Influence of physical perturbation on Fe(II) supply in coastal marine sediments.
Influence of physical perturbation on Fe(II) supply in coastal marine sediments.
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DOI：
10.1021/acs.est.9b06278
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发表时间：
2020-02
影响因子：
11.4
通讯作者：
Ulf Lueder;M. Maisch;K. Laufer;B. Jørgensen;A. Kappler;C. Schmidt
中科院分区：
文献类型：
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作者：
Ulf Lueder;M. Maisch;K. Laufer;B. Jørgensen;A. Kappler;C. Schmidt
海洋沉积物中的铁 (Fe) 生物地球化学是由产生 Fe(II) 和 Fe(III) 梯度的氧化还原转化驱动的。当沉积物因波浪作用或生物扰动而物理混合时，铁梯度会定期重新建立。为了确定溶解的 Fe(II) (Fe2+) 和 Fe 矿物相对混合过程的响应，我们对 12 小时光暗循环孵育的海洋沿海沉积物进行了伏安微传感器测量、连续 Fe 提取和穆斯堡尔光谱。在 7 天的不受干扰的孵化过程中，Fe2+ 从大约下降到了 10%。 400 至 60 µM。在孵化的前 2-4 天，由于 Fe(III) 光还原，Fe2+ 在顶部 2 mm 中累积高达 100 µM。第 7 天的物理扰动后，Fe2+ 被重新激活，在 30 mm 深度达到 320 µM 的浓度，并在 2 天内降至检测限以下。穆斯堡尔光谱表明，亚稳态铁硫矿物相 (FeSx) 的相对丰度在初始培养期间增加，在扰动后减少。我们表明，影响铁氧化还原分布的物理扰动会刺激海洋沉积物中 Fe2+ 的迁移。我们的研究表明，除了微生物 Fe(III) 和非生物 Fe(III) 还原（包括 Fe(III) 光还原）之外，物理混合过程还为沉积物和栖息微生物群落提供 Fe2+。
Iron (Fe) biogeochemistry in marine sediments is driven by redox transformations creating Fe(II) and Fe(III) gradients. As sediments are physically mixed by wave action or bioturbation, Fe gradients re-establish regularly. In order to identify the response of dissolved Fe(II) (Fe2+) and Fe mineral phases towards mixing processes, we performed voltammetric microsensor measurements, sequential Fe extractions, and Mössbauer spectroscopy of 12 h light-dark-cycle incubated marine coastal sediment. Fe2+ decreased during 7 days of undisturbed incubation from approx. 400 to 60 µM. In the first 2-4 days of incubation, Fe2+ accumulated up to 100 µM in the top 2 mm due to Fe(III) photoreduction. After physical perturbation at day 7, Fe2+ was re-mobilized reaching concentrations of 320 µM in 30 mm depth, which decreased to below detection limit within 2 days afterwards. Mössbauer spectroscopy showed that the relative abundance of metastable iron-sulphur mineral phases (FeSx) increased during initial incubation and decreased after perturbation. We show that Fe2+ mobilization in marine sediments is stimulated by physical disturbances impacting the Fe redox distribution. Our study suggests that in addition to microbial Fe(III) and abiotic Fe(III) reduction, including Fe(III) photoreduction, physical mixing processes also provide sediments and the inhabiting microbial community with Fe2+.