DISSERTATION RESEARCH: Importance of Novel Microbial Pathways of Nitrate Uptake by Freshwater Sediments

论文研究：淡水沉积物吸收硝酸盐的新型微生物途径的重要性

• 批准号: 0508704
• 负责人: Stephen Hamilton
• 金额: $ 1.2万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0508704&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Importance; Novel; Microbial

DISSERTATION RESEARCH: Importance of novel microbial pathways of nitrate uptake by freshwater sedimentsIncreasing levels of nitrogen (N) in freshwaters can threaten water quality. The removal of N by wetlands and streams is of particular interest in agricultural landscapes because N export has been implicated in creating low-oxygen zones and harmful algal blooms in coastal waters. Studies indicate that most of the anthropogenic N added to watersheds (e.g., as fertilizer) is lost in transit through the ground and surface waters of the hydrologic system before reaching the oceans. Nitrate is the most important N form moving through hydrologic systems. To date, the majority of nitrate removal has been attributed to a bacterial process called respiratory denitrification, and much of this removal is suspected to occur in small streams and wetlands. However, recent research has highlighted other bacterial processes that may be important in removing nitrate from freshwater systems, including dissimilatory nitrate reduction to ammonium (DNRA), sulfide oxidation coupled to denitrification, and abiotic conversion to DON via iron. The goal of this research is to assess the prevalence and importance of these alternative pathways of nitrate removal in freshwater ecosystems. The most general hypothesis is that various freshwater systems will differ in the relative importance of alternative processes, and that these differences will arise primarily from the system's biogeochemical and hydrological setting. The removal pathways will be quantified using landscape survey and stable isotope techniques in a variety of freshwater ecosystems. The results will have implications for the management of ecosystems to promote nitrate removal.

论文研究：淡水沉积物在淡水中的氮含量（N）水平的硝酸盐吸收新硝酸盐摄取的新型微生物途径的重要性可能威胁到水质。 湿地和溪流清除N在农业景观中特别感兴趣，因为N出口与在沿海水域中建立低氧区和有害的藻类开花有关。 研究表明，在到达海洋之前，大多数添加到流域（例如，作为肥料）通过地面和地表水丢失的大多数人为N（例如，作为肥料）丢失了。 硝酸盐是通过水文系统移动的最重要的N形式。 迄今为止，大多数硝酸盐去除量已归因于一种称为呼吸道硝化的细菌过程，并且怀疑这些去除的大部分被怀疑发生在小流和湿地中。 然而，最近的研究突出了其他细菌过程，这些过程可能对从淡水系统中去除硝酸盐，包括脱硝酸盐水降低到铵（DNRA），硫化物氧化与硝酸盐结合的硫化物氧化以及非生物转化为DON通过铁。 这项研究的目的是评估淡水生态系统中硝酸盐去除这些替代途径的普遍性和重要性。 最一般的假设是，各种淡水系统的相对重要性将有所不同，并且这些差异将主要来自该系统的生物地球化学和水文环境。 将使用各种淡水生态系统中的景观调查和稳定的同位素技术来量化去除途径。 结果将对生态系统的管理有影响，以促进硝酸盐去除。