Collaborative Research: Environmental Controls on Anammox and Denitrification Rates in Estuarine and Marine Sediments

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。新发现的厌氧氨氧化过程(Anammox)是海洋环境中的一个重要过程。然而，Anammox对全球N预算的贡献仍然非常不确定。在这个项目中，来自布朗大学和海洋生物实验室生态系统中心的研究人员将检验这一假设，即有机质和硝酸盐输送到缺氧硝酸盐呼吸区域的耦合变化驱动了从异养反硝化到厌氧氨氧化的转换。他们将通过结合建模、实验室实验和现场测量来评估这一假说，目标如下：(1)开发和经验性地测试生物反应网络模型，以预测不同有机碳和硝酸盐下的氮汇路径的相对通量；(2)在沉积物微观实验中测试不同有机质和硝酸盐输送速率的交互作用；以及(3)在马萨诸塞湾和普鲁姆岛海湾河口沿自然环境梯度进行实地测量。微观实验应提供对以下假设的直接检验：在硝酸盐输送速率相对于有机物负荷较高的条件下，厌氧氨氧化是有利的。现场测量将检验模型在现场条件下的预测能力。除了营养通量测量和沉积物孔隙水剖面外，还将使用基于同位素配对技术的两种方法来测量厌氧氨氧化和反硝化速率：在原地条件下的传统泥浆和完整岩芯。广泛影响：这项研究的理论和方法进展将通过反硝化研究协调网络分发给社区。拟议的研究将支持Brown-MBL项目中的一名研究生和一名博士后研究员，加强机构合作伙伴关系，使研究生、博士后研究员和个人投资者互惠互利。本科生将参与暑期研究项目，以及通过布朗大学在当地高中服务于不同种族学生的Rise计划的教育推广活动。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The newly discovered process of anaerobic ammonium oxidation (anammox) is an important process in marine environments. The contribution of anammox to global N budgets remains highly uncertain, however. To develop a predictive understanding of nitrogen sinks, comprehensive knowledge on the dynamics of environmental controls that trigger a switch from heterotrophic denitrification to anammox is necessary.In this project, researchers from Brown University and the Ecosystems Center at the Marine Biological Laboratory will test the hypothesis that coupled variation in organic matter and nitrate delivery to the zone of anoxic nitrate respiration drives the switch from heterotrophic denitrification to anammox. They will assess this hypothesis by integrating modeling, laboratory experiments, and field measurements, with the following three objectives: (1) to develop and empirically test bioreaction network models to predict the relative flux of nitrogen sink pathways under varying organic carbon and nitrate; (2) to test the interactive effects of varying organic matter and nitrate delivery rates in sediment microcosm experiments; and (3) to conduct field measurements along natural environmental gradients in Massachusetts Bay and Plum Island Sound Estuary.The microcosm experiment should provide a direct test of the hypothesis that anammox is favored under conditions when nitrate delivery rates are high relative to organic matter loading. The field measurements will test the predictive power of models under in situ conditions. In addition to nutrient flux measurements and sediment porewater profiles, anammox and denitrification rates will be measured using two methods, based on the isotope pairing technique: conventional slurries and intact cores under in situ conditions.Broader impacts: Theoretical and methodological advances from this research will be distributed to the community through the Denitrification Research Coordination Network. The proposed research will support a graduate student and a postdoctoral researcher in the Brown-MBL program, strengthening institutional partnerships to the mutual benefit of the graduate student, postdoctoral researcher and PIs. Undergraduate students will be involved in summer research projects, as well as educational outreach activities through Brown University's ARISE program in local high schools that serve racially diverse students.