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Influence of Physical Perturbation on Fe(II) Supply in Coastal Marine Sediments.
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2020-02-15 , DOI: 10.1021/acs.est.9b06278
Ulf Lueder 1 , Markus Maisch 1 , Katja Laufer 2, 3 , Bo Barker Jo Rgensen 2 , Andreas Kappler 1, 2 , Caroline Schmidt 1
Affiliation  

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 toward 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 approximately 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 afterward. Mössbauer spectroscopy showed that the relative abundance of metastable iron-sulfur mineral phases (FeSx) increased during initial incubation and decreased together with pyrite (FeS2) after perturbation. We show that Fe2+ mobilization in marine sediments is stimulated by chemical changes caused by physical disturbances impacting the Fe redox distribution. Our study suggests that, in addition to microbial and abiotic Fe(III) reduction, including Fe(III) photoreduction, physical mixing processes induce chemical changes providing sediments and the inhabiting microbial community with Fe2+.

中文翻译:

物理扰动对沿海海洋沉积物中Fe(II)供给的影响。

海洋沉积物中的铁(Fe)生物地球化学受到氧化还原转换的驱动,从而形成Fe(II)和Fe(III)梯度。由于沉积物是通过波动作用或生物扰动而物理混合的,因此Fe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,我们进行了伏安法微传感器测量,连续的Fe提取和Mössbauer光谱,研究了12小时的光暗循环温育的海洋沿海沉积物。在不受干扰的孵育7天中,Fe2 +从大约400μM降至60μM。在孵育的前2-4天,由于Fe(III)的光还原作用,Fe2 +在顶部2 mm处累积高达100μM。在第7天进行物理扰动后,Fe2 +被重新移动至30 mm深度,浓度达到320μM,此后两天内降至检测极限以下。Mössbauer光谱显示,亚稳铁硫矿物相(FeSx)的相对丰度在初始孵育期间增加,而在扰动后与黄铁矿(FeS2)相对减少。我们表明,海洋沉积物中的Fe2 +动员是由物理变化(影响Fe氧化还原分布)引起的化学变化刺激的。我们的研究表明,除了微生物和非生物形式的Fe(III)还原(包括Fe(III)光还原)外,物理混合过程还会诱导化学变化,从而为沉积物和Fe2 +的微生物群落提供栖息地。Mössbauer光谱显示,亚稳铁硫矿物相(FeSx)的相对丰度在初始孵育期间增加,而在扰动后与黄铁矿(FeS2)相对减少。我们表明,海洋沉积物中的Fe2 +动员是由物理变化(影响Fe氧化还原分布)引起的化学变化刺激的。我们的研究表明,除了微生物和非生物形式的Fe(III)还原(包括Fe(III)光还原)外,物理混合过程还会诱导化学变化,从而为沉积物和Fe2 +的微生物群落提供栖息地。Mössbauer光谱显示,亚稳铁硫矿物相(FeSx)的相对丰度在初始孵育期间增加,而在扰动后与黄铁矿(FeS2)相对减少。我们表明,海洋沉积物中的Fe2 +动员是由物理变化(影响Fe氧化还原分布)引起的化学变化刺激的。我们的研究表明,除了微生物和非生物形式的Fe(III)还原(包括Fe(III)光还原)外,物理混合过程还会诱导化学变化,从而为沉积物和Fe2 +的微生物群落提供栖息地。
更新日期:2020-02-27
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