Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Mechanistic roles of soil humus and minerals in the sorption of nonionic organic compounds from aqueous and organic solutions
Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral contents. In aqueous systems, observed sorptive characteristics suggest that solute partitioning into the soil-humic ph
Authors
C. T. Chiou, T.D. Shoup, P.E. Porter
Errors and parameter estimation in precipitation-runoff modeling: 1. Theory
Errors in complex conceptual precipitation-runoff models may be analyzed by placing them into a statistical framework. This amounts to treating the errors as random variables and defining the probabilistic structure of the errors. By using such a framework, a large array of techniques, many of which have been presented in the statistical literature, becomes available to the modeler for quantifying
Authors
Brent M. Troutman
Origin of caves and other solution openings in the unsaturated (vadose) zone of carbonate rocks: A model for CO2 generation
The enigma that caves and other solution openings form in carbonate rocks at great depths below land surface rather than forming from the surface downward can be explained by the generation of CO2 within the aquifer system. In the proposed model, CO2 is generated by the oxidation of particulate and/or dissolved organic carbon that is transported from the land surface deep into the unsaturated zone
Authors
W.W. Wood
Geophysical techniques for reconnaissance investigations of soils and surficial deposits in mountainous terrain
Two techniques were assessed for their capabilities in reconnaissance studies of soil characteristics: depth to the water table and depth to bedrock beneath surficial deposits in mountainous terrain. Ground-penetrating radar had the best near-surface resolution in the upper 2 m of the profile and provided continuous interpretable imagery of soil profiles and bedrock surfaces. Where thick colluvium
Authors
C.G. Olson, J.A. Doolittle
Simulation of steady-state flow in three-dimensional fracture networks using the boundary-element method
An efficient method for simulating steady-state flow in three-dimensional fracture networks is formulated with the use of the boundary-element method. The host rock is considered to be impervious, and the fractures can be of any orientation and areal extent. The fractures are treated as surfaces where fluid movement is essentially two-dimensional. Fracture intersections are regarded as one-dimensi
Authors
A.M. Shapiro, J. Andersson
Assessment of long-term salinity changes in an irrigated stream-aquifer system
Changes in salinity in groundwater and surface water in the Arkansas River valley of southeastern Colorado are primarily related to irrigation practices. A solute transport model was applied to an 11-mile reach of the valley to compute salinity changes in response to spatially and temporally varying stresses. The model was calibrated in 1973 using detailed field measurements made during 1971 and 1
Authors
Leonard F. Konikow, Mark Person
Culturing Selenastrum capricornutum (Chlorophyta) in a synthetic algal nutrient medium with defined mineral particulates
Algal nutrient studies in chemically-defined media typically employ a synthetic chelator to prevent iron hydroxide precipitation. Micronutrient-particulate interactions may, however, significantly affect chemical speciation and hence biovailability of these nutrients in natural waters. A technique is described by which Selenastrum capricornutum Printz (Chlorophyta) may be cultured in a medium wher
Authors
James S. Kuwabara, J.A. Davis, Cecily C.Y. Chang
Geochemical investigations of polychlorinated dibenzo-p-dioxins in the subsurface environment at an abandoned wood-treatment facility
The discharge of effluents containing creosote and pentachlorophenol into two unlined surface impoundments at a wood-treatment facility in Pensacola, Florida, resulted in contamination of the underlying sand and gravel aquifer. These wastes contained significant amounts of chlorinated dioxins, such as isomers of hexa- and heptachlorodibenzo-p-dioxins and octachlorodibenzo-p-dioxin, probably derive
Authors
W. E. Pereira, C.E. Rostad, M.E. Sisak
Modeling the rate-controlled sorption of hexavalent chromium
Sorption of chromium VI on the iron-oxide- and hydroxide-coated surface of alluvial material was numerically simulated with rate-controlled reactions. Reaction kinetics and diffusional processes, in the form of film, pore, and particle diffusion, were simulated and compared with experimental results. The use of empirically calculated rate coefficients for diffusion through the reacting surface was
Authors
D.B. Grove, Kenneth G. Stollenwerk
Partition coefficients of organic compounds in lipid-water systems and correlations with fish bioconcentration factors
Triolein-water partition coefficients (KtW) have been determined for 38 slightly water-soluble organic compounds, and their magnitudes have been compared with the corresponding octanol-water partition coefficients (KOW). In the absence of major solvent-solute interaction effects in the organic solvent phase, the conventional treatment (based on Raoult's law) predicts sharply lower partition coeffi
Authors
C. T. Chiou
Dissolution of alkaline earth sulfates in the presence of montmorillonite
In a study of the effect of montmorillonite on the dissolution of BaSO4 (barite), SrSO4 (celestite), and 226Ra from U mill tailings, it was found that: (1) More of these substances dissolve in an aqueous system that contains montmorillonite than dissolve in a similar system without clay, due to the ion exchange properties of the clay; (2) Na-montmorillonite is more effective in aiding dissolution
Authors
D. D. Eberl, Edward R. Landa
Phosphorus-zinc interactive effects on growth by Selenastrum capricornutum (chlorophyta)
No abstract available.
Authors
J.S. Kuwabara