Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Adsorption of benzene, toluene, and xylene by two tetramethylammonium-smectites having different charge densities
A high-charge smectite from Arizona [cation-exchange capacity (CEC) = 120 meq/100 g] and a low-charge smectite from Wyoming (CEC = 90 meq/100 g) were used to prepare homoionic tetramethylammonium (TMA)-clay complexes. The adsorption of benzene, toluene, and o-xylene as vapors by the dry TMA-clays and as solutes from water by the wet TMA-clays was studied. The adsorption of the organic vapors by th
Authors
Jiunn-Fwu Lee, Max M. Mortland, Cary T. Chiou, Daniel E. Kite, Stephen A. Boyd
Conducting field studies for testing pesticide leaching models
A variety of predictive models are being applied to evaluate the transport and transformation of pesticides in the environment. These include well known models such as the Pesticide Root Zone Model (PRZM), the Risk of Unsaturated-Saturated Transport and Transformation Interactions for Chemical Concentrations Model (RUSTIC) and the Groundwater Loading Effects of Agricultural Management Systems Mode
Authors
Charles N. Smith, Rudolph S. Parrish, David S. Brown
Fluorescent polycyclic aromatic hydrocarbons as probes for studying the impact of colloids on pollutant transport in groundwater
No abstract available.
Authors
Debera A. Backhus, Philip M. Gschwend
Geohydrology and water quality of the Roubidoux Aquifer, northeastern Oklahoma
The Roubidoux aquifer is an important source of freshwater for public supplies, commerce, industry, and rural water districts in northeastern Oklahoma. Ground-water withdrawals from the aquifer in 1981 were estimated to be 4.8 million gallons per day, of which about 90 percent was withdrawn in Ottawa County. Wells drilled at the beginning of the 20th century originally flowed at the land surface,
Authors
Scott C. Christenson, David L. Parkhurst, Roy W. Fairchild
Solid-solution aqueous-solution equilibria: Thermodynamic theory and representation
Thorstenson and Plummer's (1977) "stoichiometric saturation' model is reviewed, and a general relation between stoichiometric saturation Kss constants and excess free energies of mixing is derived for a binary solid-solution B1-xCxA: GE = RT[ln Kss - xln(xKCA) - (l-x)ln((l-x)KBA)]. This equation allows a suitable excess free energy function, such as Guggenheim's (1937) sub-regular function, to be
Authors
P. D. Glynn, E.J. Reardon
Well-purging criteria for sampling purgeable organic compounds
The results indicate that 1) purgeable organic compound concentrations stabilized when three casing volume were purged in only 55% of the cases evaluated in this study, 2) purgeable organic compounds concentrations did not consistently follow the temporal variation of, nor stabilize at the same time as, the measure field characteristics, and 3) purging to achieve hydraulic equilibrium between casi
Authors
J. Gibs, T.E. Imbrigiotta
Anaerobic oxidation of toluene, phenol, and p-cresol by the dissimilatory iron-reducing organism, GS-15
The dissimilatory Fe(III) reducer, GS-15, is the first microorganism known to couple the oxidation of aromatic compounds to the reduction of Fe(III) and the first example of a pure culture of any kind known to anaerobically oxidize an aromatic hydrocarbon, toluene. In this study, the metabolism of toluene, phenol, and p-cresol by GS-15 was investigated in more detail. GS-15 grew in an anaerobic me
Authors
D. R. Lovley, D.J. Lonergan
Rates of microbial metabolism in deep coastal plain aquifers
Rates of microbial metabolism in deep anaerobic aquifers of the Atlantic coastal plain of South Carolina were investigated by both microbiological and geochemical techniques. Rates of [2-14C]acetate and [U-14C]glucose oxidation as well as geochemical evidence indicated that metabolic rates were faster in the sandy sediments composing the aquifers than in the clayey sediments of the confining layer
Authors
F. H. Chapelle, D. R. Lovley
Nitrogen fixation dynamics of two diazotrophic communities in Mono Lake, California
Two types of diazotrophic microbial communities were found in the littoral zone of alkaline hypersaline Mono Lake, California. One consisted of anaerobic bacteria inhabiting the flocculent surface layers of sediments. Nitrogen fixation (acetylene reduction) by flocculent surface layers occurred under anaerobic conditions, was not stimulated by light or by additions of organic substrates, and was i
Authors
R.S. Oremland
Determination of trace levels of herbicides and their degradation products in surface and ground waters by gas chromatography/ion-trap mass spectrometry
A rapid, specific and highly sensitive method is described for the determination of several commonly used herbicides and their degradation products in surface and ground waters by using gas chromatography/ion-trap mass spectrometry. The compounds included atrazine, and its degradation products desethylatrazine and desisopropylatrazine; Simazine; Cyanazine; Metolachlor; and alachlor and its degrada
Authors
W. E. Pereira, C.E. Rostad, T.J. Leiker
Prediction of stream volatilization coefficients
Equations are developed for predicting the liquid-film and gas-film reference-substance parameters for quantifying volatilization of organic solutes from streams. Molecular weight and molecular-diffusion coefficients of the solute are used as correlating parameters. Equations for predicting molecular-diffusion coefficients of organic solutes in water and air are developed, with molecular weight an
Authors
Ronald E. Rathbun
Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems
Equations are presented describing equilibrium in binary solid-solution aqueous-solution (SSAS) systems after a dissolution, precipitation, or recrystallization process, as a function of the composition and relative proportion of the initial phases. Equilibrium phase diagrams incorporating the concept of stoichiometric saturation are used to interpret possible reaction paths and to demonstrate rel
Authors
P. D. Glynn, E.J. Reardon, Niel Plummer, E. Busenberg