NNA: Collaborative Research: Interactions of the Microbial Iron and Methane Cycles in the Tundra Ecosystem

NNA：合作研究：苔原生态系统中微生物铁和甲烷循环的相互作用

• 批准号: 1754358
• 负责人: David Emerson
• 金额: $ 77.17万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1754358&HistoricalAwards=false
• 关键词: NNA; Collaborative; Research; Interactions; Microbial

There is great concern about changing conditions in the Arctic due to environmental transformations that are impacting tundra and its underlying permafrost. At the same time there are major gaps in our understanding of tundra/permafrost microbiology and elemental cycling. Filling these knowledge gaps will enable a better overall understanding of the tundra, and can provide crucial information about how this globally important, but fragile ecosystem will respond to change. The particular knowledge gap this research will fill centers around iron and the bacteria that control its availability. Iron is an essential micro-nutrient for animals, plants, and microbes. It also serves as a growth substrate for certain groups of bacteria, many of which fix carbon dioxide to grow. Some of these bacteria directly compete with other groups of microbes that produce or consume methane, the atmospheric concentration of which is continuing to increase. It is particularly important to understand the dynamics of carbon dioxide and methane in the Arctic because there is a large amount of organic carbon stored in permafrost that could be converted into these two gases. The research team consists of a microbial ecologist with considerable experience in iron cycling bacteria; a mathematical modeler who will quantify the relative impacts of different microbial processes, and a tundra ecologist with extensive experience in elemental cycling in permafrost environments. This project will, for the first time, systematically characterize and quantify microbial communities responsible for iron cycling in the tundra/permafrost of Alaska?s North Slope, and increase our understanding of how these microbes interact with the carbon cycle by suppressing methane production. The basic supposition of this research is that conditions in the Arctic are beneficial to an active iron cycle because the shallow depth permafrost prevents ferrous iron-laden waters from percolating into deep aquifers (a common route for iron removal from temperate ecosystems). Furthermore, cool water temperatures slow the chemical oxidation of iron, and a short, but intense growing season provides a source of labile carbon that helps fuel iron reduction. These ideas will be tested by conducting field and laboratory studies at the Toolik Field Station on the North Slope of Alaska. Previous work has revealed there are extensive populations of iron-oxidizing and iron-reducing bacteria associated with microbial iron mats in this region, but in general, little is known about their diversity or function. This work will utilize cultivation-independent, amplicon-based community analysis and metagenomics to further characterize community diversity and function among these chemosynthetic communities. The team will measure methane production at tundra sites with high rates of iron cycling and compare these to sites that are similar in terms of hydrology and landform, but have lower rates of iron-cycling to assess the direct impact of the iron cycle on methane production and consumption. The microbiomes of these sites will also be compared using molecular analysis. In addition to these field measurements, the researchers will construct a laboratory microcosm that can be seeded with soils and microbial iron mats collected from Toolik. This will allow controlled conditions to simulate interactions of the iron and methane cycles under conditions where key parameters such as iron and oxygen concentrations can be controlled. From both field and laboratory data a reaction-based model will be developed using a series of kinetic equations. These will form the basis for a predictive model that can estimate the suppressive effects of iron cycling on methane production. In terms of broader impacts, the work will provide unique opportunities for training undergraduate, and graduate students, as well as a postdoctoral researcher, in combining field, laboratory, and modelling based science to fill an important gap in our knowledge of the tundra ecosystem. To broaden public outreach two artists will be engaged to create a unique art-science dialog that will broaden the interpretation of the project results, and provide museum quality creative work that can be displayed in either science or art exhibits.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.

