Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Effects of delta outflow and local stream flow on salinity in south San Francisco Bay: 1995-1998
No abstract available.
Authors
Laurence E. Schemel
Results from the hydrodynamic element of the 1994 entrapment zone study in Suisun Bay
The entrapment zo as long been considered an important region of the San Francisco estuary. It has been the subject of several previous studies, and its location has been suggested as an index of condition of the estuarine ecosystem.A close correlate of this location, X2 1, is now used as a management objective on the basis that X2 is correlated with the abundance or survival of several estuarine-
Authors
J.R. Burau, J. W. Gartner, M. Stacey
Regression models of herbicide concentrations in outflow from reservoirs in the midwestern USA, 1992-1993
Reservoirs are used to store water for public water supply, flood control, irrigation, recreation, hydropower, and wildlife habitat, but also often store undesirable substances such as herbicides. The outflow from 76 reservoirs in the midwestern USA, was sampled four times in 1992 and four times in 1993. At least one herbicide was detected in 82.6 percent of all samples, and atrazine was detected
Authors
W.A. Battaglin, D. A. Goolsby
Reductive dissolution and reactive solute transport in a sewage-contaminated glacial outwash aquifer
Contamination of shallow ground water by sewage effluent typically contains reduced chemical species that consume dissolved oxygen, developing either a low oxygen geochemical environment or an anaerobic geochemical environment. Based on the load of reduced chemical species discharged to shallow ground water and the amounts of reactants in the aquifer matrix, it should be possible to determine chem
Authors
R. W. Lee, P.C. Bennett
A comparison of zero-order, first-order, and monod biotransformation models
Under some conditions, a first-order kinetic model is a poor representation of biodegradation in contaminated aquifers. Although it is well known that the assumption of first-order kinetics is valid only when substrate concentration, S, is much less than the half-saturation constant, K(s), this assumption is often made without verification of this condition. We present a formal error analysis show
Authors
B.A. Bekins, E. Warren, E.M. Godsy
System controls on the aqueous distribution of mercury in the northern Florida Everglades
The forms and partitioning of aqueous mercury species in the canals and marshes of the Northern Florida Everglades exhibit strong spatial and temporal variability. In canals feeding Water Conservation Area (WCA) 2A, unfiltered total Hg (HgT(U)) is less than 3 ng L-1 and relatively constant. In contrast, methyl mercury (MeHg) exhibited a strong seasonal pattern, with highest levels entering WCA-2A
Authors
J.P. Hurley, D. P. Krabbenhoft, L.B. Cleckner, M.L. Olson, G. R. Aiken, P.S. Rawlik
Ground water age and nitrate distribution within a glacial aquifer beneath a thick unsaturated zone
The impact on ground water quality from increasing fertilizer application rates over the past 40 years is evaluated within a glacial aquifer system beneath a thick unsaturated zone. Ground water ages within the aquifer could not be accurately determined from the measured distribution of 3H and as a result, chlorofluorocarbon (CFC) and 3H/3He dating techniques were applied. Beneath a 25 m thick uns
Authors
C.T. Johnston, P.G. Cook, S.K. Frape, Niel Plummer, Eurybiades Busenberg, R.J. Blackport
Aqueous infrared carboxylate absorbances: Aliphatic di-acids
Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric
Authors
S.E. Cabaniss, J. A. Leenheer, I.F. McVey
Trophic transfer of methyl mercury in the northern Florida Everglades
There are spatial differences in methyl mercury (MeHg) concentrations in biota in Water Conservation Areas 2 and 3 in the Everglades, with higher concentrations generally found in the southern areas. Fish and hemipterans had the most MeHg on a wet weight basis, with levels exceeding 30 ng g-1. The magnitude of MeHg accumulation in biota varies seasonally and does not always appear to be associated
Authors
L.B. Cleckner, P.J. Garrison, J.P. Hurley, M.L. Olson, D. P. Krabbenhoft
Effects of arctic temperatures on distribution and retention of the nuclear waste radionuclides 241Am, 57Co, and 137Cs in the bioindicator bivalve Macoma balthica
The disposal of radioactive wastes in Arctic seas has made it important to understand the processes affecting the accumulation of radionuclides in food webs in coldwater ecosystems. We examined the effects of temperature on radionuclide assimilation and retention by the bioindicator bivalve Macoma balthica using three representative nuclear waste components, 241Am, 57Co, and 137Cs. Experiments wer
Authors
D.A. Hutchins, I. Stupakoff, S. Hook, Samuel N. Luoma, N.S. Fisher
The hyporheic zone as a source of dissolved organic carbon and carbon gases to a temperate forested stream
The objective of this study was to examine chemical changes in porewaters that occur over small scales (cm) as groundwater flows through the hyporheic zone and discharges to a stream in a temperate forest of northern Wisconsin. Hyporheic-zone porewaters were sampled at discrete depths of 2, 10, 15, 61, and 183 cm at three study sites in the study basin. Chemical profiles of dissolved organic carbo
Authors
J.E. Schindler, D. P. Krabbenhoft
Solution of the advection-dispersion equation in two dimensions by a finite-volume Eulerian-Lagrangian localized adjoint method
We extend the finite-volume Eulerian-Lagrangian localized adjoint method (FVELLAM) for solution of the advection-dispersion equation to two dimensions. The method can conserve mass globally and is not limited by restrictions on the size of the grid Peclet or Courant number. Therefore, it is well suited for solution of advection-dominated ground-water solute transport problems. In test problem comp
Authors
Richard W. Healy, T.F. Russell