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The regional nature of hydrologic processes is generally defined in terms of shared meteorological and basin characteristics. Inferences have been attempted by regressing the parameters of hydrologic interest against these characteristics. Such analyses have not been able to fully explain the variations, extremes or persistence of discharge patterns observed within a geographic area. An accounting of anthropogenic effects on basin characteristics needs to be made. Longer term influences such as decadal to centennial, and millennial climatic fluctuations need to be considered, and the stochastic structure of the hydrologic process itself needs to be studied. The objectives of this project are (1.) to develop secular...
Aqueous chemical models have become popular tools for the interpretation of natural water chemistry. Unfortunately, these models have deficiencies because of (1) incorrect or inconsistent thermodynamic data, (2) invalid assumption regarding the equilibrium state, (3) inappropriate or invalidated corrections for nonideality, (4) inadequate expressions for temperature dependence, (5) invalidated limitations for ionic strength, composition and temperature, and (6) lack of data on solid solution solubility. The plethora of models and databases has prompted federal agencies, especially hazardous waste and nuclear waste managers, to request geochemical code validation. Acid mine waters are a major source of water pollution...
Reactions and processes that control the chemical character of ground water need to be identified in order to predict physical and chemical changes that occur in both natural and stressed environments. This project focuses on effects of these reactions in (1) regional limestone aquifers, and (2) contaminated environments. The objectives of this project are: to study geochemical reactions that relate to geologic processes, including karstification, diagenesis, and ore deposition; generation, migration, and attenuation of leachate components; and processes of isotopic fractionation; and to demonstrate contributions that can be made to ground-water science by study of historical aspects and the role of hydrogeology...
Categories: Project
Release of various synthetic organic compounds to the environment has caused soil and ground-water pollution in many places. The processes which control the persistence and movement of these materials are not well understood. A better understanding is necessary to aid in construction of models to predict movement and fate of pollutants in the subsurface and for design of control and abatement techniques. Project objectives are to determine the transformation pathways of selected organic compounds using a combination of field observations and laboratory simulations of environmental conditions; assess the relative importance of physical, chemical, and biochemical processes in the transformation of these compounds...
Categories: Project; Tags: Organic Compounds
Various processes within the unsaturated zone affect ground-water availability and portability, as well as concentrations of water vapor and trace gases in the atmosphere. The rate at which precipitation or applied irrigation water infiltrates, its redistribution following infiltration, and the partitioning of the redistributed soil moisture between ground-water recharge and evapotranspiration affect the rate at which the ground-water reservoir is replenished and the degree to which ground water might be contaminated by chemical applications, spills, or disposal. Consequently, knowledge of and methods to quantitatively measure and predict these processes are needed to determine the impact of such societal practices...
Benthic sediment exchange processes are potentially a very significant source/ sink of nutrients and metals within an aquatic system. Too often the quantitative effects of these processes are only estimated when considering biogeochemical cycling and ecological responses. Understanding geochemical processes that control nutrient and transition metal chemistry of natural waters is requisite for predicting the effects man-induced events will have upon natural geochemical cycles and for determining their utilization as a natural resource (e.g. estuarine waters as food resources). Objectives of this project are to (1) study the important geochemical processes affecting the nutrient and metal composition of and exchange...
The goal of my research is to develop innovative approaches for the detection trace gases and expanding our understanding of their environmental cycles. Dissolved gases can be used as age tracers and climate markers, provide information about biological activity and recharge conditions, and provide unique fingerprints of superficial activity in aquifer systems. This sort of information is valuable to both scientific and resource management communities, and there are many benefits to enhancing our knowledge of the class of compounds.
I conduct long-term investigations on the fate and geochemical effect of organic contaminants in subsurface environments. I use a combined field and laboratory approach in a variety of hydrogeologic environments in order to meet these objectives. The principal questions being addressed by this project are: 1. How do long-term changes in biogeochemical processes affect the fate of organic and inorganic constituents in aquatic environments? and 2. Does availability of electron acceptors and electron donors control the progress of degradation reactions? My overarching objective is to increase our understanding of the transformation of contaminants from hydrocarbon spills, wastewaters from oil and gas development,...
Dams have been built in this century that impound virtually all major rivers in the United States. The purposes vary and include flood control, navigation, hydropower generation, and storage for irrigation and domestic uses. About 2,500 reservoirs of 5,000 acre-feet or more, store about 480 million acre-feet, about 1/4 of the annual runoff. Storage capacity is dominated by large reservoirs such that the 600 largest store more than 90 percent of the total. Lake Powell, behind Glen Canyon dam, stores water (ca. 27 million acre-feet) in the Upper Basin of the Colorado River for controlled release according to the Colorado River Compact (8.23 million acre-feet per year) and to generate electricity for sale to consumers...
Categories: Project; Tags: Lakes, Water Quality
Analysis of heat and fluid flow in geothermal systems is needed to adequately describe both the natural state of such systems and their response to fluid production for energy development. The analysis may involve analytical or numerical solution techniques, but requires delineation of realistic conceptual models for specific geothermal systems. This, in turn, requires the collection and synthesis of geologic, geophysical, geochemical, and hydrologic data. Periodic monitoring of changes in geothermal systems, including surficial thermal manifestations, can aid in understanding the natural conditions of flow and effects caused by crustal unrest and geothermal development. Objectives are to elucidate the processes...
