- LIMS
for Light Stable Isotopes – LIMS for Light Stable Isotopes
is a Laboratory Information Management Program based on Microsoft Access
for managing samples, analyses, reports, and other data in a stable
isotope laboratory.
- 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.
- Isotope
Reference Materials - Project personnel have produced internationally
distributed isotopic reference materials and assessed the isotopic homogeneity
and interlaboratory calibrations of isotopic reference materials.
- Mass
Spectrometry - Studies to assess the performance of carbon dioxide
and hydrogen isotope ratio mass spectrometers have been carried out
by project personnel.
- 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.
- 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.
- 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.
- 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
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.
- 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.
- 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.
- Surface
water - Oxygen and hydrogen isotope ratios of surface-water and
precipitation samples provide fundamental background information for
isotopic hydrology studies.
- 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.
- Isotope
Hydrology - Stable isotope measurements have been used to investigate
fundamental ground-water transport processes.
- 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.
- Perchlorate
– Studies of perchlorate in the environment are of increasing
importance.
- Publications listed
by Date
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