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

该奖项是根据2009年美国恢复和再投资法案（公法111-5）资助的。新发现的厌氧氨氧化（anammox）过程是海洋环境中的一个重要过程。然而，厌氧氨氧化对全球氮收支的贡献仍然高度不确定。要发展一个预测性的了解氮汇，全面的知识，触发开关从异养反硝化到厌氧氨氧化的环境控制的动态是必要的。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测试一个假设，即有机物和硝酸盐输送到缺氧硝酸盐呼吸区的耦合变化驱动了从异养反硝化到厌氧氨氧化的转变。他们将通过整合建模、实验室实验和现场测量来评估这一假设，其目标有以下三个：（1）开发和实证检验生物反应网络模型，以预测不同有机碳和硝酸盐条件下氮汇途径的相对通量;（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相互作用效应;（3）在马萨诸塞州湾和普拉姆岛河口沿沿着自然环境梯度进行实地测量。微宇宙实验应该提供一个直接的假设，即厌氧氨氧化是有利的条件下，硝酸盐输送率相对于有机物负荷高的测试。实地测量将测试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，厌氧氨氧化和反硝化速率将使用两种方法进行测量，基于同位素配对技术：传统的泥浆和完整的岩心在原位条件下。更广泛的影响：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。拟议的研究将支持研究生和博士后研究员在布朗MBL计划，加强机构合作伙伴关系，以研究生，博士后研究员和PI的共同利益。本科生将参与夏季研究项目，以及通过布朗大学的ARISE计划在当地高中为种族多样化的学生服务的教育推广活动。

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.