Collaborative Research: MSB: Impact of sea level rise on sedimentary nitrogen removal processes in tidal freshwater ecosystems

合作研究：MSB：海平面上升对潮汐淡水生态系统沉积氮去除过程的影响

• 批准号: 1020944
• 负责人: Bongkeun Song
• 金额: $ 50.02万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1020944&HistoricalAwards=false
• 关键词: Collaborative; Research; MSB; Impact; sea

Tidal freshwater ecosystems such as rivers and estuaries are located at the interface between land and sea. These ecosystems provide important natural services including primary production, nutrient distribution and regulation, and waste management - services that are at risk due to climate change. Two aspects of climate change, sea level rise and lower precipitation in some watersheds, will shift the location of freshwater-saltwater mixing zones to upper rivers and continuously increase salinity intrusion into freshwater habitats. Sea level is predicted to rise up to 100 cm by 2100, and by itself can have multiple impacts on freshwater ecosystems, including direct toxic effects, habitat degradation and alteration of nutrient cycles. Salinity increases may also have significant effects on the nitrogen (N) dynamics of freshwater habitats. Nitrification (ammonia conversion to nitrate) and denitrification (nitrate conversion to dinitrogen) are key microbial processes controlling the intensity and duration of eutrophication caused by excess N loading. Salinity intrusion might diminish microbial N removal capacity in freshwater sediments as nitrification and denitrification are reduced due to substrate limitation and physiological inhibition. This could result in prolonged eutrophication and hypoxia at rivers and estuaries. Alternatively, anaerobic ammonium oxidation (anammox; ammonium and nitrite conversion to dinitrogen gas) may become a more important microbial N removal process and help recover N removal capacity in freshwater sediments since anammox bacteria can tolerate salinity increases. This project will study 1) the importance of anammox in tidal freshwater sediments, 2) the effects of salinity on freshwater anammox bacteria and the sedimentary N cycle, and 3) predictions of an alternative N removal pathway in sedimentary communities threatened by sea level rise. The proposed research will integrate molecular microbial techniques, chemical tracer methods and mathematical models to examine sedimentary N removal processes in the Cape Fear River and New River of North Carolina. This proposal will result in the following benefits and outcomes; 1) revealing the structures and activities of microbial communities involved in N removal processes in tidal freshwater sediments, 2) determining differential responses of sediment communities to seawater intrusion, 3) understanding the impacts of sea level rise on sedimentary N removal processes in freshwater ecosystems, 4) predicting a key microbial process for net N removal capacity of freshwater ecosystems experiencing sea level rise. This project will also provide an in-depth understanding of microbial responses in freshwater sediment communities under threat of sea level rise. Interdisciplinary approaches will provide insight into the linkages between community structure and activity as well as salinity effects on riverine sedimentary N cycling. Broader impacts will be manifested through diverse educational components, outreach, and improved research infrastructure at the University of North Carolina Wilmington (UNCW) and the University of Connecticut. Three PIs (microbial ecologist, biogeochemist and ecosystem modeler) will provide interdisciplinary training to at least three graduate students seeking a M.S. or Ph.D. degree. Additional educational impact will be accomplished both in the classrooms and through individual undergraduate research projects at the two institutions. Research experience for high school students will be achieved by including the project within the UNCW "Summer Ocean Ventures" and "Ocean17" programs. The high school students will participate in DNA analysis and mesocosm experiments. The PI will provide a lecture on the microbial nitrogen cycle to the students and design three days of laboratory and field courses to detect and measure denitrification during the Ocean 17 camp. The graduate students recruited for this proposed research will act as teaching assistants for the high school students. The program will culminate with a Summer Ventures Symposium where students will present their work. Outreach will be facilitated by partnering with a local citizens group (NC-Coastal Ocean Federation) to recruit volunteers to participate in sampling cruises and water monitoring program, and by using the existing UNCW "Planet Ocean" lecture series as a public platform to discuss coastal water resources issues and actions.

潮汐淡水生态系统（例如河流和河口）位于陆地和海洋之间的界面。这些生态系统提供重要的自然服务，包括初级生产，营养分布和监管以及废物管理 - 由于气候变化而面临风险的服务。气候变化的两个方面，某些流域的海平面上升和降水量下降，将把淡水盐水混合区的位置转移到上游河流，并不断增加盐度侵入淡水栖息地。预计到2100年，海平面将上升到100 cm，并且本身可能会对淡水生态系统产生多种影响，包括直接有毒作用，栖息地降解和营养周期的改变。盐度增加也可能对淡水栖息地的氮（N）动态产生重大影响。硝化（氨转化为硝酸盐）和硝酸盐（硝酸盐转化为二氮）是控制过多的N负载引起的富营养化的强度和持续时间的关键微生物过程。盐度侵入可能会降低淡水沉积物中的微生物N去除能力，因为硝化和反硝化由于底物限制和生理抑制而降低。这可能导致河流和河口的富营养化和缺氧。另外，厌氧铵氧化（苯甲酸铵；铵和亚硝酸盐转化为二氮气体）可能会成为更重要的微生物N去除过程，并有助于恢复淡水沉积物中的N去除能力，因为Anammox细菌可以耐受盐度的增加。该项目将研究1）ANAMMOX在潮汐淡水沉积物中的重要性，2）盐度对淡水Anammox细菌和沉积N周期的影响，以及3）预测，在海平面上升的沉积社区中，替代n去除途径。拟议的研究将整合分子微生物技术，化学示踪剂方法和数学模型，以检查北卡罗来纳州开普恐惧河和新河中的沉积N去除过程。该提案将带来以下收益和成果； 1）揭示潮汐淡水沉积物中涉及N去除过程的微生物群落的结构和活动，2）确定沉积物群落对海水入侵的差异反应，3）3）了解海平面上升对淡水生态系统中淡水生态系统中海平面清除过程的影响，4）预测新鲜n net net net net wrestwater newll efress net net whrest nertwers forls net whrest nerf nater forl nerth nerfl offers nefter nerflwater a nerth Freshwater a nerth Freshwater a nerth Freshwater a nerth Freshwater a nerth Freshwater a。该项目还将在海平面上升的威胁下对淡水沉积物群落的微生物反应有深入的了解。跨学科的方法将洞悉社区结构与活动之间的联系以及对河流沉积N循环的盐度影响。北卡罗来纳大学威尔明顿大学（UNCW）和康涅狄格大学的各种教育组成部分，外展和改进的研究基础设施将表现出更广泛的影响。三个PI（微生物生态学家，生物地球化学家和生态系统建模者）将为至少三名寻求M.S.的研究生提供跨学科培训。或博士学位程度。在教室和两个机构的个人本科研究项目中，都将实现其他教育影响。将在UNCW“ Summer Ocean Ventures”和“ Ocean17”计划中包括该项目来实现高中生的研究经验。高中生将参加DNA分析和中验实验。 PI将为学生提供有关微生物氮循环的讲座，并设计三天的实验室和现场课程，以检测和测量17个海洋训练营期间的硝化。为这项拟议的研究招募的研究生将担任高中生的助教。该计划将通过夏季企业研讨会达到高潮，学生将在其中展示他们的作品。与当地公民团体（NC-Coastal Ocean Federation）合作，将促进外展活动，以招募志愿者参加采样巡游和水监测计划，并将现有的UNCW“ Planet Ocean”讲座系列作为公共平台，以讨论沿海水资源问题和行动。