Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Analysis of chlorinated organic compounds in estuarine biota and sediments by chemical ionization tandem mass spectrometry
Complex sample matrices of estuarine biota tissue and bed sediment extracts were analyzed for selected chlorinated compounds. By using gas chromatography/positive chemical ionization/tandem mass spectrometry, the coeluting interferences present in gas chromatography/electron ionization mass spectrometry were eliminated in the biota tissue and bed sediment extracts. The selected chlorinated compoun
Authors
C.E. Rostad, W. E. Pereira
Convergent radial dispersion: A Laplace transform solution for aquifer tracer testing
A Laplace transform solution was obtained for the injection of a tracer in a well situated in a homogeneous aquifer where steady, horizontal, radially convergent flow has been established due to pumping at a second well. The standard advection-dispersion equation for mass transfer was used as the controlling equation. For boundary conditions, mass balances that account for mixing of the tracer wit
Authors
Allen F. Moench
Trace metal associations in the water column of South San Francisco Bay, California
Spatial distributions of copper (Cu), zinc (Zn) and cadmium (Cd) were followed along a longitudinal gradient of dissolved organic carbon (DOC) in South San Francisco Bay (herein referred to as the South Bay). Dissolved Cu, Zn and Cd concentrations ranged from 24 to 66 nM, from 20 to 107 nM and from 1·2 to 4·7 nM, respectively, in samples collected on five dates beginning with the spring phytoplank
Authors
J.S. Kuwabara, Cecily C.Y. Chang, J. E. Cloern, T. L. Fries, J.A. Davis, S. N. Luoma
Simulation of calcite dissolution and porosity changes in saltwater mixing zones in coastal aquifers
Thermodynamic models of aqueous solutions have indicated that the mixing of seawater and calcite-saturated fresh groundwater can produce a water that is undersaturated with respect to calcite. Mixing of such waters in coastal carbonate aquifers could lead to significant amounts of limestone dissolution. The potential for such dissolution in coastal saltwater mixing zones is analyzed by coupling th
Authors
Ward E. Sanford, Leonard F. Konikow
Chemical hydrogeology in natural and contaminated environments
Chemical hydrogeology, including organic and inorganic aspects, has contributed to an increased understanding of groundwater flow systems, geologic processes, and stressed environments. Most of the basic principles of inorganic-chemical hydrogeology were first established by investigations of organic-free, regional-scale systems for which simplifying assumptions could be made. The problems of grou
Authors
W. Back, M.J. Baedecker
Preliminary evaluations of regional ground-water quality in relation to land use
Preliminary results from New York, New Jersey, Connecticut, Florida, Nebraska, and Colorado indicate that regional ground-water quality has been affected by human activities. The frequencies of detection of volatile organic compounds and some trace elements were larger in ground water underlying urban or industrial areas in comparison to undeveloped areas. Ground water in agricultural areas genera
Authors
D. Cain, D.R. Helsel, S.E. Ragone
Calorimetry of heterogeneous systems: H+ binding to TiO2 in NaCl
A simultaneous calorimetric and potentiometric technique has been developed for measuring the thermodynamics of proton binding to mineral oxides in the presence of a supporting electrolyte. Modifications made to a commercial titration calorimeter to add a combination pH electrode and maintain an inert atmosphere in the calorimeter reaction vessel are described. A procedure to calibrate potentiomet
Authors
S.R. Mehr, D.J. Eatough, L.D. Hansen, E.A. Lewis, J.A. Davis
Transport of microspheres and indigenous bacteria through a sandy aquifer: Results of natural- and forced-gradient tracer experiments
Transport of indigenous bacteria through sandy aquifer sediments was investigated in forced- and natural-gradient tracer teste. A diverse population of bacteria was collected and concentrated from groundwater at the site, stained with a DNA-specific fluorochrome, and injected back into the aquifer. Included with the injectate were a conservative tracer (Br- or Cl-) and bacteria-sized (0.2-1.3-??m)
Authors
R.W. Harvey, L.H. George, R. L. Smith, D.R. LeBlanc
Organic markers as source discriminants and sediment transport indicators in south San Francisco Bay, California
Sediment samples from nearshore sites in south San Francisco Bay and from streams flowing into that section of the Bay have been characterized in terms of their content of biogenic and anthropogenic molecular marker compounds. The distributions, input sources, and applicability of these compounds in determining sediment movement are discussed. By means of inspection and multivariate analysis, the
Authors
F. D. Hostettler, J. B. Rapp, K. A. Kvenvolden, N L. Samuel
Can we determine the biological availability of sediment-bound trace elements?
It is clear from available data that the susceptibility of biological communities to trace element contamination differs among aquatic environments. One important reason is that the bioavailability of metals in sediments appears to be altered by variations in sediment geochemistry. However, methods for explaining or predicting the effect of sediment geochemistry upon metal bioavailability are poor
Authors
Samuel N. Luoma
Discussion of "Influence of temperature on oxygen transfer" by Allen C. Chao, David S. Chang, Charles Smallwood, Jr., and William S. Galler (August, 1987, Vol. 113, No. 4)
No abstract available.
Authors
R.E. Rathburn
Mineral saturation states in natural waters and their sensitivity to thermodynamic and analytical errors
Saturation indices computed with WATEQ4F chemical analyses from a groundwater in crystalline bedrock and a surface water receiving acid mine drainage are frequently at or above saturation with respect to calcite, fluorite, barite, gibbsite and ferrihydrite. Deep granitic groundwaters from Stripa, Sweden, are supersaturated with respect to calcite and fluorite. Acid mine waters from the Leviathan M
Authors
D. Kirk Nordstrom, James W. Ball