Collaborative Research: Predicting Controls of Partitioning between Dissimilatory Ntirate Reduction to Ammonium (DNRA) and Dinitrogen Production in Marine Sediments

合作研究：预测海洋沉积物中异化硝酸盐还原成铵（DNRA）和氮生成之间的分配控制

• 批准号: 1635099
• 负责人: Anne Giblin
• 金额: $ 37.02万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635099&HistoricalAwards=false
• 关键词: Collaborative; Research; Predicting; Controls; Partitioning

Microbial processes in marine sediments play a major role in the global nitrogen cycle. Because the presence of nitrogen compounds dissolved in seawater largely controls biological growth, understanding how the sedimentary nitrogen budget changes with altered circulation, acidity, and biological productivity is of critical importance to predict oceanic function in future climate scenarios. Surprisingly, we do not know definitively if nitrogen exchange between sediments and the water column is in balance, and if not, how it varies over time and space. We do know that two bacterially mediated chemical reactions are primarily responsible for removing nitrogen from marine ecosystems by converting biologically usable forms of dissolved nitrogen back to nitrogen gas (N2) that is not generally available for biological production. These reactions are called denitrification and anaerobic ammonium oxidation (anammox); the latter operating only where oxygen is zero. This project will investigate a third reaction, called dissimilatory nitrate reduction (DNRA), which competes directly with anammox to limit N2 production and the consequent "loss" of nitrogen, thus retaining nitrogen for use in marine ecosystems. The role of DNRA has not been fully explored and quantifying this reaction could help evaluate the overall nitrogen balance in ocean systems. The researchers here will use novel experimental reactors that contain collected marine sediments and, by varying environmental conditions (pH, temperature, oxygen, organic carbon), will discover and quantify what controls rates of DNRA, denitrification, and anammox in sediments. This will provide a direct test and further development of theoretical sedimentary nitrogen models that can be used to predict possible changes in the global nitrogen cycle resulting with various future climate scenarios. Two graduate students will participate in the research and collaborations with the Maine Coastal Observing Alliance (MCOA) and the Gulf of Maine Institute (GOMI), as well as the Institute for Broadening Participation (IBP) will generate minority student involvement and enhanced outreach activity.This project uses thermodynamic calculations and empirical evidence as a basis to evaluate the ratio of available organic carbon (C) to nitrate (NO3-) as a key controlling factor of nitrogen redox partitioning; with higher ratios believed to favor dissimilatory nitrate reduction (DNRA) over N2 production. The investigator's theoretical model predicts rapid and reversible transitions between DNRA and N2 production over relatively small changes in C/NO3-. This suggests that partitioning could be sensitive to seasonal and possibly inter-annual differences in organic C deposition as well as processes that control nitrate flux to the sediments such as water column stratification. Quantitative relationships between sedimentary C/NO3- and nitrogen partitioning remain poorly defined, and a number of other factors including T, H2S, and Fe(II), are known to influence N partitioning. This study will investigate the hypothesis that relationships between nitrogen redox partitioning and C/NO3-, and by extension H2S/NO3-, are predicted by the proposed theoretical sedimentary nitrogen model. Experiments will varying NO3 fluxes while providing hydrogen sulfide (H2S) and 13C-labelled detritus as electron donors, and measure transformation rates of 15NO3- to 15NH4+ and 29/30N2 in thin disc reactors to determine rates and pathways of DNRA and N2 production. The proposed integration of these experiments with a theoretically-based biogeochemical model will develop a quantifiable and testable understanding of the marine nitrogen cycle. This study should provide a major advance that could be broadly applied to quantitatively predict the sedimentary balance between nitrogen retention and loss across marine ecosystems.

海洋沉积物中的微生物过程在整体氮循环中起主要作用。因为溶解在海水中的氮化合物的存在很大程度上控制了生物学生长，因此了解沉积性氮预算如何随着循环，酸度和生物生产力的改变而变化，对于预测未来气候场景中的海洋功能至关重要。令人惊讶的是，我们不确定地知道沉积物和水柱之间的氮交换是否平衡，如果没有，则它如何随时间和空间变化。我们确实知道，两种细菌介导的化学反应主要负责从海洋生态系统中去除氮，通过将溶解的氮的可溶解形式转化为氮气（N2），这些形式通常不适用于生物生产。这些反应称为反硝化和厌氧铵氧化（Anammox）。后者仅在氧气为零的地方工作。该项目将研究第三个反应，称为异化硝酸盐还原（DNRA），该反应直接与Anammox竞争以限制N2的产生和随之而来的氮损失，从而将氮保留在海洋生态系统中。 DNRA的作用尚未得到充分探索，量化了这种反应可以帮助评估海洋系统中的整体氮平衡。这里的研究人员将使用包含收集到的海洋沉积物的新型实验反应堆，并且通过不同的环境条件（pH，温度，氧气，有机碳），将发现和量化在沉积物中控制DNRA，非硝化和Anammox的速率。这将提供直接测试并进一步开发理论沉积氮模型，该模型可用于预测全球氮循环的可能变化，从而导致各种未来的气候情况。两名研究生将与缅因州沿海观察联盟（MCOA）和缅因州湾（GOMI）（GOMI）以及宽广参与研究所（IBP）参与研究和合作（NO3-）作为氮氧化还原分配的关键控制因素；据信较高的比率比N2产量相比有利于异化硝酸盐减少（DNRA）。研究者的理论模型预测了DNRA和N2产生之间的快速和可逆转变，而C/NO3-的变化相对较小。这表明分配可能对有机c沉积中的季节性和可能的​​年际差异以及控制硝酸盐通量对沉积物（例如水柱分层）的过程敏感。众所周知，沉积物C/NO3和氮分配之间的定量关系仍然很差，包括T，H2S和Fe（II）在内的许多其他因素都会影响N分配。这项研究将调查以下假设：氮氧化还原分配与C/NO3-以及通过扩展H2S/NO3-之间的关系由所提出的理论沉积氮模型预测。实验将在提供硫化氢（H2S）和13C标记的碎屑作为电子供体时将NO3通量变化，并在薄盘反应器中测量15NO3-至15NH4+和29/30N2的转化速率，以确定DNRA和N2生产的速率和途径。这些实验与理论上的生物地球化学模型的提议集成将对海洋氮循环产生可量化且可测试的理解。这项研究应提供一个重大进步，可以广泛应用，以定量预测氮的保留与跨船用生态系统损失之间的沉积平衡。

项目成果

Anaerobic ammonium oxidation (anammox) and denitrification in Peru margin sediments

• DOI: 10.1016/j.jmarsys.2018.09.007
• 发表时间: 2020-07
• 期刊: Journal of Marine Systems
• 影响因子: 2.8
• 作者: J. J. Rich-J.;P. Arevalo;B. Chang;A. Devol;B. Ward

Similar temperature responses suggest future climate warming will not alter partitioning between denitrification and anammox in temperate marine sediments

• DOI: 10.1111/gcb.13370
• 发表时间: 2017-01
• 期刊: Global Change Biology
• 影响因子: 11.6
• 作者: Lindsay D. Brin;A. Giblin;J. J. Rich-J.