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Agricultural Nitrate — Project personnel have worked with colleagues in several areas of the U.S. to assess the history and fate of agricultural contamination of ground water. The studies incorporate ground-water dating along with a variety of chemical and isotopic approaches.
Atomic Weights of the Elements — Through an association with the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry, project personnel have published updates, summaries, and reviews of the atomic weights of the elements.
Desert Nitrate — Stable isotope studies have identified both natural and anthropogenic sources of nitrate in arid regions of North and South America.
Ground-Water and Surface-Water Interactions — Interactions between surface water and ground water have been investigated by project personnel using hydrogen, carbon, nitrogen, and oxygen isotope ratios and geochemical techniques in several geographic settings.
Hydrothermal Systems — Stable and radioactive isotope measurements have been used to investigate water-rock interactions and sources of dissolved constituents in a variety of active and inactive hydrothermal systems.
Isotope Hydrology — Stable isotope measurements have been used to investigate fundamental ground-water transport processes.
Isotope-Ratio Reporting Guidelines — Project personnel have published guidelines for reporting hydrogen, carbon, nitrogen, oxygen, and sulfur isotope ratio data, aimed at improving comparability of measurements by different laboratories.
Isotopic Normalization Tool for Carbonates
Isotopic Reference Materials — Project personnel have produced internationally distributed isotopic reference materials and assessed the isotopic homogeneity and interlaboratory calibrations of isotopic reference materials.
Isotopic Variability — More than 10 chemical elements have been identified whose standard atomic-weight uncertainties are due to isotopic abundance variations in substances of natural terrestrial origin. Reports by project personnel compile published minimum and maximum isotopic abundances of hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, calcium, chromium, iron, copper, zinc, selenium, molybdenum, palladium, tellurium, and thallium in compounds or materials of natural terrestrial origin.
LIMS for Light Stable Isotopes — LIMS for Light Stable Isotopes is a Laboratory Information Management System based on Microsoft Access for managing samples, analyses, reports, and other data in a stable isotope laboratory.
Mass Spectrometry — Studies to assess the performance of carbon dioxide and hydrogen isotope ratio mass spectrometers have been carried out by project personnel.
Methods and Techniques — Project personnel have improved and developed methods for preparing samples for hydrogen, carbon, nitrogen, oxygen, and sulfur isotope ratio determination. Some of these involve innovative techniques to quantitatively separate mixtures of gases, liquids, or solids.
Organic Degradation — Project personnel have investigated the production and consumption of methane in the saturated zone of a crude oil spill near Bemidji, Minnesota. Methane is produced by acetate fermentation with concomitant increase in bicarbonate concentration, rather than carbon dioxide reduction.
Paleoclimatic Records — Isotope measurements of water samples and mineral deposits have been used to investigate past climates and climatic processes from hundreds of years in age to millions of years in age.
Perchlorate — Studies of perchlorate in the environment are of increasing importance.
Surface Water — Oxygen and hydrogen isotope ratios of surface-water and precipitation samples provide fundamental background information for isotopic hydrology studies.
Wastewater Contamination — Collaborative studies have been done on transport and reaction of carbon, nitrogen, and oxygen in ground waters containing "point-source" contaminants from waste-water disposal.