由于环境转变影响了苔原及其基本的多年冻土，因此人们非常担心北极状况的变化。同时，我们对苔原/多年冻土微生物学和元素循环的理解存在重大差距。填补这些知识差距将使对苔原有更好的总体理解，并可以提供有关该全球重要但脆弱的生态系统将对变化做出反应的关键信息。这项研究的特定知识差距将填补围绕铁和控制其可用性的细菌的中心。铁是动物，植物和微生物的必不可少的微营养素。它也是某些细菌组的生长底物，其中许多固定二氧化碳生长。这些细菌中的一些直接与产生或食用甲烷的其他微生物竞争，其大气浓度正在继续增加。了解北极中二氧化碳和甲烷的动力学尤为重要，因为在多年冻土中存储了大量有机碳，可以转化为这两种气体。研究小组由一名微生物生态学家组成，在铁循环细菌方面具有丰富的经验。一位数学建模者，将量化不同微生物过程的相对影响，以及一位在多年冻土环境中具有丰富经验的苔原生态学家。 该项目将首次系统地表征和量化负责铁循环的微生物群落/阿拉斯加北坡的苔原/多年冻土，并通过抑制甲烷产生来与碳循环相互作用。这项研究的基本假设是，北极的条件对活性铁循环有益，因为浅深度永久冻土阻止了含铁的铁水域渗透到深层含水层中（从温带生态系统中去除铁的常见途径）。此外，凉爽的水温减慢了铁的化学氧化，而短暂但强烈的生长季节则提供了不稳定的碳来源，有助于减少铁的燃油。这些想法将通过在阿拉斯加北坡的工具现场站进行现场和实验室研究来测试。先前的工作表明，与该地区的微生物铁垫相关的氧化和还原细菌种群广泛，但通常，对它们的多样性或功能知之甚少。这项工作将利用基于培养的，基于扩增的社区分析和宏基因组学来进一步表征这些化学合成社区中的社区多样性和功能。该团队将在铁循环速率高的苔原站点测量甲烷生产，并将其与在水文学和地形方面相似的地点进行比较，但铁循环速率较低，以评估铁循环对甲烷生产和消耗的直接影响。这些位点的微生物组也将使用分子分析进行比较。除了这些现场测量值外，研究人员还将构建一个实验室缩影，该实验室可与工具库中收集的土壤和微生物铁垫子播种。这将允许受控条件在可以控制的关键参数（例如铁和氧气浓度）的条件下模拟铁和甲烷循环的相互作用。从现场和实验室数据中，将使用一系列动力学方程开发基于反应的模型。这些将构成一个预测模型的基础，该模型可以估计铁循环对甲烷产生的抑制作用。在更广泛的影响方面，这项工作将为培训本科生，研究生以及博士后研究员提供独特的机会，并在结合了领域，实验室和基于建模的科学方面，以填补我们对苔原生态系统的了解的重要空白。为了扩大公众的宣传，将聘请两位艺术家创建独特的艺术科学对话框，该对话将扩大对项目结果的解释，并提供博物馆优质的创意作品，可以在科学或艺术展览中展示。该奖项反映了NSF的法定任务，并通过使用该基金会的知识分子的功能和广泛影响来评估NSF的法定任务，并被视为值得的支持。

项目成果

Spatial distribution and biogeochemistry of redox active species in arctic sedimentary porewaters and seeps

北极沉积孔隙水和渗漏中氧化还原活性物质的空间分布和生物地球化学

• DOI: 10.1039/d1em00505g
• 发表时间: 2022
• 期刊: Environmental Science: Processes & Impacts
• 作者: Hudson, Jeffrey M.;Michaud, Alexander B.;Emerson, David;Chin, Yu-Ping
• 通讯作者: Chin, Yu-Ping

Microbial iron cycling is prevalent in water-logged Alaskan Arctic tundra habitats, but sensitive to disturbance

微生物铁循环在淹水的阿拉斯加北极苔原栖息地中普遍存在，但对干扰敏感

• DOI: 10.1093/femsec/fiad013
• 发表时间: 2023
• 期刊: FEMS Microbiology Ecology
• 影响因子: 4.2
• 作者: Michaud, Alexander B.;Massé, Rémi O.;Emerson, David
• 通讯作者: Emerson, David

Overwinter oxygen and silicate dynamics in a high Arctic lake (Immerk Lake, Devon Island, Canada)

北极高海拔湖泊（加拿大德文岛伊默克湖）的越冬氧气和硅酸盐动态

• DOI: 10.1080/20442041.2022.2063623
• 发表时间: 2022
• 期刊: Inland Waters
• 影响因子: 3.1
• 作者: Michaud, Alexander B.;Apollonio, Spencer
• 通讯作者: Apollonio, Spencer