Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Kinetics of DCE and VC mineralization under methanogenic and Fe(III)- reducing conditions
The kinetics of anaerobic mineralization of DCE and VC under methanogenic and Fe(III)-reducing conditions as a function of dissolved contaminant concentration were evaluated. Microorganisms indigenous to creek bed sedi ments, where groundwater contaminated with chlorinated ethenes continuously discharges, demonstrated significant mineralization of DCE and VC under methanogenic and Fe(III)-reducing
Authors
P. M. Bradley, F. H. Chapelle
Response characteristics of DOC flushing in an alpine catchment
The spatial distribution of source areas and associated residence times of water in the catchment are significant factors controlling the annual cycles of dissolved organic carbon (DOC) concentration in Deer Creek (Summit County, Colorado). During spring snowmelt (April-August 1992), stream DOC concentrations increased with the rising limb of the hydrograph, peaked before maximum discharge, then d
Authors
E. W. Boyer, G.M. Hornberger, K.E. Bencala, Diane M. McKnight
Stream bed temperature profiles as indicators of percolation characteristics beneath arroyos in the middle Rio Grande Basin, USA
Stream bed temperature profiles were monitored continuously during water year 1990 and 1991 (WY90 and 91) in two New Mexico arroyos, similar in their meteorological features and dissimilar in their hydrological features. Stream bed temperature profiles between depths of 30 and 300 cm were examined to determine whether temporal changes in temperature profiles represent accurate indicators of the ti
Authors
J. Constantz, C. L. Thomas
Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst
In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [18O/16O (δ18O), 2H/1H (δD), 13C/12C (δ13C), tritium (3H), and strontium‐87/strontium‐86 (87Sr/86Sr)] along with geochemical mass‐balance modeling were used to identify the dominant hydroche
Authors
B. G. Katz, T. B. Coplen, T.D. Bullen, J. Hal Davis
Microbial reduction of iodate
The different oxidation species of iodine have markedly different sorption properties. Hence, changes in iodine redox states can greatly affect the mobility of iodine in the environment. Although a major microbial role has been suggested in the past to account for these redox changes, little has been done to elucidate the responsible microorganisms or the mechanisms involved. In the work presented
Authors
T.B. Councell, E. R. Landa, D. R. Lovley
Constant-concentration boundary condition: Lessons from the HYDROCOIN variable-density groundwater benchmark problem
In a solute-transport model, if a constant-concentration boundary condition is applied at a node in an active flow field, a solute flux can occur by both advective and dispersive processes. The potential for advective release is demonstrated by reexamining the Hydrologic Code Intercomparison (HYDROCOIN) project case 5 problem, which represents a salt dome overlain by a shallow groundwater system.
Authors
Leonard F. Konikow, W. E. Sanford, P.J. Campbell
Organic carbon and nitrogen content associated with colloids and suspended particulates from the Mississippi River and some of its tributaries
Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July-August 1991, October-November 1991, and April-May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate frac
Authors
C.E. Rostad, J. A. Leenheer, S.R. Daniel
Method for determination of methyl tert-butyl ether and its degradation products in water
An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method invo
Authors
C.D. Church, L.M. Isabelle, J. F. Pankow, D.L. Rose, P.G. Tratnyek
Effects of exchanged cation on the microporosity of montmorillonite
The micropore volumes of 2 montmorillonites (SAz-1 and SWy-1), each exchanged with Ca, Na, K, Cs and tetramethylammonium (TMA) ions, were calculated from the measured vapor adsorption data of N2 and neo-hexane by use of t- and αs-plots. The corresponding surface areas of the exchanged clays were determined from Brunauer-Emmett-Teller (BET) plots of N2 adsorption data. Micropore volumes and surface
Authors
David W. Rutherford, Cary T. Chiou, Dennis D. Eberl
Resolution of matrix effects on analysis of total and methyl mercury in aqueous samples from the Florida Everglades
Aqueous samples from the Florida Everglades present several problems for the analysis of total mercury (HgT) and methyl mercury (MeHg). Constituents such as dissolved organic carbon (DOC) and sulfide at selected sites present particular challenges due to interferences with standard analytical techniques. This is manifested by 1) the inability to discern when bromine monochloride (BrCl) addition i
Authors
M.L. Olson, L.B. Cleckner, J.P. Hurley, D. P. Krabbenhoft, T.W. Heelan
Iron deposition as acidic groundwater encounters carbonates in the alluvium of Pinal Creek, Arizona, U.S.A.
In a column experiment, acidic groundwater from Pinal Creek Arizona, a Cu mining area, was eluted through a composited alluvial sample obtained from a core that had been removed from a well downgradient of the acidic groundwater. The minerals present in typical grains and flakes in the alluvium before and after the elution were determined by X-ray diffraction (XRD), scanning electron microscopy, a
Authors
Carol J. Lind, R.L. Oscarson
Chemical characteristics of particulate, colloidal, and dissolved organic material in Loch Vale Watershed, Rocky Mountain National Park
The chemical relationships among particulate and colloidal organic material and dissolved fulvic acid were examined in an alpine and subalpine lake and two streams in Loch Vale Watershed, Rocky Mountain National Park. The alpine lake, Sky Pond, had the lowest dissolved organic carbon (DOC) (0.37 mgC/L), the highest particulate carbon (POC) (0.13 mgC/L), and high algal biomass. The watershed of Sky
Authors
Diane M. McKnight, R. Harnish, R. L. Wershaw, Jill Baron, S. Schiff