Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3746
Elevational dependence of projected hydrologic changes in the San Francisco Estuary and watershed
California's primary hydrologic system, the San Francisco Estuary and its upstream watershed, is vulnerable to the regional hydrologic consequences of projected global climate change. Previous work has shown that a projected warming would result in a reduction of snowpack storage leading to higher winter and lower spring-summer streamflows and increased spring-summer salinities in the estuary. The
Authors
N. Knowles, D.R. Cayan
Albert H. Munsell: A sense of color at the interface of art and science
The color theory conceived and commercialized by Albert H. Munsell (1858-1918) has become a universal part of the lexicon of soil science. An American painter noted for his seascapes and portraits, he had a long-standing interest in the description of color. Munsell began studies aimed at standardizing color description, using hue, value, and chroma scales, around 1898. His landmark treatise, "A C
Authors
E. R. Landa
Hydrologic variability, water chemistry, and phytoplankton biomass in a large flood plain of the Sacramento River, CA, U.S.A.
The Yolo Bypass, a large, managed floodplain that discharges to the headwaters of the San Francisco Estuary, was studied before, during, and after a single, month-long inundation by the Sacramento River in winter and spring 2000. The primary objective was to identify hydrologic conditions and other factors that enhance production of phytoplankton biomass in the floodplain waters. Recent reductions
Authors
L. E. Schemel, T.R. Sommer, A. B. Muller-Solger, W.C. Harrell
Assessing denitrification in groundwater using natural gradient tracer tests with 15N: In situ measurement of a sequential multistep reaction
Denitrification was measured within a nitrate‐contaminated aquifer on Cape Cod, Massachusetts, using natural gradient tracer tests with 15N nitrate. The aquifer contained zones of relatively high concentrations of nitrite (up to 77 μM) and nitrous oxide (up to 143 μM) and has been the site of previous studies examining ground water denitrification using the acetylene block technique. Small‐scale (
Authors
Richard L. Smith, John K. Böhlke, Stephen P. Garabedian, Kinga M. Revesz, Tadashi Yoshinari
Occurrence of hexavalent chromium in ground water in the western Mojave Desert, California
About 200 samples from selected public supply, domestic, and observation wells completed in alluvial aquifers underlying the western Mojave Desert were analyzed for total dissolved Cr and Cr(VI). Because Cr(VI) is difficult to preserve, samples were analyzed by 3 methods. Chromium(VI) was determined in the field using both a direct colorimetric method and EPA method 218.6, and samples were speciat
Authors
J. W. Ball, J. A. Izbicki
Identifying areas of basin-floor recharge in the Trans-Pecos region and the link to vegetation
Comparative water potential and chloride profiles (∼10 m deep) collected from four vegetation communities in the Trans-Pecos region of the Chihuahuan Desert were assessed to evaluate the potential for using vegetation patterns as a means of efficiently improving large-scale estimates of basin-floor recharge in semiarid and arid regions. Analytical solutions and multiphase flow and transport modeli
Authors
Michelle Ann Walvoord, Fred M. Phillips
Radon (222Rn) in ground water of fractured rocks: A diffusion/ion exchange model
Ground waters from fractured igneous and high‐grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water‐transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surfac
Authors
W.W. Wood, T. F. Kraemer, A. Shapiro
Determination of pharmaceutical compounds in surface- and ground-water samples by solid-phase extraction and high-performance liquid chromatography-electrospray ionization mass spectrometry
Commonly used prescription and over-the-counter pharmaceuticals are possibly present in surface- and ground-water samples at ambient concentrations less than 1 μg/L. In this report, the performance characteristics of a combined solid-phase extraction isolation and high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC–ESI-MS) analytical procedure for routine determi
Authors
J.D. Cahill, E. T. Furlong, M.R. Burkhardt, D. Kolpin, L.G. Anderson
Using chromium stable isotope ratios to quantify Cr(VI) reduction: Lack of sorption effects
Chromium stable isotope values can be effectively used to monitor reduction of Cr(VI) in natural waters. We investigate effects of sorption during transport of Cr(VI) which may also shift Cr isotopes values, complicating efforts to quantify reduction. This study shows that Cr stable isotope fractionation caused by sorption is negligible. Equilibrium fractionation of Cr stable isotopes between diss
Authors
A.S. Ellis, T. M. Johnson, T.D. Bullen
Methods for estimating adsorbed uranium(VI) and distribution coefficients of contaminated sediments
Assessing the quantity of U(VI) that participates in sorption/desorption processes in a contaminated aquifer is an important task when investigating U migration behavior. U-contaminated aquifer sediments were obtained from 16 different locations at a former U mill tailings site at Naturita, CO (U.S.A.) and were extracted with an artificial groundwater, a high pH sodium bicarbonate solution, hydrox
Authors
M. Kohler, G.P. Curtis, D.E. Meece, J.A. Davis
Preservation of water samples for arsenic(III/V) determinations: An evaluation of the literature and new analytical results
Published literature on preservation procedures for stabilizing aqueous inorganic As(III/V) redox species contains discrepancies. This study critically evaluates published reports on As redox preservation and explains discrepancies in the literature. Synthetic laboratory preservation experiments and time stability experiments were conducted for natural water samples from several field sites. Any f
Authors
R. Blaine McCleskey, D. Kirk Nordstrom, A.S. Maest
Sorption of 99mTc radiopharmaceutical compounds by soils
Study of the sorption of 99mTc radiopharmaceutical compounds by soils has assessed the fate of these compounds in the event of a surface spill and examined the potential of these compounds as hydrologic tracers. Sorption from deionized water, filtered Missouri River water, and artificial seawater by five surface soils was investigated. For all water types, the Tc radiopharmaceutical compounds show
Authors
S. Jurisson, J. Gawenis, E. R. Landa