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The NRP had its beginnings in the late 1950's. Since that time, the program has grown to encompass a broad spectrum of scientific investigations. The sciences of hydrology, mathematics, chemistry, physics, ecology, biology, geology, and engineering are used to gain a fundamental understanding of the processes that affect the availability, movement, and quality of the Nation's water resources. Results of NRP's long-term research investigations often lead to the development of new concepts, techniques, and approaches that are applicable not only to the solution of current water problems, but also to future issues that may affect the Nation's water resources. Basic tools of hydrology that have been developed by the...
Categories: Project; Types: ScienceBase Project; Tags: Acid Mine Drainage, Aquatic Habitat, Arid Land Hydrology, Carbon Cycle, Contaminant Reactions and Transport, All tags...
The purpose of my research group is to develop new methods and applications of environmental isotopes to solve problems of national importance. In specific, the overall goal is to use environmental isotopes, combined with other biogeochemical measurements and hydrologic and biogeochemical modeling, to increase our understanding of biogeochemical and hydrological processes, nutrient and organic matter sources, subsurface flowpaths, and water age distributions in diverse environments. Many of our studies piggyback on the sampling efforts of major monitoring programs to investigate causes of hypoxia and food web problems. Our work provides critical scientific support for these monitoring programs. A long-term career...
Stable and radioactive isotopes such as oxygen, hydrogen, carbon, nitrogen and sulfur have proved to be extremely useful tracers of hydrologic pathways, biogeochemical processes, and residence times of waters and solutes. However, use of these isotopes as tracers is presently hampered by our limited understanding of the physical processes and chemical reactions influencing isotopic compositions. The unsaturated zone, particularly the soil zone and the top of the water table, is probably the portion of the hydrologic system most responsible for alteration of the isotopic compositions of potential isotope tracers, this environmental component is also one of the least studied. The overall goal of this project is to...
Categories: Project; Tags: Isotopic Tracers, Radioisotopes
My research is concerned broadly with the use of stable isotopes, primarily hydrogen, carbon and oxygen, to examine the dynamics of hydrological systems and associated geochemical problems. I perform studies in the identification and quantification of ground-water recharge, discharge, surface-water/ground-water interaction, redox processes in contaminated aquifers, as well as source identification of stray methane gas in drinking water wells. I develop new sample- preparation techniques in the laboratory including inlet systems for continuous- flow isotope- ratio analytical techniques , such as EA, TC/EA, GPI, Gasbench, GCC, TC/GCC, and TIC/TOC and publish Sandard Operating Procedures in the U.S. Geological Survey...
Categories: Project; Tags: Contaminants, Isotopic Tracers
Improve understanding of physical and biogeochemical processes affecting water quality of groundwater and surface water. Research focus includes multidisciplinary field and laboratory studies to determine factors affecting sources, movement, and fate of nutrients and reactive inorganic contaminants in the hydrologic cycle. Improve the usefulness of stable isotopes and other environmental tracers in hydrology and biogeochemistry by developing new techniques and approaches. Research topics include analytical techniques for stable isotopes in compounds separated from groundwater and surface water, stable isotope forensics, enriched isotope tracer experiments to quantify transport and reaction rates, field and...
Uranium mill tailings and related forms of low-level radioactive waste contain elevated contents of naturally occurring radionuclides that have been brought to the surface, processed for the recovery of uranium and/or other components and then disposed of in near-surface impoundments. The long-term fate of the tailings and their constituents will be determined by surficial earth processes. Project objectives are to study the chemical form in which radionuclides and selected stable elements are retained in surficial earth materials, particularly uranium mill tailings, and to identify processes operating in natural aqueous and terrestrial systems that may influence the transport of these constituents from these earth...
Uranium mill tailings and related forms of low-level radioactive waste contain elevated contents of naturally occurring radionuclides that have been brought to the surface, processed for the recovery of uranium and/or other components and then disposed of in near-surface impoundments. The long-term fate of the tailings and their constituents will be determined by surficial earth processes. Project objectives are to study the chemical form in which radionuclides and selected stable elements are retained in surficial earth materials, particularly uranium mill tailings, and to identify processes operating in natural aqueous and terrestrial systems that may influence the transport of these constituents from these earth...
This project studies evaporation, groundwater mixing, surface-water circulation, groundwater/surface-water interactions, contaminant migration and remediation, and other hydrochemical and biologic processes. The isotope variations are related to (1) purely physical processes, (2) heterogeneous chemical equilibria, and (3) reaction kinetics. The isotope effects of many of these processes are not sufficiently understood or quantified to make the most effective use of stable isotope techniques in hydrologic research. This project aims to develop theoretical and instrumental mass spectrometric techniques through experimental investigation, and to test applications in suitable field locations to improve the utility of...
Uranium mill tailings and related forms of low-level radioactive waste contain elevated contents of naturally occurring radionuclides that have been brought to the surface, processed for the recovery of uranium and/or other components and then disposed of in near-surface impoundments. The long-term fate of the tailings and their constituents will be determined by surficial earth processes. Project objectives are to study the chemical form in which radionuclides and selected stable elements are retained in surficial earth materials, particularly uranium mill tailings, and to identify processes operating in natural aqueous and terrestrial systems that may influence the transport of these constituents from these earth...
Uranium mill tailings and related forms of low-level radioactive waste contain elevated contents of naturally occurring radionuclides that have been brought to the surface, processed for the recovery of uranium and/or other components and then disposed of in near-surface impoundments. The long-term fate of the tailings and their constituents will be determined by surficial earth processes. Project objectives are to study the chemical form in which radionuclides and selected stable elements are retained in surficial earth materials, particularly uranium mill tailings, and to identify processes operating in natural aqueous and terrestrial systems that may influence the transport of these constituents from these earth...
Research objectives: i) To determine whether metals, including dissolved, colloidal and particulate metals, are bioavailable and toxic to organisms; ii) To characterize and parameterize the physiological and geochemical processes governing metal bioaccumulation, toxicity and ultimately trophic transfer in aquatic ecosystems. iii) To model metal bioaccumulation and toxicity using kinetic models iv) To develop approaches that use isotopically modified metals, metal nanoparticles and metal bound to distinct mineral phases (such as Cu on ferric oxides) to quantify their bioavailability and toxicity to organisms, in particular invertebrates; v) To use enriched metal isotopes to gain mechanistic understanding of...
The objectives of my work are to better understand nutrient sources and cycling in specific environments to aid in resource management and pollution abatement and to improve and develop isotopic analytical methodologies.
The purpose of my research group is to develop new methods and applications of environmental isotopes to solve problems of national importance. In specific, the overall goal is to use environmental isotopes, combined with other biogeochemical measurements and hydrologic and biogeochemical modeling, to increase our understanding of biogeochemical and hydrological processes, nutrient and organic matter sources, subsurface flowpaths, and water age distributions in diverse environments. Many of our studies piggyback on the sampling efforts of major monitoring programs to investigate causes of hypoxia and food web problems. Our work provides critical scientific support for these monitoring programs. A long-term career...
1) Linking stable isotope signatures of precipitation to climate patterns and atmospheric temperatures in the tropics, for use in climate change and paleoclimate studies. 2) Using stable isotopes of groundwater and surface water as tracers, to understand how climate change may affect recharge and water supply. 3) Quantifying cloud water and fog deposition to land surface, and tracking it through the water cycle in ecosystems where it is an important precipitation source.