Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Uranium adsorption on ferrihydrite - Effects of phosphate and humic acid
Uranium adsorption on ferrihydrite was studied as a function of pH in systems equilibrated with air, in the presence and absence of added phosphate and humic acid (HA). The objective was to determine the influence of PO43- and HA on uranium uptake. Below pH 7, the sorption of UO22+ typically increases with increasing pH (the 'low pH sorption edge'), with a sharp decrease in sorption above this pH
Authors
T.E. Payne, J.A. Davis, T.D. Waite
Kinetic determinations of trace element bioaccumulation in the mussel Mytilus edulis
Laboratory experiments employing radiotracer methodology were conducted to determine the assimilation efficiencies from ingested natural seston, the influx rates from the dissolved phase and the efflux rates of 6 trace elements (Ag, Am, Cd, Co, Se and Zn) in the mussel Mytilus edulis. A kinetic model was then employed to predict trace element concentration in mussel tissues in 2 locations for whic
Authors
W.-X. Wang, N.S. Fisher, S. N. Luoma
Covalent binding of aniline to humic substances. 1. Kinetic studies
The reaction kinetics for the covalent binding of aniline with reconstituted IHSS humic and fulvic acids, unfractionated DOM isolated from Suwannee River water, and whole samples of Suwannee River water have been investigated. The reaction kinetics in each of these systems can be adequately described by a simple second-order rate expression. The effect of varying the initial concentration of anili
Authors
E.J. Weber, D.L. Spidle, K. A. Thorn
Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective
Nitrate reduction and denitrification were measured in swamp forest streams draining lowland rain forest on Costa Rica's Atlantic slope foothills using the C2H2-block assay and sediment-water nutrient fluxes. Denitrification assays using the C2H2-block technique indicated that the full suite of denitrifying enzymes were present in the sediment but that only a small fraction of the functional activ
Authors
J.H. Duff, C. M. Pringle, F.J. Triska
Pesticides in ground water: Do atrazine metabolites matter?
Atrazine and atrazine-residue (atrazine + two metabolites - deethylatrazine and deisopropylatrazine) concentrations were examined to determine if consideration of these atrazine metabolites substantially adds to our understanding of the distribution of this pesticide in groundwater of the midcontinental United States. The mean of atrazine.residue concentrations was 53 percent greater than that of
Authors
S. Liu, S.T. Yen, D.W. Kolpin
Removal of selenium from contaminated agricultural drainage water by nanofiltration membranes
Seleniferous agricultural drainage wastewater has become a new major source of pollution in the world. In the USA, large areas of farmland in 17 western states, generate contaminated salinized drainage with Se concentrations much higher than 5 ??g/l, the US Environmental Protection Agency water-quality criterion for the protection of aquatic life; Se values locally reach 4200 ??g/l in western San
Authors
Y.K. Kharaka, G. Ambats, T. S. Presser, R. A. Davis
Deformation-induced changes in hydraulic head during ground-water withdrawal
Ground-water withdrawal from a confined or semiconfined aquifer causes three-dimensional deformation in the pumped aquifer and in adjacent layers (overlying and underlying aquifers and aquitards). In response to the deformation, hydraulic head in the adjacent layers could rise or fall almost immediately after the start of pumping. This deformation-induced effect suggest that an adjacent layer unde
Authors
Paul A. Hsieh
Multiport well design for sampling of ground water at closely spaced vertical intervals
Detailed vertical sampling is useful in aquifers where vertical mixing is limited and steep vertical gradients in chemical concentrations are expected. Samples can be collected at closely spaced vertical intervals from nested wells with short screened intervals. However, this approach may not be appropriate in all situations. An easy-to-construct and easy-to-install multiport sampling well to coll
Authors
G. N. Delin, M.K. Landon
Denitrification and mixing in a stream-aquifer system: Effects on nitrate loading to surface water
Ground water in terrace deposits of the South Platte River alluvial aquifer near Greeley, Colorado, USA, had a median nitrate concentration of 1857 μmol l−1. Median nitrate concentrations in ground water from adjacent floodplain deposits (468 μmol l−1) and riverbed sediments (461 μmol l−1), both of which are downgradient from the terrace deposits, were lower than the median concentration in the te
Authors
P. B. McMahon, J.K. Böhlke
Chloride mass-balance method for estimating ground water recharge in arid areas: Examples from western Saudi Arabia
The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in tim
Authors
A.S. Bazuhair, W.W. Wood
The use of streambed temperature profiles to estimate the depth, duration, and rate of percolation beneath arroyos
Temporal variations in a streambed temperature profile between 30 and 300 cm beneath Tijeras Arroyo, New Mexico, were analyzed at 30-min intervals for 1990 to estimate the depth, duration, and rate of percolation during streamflows. The depth of percolation was clearly documented by the rapid response of the streambed temperature profile to streamflows. Results indicate that the streambed possesse
Authors
James Constantz, Carole L. Thomas
The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst
The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between
Authors
B. G. Katz, T.D. Bullen