Expression of Microbial Nitrification in the Stable Isotopic Systematics of Oceanic Nitrite and Nitrate

微生物硝化作用在海洋亚硝酸盐和硝酸盐稳定同位素系统学中的表达

• 批准号: 0961098
• 负责人: Karen Casciotti
• 金额: $ 72.73万
• 依托单位: Woods Hole Oceanographic Institution
• 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: 2010-04-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961098&HistoricalAwards=false
• 关键词: Expression; Microbial; Nitrification; Stable; Isotopic; Expression; Microbial; Nitrification; Stable; Isotopic

Closing the marine budgets of nitrate and nitrous oxide are central goals for researchers interested in nutrient-driven changes in primary productivity and climate change. With the implementation of new methods for oxygen isotopic analysis of seawater nitrate, it will be possible to construct a budget for nitrate based on its oxygen isotopic distribution that is complementary to nitrogen isotope budgets. Before we can effectively use oxygen isotopes in nitrate to inform the current understanding of the marine nitrogen cycle, we must first understand how different processes that produce (nitrification) and consume (assimilation, denitrification) nitrate affect its oxygen isotopic signature. In this study, researchers at the Woods Hole Oceanographic Institution will provide a quantitative assessment of the oxygen isotopic systematics of nitrification in the field and thus fill a key gap in our understanding of 18O variations in nitrate, nitrite, and nitrous oxide. The primary goal is to develop a quantitative prediction of the oxygen isotopic signatures of nitrite and nitrate produced during nitrification in the sea. The researchers hypothesize that oxygen isotopic fractionation during nitrification is the primary factor setting the 18O values of newly produced nitrate and nitrite. Secondly, they hypothesize that oxygen atom exchange is low where ammonia oxidation and nitrite oxidation are tightly coupled, but may increase in regions with nitrite accumulation, such as in the primary and secondary nitrite maxima. They will test these hypotheses with a series of targeted laboratory and field experiments, as well as with measurements of nitrite and nitrate isotopic distributions extending through the euphotic zone, primary nitrite maximum, and secondary nitrite maximum of the Eastern Tropical South Pacific. The results of these experiments are expected to provide fundamental information required for the interpretation of 18O isotopic signatures in nitrite, nitrate, and N2O in the context of underlying microbial processes. A better understanding of these features and the processes involved is important for quantifying new production, controls on the N budget, and N2O production in the ocean -- which should lead to a better understanding of the direct and indirect interactions among the nitrogen cycle, marine chemistry, and climate. Broader Impacts: The results of this research should be of interest to a broad research community interested in oceanic nitrogen cycling, N2O production, and climate change, as well as nitrifier physiology and biochemistry. Student training in biogeochemistry will be an important component of the activity. A female graduate student will participate throughout this project, and will learn to integrate training in culture manipulation, laboratory and field-going research, as well as isotopic and data acquisition and analysis. There will also be opportunities for undergraduate students, including ones from under-represented minority groups, to become involved.

关闭硝酸盐和一氧化二氮的海洋预算是对对营养驱动的主要生产力和气候变化变化感兴趣的研究人员的核心目标。通过实施新方法对海水硝酸盐的同位素分析，可以根据硝酸盐的氧同位素分布来构建硝酸盐的预算，该预算互补符合氮同位素预算。在我们可以有效地使用硝酸盐中的氧同位素来告知当前对海洋氮周期的理解，我们必须首先了解产生（硝化）和消耗（同化，硝化）硝酸盐的不同过程如何影响其氧气的氧气同位素签名。在这项研究中，伍兹孔海洋学机构的研究人员将对野外硝化的氧同位素系统学进行定量评估，从而填补了我们对硝酸盐，亚硝酸盐和硝酸氧化物的18O变异的关键空白。主要目的是制定对硝酸盐和硝酸盐在海中产生的亚硝酸盐和硝酸盐的氧同位素特征的定量预测。研究人员假设硝化过程中的氧同位素分级是设定新硝酸盐和亚硝酸盐的18O值的主要因素。其次，他们假设氧原子的交换很低，而在氨氧化和亚硝酸盐氧化紧密耦合的情况下，可能会增加亚硝酸盐积累的区域，例如在原发性和二亚硝酸盐最大值中。 他们将通过一系列有针对性的实验室和现场实验以及亚硝酸盐和硝酸盐同位素分布的测量来检验这些假设。预计这些实验的结果将提供基本的基本信息，以解释基础微生物过程中亚硝酸盐，硝酸盐和N2O中的18o同位素特征。更好地了解这些特征和所涉及的过程对于量化新生产，n预算的控制以及海洋中的N2O生产至关重要 - 这应该可以更好地理解氮循环之间的直接和间接相互作用，海洋化学和气候。更广泛的影响：这项研究的结果应该引起对海洋氮循环，N2O生产和气候变化以及硝化剂生理学和生物化学感兴趣的广泛研究社区的关注。生物地球化学的学生培训将是活动的重要组成部分。一名女研究生将在整个项目中参加，并将学会整合文化操纵，实验室和现场研究的培训，以及同位素和数据获取和分析。本科生，包括代表性不足的少数群体，也将有机会参与其中。