Collaborative Research: GEOTRACES Peru-Tahiti Nitrogen Isotope Measurements

合作研究：GEOTRACES 秘鲁-塔希提岛氮同位素测量

• 批准号: 1233140
• 负责人: Meredith Hastings
• 金额: $ 15.45万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1233140&HistoricalAwards=false
• 关键词: Collaborative; Research; GEOTRACES; Peru; Tahiti

Nitrogen (N) is an essential macronutrient whose availability can limit primary production and the capacity of the biological pump to export carbon from the surface ocean on seasonal, annual, decadal, and millennial timescales. The inventory of fixed (bioavailable) N in the ocean is driven by biological processes such as nitrogen fixation, denitrification, and anaerobic ammonia oxidation (anammox). Water column oxygen deficient zones (ODZs) are important sites for fixed N loss, as well as N2O production, and they are projected to expand and intensify in the coming years as global warming increases ocean stratification and decreases ventilation. It is important to understand the distribution of nitrate, nitrite, and N2O isotopes in relation to current ocean conditions of oxygen and trace element availability order to interpret past and future changes in nitrate ä15N signals. In this project, a team of researchers from Stanford University, University of Massachusetts at Dartmouth, and Brown University will measure the nitrogen- and oxygen-isotopic composition (del15N and del18O) of nitrate, nitrite, and nitrous oxide in seawater samples collected along the GEOTRACES Pacific Peru-Tahiti Section. Values of del15N and del18O will also be measured in nitrate from aerosol and rain samples to inform our interpretation of the N isotope budget and isotopic gradients within the tropical South Pacific. Finally, N2/Ar and N2 del15N will be determined to close the N mass and isotope budgets. Nitrate del15N is a GEOTRACES "core parameter" that will complement other measurements, such as bioactive trace element concentrations and speciation, Si isotope variations, as well as redox and productivity proxies. The GEOTRACES Peru-Tahiti section provides a rare opportunity to track the fate of the isotopic signals of N loss from one of the largest water column ODZs. Furthermore, little is known about the effect of N recycling through hydrothermal vents on nitrate isotopes in the deep ocean, and this section will allow quantitative tracking of this input. Together, these measurements will yield insight into the relative rates of modern N cycle processes and will provide background information for paleoceanographic applications.Broader impacts: This project will provide a high-quality nitrate isotope data set from undersampled parts of the South Pacific for use by the broader oceanographic community via BCO-DMO. Educational impacts include the mentoring of a graduate, undergraduate, and high school students at Stanford, and the inclusion of undergraduates in state-of-the-art collaborative research at Brown and UMass-Dartmouth. The project will also support development and implementation of an oceans component for the annual 6th grade teacher workshop offered by Stanford University's School of Earth. This program includes both instruction for the teachers on cutting-edge research in Earth Science and Oceanography, and support for them to include the material into their classroom activities.

氮（N）是ES科学大量营养素，其可用性在季节性，年度，年度和千禧年的时间标准中，生物泵的生产和生物泵的capace出口碳。由氮和厌氧氨氧化（Anammox）等生物学过程的驱动。海洋分层并减少通风，nitrite和N2O同位素相对于氧气和痕量元素可用性，以解释过去和将来达特茅斯（Dartmouth）和布朗大学（Brown University）的秘密。热带南太平洋地区的同位素梯度将与硝酸盐DEL15N接近，例如地理位置“核心参数”，例如生物活性痕量元素浓度和SI同位素变化秘鲁 - 塔希提岛（Peru-Tahiti）段是从一个一个ODN OD Z中跟踪N Lars的同位素信号的命运。这些测量值将对这一点进行定量跟踪。 ，以及斯坦福大学的高中生，以及在斯坦福大学地球学院提供的年度六年级教师讲习班的Willt Developmint和Offimention contufusion。并支持材料进入他们的课堂活动。