Salinity Effects on Nitrogen Dynamics in Shallow, Coastal Sediments

盐度对浅海沿海沉积物中氮动态的影响

• 批准号: 0350651
• 负责人: Wayne Gardner
• 金额: --
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0350651&HistoricalAwards=false
• 关键词: Salinity; Effects; Nitrogen; Dynamics; Shallow

ABSTRACTOCE- 0350651In this study, researchers at the University of Texas at Austin hope to advance our understanding of the mechanisms controlling the concentrations, forms, transformation rates, and fate of biologically relevant nitrogen compounds over a range of salinities in coastal ecosystems. Nitrogen often limits primary production in coastal regions. Shallow water sediments are primary biogeochemical sites regulating the transformation and fate of N in coastal ecosystems. Upper sediment layers provide environments conducive to microbial N cycle transformations, including organic N mineralization, nitrification (to nitrite and nitrate), denitrification, and dissimilatory nitrate reduction to ammonium (DNRA), but the importance of each process varies with salinity and other factors. Recent evidence indicates that traditional paradigms of key processes, such as denitrification, may not be accurate or complete for all sediment systems. The objectives of this investigation are to compare and combine chemical, isotopic, and molecular biology methods to define N transformation mechanisms in coastal systems over a salinity gradient. Specific hypotheses to be examined are:1. Salinity and available organic matter control the fate of regenerated N by affecting sulfide concentrations in shallow coastal ecosystems.2. The importance of N2O release and DNRA, relative to N2 production, increases with salinity in reduced sediments.The experiments are expected to yield information relevant to issues of international concern including coastal eutrophication, harmful algal blooms, freshwater supply, and global change. They will advance marine methodological development by combining molecular biology techniques with chemical and stable isotopic approaches to clarify the structure and function of bacteria involved in N transformations. Opportunities will be provided for minority institution students and high school teachers and students to participate in field research on coastal environments and learn about the importance of nutrients and salinity to coastal ecosystem processes.

在这项研究中，德克萨斯大学奥斯汀分校的研究人员希望促进我们对沿海生态系统中一系列盐度上生物相关氮化合物的浓度、形态、转化速率和命运的控制机制的理解。氮常常限制沿海地区的初级生产。浅水沉积物是调节沿海生态系统中氮的转化和去向的主要生物地球化学场所。上层沉积物提供了有利于微生物N循环转化的环境，包括有机N矿化、硝化作用(亚硝酸盐和硝酸盐)、反硝化作用和异化硝酸盐还原为铵(DNRA)，但每个过程的重要性因盐度和其他因素而异。最近的证据表明，传统的关键过程范例，如反硝化，对于所有沉积物系统来说可能并不准确或完整。这项研究的目的是比较和结合化学、同位素和分子生物学方法，以确定盐度梯度上海岸系统中N的转化机制。需要检验的具体假设是：1.盐度和有效有机质通过影响浅海生态系统中硫化物的浓度来控制再生氮的命运。在减少的沉积物中，N2O的释放和DNRA相对于氮气的产生的重要性随着盐度的增加而增加。预计这些实验将产生与国际关注的问题相关的信息，包括沿海富营养化、有害藻华、淡水供应和全球变化。他们将通过将分子生物学技术与化学和稳定同位素方法相结合来澄清参与N转化的细菌的结构和功能，从而推动海洋方法学的发展。将为少数族裔机构的学生和高中教师和学生提供机会，参与关于沿海环境的实地研究，并了解营养物质和盐度对沿海生态系统过程的重要性。