Fe(III) photoreduction producing Fe2+aq in oxic freshwater sediment.
Fe(III) photoreduction producing Fe2+aq in oxic freshwater sediment.
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DOI：
10.1021/acs.est.9b05682
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发表时间：
2019-12
影响因子：
11.4
通讯作者：
Ulf Lueder;B. Jørgensen;A. Kappler;C. Schmidt
中科院分区：
文献类型：
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作者：
Ulf Lueder;B. Jørgensen;A. Kappler;C. Schmidt
铁(III) (Fe(III))光还原在上层海洋的Fe循环和Fe(II)生物利用度中发挥着重要作用。尽管对水柱有很好的描述，但目前尚不清楚光对水生沉积物中溶解的 Fe(II) (Fe2+) 的产生有多大影响。我们进行了高分辨率伏安微传感器测量，并证明了康斯坦茨湖淡水沉积物中光诱导的 Fe2+ 释放。在可见光范围 (400-700 nm) 的照射下，即使存在氧气 (100-280 µM)，Fe2+ 浓度在沉积物顶部 3 mm 处也增加至 40 µM。 Fe2+ 的释放强烈依赖于沉积物的有机物含量。在有机碳浓度<6 mg L-1 的沉积物中测量到光还原 Fe2+ 的缺乏。除了微生物和非生物 Fe2+ 被氧氧化之外，沉积物 Fe(III) 光还原的同时存在表明水生沉积物的好氧和透光区存在活跃的 Fe 氧化还原循环。在这里，我们提供了 Fe(III) 光还原对水生淡水沉积物中生物地球化学铁氧化还原循环的相关贡献的证据。
Iron(III) (Fe(III)) photoreduction plays an important role in Fe cycling and Fe(II) bioavailability in the upper ocean. Although well described for water columns, it is currently unknown to what extent light impacts the production of dissolved Fe(II) (Fe2+) in aquatic sediments. We performed high-resolution voltammetric microsensor measurements and demonstrated light-induced Fe2+ release in freshwater sediments from Lake Constance. Fe2+ concentrations increased up to 40 µM in the top 3 mm of the sediment during illumination in the visible range of light (400-700 nm), even in the presence of oxygen (100-280 µM). The Fe2+ release was strongly dependent on the organic matter content of the sediment. A lack of photo-reduced Fe2+ was measured in sediments with concentrations of organic carbon <6 mg L-1. The simultaneous presence of sedimentary Fe(III) photoreduction besides microbial and abiotic Fe2+ oxidation by oxygen suggests active Fe redox cycling in the oxic and photic zone of aquatic sediments. Here, we provide evidence for a relevant contribution of Fe(III) photoreduction to the biogeochemical Fe redox cycle in aquatic freshwater sediments.