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Collaborative Research: Manganese Cycling and Coupling Across Redox Boundaries within Stratified Basins of the Baltic Sea

合作研究：波罗的海分层盆地内锰循环和跨氧化还原边界的耦合

基本信息

批准号：
1923218
负责人：
Dalton Hardisty
金额：
$ 23.48万
依托单位：
Michigan State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-12-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1923218&HistoricalAwards=false
关键词：
Collaborative Research Manganese Cycling Coupling

项目摘要

The trace element manganese (Mn) is distributed widely throughout the global ocean where it cycles among three dominant oxidation states. Manganese in the higher oxidation states is highly reactive and thereby influences the cycling of nearly all other elemental cycles, including those of oxygen and nitrogen. The intermediate Mn species has only recently become recognized as an abundant component of the Mn pool, presenting now a previously unrecognized factor that may control the chemistry of the ocean. The Baltic Sea contains high Mn concentrations and preliminary investigations have pointed to the presence of an operationally defined "reactive" form of Mn but the composition and consequence of this Mn pool are unknown. This research will explore the cycling of Mn within the Baltic Sea enabled by an established collaboration with the Leibniz Institute for Baltic Sea Research in Warnemunde, Germany. By coupling field measurements and targeted shipboard incubations, this study will shed light on the processes controlling the Mn cycle and its link to the oxygen, iodine, and nitrogen cycles. This project will educate several undergraduate and graduate students and promote scientific exchange between research groups within the United States and Germany. Further, outreach efforts associated with this research will continue an existing collaboration between the PIs and the Boston Green Academy in South Boston to introduce high school students to chemical oceanography, and in particular biogeochemistry.Manganese (Mn) is intricately linked to nearly all elemental cycles, and yet we know little about the processes governing its redox cycling within natural systems. Over the past decade a number of key scientific discoveries have provided greater insight into the diversity of processes and mechanisms involved in Mn redox cycling and introduced Mn(III) ligand complexes as important components of the dissolved Mn pool. The Baltic Sea is one of the most well studied stratified marine systems and reactive Mn has been implicated as a key factor in the formation and maintenance of suboxic zones. Thus, the goal of this research is to explore the cycling and elemental coupling of Mn within stratified basins of the Baltic Sea. The PIs predict that reactive Mn, as Mn(III) ligand complexes and Mn oxide particles, is a primary control on the redox landscape of stratified marine waters, particularly at redox boundaries and within the suboxic zone. The PIs propose fieldwork in a local permanently stratified brackish pond to refine experimental procedures followed by two cruises to suboxic basins in the Baltic Sea enabled by an established collaboration with the Leibniz Institute for Baltic Sea Research in Warnemunde. Field measurements will be obtained using a combination of in situ sensors and ship/lab-based instrumentation at several Baltic Sea sites to define the distribution of Mn species and the rates of Mn redox transformations spanning the redoxcline along with a suite of chemical information. Further, a matrix of shipboard incubations will be conducted to constrain the underlying (a)biotic processes responsible for the observed Mn profiles. Specifically, across oxygen and Mn gradients spanning the redoxcline, the PIs will interrogate the link between the Mn cycle and iodine and nitrogen species, which will ultimately help constrain current gaps in the mass balance of these elements in Baltic Sea models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

微量元素锰在全球海洋中广泛分布，在三种主要氧化态之间循环。处于较高氧化态的锰是高度活性的，因此影响几乎所有其他元素循环，包括氧和氮的循环。直到最近，中间的锰物种才被认为是锰池的丰富组成部分，现在是一个以前未被认识到的因素，可能控制着海洋的化学成分。波罗的海含有高浓度的锰，初步调查表明存在一种在操作上被定义为“活性”的锰，但这一锰池的组成和后果尚不清楚。这项研究将探索与德国瓦尔尼蒙德的莱布尼茨波罗的海研究所建立的合作关系，使波罗的海内的锰循环成为可能。通过结合现场测量和有针对性的船上培养，这项研究将阐明控制锰循环的过程及其与氧、碘和氮循环的联系。该项目将培养几名本科生和研究生，并促进美国和德国境内研究小组之间的科学交流。此外，与这项研究相关的推广工作将继续PIs和南波士顿波士顿绿色学院之间的现有合作，向高中生介绍化学海洋学，特别是生物地球化学。锰(Mn)与几乎所有元素循环都有错综复杂的联系，但我们对其在自然系统中氧化还原循环的过程知之甚少。在过去的十年里，一些重要的科学发现使人们更深入地了解了锰的氧化还原循环过程和机制的多样性，并引入了锰(III)配体络合物作为溶解锰池的重要组成部分。波罗的海是研究最充分的层状海洋系统之一，活性锰被认为是亚氧基带形成和维持的关键因素。因此，这项研究的目的是探索波罗的海层状盆地中锰的循环和元素耦合。PI预测，作为锰(III)配体络合物和氧化锰颗粒的活性锰是分层海洋水域氧化还原地貌的主要控制因素，特别是在氧化还原边界和亚缺氧区。PIS建议在当地一个永久分层的微咸水池塘进行实地工作，以完善实验程序，然后通过与设在瓦尔内蒙德的莱布尼茨波罗的海研究所的既定合作，两次巡航波罗的海的亚氧盆地。将在波罗的海的几个地点使用现场传感器和船舶/实验室仪器相结合的方式进行现场测量，以确定锰物种的分布和整个氧化还原跃层中锰的氧化还原转化率以及一系列化学信息。此外，将进行船上孵化矩阵，以限制对观测到的锰剖面负有责任的潜在(A)生物过程。具体地说，跨越氧化跃层的氧和锰梯度，PI将询问锰循环与碘和氮物种之间的联系，这最终将有助于限制波罗的海模式中这些元素质量平衡的当前差距。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。