Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 4094
Crude oil identification with electrothermal vaporization-multiple wavelength absorption spectrometry
A spectrometric technique utilizing electrothermal vaporization (graphite furnace) and gas phase-multiple wavelength absorption with photodiode array detection is used to characterize crude oil.
Authors
J.M. Shekiro, R. K Skogerboe, Howard E. Taylor
An empirical model for estimating phytoplankton productivity in estuaries
e have previously shown that primary productivity in San Francisco Bay, USA, is highly correlated with phytoplankton biomass B (chlorophyll a concentration) and an index of light avallability in the photic zone, 2, I, (photic depth times surface irradiance). To test the generality of this relation, we compiled data from San Francisco Bay and 5 other USA estuarine systems (Neuse and South Rivers, P
Authors
B.E. Cole, J. E. Cloern
A compositional multiphase model for groundwater contamination by petroleum products: 1. Theoretical considerations
A mathematical model is developed to describe the fate of hydrocarbon constituents of petroleum products introduced to soils as an immiscible liquid from sources such as leaking underground storage tanks and ruptured pipelines. The problem is one of multiphase transport (oil (immiscible), air, and water phases) of a reactive contaminant with constituents such as benzene, toluene, and xylene found
Authors
M. Yavuz Corapcioglu, Arthur L. Baehr
Unsaturated flow in a centrifugal field: Measurement of hydraulic conductivity and testing of Darcy's Law
A method has been developed to establish steady state flow of water in an unsaturated soil sample spinning in a centrifuge. Theoretical analysis predicts moisture conditions in the sample that depend strongly on soil type and certain operating parameters. For Oakley sand, measurements of flux, water content, and matric potential during and after centrifugation verify that steady state flow can be
Authors
John R. Nimmo, J. Rubin, D.P. Hammermeister
Reduction of selenate to selenide by sulfate-respiring bacteria: Experiments with cell suspensions and estuarine sediments
Washed cell suspensions of Desulfovibrio desulfuricans subsp. aestuarii were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate inhibited rates of
Authors
J.P. Zehr, Ronald S. Oremland
Direct comparison of kinetic and local equilibrium formulations for solute transport affected by surface reactions
Modeling transport of reacting solutes in porous media often requires a choice between models based on the local equilibrium assumption (LEA) and models involving reaction kinetics. Direct comparison of the mathematical formulations for these two types of transport models can aid in this choice. For cases of transport affected by surface reaction, such a comparison is made possible by a new deriva
Authors
Jean M. Bahr, Jacob Rubin
Processes and kinetics of Cd2+ sorption by a calcareous aquifer sand
The rate of Cd2+ sorption by a calcareous aquifer sand was characterized by two reaction steps, with the first step reaching completion in 24 hours. The second step proceeded at a slow and nearly constant rate for at least seven days. The first step includes a fast adsorption reaction which is followed by diffusive transport into either a disordered surface film of hydrated calcium carbonate or in
Authors
C. C. Fuller, J.A. Davis
A model for trace metal sorption processes at the calcite surface: Adsorption of Cd2+ and subsequent solid solution formation
The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded at a slow and nearly constant rate for at least 7 days. The rate of calcite recrystallizati
Authors
J.A. Davis, C. C. Fuller, A.D. Cook
Fate and movement of azaarenes and their anaerobic biotransformation products in an aquifer contaminated by wood-treatment chemicals
Infiltration of wastes containing creosote and pentachlorophenol from surface impoundments at an abandoned wood-treatment facility near Pensacola, Florida, resulted in contamination of the underlying sand and gravel aquifer. Pond sludges and sediments near the source were contaminated with 2- to 5-ring azaarenes having log Kow values of from 2.0 to 5.6. However, the ground water contained only aza
Authors
W. E. Pereira, C.E. Rostad, D.M. Updegraff, J.L. Bennett
Determination of alkylbenzenesulfonate surfactants in groundwater using macroreticular resins and carbon-13 nuclear magnetic resonance spectrometry
Alkylbenzenesulfonate surfactants were determined in groundwater at concentrations as low as 0.3 mg/L. The method uses XAD-8 resin for concentration, followed by elution with methanol, separation of anionic and nonionic surfactants by anion exchange, quantitation by titration, and identification by 13C nuclear magnetic resonance spectrometry. Laboratory standards and field samples containing strai
Authors
E. Michael Thurman, T. Willoughby, Larry B. Barber, Kevin A. Thorn
Growth determinations for unattached bacteria in a contaminated aquifer
Growth rates of unattached bacteria in groundwater contaminated with treated sewage and collected at various distances from the source of contamination were estimated by using frequency of dividing cells and tritiated-thymidine uptake and compared with growth rates obtained with unsupplemented, closed-bottle incubations. Estimates of bacterial generation times [(In 2)/μ] along a 3-km-long transect
Authors
R.W. Harvey, L.H. George
Big Soda Lake (Nevada). 1. Pelagic bacterial heterotrophy and biomass
Bacterial activities and abundance were measured seasonally in the water column of meromictic Big Soda Lake which is divided into three chemically distinct zones: aerobic mixolimnion, anaerobic mixolimnion, and anaerobic monimolimnion. Bacterial abundance ranged between 5 and 52 x 106 cells ml−1, with highest biomass at the interfaces between these zones: 2–4 mg C liter−1 in the photosynthetic bac
Authors
Jon P. Zehr, Ronald W. Harvey, Ronald S. Oremland, James E. Cloern, Leah H. George, Judith L. Lane