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Publications

Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).

Filter Total Items: 4098

In situ bacterial selenate reduction in the agricultural drainage systems of western Nevada 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...
Authors
R.S. Oremland, N.A. Steinberg, T. S. Presser, L.G. Miller

In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests 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...
Authors
R. L. Smith, B.L. Howes, S. P. Garabedian

Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 1. Sulfate from confining beds as an oxidant in microbial CO2 production Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 1. Sulfate from confining beds as an oxidant in microbial CO2 production

A primary source of dissolved inorganic carbon (DIC) in the Black Creek aquifer of South Carolina is carbon dioxide produced by microbially mediated oxidation of sedimentary organic matter. Groundwater chemistry data indicate, however, that the available mass of inorganic electron acceptors (oxygen, Fe(III), and sulfate) and observed methane production is inadequate to account for...
Authors
F. H. Chapelle, P.B. McMahon

Selectivity and effectiveness of extractants used to release metals associated with organic matter Selectivity and effectiveness of extractants used to release metals associated with organic matter

Partial extraction procedures can be used to release metals associated with organic matter in natural materials. Reagents commonly employed for this purpose include hydrogen peroxide, Na hypochlorite and Na pyrophosphate. This study tested the selectivity of these reagents by comparing the amount of Fe, Mn, Zn and Cu they released from sulfide and oxide minerals and determined the...
Authors
C. S.E. Papp, L.H. Filipek, K. S. Smith

Coprecipitation mechanisms and products in manganese oxidation in the presence of cadmium Coprecipitation mechanisms and products in manganese oxidation in the presence of cadmium

Manganese oxidation products were precipitated in an aerated open-aqueous system where a continuous influx of mixed Mn2+ and Cd2+ solution was supplied and pH was maintained with an automated pH-stat adding dilute NaOH. X-ray diffraction and electron diffraction identified the solids produced as mixtures of Cd2Mn34+O8, Mn2+2Mn4+3O8, MnO2 (ramsdellite), and CdCO3. Mean oxidation numbers...
Authors
J.D. Hem, Carol J. Lind

Use of colloid filtration theory in modeling movement of bacteria through a contaminated sandy aquifer Use of colloid filtration theory in modeling movement of bacteria through a contaminated sandy aquifer

\A filtration model commonly used to describe removal of colloids during packed-bed filtration in water treatment applications was modified for describing downgradient transport of bacteria in sandy, aquifer sediments. The modified model was applied to the results of a small-scale (7 m), natural-gradient tracer test and to observations of an indigenous bacterial population moving...
Authors
R.W. Harvey, S. P. Garabedian

Herbicides in surface waters of the midwestern United States: The effect of spring flush Herbicides in surface waters of the midwestern United States: The effect of spring flush

Approximately three-fourths of all preemergent herbicides used in the United States are applied to row crops over a 12-state area, called the "corn belt" (I). The application of these compounds may cause widespread degradation of water quality (2). Because herbicides are water soluble, there is the potential for leaching into groundwater and surface water (3, 4), as well as aerial...
Authors
E.M. Thurman, D. A. Goolsby, M. T. Meyer, D.W. Kolpin

Convergent radial dispersion: A note on evaluation of the Laplace transform solution Convergent radial dispersion: A note on evaluation of the Laplace transform solution

A numerical inversion algorithm for Laplace transforms that is capable of handling rapid changes in the computed function is applied to the Laplace transform solution to the problem of convergent radial dispersion in a homogeneous aquifer. Prior attempts by the author to invert this solution were unsuccessful for highly advective systems where the Peclet number was relatively large. The...
Authors
Allen F. Moench
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