Siderophore-promoted transfer of rare earth elements and iron from volcanic ash into glacial meltwater, river and ocean water
Siderophore-promoted transfer of rare earth elements and iron from volcanic ash into glacial meltwater, river and ocean water
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DOI：
10.1016/j.epsl.2013.01.002
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发表时间：
2013-02-15
影响因子：
5.3
通讯作者：
Mohwinkel, Dennis
中科院分区：
文献类型：
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作者：
Bau, Michael;Tepe, Nathalie;Mohwinkel, Dennis
稀土元素 (REE) 是一组在海洋中停留时间较短的微量元素，在河流、湖泊和海洋表层水中通常与有机和无机颗粒相关。火山喷发（例如 2010 年冰岛埃亚菲亚德拉冰盖火山喷发）会产生火山灰颗粒，这些颗粒可能是水生生物铁和其他营养物质的重要来源。然而，为了变得可生物利用，这种铁需要通过络合剂（例如铁载体）溶解。这种螯合剂的一个经过充分研究的例子是生物铁载体去铁胺-B (DFOB)。根据对冰岛南部富含冰川融水的河水（富含悬浮火山灰，并分别在有和没有 DFOB 的情况下进行孵化）的孵化实验结果，我们在此表明，铁载体不仅增强了铁的释放，而且还促进了这些颗粒中稀土元素的动员。在 DFOB 存在的情况下，火山灰（可能还有其他岩屑颗粒）的部分溶解会产生大量溶解的 REE 进入周围水域，其特征是中型 REE 上的轻质 REE 耗尽，并且由于形成溶解的 Ce(IV)-DFOB 复合物而选择性富集铈。在富含铁载体的环境中，这种与铁载体结合的稀土元素通量有可能改变冰川融水、河水和海水中溶解的稀土元素和溶解的 Nd 同位素组成的浓度和分布，并且可能是陆架沉积物和海水之间边界效应的一个组成部分，这被认为是解释海水“缺失 Nd 通量”的原因。热力学数据进一步表明，铁载体促进的元素动员对于其他多价（痕量）元素（例如 Hf）也很重要。 (C) 2013 Elsevier B.V. 保留所有权利。
The rare earth elements (REE) are a group of trace elements that have short marine residence times and that in river, lake and marine surface waters are typically associated with organic and inorganic particles. Explosive volcanic eruptions, such as the 2010 eruptions of Eyjafjallajokull volcano in Iceland, produce volcanic ash particles which can be an important source of iron and other nutrients for aquatic organisms. To become bioavailable, however, this iron needs to be solubilized by complexing agents, such as siderophores. A well-studied example of such a chelator is the biogenic siderophore desferrioxamin-B (DFOB). Based on results from incubation experiments with glacial meltwater-rich river waters from southern Iceland, which are rich in suspended volcanic ash and that had been incubated with and without DFOB, respectively, we here show that siderophores not only enhance the release of iron, but also promote the mobilization of REE from these particles. In the presence of DFOB, partial dissolution of volcanic ash (and presumably other lithic particles) produces a flux of dissolved REE into ambient waters, that is characterized by depletion of the light REE over the middle REE and by selective enrichment of cerium, due to the formation of dissolved Ce(IV)-DFOB complexes. In siderophore-rich environments, this siderophore-bound REE flux has the potential to modify the concentrations and distribution of the dissolved REE and of the isotopic composition of dissolved Nd in glacial meltwaters, river waters and seawater and might be a component of the boundary effects between shelf sediments and seawater, which are assumed to account for the "missing Nd flux" to seawater. Thermodynamic data further suggest that siderophore-promoted element mobilization could also be important for other polyvalent (trace) elements, such as Hf. (C) 2013 Elsevier B.V. All rights reserved.