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The impact of light on microbial iron(II) oxidation in freshwater sediments.

光对淡水沉积物中微生物铁（II）氧化的影响。

基本信息

批准号：
413659503
负责人：
Professor Dr. Andreas Kappler, since 9/2019
金额：
--
依托单位：
Arbeitsgruppe Geomikrobiologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/413659503?language=en
关键词：
impact light microbial iron II

项目摘要

Biogeochemical iron cycling has been recognized as an important reaction network that affects a series of environmentally relevant processes in sediments. Iron(II)-oxidizing and iron(III)-reducing bacteria control to large extent the turnover and the (im)mobilization of iron. In the classical view of the sedimentary biogeochemical iron cycle iron(II)-oxidizing bacteria are fed by an iron(II) flux that originates from the zone of microbial iron(III) reduction, typically located in deeper depth of redox stratified sediments. Although studied for open water systems, the process of iron(III) photoreduction and the consequent provision of iron(II) has so far been neglected for sedimentary systems. In the proposed study, we hypothesize that iron(III) photoreduction provides additional iron(II) as substrate for the iron(II)-oxidizing community in the top sunlit layers of sediments – in a zone that is currently characterized by the oxidative processes and the formation of iron(III). Along these lines we will measure light and geochemical parameters (oxygen, dissolved iron(II), H2O2 and pH) with microsensors and iron(III) mineralogy (Mössbauer and acid extraction) on high spatial and temporal resolution as a function of illumination in freshwater sediment cores. In addition to that we will examine how natural organic matter drives iron(III) photoreduction and the availability of iron(II) for microbial oxidation in sedimentary systems. Furthermore, reactive oxygen species will be detected as a function of aeration and their effect on the stability and availability of iron(II) for microbial oxidation will be assessed. The proposed research project will open doors towards a so far neglected reaction mechanisms and heads towards revision of our current understanding of the biogeochemical iron cycle and related substrate fluxes across redox gradients in sediments.

生物地球化学铁循环是影响沉积物中一系列环境相关过程的重要反应网络。铁（II）氧化菌和铁（III）还原菌在很大程度上控制着铁的周转和（im）动员。在沉积生物地球化学铁循环的经典观点中，铁（II）氧化细菌是由铁（II）通量供给的，铁（II）通量来自微生物铁（III）还原带，通常位于氧化还原层状沉积物的较深深度。虽然研究了开放水域体系的铁（III）光还原过程及其对铁（II）的提供，但迄今为止，沉积体系的铁（III）光还原过程一直被忽视。在提出的研究中，我们假设铁（III）光还原为沉积物顶部阳光照射层中的铁（II）氧化群落提供了额外的铁（II）作为底物，该区域目前以氧化过程和铁（III）的形成为特征。沿着这些路线，我们将测量光和地球化学参数（氧，溶解铁（II）， H2O2和pH）与微传感器和铁（III）矿物学（Mössbauer和酸萃取）在高空间和时间分辨率作为淡水沉积物岩心照明的函数。除此之外，我们还将研究天然有机物如何驱动铁（III）光还原以及沉积系统中铁（II）的微生物氧化可用性。此外，将检测活性氧作为曝气的功能，并评估其对微生物氧化铁（II）的稳定性和可用性的影响。拟议的研究项目将为迄今为止被忽视的反应机制打开大门，并朝着修订我们目前对生物地球化学铁循环和相关沉积物中氧化还原梯度的底物通量的理解。