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

University Of Hawaii, Honolulu

Investigators

Abstract

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.