Equipment: MRI: Track 1 Acquisition of a Stable Isotope Mass Spectrometer for Earth and Ocean Science Research

该项目由地球科学部和促进竞争性研究的既定计划（EPSCoR）共同资助。该主要研究仪器（MRI）奖支持购买最先进的同位素比质谱仪，用于地球和海洋科学研究。该仪器将并入现有的稳定同位素生物地球化学实验室，并将取代1991年在马诺阿夏威夷大学购买的过时和日益不可靠的质谱仪。该设备将主要用于硝酸盐、亚硝酸盐和铵的同位素分析，这对于促进夏威夷生物地球化学方面的新研究能力和支持现有研究力量至关重要。新的同位素比质谱仪将为夏威夷大学的教育目标做出贡献，通过新的合作、教学努力和“种子分析”计划，培训各个层次的研究人员（例如教授、博士后、学生）进行稳定同位素分析，并为正在进行的NSF REU计划和UH本科生研究机会计划提供支持。同位素比例质谱仪还将支持三名年轻教员的研究，其中包括两名夏威夷土著血统的nā wāhine（女性）。在夏威夷和太平洋的其他火山岛，流入地下水含水层的氮污染了饮用水供应。确定地下水污染途径对夏威夷这样的岛屿环境至关重要，因为那里99%的生活用水来自地下水。海底地下水排放富营养水会污染近岸环境，也会促进近岸珊瑚礁生态系统的生态变化。了解地下含水层的地下流动路径可以评估土地利用与地下水污染的关系，硝酸盐、亚硝酸盐和铵的同位素分析可以用来确定地下水和近岸环境中氮污染的来源和命运，包括住宅污水池和污水注入地下水。在夏威夷使用的11万个住宅现场处理系统中，大多数是化粪池，在全州范围内每天向地下水排放约2.65亿升未经最低限度处理的污水。夏威夷州的新法规要求到2050年，所有的污水池必须“升级、改造或关闭”。必须确定化粪池污水热点，并确定适当的住宅污水处理替代方案。新设备促进了硝酸盐、亚硝酸盐和铵的同位素分析，将支持夏威夷和其他太平洋岛屿的科学研究，以应对这些挑战。海水中硝酸盐和亚硝酸盐的同位素分析是量化海洋中氮循环的基本测量方法。夏威夷大学的研究人员使用15n标记的硝酸盐和亚硝酸盐来研究几种海洋环境中的微生物硝化作用。海洋中的硝化作用通过改变N发生的形式在氮循环中起着关键作用，反过来影响不同生物群体和过程对氮的可及性和有效性。使用15n标记底物的研究提供了关于氨和亚硝酸盐氧化速率的关键信息，并且当与遗传分析相结合时，揭示了对所有海洋系统中这些生物地球化学重要过程的生态学和调控的重要见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is jointly funded by the Division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR). This Major Research Instrumentation (MRI) award supports acquisition of a state-of-the-art isotope ratio mass spectrometer to be used for earth and ocean science research. The instrument will be integrated into the existing stable isotope biogeochemistry laboratory and will replace an obsolete and increasingly unreliable mass spectrometer purchased in 1991 at the University of Hawaii at Manoa. The equipment will be used principally for isotope analyses of nitrate, nitrite and ammonium that are crucial for catalyzing new research capacity and supporting existing research strengths in biogeochemistry in Hawaii. The new isotope ratio mass spectrometer will contribute to University of Hawaii’s educational goals by training researchers at every level (e.g., professors, postdocs, students) for stable isotope analyses, though new collaborations, teaching efforts, and a “seed analysis” program as well as provide support for ongoing NSF REU programs and the UH Undergraduate Research Opportunities Program. The isotope ratio mass spectrometer will also support the research of three young faculty including two nā wāhine (women) of native Hawaiian ancestry.Nitrogen inputs into groundwater aquifers in Hawaii and other volcanic islands in the Pacific pollutes drinking water supplies. Identification of groundwater contamination pathways is critically important for island environments like Hawaii where 99% of domestic water supply is from groundwater. Submarine ground water discharge of nutrient-rich waters can contaminate nearshore environments as well as promote ecological changes in nearshore reef ecosystems. Knowing pathways of ground flow in aquifers allows assessment of how land use relates to groundwater contamination and isotope analyses of nitrate, nitrite and ammonium can be used to identify sources and fates of nitrogen contamination in groundwater and nearshore environments, which includes residential cesspools and sewage injection into groundwater. Of the 110,000 residential on-site disposal systems in use in Hawaii, the majority are cesspools that State-wide discharge ~265 million liters per day of minimally treated sewage effluent into groundwater. New State of Hawaii regulations require that all cesspools must be “upgraded, converted, or closed” by 2050. Cesspool sewage hotspots must be identified and appropriate alternatives to residential sewage disposal determined. Isotopic analyses of nitrate, nitrite and ammonium facilitated by the new equipment will support scientific studies in Hawaii and on other Pacific Islands that will address these challenges. Isotope analyses of nitrate and nitrite in seawater are fundamental measurement used to quantify nitrogen cycling in the ocean. Researchers at University of Hawaii have used 15N-labeled nitrate and nitrite to study microbial nitrification in several marine environments. Nitrification in the ocean plays a critical role in the nitrogen cycle by changing the form in which N occurs—in turn influencing the accessibility and availability of nitrogen to different groups of organisms and processes. Studies using 15N-labeled substrates provide critical information on rates of ammonia and nitrite oxidation, and when coupled with genetic analyses, reveal important insights into the ecology and regulation of these biogeochemically-important processes in all marine systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.