indicator of fresh organic matter in upwelling sediments
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DOI：
10.1016/j.gca.2015.04.027
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发表时间：
2015-08-01
影响因子：
5
通讯作者：
Brumsack, Hans-Juergen
中科院分区：
文献类型：
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作者：
Boening, Philipp;Shaw, Tim;Brumsack, Hans-Juergen
微量金属参与生物循环（如镉，铜，镍，锌）通常积累在上升流沉积物中，由于高生产力相关的颗粒通量和增强的深度保存。然而，缺乏对成岩金属组分、早期成岩转化过程和人为金属输入贡献的约束可能会使沉积物金属特征复杂化。在这里，我们结合联合收割机数据，从各种短的核心（上50厘米）和两个较长的核心有机丰富的上升流沉积物（秘鲁，纳米比亚，智利和加州湾），这表明一个非常显着的，线性和统一的关系Ni和总有机碳（TOC）的来源和积累机制的验证是必不可少的。整体高镍富集可能是由硅藻的出现，在这些系统中占主导地位的生产力解释。秘鲁表层沉积物（上2厘米）显示出不太明显的镍-TOC的关系，并支持低Ni/TOC比的东太平洋水柱颗粒和较高的Ni/TOC比在更深的沉积物中观察到的过渡。在秘鲁表层沉积物中，该过程被确认为镍和总氯（叶绿素色素的直接降解产物），这是没有观察到的Cu或Zn.Our数据之间的化学计量关系强烈支持以前的研究结果，镍是一个明确的（如果不是最好的）指标的有机下沉通量。这也是由于镍特征经历与硫和锰循环相关的较少的改变以及来自人为来源的低贡献。显然独特的镍-二氢卟酚化学计量表明，镍可能与参与光合自养生产的酶有关，这强调了之前实验室实验和野外工作的发现，即硅藻在海洋镍循环中发挥主导作用。镍/氯比随沉积深度的增加而增加，表明氯受到正在进行的成岩作用的影响。因此，镍可以作为一个可靠的指示剂的原始叶绿素通量，而不是二氯酚。镍和TOC之间的非常好的相关性和优先保存的镍超过TOC证明以前（古）生产力估计的基础上，镍积累。(C)2015由Elsevier Ltd.出版
Trace metals involved in biological cycling (e.g. Cd, Cu, Ni, Zn) typically accumulate in upwelling sediments due to a high productivity-related particle flux and an enhanced preservation at depth. However, poor constraint on the contribution of lithogenic metal fraction, early diagenetic transformation processes and anthropogenic metal inputs may complicate sediment metal signatures. The identification of source and accumulation mechanisms is essential to the validation of these metals as productivity proxies.Here we combine data from various short cores (upper 50 cm) and two longer cores of organic-rich upwelling sediments (Peru, Namibia, Chile and Gulf of California), which suggest a highly significant, linear and uniform relationship between Ni and total organic carbon (TOC). The overall high Ni enrichment may be explained by the occurrence of diatoms, which dominate productivity in these systems. The Peru surface sediments (upper 2 cm) show a less pronounced Ni-TOC relationship and support a transition between lower Ni/TOC ratio of East Pacific water column particles and the higher Ni/TOC ratio observed in deeper sediments. In Peru surface sediments, the process is confirmed as a stoichiometric relation between Ni and total chlorins (the immediate degradation products of chlorophyll pigments), which is not observed for Cu or Zn.Our data strongly support previous findings that Ni is a clear (if not the best) indicator of the organic sinking flux. This is also due to the fact that Ni signatures undergo less alteration associated with sulfur and manganese cycling and low contribution from anthropogenic sources. The apparently exclusive Ni-chlorin stoichiometry suggests that Ni may be associated with enzymes that are involved in photoautotrophic production, which underlines the previous finding from laboratory experiments and field work that diatoms have a dominant role in marine Ni cycling. The Ni/chlorin ratio increases with increasing sediment depth suggesting that chlorins are effected by on-going diagenesis. Therefore, Ni may serve as a reliable indicator of the original chlorophyll flux rather than chlorins. The very good correlation between Ni and TOC and the preferential preservation of Ni over TOC justify previous (paleo) productivity estimates based on Ni accumulation. (C) 2015 Published by Elsevier Ltd.