Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3746
Selenium isotope fractionation during reduction by Fe(II)-Fe(III) hydroxide-sulfate (green rust)
We have determined the extent of Se isotope fractionation induced by reduction of selenate by sulfate interlayered green rust (GRSO4), a Fe(II)-Fe(III) hydroxide-sulfate. This compound is known to reduce selenate to Se(0), and it is the only naturally relevant abiotic selenate reduction pathway documented to date. Se reduction reactions, when they occur in nature, greatly reduce Se mobility and bi
Authors
T. M. Johnson, Thomas D. Bullen
Mobilization of radionuclides from uranium mill tailings and related waste materials in anaerobic environments
Specific extraction studies in our laboratory have shown that iron and manganese oxide- and alkaline earth sulfate minerals are important hosts of radium in uranium mill tailings. Iron- and sulfate-reducing bacteria may enhance the release of radium (and its analog barium) from uranium mill tailings, oil field pipe scale [a major technologically enhanced naturally occurring radioactive material (T
Authors
E. R. Landa
A finite-volume ELLAM for three-dimensional solute-transport modeling
A three-dimensional finite-volume ELLAM method has been developed, tested, and successfully implemented as part of the U.S. Geological Survey (USGS) MODFLOW-2000 ground water modeling package. It is included as a solver option for the Ground Water Transport process. The FVELLAM uses space-time finite volumes oriented along the streamlines of the flow field to solve an integral form of the solute-t
Authors
T.F. Russell, C.I. Heberton, Leonard F. Konikow, G.Z. Hornberger
Use of hydraulic head to estimate volumetric gas content and ebullition flux in northern peatlands
Hydraulic head was overpressured at middepth in a 4.2‐m thick raised bog in the Glacial Lake Agassiz peatlands of northern Minnesota, and fluctuated in response to atmospheric pressure. Barometric efficiency (BE), determined by calculating ratios of change in hydraulic head to change in atmospheric pressure, ranged from 0.05 to 0.15 during July through November of both 1997 and 1998. The overpress
Authors
Donald O. Rosenberry, Paul H. Glaser, Donald I. Siegel, Edwin P. Weeks
Excess nitrogen in selected thermal and mineral springs of the Cascade Range in northern California, Oregon, and Washington: Sedimentary or volcanic in origin?
Anomalous N2/Ar values occur in many thermal springs and mineral springs, some volcanic fumaroles, and at least one acid-sulfate spring of the Cascade Range. Our data show that N2/Ar values are as high as 300 in gas from some of the hot springs, as high as 1650 in gas from some of the mineral springs, and as high as 2400 in gas from the acid-sulfate spring on Mt. Shasta. In contrast, gas dischargi
Authors
Robert H. Mariner, William C. Evans, T. S. Presser, L. D. White
Escherichia coli and enterococci at beaches in the Grand Traverse Bay, Lake Michigan: Sources, characteristics, and environmental pathways
This study quantified Escherichia coli(EC) and enterococci (ENT) in beach waters and dominant source materials, correlated these with ambient conditions, and determined selected EC genotypes and ENT phenotypes. Bathing-water ENT criteria were exceeded more frequently than EC criteria, providing conflicting interpretations of water quality. Dominant sources of EC and ENT were bird feces (108/d/bird
Authors
S.K. Haack, L.R. Fogarty, C. Wright
Geomorphic and hydrologic assessment of erosion hazards at the Norman municipal landfill, Canadian River floodplain, central Oklahoma
The Norman, Oklahoma, municipal landfill closed in 1985 after 63 years of operation, because it was identified as a point source of hazardous leachate composed of organic and inorganic compounds. The landfill is located on the floodplain of the Canadian River, a sand-bed river characterized by erodible channel boundaries and by large variation in mean monthly discharges. In 1986, floodwaters erode
Authors
Jennifer A. Curtis, John W. Whitney
Dissolved nickel and benthic flux in South San Francisco Bay: A potential for natural sources to dominate
No abstract available.
Authors
B.R. Topping, J.S. Kuwabara
Kinetic dissolution of carbonates and Mn oxides in acidic water: Measurement of in situ field rates and reactive transport modeling
The kinetics of carbonate and Mn oxide dissolution under acidic conditions were examined through the in situ exposure of pure phase samples to acidic ground water in Pinal Creek Basin, Arizona. The average long-term calculated in situ dissolution rates for calcite and dolomite were 1.65??10-7 and 3.64??10-10 mmol/(cm2 s), respectively, which were about 3 orders of magnitude slower than rates deriv
Authors
J. G. Brown, P. D. Glynn
Stable isotope fractionation of selenium by natural microbial consortia
The mobility and bioavailability of Se depend on its redox state, and reduction of Se oxyanions to less mobile, reduced species controls transport of this potentially toxic element in the environment. Stable isotope fractionation of Se is currently being developed as an indicator of Se immobilization through reduction. In this study, Se isotope fractionation resulting from reduction of Se(VI) and
Authors
A.S. Ellis, T. M. Johnson, M.J. Herbel, T.D. Bullen
Interactions between dissolved organic matter and mercury in the Florida Everglades
Experiments were conducted using organic matter isolated from various surface waters in the Florida Everglades to study the interactions between dissolved organic matter (DOM) and Hg (II). Conditional distribution coefficients ( ), obtained using an equilibriurn dialysis ligand exchange method, were strongly affected by the Hg/DOM concentration ratio. Very strong interactions ( = 10 L kg -1), in
Authors
G. Aiken, M. Haitzer, J. N. Ryan, K. Nagy, George Aiken
Simplified method for detecting tritium contamination in plants and soil
Cost-effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. The objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. The method entailed collectio
Authors
Brian J. Andraski, Mark W. Sandstrom, R. L. Michel, J.C. Radyk, David A. Stonestrom, M. J. Johnson, C.J. Mayers