Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Flame ionization mass spectrometry--Isotope ratio determinations for potassium
The air/acetylene flame provides a convenient ion source for the determination of potassium isotopic ratios by mass spectrometry. Unlike the argon inductively coupled plasma (ICP), the flame provides low background in the mass region of interest. Ion production is quite satisfactory for isotope ratio measurements at the micrograms per milliliter (μg/mL) level and slightly below, with 1 μg/mL potas
Authors
Howard E. Taylor, John R. Garbarino, S.R. Koirtyohann
Downstream effects of mine effluent on an intermontane riparian system
Metal concentrations were determined in benthic biota, fish livers, water, and fine-grained sediment through 215 km of an intermontane river system (Blackfoot River, Montana, USA) affected by headwater inputs of acid-mine effluent. Solute and particulate contaminants decreased rapidly downstream from headwater sources, but some extended through an extensive marsh system. Particulate contaminants p
Authors
Johnnie N. Moore, Samuel N. Luoma, Donald Peters
Reduction of nitrate in aquifer microcosms by carbon additions
Aquifer microcosms were used to examine the effects of NO−3 and C amendments on groundwater from the Claiborne aquifer. Nitrate concentrations of 12.17 mg L−1 in aquifer microcosms were reduced 0.92%/d to 5.84 mg L−1 by the addition of 10 mg C L−1 for 35 d. Nitrate disappearance correlated with increases in number of denitrifiers and dissolved N2O concentration and decreases in dissolved oxygen, s
Authors
Donald C. Obenhuber, Richard Lowrance
Fate of silicate minerals in a peat bog
An investigation of silicate weathering in a Minnesota mire indicates that quartz and aluminosilicates rapidly dissolve in anoxic, organic-rich, neutral- pH environments. Vertical profiles of pH, dissolved silicon, and major cations were obtained at a raised bog and a spring fen and compared. Profiles of readily extractable silicon, diatom abundance, ash mineralogy, and silicate surface texture we
Authors
Philip C. Bennett, Donald I. Siegel, Barbara M. Hillier, Paul H. Glaser
In situ bacterial selenate reduction in the agricultural drainage systems of western Nevada
Dissimilatory in situ selenate reduction to elemental selenium in sediments from irrigated agricultural drainage regions of western Nevada was measured at ambient Se oxyanion concentrations. Selenate reduction was rapid, with turnover rate constants ranging from 0.04 to 1.8 h-1 at total Se concentrations in pore water of 13 to 455 nM. Estimates of removal rates of selenium oxyanions were 14, 38, a
Authors
R.S. Oremland, N.A. Steinberg, T. S. Presser, L.G. Miller
Fate of acetone in an outdoor model stream with a nitrate supplement, southern Mississippi, U.S.A.
The fate of acetone in an outdoor model stream to which nitrate was added as a nutrient supplement was determined. The stream, in southern Mississippi, U.S.A. was 234 m long. Water was supplied to the stream by an artesian well at about 1.21 s−1, resulting in a mean water velocity of about 0.5 m min−1. Acetone was injected continuously for 26 days resulting in concentrations of 20–40 mg l−1. A nit
Authors
R. E. Rathbun, D. W. Stephens, D. Y. Tai
Electron transport in the dissimilatory iron reducer, GS-15
Mechanisms for electron transport to Fe(III) were investigated in GS-15, a novel anaerobic microorganism which can obtain energy for growth hy coupling the complete oxidation of organic acids or aromatic compounds to the reduction of Fe(III) to Fe(II). The results indicate that Fe(III) reduction proceeds through a type b cytochrome and a membrane-bound Fe(III) reductase which is distinct from the
Authors
Y. A. Gorby, D. R. Lovley
Methylmercury decomposition in sediments and bacterial cultures: Involvement of methanogens and sulfate reducers in oxidative demethylation
Demethylation of monomethylmercury in freshwater and estuarine sediments and in bacterial cultures was investigated with 14CH3HgI. Under anaerobiosis, results with inhibitors indicated partial involvement of both sulfate reducers and methanogens, the former dominating estuarine sediments, while both were active in freshwaters. Aerobes were the most significant demethylators in estuarine sediments,
Authors
R.S. Oremland, C.W. Culbertson, M.R. Winfrey
In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests
Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain th
Authors
R. L. Smith, B.L. Howes, S. P. Garabedian
Water and tritium movement through the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois, 1981-85
The movement of water and tritium through the unsaturated zone was studied at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois, from 1981 to 1985. Water and tritium movement occurred in an annual, seasonally timed cycle; recharge to the saturated zone generally occurred in the spring and early summer. Mean annual precipitation (1982-85) was 871 millimeters; mean
Authors
P.C. Mills, R. W. Healy
Work plan for regional reconnaissance for selected herbicides and nitrate in ground water of the mid-continent United States, 1991
An approach was developed to obtain a consistent, regional distribution of herbicide and nitrate data from near-surface aquifers in the corn and soybean producing region of the mid-continent. Near-surface aquifers are defined as those with the top of aquifer material within 50 feet of land surface, regardless of whether the material is saturated or unsaturated. Three hundred wells will be selected
Authors
D.W. Kolpin, M. R. Burkart