Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Selenium isotope ratios as indicators of selenium sources and oxyanion reduction
Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble o
Authors
T. M. Johnson, M.J. Herbel, T.D. Bullen, P.T. Zawislanski
Robowell: An automated process for monitoring ground water quality using established sampling protocols
Robowell is an automated process for monitoring selected ground water quality properties and constituents by pumping a well or multilevel sampler. Robowell was developed and tested to provide a cost-effective monitoring system that meets protocols expected for manual sampling. The process uses commercially available electronics, instrumentation, and hardware, so it can be configured to monitor gro
Authors
G.E. Granato, K.P. Smith
Molecular aggregation of humic substances
Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into a
Authors
Robert L. Wershaw
Agrichemicals in ground water of the midwestern USA: Relations to soil characteristics
A comprehensive set of soil characteristics were examined to determine the effect of soil on the transport of agrichemicals to ground water. This paper examines the relation of local soil characteristics to concentrations and occurrence of nitrate, atrazine (2-chloro-4 ethylamino-6-isopropylamino-s-trazine), and atrazine residue [atrazine + deethylatrazine (2-amino-4-chloro-6-isopropylamino-s-tria
Authors
M. R. Burkart, D.W. Kolpin, R.J. Jaquis, K.J. Cole
Simultaneous reduction of nitrate and selenate by cell suspensions of selenium-respiring bacteria
Washed-cell suspensions of Sulfurospirillum barnesiireduced selenate [Se(VI)] when cells were cultured with nitrate, thiosulfate, arsenate, or fumarate as the electron acceptor. When the concentration of the electron donor was limiting, Se(VI) reduction in whole cells was approximately fourfold greater in Se(VI)-grown cells than was observed in nitrate-grown cells; correspondingly, nitrate reducti
Authors
R.S. Oremland, J.S. Blum, A.B. Bindi, P.R. Dowdle, M. Herbel, J.F. Stolz
Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport
The development and distribution of phytoplankton blooms in estuaries are functions of both local conditions (i.e. the production-loss balance for a water column at a particular spatial location) and large-scale horizontal transport. In this study, the second of a 2-paper series, we use a depth-averaged hydrodynamic-biological model to identify transport-related mechanisms impacting phytoplankton
Authors
L.V. Lucas, Jeffrey R. Koseff, Stephen G. Monismith, J. E. Cloern, J.K. Thompson
A siphon gage for monitoring surface-water levels
A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standp
Authors
Timothy D. McCobb, Denis R. LeBlanc, Roy S. Socolow
Bioaccumulation of metals by the bivalve Macoma balthica at a site in South San Francisco Bay between 1977 and 1997: Long-term trends and associated biological effects with changing pollutant loadings
No abstract available.
Authors
Michelle I. Hornberger, S. N. Luoma, D. Cain, F. Parchaso, C. Brown, R. Bouse, C.J. Wellise, John Thompson
Numerical simulation of vertical ground-water flux of the Rio Grande from ground-water temperature profiles, central New Mexico
An important gap in the understanding of the hydrology of the Middle Rio Grande Basin, central New Mexico, is the rate at which water from the Rio Grande recharges the Santa Fe Group aquifer system. Several methodologies-including use of the Glover-Balmer equation, flood pulses, and channel permeameters- have been applied to this problem in the Middle Rio Grande Basin. In the work presented here,
Authors
James R. Bartolino, Richard G. Niswonger
Water-quality variability in San Francisco Bay: general patterns of change during 1997
The 1997 Annual Report is the fifth Annual Report from the Regional Monitoring Program for Trace Substances (RMP) and contains a comprehensive description of RMP results from the 1997 monitoring year. As in previous years, the report includes results from the Base Program (water, sediment, and bivalve monitoring) and results from Pilot and Special Studies completed in 1997, in addition to an updat
Authors
J. E. Cloern, B.E. Cole, J.L. Edmunds, J.I. Baylosis
Water-quality, bed-sediment and biological data (October 1997 through September 1998) and statistical summaries of data for streams in the upper Clark Fork basin, Montana
No abstract available.
Authors
K. A. Dodge, Michelle I. Hornberger, R. M. Bouse
Sediment chronology in San Francisco Bay, California, defined by 210Pb, 234Th, 137Cs, and 239,340Pu
Sediment chronologies based on radioisotope depth profiles were developed at two sites in the San Francisco Bay estuary to provide a framework for interpreting historical trends in organic compound and metal contaminant inputs. At Richardson Bay near the estuary mouth, sediments are highly mixed by biological and/or physical processes. Excess penetration ranged from 2 to more than 10 cm at eight
Authors
C. C. Fuller, Alexander van Geen, M. Baskaran, R. Anima