Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 4094
Movement of agricultural chemicals between surface water and ground water, lower Cedar River basin, Iowa
Movement of agricultural chemicals alachlor, atrazine, cyanazine, deethylatrazine, deisopropylatrazine, and metolachlor between surface water and ground water is documented by data collected from May 1989 through July 1991 at an unfarmed study site adjacent to the Cedar River in Iowa. During periods of runoff, these chemicals moved from the Cedar River into the alluvial aquifer with bank-storage w
Authors
Paul J. Squillace, J.P. Caldwell, P.M. Schulmeyer, C.A. Harvey
Automated, colorimetric methods for determination of nitrate plus nitrite, nitrite, ammonium and orthophosphate ions in natural water samples
The apparatus and methods used for the automatic, colorimetric determinations of dissolved nutrients (nitrate plus nitrite, nitrite, ammonium and orthophosphate) in natural waters are described. These techniques allow for the determination of nitrate plus nitrite for the concentration range 0.02 to 8 mg/L (milligrams per liter) as N (nitrogen); for nitrite, the range is 0.002 to 1.0 mg/L as N; for
Authors
Ronald C. Antweiler, Charles J. Patton, Howard E. Taylor
Chemical and stable-isotope data from an experiment to examine temporal variability in water samples from screened wells on Cape Cod, Massachusetts, 1994
No abstract available.
Authors
T. E. Reilly, D.R. LeBlanc, K.W. Bussey, T.B. Councell, R. L. Smith, J.K. Böhlke
Summary of suspended-solids concentration data, San Francisco Bay, California, water year 1994
Suspended-solids concentration data were collected in San Francisco Bay during water year 1994. Optical backscatterance sensors and water samples were used to monitor suspended solids continuously at two sites in Suisun Bay, two sites in Central San Francisco Bay, and three sites in South San Francisco Bay. Sensors were positioned at two depths at each site. In addition, a shallow-water instrument
Authors
P.A. Buchanan, D. H. Schoellhamer, R.C. Sheipline
Quantification of natural vapor fluxes of trichloroethene in the unsaturated zone at Picatinny Arsenal, New Jersey
The upward flux of trichloroethene (TCE) vapor through the unsaturated zone above a contaminated, water-table aquifer at Picatinny Arsenal, New Jersey, has been studied under natural conditions over a 12-month period. Vertical gas-phase diffusion fluxes were estimated indirectly by measuring the TCE vapor concentration gradient in the unsaturated zone and using Fick's law to calculate the flux. Th
Authors
James A. Smith, Amy K. Tisdale, H. Jean Cho
Comparison of Eh and H2 measurements for delineating redox processes in a contaminated aquifer
Measurements of oxidation-reduction potential (Eh) and concentrations of dissolved hydrogen (H2) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. Eh measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured Eh and pH val
Authors
Francis H. Chapelle, Sheridan K. Haack, Peter Adriaens, Mark A. Henry, Paul M. Bradley
Geochemical and hydrologic controls on phosphorus transport in a sewage-contaminated sand and gravel aquifer near Ashumet Pond, Cape Cod, Massachusetts
Currently (1993), about 170 kg/yr of phosphorus discharges into Ashumet Pond on Cape Cod from a plume of sewage-contaminated ground water. Phosphorus in the plume is mobile in two distinct geochemical environments--an anoxic zone containing dissolved iron and a suboxic zone containing dissolved oxygen. Phosphorus mobility in the suboxic zone is due to saturation of available sorption sites. Phosph
Authors
Donald A. Walter, Brigid A. Rea, Kenneth G. Stollenwerk, Jennifer G. Savoie
Naturally occurring and mining-affected dissolved metals in two subbasins of the Upper Animas River Basin, southwestern Colorado
No abstract available.
Authors
Winfield G. Wright, Cathy J. Janik
Identification of hydraulic conductivity structure in sand and gravel aquifers: Cape Cod data set
This study evaluates commonly used geostatistical methods to assess reproduction of hydraulic conductivity (K) structure and sensitivity under limiting amounts of data. Extensive conductivity measurements from the Cape Cod sand and gravel aquifer are used to evaluate two geostatistical estimation methods, conditional mean as an estimate and ordinary kriging, and two stochastic simulation methods,
Authors
J.R. Eggleston, S.A. Rojstaczer, J.J. Peirce
Overview of a simple model describing variation of dissolved organic carbon in an upland catchment
Hydrological mechanisms controlling the variation of dissolved organic carbon (DOC) were investigated in the Deer Creek catchment located near Montezuma, CO. Patterns of DOC in streamflow suggested that increased flows through the upper soil horizon during snowmelt are responsible for flushing this DOC-enriched interstitial water to the streams. We examined possible hydrological mechanisms to expl
Authors
Elizabeth W. Boyer, George M. Hornberger, Kenneth E. Bencala, Diane M. McKnight
Glutathione conjugation and contaminant transformation
The recent identification of a novel sulfonated metabolite of alachlor in groundwater and metolachlor in soil is likely the result of glutathione conjugation. Glutathione conjugation is an important biochemical reaction that leads, in the case of alachlor, to the formation of a rather difficult to detect, water-soluble, and therefore highly mobile, sulfonated metabolite. Research from weed science
Authors
Jennifer A. Field, E.M. Thurman
Benthic processes in South San Francisco Bay: The role of organic inputs and bioturbation
No abstract available.
Authors
J.M. Caffrey, Douglas E. Hammond, James S. Kuwabara, L.G. Miller, R.R. Twilley