Nitrification in Aquatic Sediments: Interactions with Methane and Hydrogen Sulfide

9521983乔伊硝化是氮循环中的一个中心过程，可能会显著改变再生氮通量的分配，即通过耦合反硝化作用从沉积物释放到水柱的氨氮与作为氮气损失的氮。淡水沉积物释放的氮包括相当数量的氮气和离子形式，这表明耦合硝化-反硝化在淡水环境中比在海洋环境中更有效。这组研究人员将研究甲烷和硫化氢对硝化作用的影响，这两种物质在海洋和淡水环境中的浓度和分布不同。他们假设，共代谢会影响水生沉积物中硝化作用的时空分布，特别是在淡水环境中。他们将研究竞争性(底物)相互作用的作用，以及氧化细菌群落组成(硝化细菌和甲烷氧化菌的存在)对硝化作用的影响。他们还假设，硫化氢是一种有效的硝化抑制剂，可能会影响海洋沉积物中硝化作用的时空分布。了解细菌群落组成、细菌生理学和地球化学驱动的生理学变化之间的关系将提高我们对沉积物中氮循环的理解，并将为改进硝化-反硝化耦合预测模型提供概念框架。

9521983 Joye Nitrification, a central process in the nitrogen cycle, may significantly alter partitioning of the regenerated nitrogen flux between release from sediments to the water column as ammonium versus loss as dinitrogen gas via coupled denitrification. Nitrogen release from freshwater sediments consists of comparable amounts of dinitrogen gas and ionic forms, suggesting that coupled nitrification-denitrification is more efficient in freshwater than in marine environments. This team of investigators will examine the effects of methane and hydrogen sulfide, which differ in concentration and distribution between marine and freshwater environments, on nitrification. They hypothesize that co-metabolism affects the spatial and temporal distribution of nitrification in aquatic sediments, particularly in freshwater environments. They will examine the role of competitive (substrate) interactions and the effect of variations in the oxidizing bacterial community composition (presence of nitrifying vs. methane-oxidizing bacteria) on nitrification. They also hypothesize that hydrogen sulfide, a potent inhibitor of nitrification, may affect the spatial and temporal distribution of nitrification in marine sediments. Understanding the relationship between bacterial community composition, bacterial physiology and geochemically-driven changes in physiology will improve our understanding of nitrogen cycling in sediments and will provide a conceptual framework for improved predictive models of coupled nitrification-denitrification.