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：淡水沉积物吸收硝酸盐的新微生物途径的重要性淡水中氮(N)水平的增加会威胁到水质。湿地和溪流对氮的去除在农业景观中特别重要，因为氮的出口与在沿海水域造成低氧区和有害藻华有关。研究表明，加入流域的大部分人为氮(例如，作为肥料)在进入海洋之前在通过水文系统的地面和地表水的运输过程中损失。硝酸盐是在水文系统中迁移的最重要的氮形态。到目前为止，大部分硝酸盐的去除都归因于一种名为呼吸反硝化的细菌过程，而这种去除大部分被怀疑发生在小溪和湿地中。然而，最近的研究强调了其他可能在从淡水系统中去除硝酸盐的重要细菌过程，包括异化硝酸盐还原为铵(DNRA)、硫化物氧化与反硝化作用相结合，以及通过铁将非生物转化为DON。这项研究的目标是评估这些替代途径在淡水生态系统中去除硝酸盐的普遍性和重要性。最普遍的假设是，不同的淡水系统将在替代过程的相对重要性上有所不同，这些差异主要来自系统的生物地球化学和水文环境。清除路径将使用景观调查和稳定同位素技术在各种淡水生态系统中进行量化。这一结果将对促进硝酸盐去除的生态系统管理产生影响。