Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Concentrations, transport and biological effects of dormant spray pesticides in the San Francisco Estuary, California
The transport and biological effects of dormant spray pesticides were examined in the San Francisco Estuary, California, by measuring dissolved- pesticide concentrations and estimating toxicity using bioassays at a series of sites in January and February 1993. Distinct pulses of pesticides, including diazinon, methidathion, and chlorpyrifos, were detected in the San Joaquin River in January and Fe
Authors
K.M. Kuivila, C.G. Foe
A comparison of two nitrification inhibitors used to measure nitrification rates in estuarine sediments
Nitrification rates were measured using intact sediment cores from South San Francisco Bay and two different nitrification inhibitors: acetylene and methyl fluoride. Sediment oxygen consumption and ammonium and nitrate fluxes were also measured in these cores. Four experiments were conducted in the spring, and one in the fall of 1993. There was no significant difference in nitrification rates meas
Authors
J.M. Caffrey, L.G. Miller
Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments
Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell
Authors
R.W. Harvey, N.E. Kinner, A. Bunn, D. MacDonald, D. Metge
Determination of water retention in stratified porous materials
Predicted and measured water-retention values,θ(ψ), were compared for repacked, stratified core samples consisting of either a sand with a stone-bearing layer or a sand with a clay loam layer in various spatial orientations. Stratified core samples were packed in submersible pressure outflow cells, then water-retention measurements were performed between matric potentials,ψ, of 0 to -100 kPa. Pred
Authors
J. Constantz
Sewage contamination in the upper Mississippi River as measured by the fecal sterol, coprostanol
The molecular sewage indicator, coprostanol, was measured in bed sediments of the Mississippi River for the purpose of determining sewage contamination. Coprostanol is a non-ionic, non-polar, organic molecule that associates with sediments in surface waters, and concentrations of coprostanol in bed sediments provide an indication of long-term sewage loads. Because coprostanol concentrations are de
Authors
J.H. Writer, J. A. Leenheer, L. B. Barber, G.L. Amy, S.C. Chapra
Paleohydrologic record from lake brine on the southern High Plains, Texas
The timing of changes in the stage and salinity of Double Lakes of Lynn County, Texas, was estimated using dissolved-chloride profiles across an underlying shale layer. Lake conditions over the past 30 to 50 ka can be inferred from the chloride profiles by using the advective velocity of the pore water through the shale and an appropriate coefficient of molecular diffusion. The profiles suggest th
Authors
Ward E. Sanford, Warren W. Wood
Interpretation of prematurely terminated air-pressurized slug tests
An air-pressurized slug test consists of applying a constant pressure to the column of air in a well, monitoring the declining water level, and then releasing the air pressure and monitoring the recovering water level. Such tests offer a means of estimating formation transmissivity and storativity without extensive downhole equipment and the associated safety risks. This paper analyzes data from p
Authors
Allen M. Shapiro, Earl A. Greene
Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures
Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the a-ether or a-ester groups were in cyclic structures with two to three additional electronegative functional groups (carboxyl, ester, ketone, aromatic groups) at adjac
Authors
J. A. Leenheer, R. L. Wershaw, M.M. Reddy
Rapid toluene mineralization by aquifer microorganisms at Adak, Alaska: Implications for intrinsic bioremediation in cold environments
No abstract available.
Authors
P. M. Bradley, F. H. Chapelle
Fate, bioavailability and toxicity of silver in estuarine environments
The chemistry and bioavailability of Ag contribute to its high toxicity in marine and estuarine waters. Silver is unusual, in that both the dominant speciation reaction in seawater and the processes important in sorbing Ag in sediments favour enhanced bioavailability. Formation of a stable chloro complex favours dispersal of dissolved Ag, and the abundant chloro complex is available to biota. Sequ
Authors
S. N. Luoma, Y.B. Ho, G.W. Bryan
Partition of nonpolar organic pollutants from water to soil and sediment organic matters
The partition coefficients (Koc) of carbon tetrachloride and 1,2-dichlorobenzene between normal soil/sediment organic matter and water have been determined for a large set of soils, bed sediments, and suspended solids from the United States and the People's Republic of China. The Koc values for both solutes are quite invariant either for the soils or for the bed sediments; the values on bed sedime
Authors
Daniel E. Kile, C. T. Chiou, H. Zhou
Groundwater transport of crater-lake brine at Poas Volcano, Costa Rica
Poa´s Volcano is an active stratovolcano in Costa Rica that has a lake in its active crater. The crater lake has high temperatures (50–90 °C), high acidity (pH ≈ 0.0), and a high dissolved-solids content (100 g/kg). The volcano has numerous freshwater springs on its flanks, but a few on the northwestern flank are highly acidic (pH = 1.6–2.5) and have high dissolved-solids concentrations (2–22 g/kg
Authors
Ward E. Sanford, Leonard F. Konikow, Gary L. Rowe, Susan L. Brantley