Categories: Project; Tags: Geothermal Resources
The determination of inorganic constituents and their impact on water quality requires an in-depth knowledge of the interactive water chemistry relationships. The ability to measure trace and ultratrace concentration levels of inorganic constituents as well as their chemical form and speciation plays a significant role on the chemical, toxicological, transport and overall environmental impact on surface- and ground-water hydrology. The development of state-of-the-art analytical chemistry technology to the solution of specific hydrologically related problems requires extensive laboratory and field research and development effort. Project objectives are to (1) Investigate and develop new concepts and approaches to...
Categories: Project; Tags: Trace Elements, Water Quality
Many hydrological and geochemical processes associated with lakes and wetlands are poorly understood. Characteristics of wind and vapor profiles over lakes, which are basic controls on evaporation, have been studied in detail for only a few large reservoirs in the western United States. Many commonly used methods of estimating surface runoff to lakes and wetlands, are inaccurate. Hydrogeologic controls on seepage to and from all surface-water bodies have not been studied adequately, either from theoretical or field perspectives. Research on these components of lake and wetland hydrology is especially critical to individuals responsible for management, protection, and restoration of these resources. The major objective...
My research objectives include characterization of dissolved and particulate natural organic acid influence on the reactivity, bioavailability, and mobility of metal ions and inorganic surfaces in aquatic environments. An important research objective of my project is examination of formation and dissolution rates of carbonate minerals. Biocalcification is a significant carbon sink in the world carbon budget and requires further investigation. I study aspects of biocalcification processes that proceed through a highly unstable calcium carbonate polymorph – amorphous calcium carbonate (ACC) stabilized by organic acids. I use chemical thermodynamics and kinetics to better describe and predict the fate and distribution...
Develop, enhance, and extend theory and methods to investigate and characterize fluid flow, solute transport, heat transport, and stress/deformation changes in fractured and porous media for application to diverse areas, including the assessment of groundwater availability in bedrock terrains, remediation of contaminated sites, and evaluation of potential hazards such as induced seismicity from fluid injection.
The intrusion of industrial, agricultural and domestically produced organic chemicals and wastes into the aquatic environment is a well known reality and is considered to be one of the most important environmental problems. The widespread finding of these anthroprogenic substances, in addition to naturally occurring organics, and their detrimental impact on the Nation's water resources points to our need to understand how these substances act and react in the environment. Knowledge of transport, persistence, transformation, solubility, sorption, and reaction kinetics is needed to determine the fate of the substances in the hydrosphere. Objectives of project are to (1) identify organic substances associated with...
Categories: Project; Tags: Contaminants, Organic Compounds
My research program is multifaceted and involves the development of integrated hydrological, geochemical, and biological knowledge on the source-to-receptor approach to assessing impacts of emerging contaminants (hormones, personal care products, pharmaceuticals, commercial cleaning products). This applied research is targeted on issues important to water-resource managers and policy makers, and the results communicated to a spectrum of stakeholders. The current focus of my research is the impact of biologically-active contaminants on aquatic organisms, and the relationship to receiving water (surface water and groundwater) attenuation capacity. Several major classes of contaminants are being investigated – endocrine...
Biotic responses to climatic change or human manipulation are inherently complex because of wide differences in organism sensitivities and response times, the influence of history and scale, and the various interactions between organisms and with the physical system. In arid and semi-arid lands, which cover about 12.5 percent of the Earth's land surface, the effects of climatic variability on vegetation are greatly magnified, particularly because most plants exist near their physiological limits. How arid land vegetation might in turn affect climate is uncertain, though there is some indication that decreasing cover and increasing albedo could promote regional drought. Whether in response to projected Greenhouse...
A large amount of geophysical data is recorded in water wells and test holes but interpretation is subject to significant uncertainties. The data are used in ground-water models; to evaluate potential waste disposal sites; the effects of ground- water contamination, and to guide aquifer development, including geothermal reservoirs. The development of quantitative log interpretation techniques to derive more accurate data and to evaluate the statistical uncertainties in the data will reduce costs in ground-water investigations. Project objectives are to evaluate presently available logging equipment and log interpretation techniques and develop improved instrumentation and analytical techniques for specific ground-water...
Categories: Project; Tags: Fractured Rock, Hydrogeology
Benthic invertebrate communities, composed of sessile, relatively long-lived species, provide a record of effects of short- and long-term environmental changes through species composition and abundance changes. Thus, they are often used as water-quality indicators. However, their use in water-quality studies requires assumptions that communities remain at steady state except when influenced by human activity. Long-term studies show that natural variation over a variety of time scales often masks human-induced changes. Estuarine benthic communities, often dominated by suspension feeders, have an unknown but potentially large controlling effect on phytoplankton biomass, and thus may be important in limiting eutrophication....
Categories: Project
The Tropical and Arid Regions Climate Project seeks to quantify past variations in climate and the hydrologic balance through studies of paleo and modern surface- and ground-water systems using stable isotope and other chemical methodologies. Objectives of the Tropical and Arid Regions Climate Projects are to determine: (1) the frequency and severity of drought during the past 10,000 years, (2) the frequency and severity of major cooling events that led to glacial advances in the Colorado Rockies, (3) the frequency of hurricanes that impacted the Carribbean and Gulf of Mexico over the past 400 years, and (4) the impact of climate change on prehistoric Native Americans.