Role of manganese in suboxic biogeochemical cycles

锰在低氧生物地球化学循环中的作用

• 批准号: 372543-2009
• 负责人: Sundby, Bjorn
• 金额: $ 6.56万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Ship Time
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=435244
• 关键词: Role; manganese; suboxic; biogeochemical; cycles

Manganese is an important component of marine oxidation-reduction cycles because it exists in multiple redox states and is rapidly cycled between these states by bacterially mediated processes. The ease with which electrons are transferred between manganese species allows the manganese cycle to be readily coupled to other redox cycles. In nature, manganese exists in three oxidation states: Mn(II), Mn(III), and Mn(IV). Of these, Mn(III) has mostly been ignored. Different approaches to measuring manganese give contradictory information about the distribution of manganese dissolved in sediment pore waters that suggests that the suboxic part of the sediment contains not one but two soluble species, Mn(II) and Mn(III). The presence of Mn(III) in suboxic water and pore water can resolved several important issues. It would provide a mechanism for transferring dissolved Mn from sediment to water column; and it would provide evidence for a novel pathway in the nitrogen cycle whereby ammonia is oxidized directly to nitrogen gas by manganese. We propose to conduct a biogeochemical and microbiological study, in collaboration with researchers from two US universities, of the nature, stoichiometry, and rate of reactions that respectively produce and consume dissolved Mn(III). The study will be carried out in the St. Lawrence Estuary - Saguenay fjord environment for these reasons: 1)We have nearly 30 years worth of data on manganese in sediment and water column. 2) The sediments contain high concentrations of manganese, and manganese cycling is a dominant diagenetic process. 3) The solid phase manganese distribution is in steady state over decadal time scales, whereas the distribution of dissolved manganese is not. 4) The system provides excellent examples of low oxygen and high oxygen bottom waters that can help us compare and contrast end-member environments. 5) Many of the scientific questions we will investigate stem from previous work carried out in this system.

锰是海洋氧化还原循环的重要组成部分，因为它以多种氧化还原状态存在，并通过细菌介导的过程在这些状态之间快速循环。电子在锰物质之间转移的容易性允许锰循环容易地与其他氧化还原循环耦合。在自然界中，锰以三种氧化态存在：Mn（II）、Mn（III）和Mn（IV）。其中，Mn（III）大多被忽略。不同的方法来测量锰给矛盾的信息锰溶解在沉积物孔隙沃茨，这表明，沉积物的亚氧部分含有不是一个，而是两个可溶性物种，锰（II）和锰（III）的分布。Mn（III）在低氧水和孔隙水中的存在可以解决几个重要问题。这将提供一种机制，将溶解锰从沉积物中转移到水柱中，它将提供证据，氮循环中的一个新的途径，即氨直接氧化为氮气的锰。我们建议进行生物化学和微生物的研究，与来自美国两所大学的研究人员合作，分别产生和消耗溶解锰（III）的反应的性质，化学计量和速率。这项研究将在圣劳伦斯河口-萨格奈峡湾环境中进行，原因如下：1）我们有近30年的沉积物和水柱中锰的数据。2)沉积物中含有高浓度的锰，锰循环是一个主要的成岩过程。3)在十年尺度上，固相锰的分布是稳定的，而溶解态锰的分布则不是。4)该系统提供了低氧和高氧底部沃茨的极好例子，可以帮助我们比较和对比端员环境。5)我们将研究的许多科学问题都源于这个系统以前的工作。