CAREER: The biological nitrogen isotope systematics of ammonium consumption and production

职业：铵消耗和生产的生物氮同位素系统学

• 批准号: 1554474
• 负责人: Julie Granger
• 金额: $ 79.15万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1554474&HistoricalAwards=false
• 关键词: CAREER; biological; nitrogen; isotope; systematics

The nitrogen (N) cycle in the marine environment is controlled by biological processes. Unfortunately, quantifying these processes and assessing their effect on the N cycle is difficult by direct measurements because of large spatial and temporal differences. Isotopic composition measurements of N provide a means to constrain these processes indirectly; however, there is still a great deal to be understood about isotope fractionation of recycled nitrogen through biological processes, which has made interpretation of novel nitrogen isotope data difficult. A researcher from the University of Connecticut plans to determine the influence of biological consumption and production on the isotope fractionation in ammonium. By helping to understand the processes surrounding fractionation of recycled ammonium at the organism level, this research will create a basis for which future researchers can better interpret isotope composition data to infer nitrogen cycle dynamics. A graduate student, a postdoctoral fellow, and two or more undergraduate students will be involved in the research. The researcher plans to integrate science with community-engaged learning by developing an undergraduate field and laboratory course that will require the students to present their research to stakeholders in the community. There will be a manual created for this course that will be disseminated in open-access forums for teachers hoping to develop similar courses. Biological nitrogen isotope fractionation associated with nitrogen recycling remains poorly constrained despite the advent of a variety of new techniques to analyze nitrogen isotopes in recent years. The use of isotopic composition data can be incredibly useful to interpreting nitrogen cycle processes in the ocean that are difficult to measure directly, which makes it crucial to further understand the processes behind fractionation to catch up with the advancement of the datasets available to researchers. This research will characterize the isotope fractionation dynamics of ammonium during biological consumption and production. The researchers will investigate whether the characteristic low concentrations of ammonium in the surface ocean affect isotope fractionation when the ammonium is recycled and whether there is a trophic isotope effect associated with ammonium recycling by protozoan grazers. With this research, there will be a baseline from which researchers can interpret recycled nitrogen dynamics from ammonium isotope datasets. The methods of comparing nitrogen cycling studies will become significantly clearer with such a standard making interpretation uniform by removing significant uncertainties.

海洋环境中的氮（N）周期受生物过程控制。 不幸的是，由于存在较大的空间和时间差异，很难通过直接测量来量化这些过程并评估它们对N周期的影响。 N的同位素组成测量提供了一种间接限制这些过程的方法；但是，关于通过生物学过程的再生氮的同位素分馏仍然可以理解，这使得对新的氮同位素数据的解释变得困难。康涅狄格大学的研究人员计划确定生物消费和生产对铵同位素分馏的影响。 通过帮助了解生物体一级再生铵分馏的过程，这项研究将为未来的研究人员提供更好的解释同位素组成数据以推断氮循环动态。研究生，博士后研究员和两个或更多本科生将参与研究。研究人员计划通过开发本科生领域和实验室课程将科学与社区参与的学习融为一体，这将要求学生向社区中的利益相关者展示他们的研究。将为本课程创建的手册，该手册将在开放式论坛中为希望开发类似课程的教师传播。尽管近年来有多种新技术来分析氮同位素，但与氮回收相关的生物氮同位素分馏仍然受到限制。同位素组合数据的使用对于解释很难直接测量的海洋中的氮循环过程非常有用，这对于进一步了解分馏后的过程以赶上研究人员可用的数据集的进步至关重要。这项研究将表征生物消费和生产过程中铵的同位素分馏动态。研究人员将研究当铵被回收时，表面海洋中的特征低浓度铵是否会影响同位素分馏，以及是否存在与原生动物放牧者回收铵相关的营养同位素效应。通过这项研究，将有一个基线，研究人员可以从同位素数据集中解释回收的氮动力学。通过消除明显的不确定性，通过这种标准的解释统一，比较氮循环研究的方法将变得更加清晰。