Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 4094
Hydrogeology of the Hawaii Scientific Drilling Project borehole KP-1 2. Groundwater geochemistry and regional flow patterns
A series of downhole and surface water samples were taken from the 1‐km‐deep KP‐1 borehole located on the eastern flank of the island of Hawaii. Early samples from depths of more than 700 m showed salinities nearly equivalent to seawater but having anomalous cation concentrations that are attributed to ion exchange between formation fluids and residual drilling mud clays. Later deep samples found
Authors
D. M. Thomas, Frederick L. Paillet, M.E. Conrad
A Generalized Approach for the Interpretation of Geophysical Well Logs in Ground-Water Studies:Theory and Application
Quantitative analysis of geophysical logs in ground-water studies often involves at least as broad a range of applications and variation in lithology as is typically encountered in petroleum exploration, making such logs difficult to calibrate and complicating inversion problem formulation. At the same time, data inversion and analysis depend on inversion model formulation and refinement, so that
Authors
Frederick L. Paillet, R.E. Crowder
Geochemistry of aquatic humic substances in the Lake Fryxell basin, Antarctica
Dissolved organic carbon (DOC) in Lake Fryxell, 10 streams flowing into the lake, and the moat surrounding the lake was studied to determine the influence of sources and biogeochemical processes on its distribution and chemical nature. Lake Fryxell is an amictic, permanently ice-covered lake in the McMurdo Dry Valleys which contains benthic and planktonic microbial populations, but receives essent
Authors
G. Aiken, D. McKnight, R. Harnish, R. Wershaw
Reduction of aqueous transition metal species on the surfaces of Fe(II)-containing oxides
Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1–7 at 25°C. For an aqueous transition metal m, such reactions are3[Fe2+Fe23+]O4(magnetite)+2/nmz→4[Fe23+]O3(magnetite)+Fe2++2/nmz−nand3[Fe2+Ti]O3(ilmenite)+2/nmz→Fe23+Ti3O9(pseudorutile)+Fe2++2/nmz−n,w
Authors
A. F. White, M. L. Peterson
Analysis of nitrate in near-surface aquifers in the midcontinental United States: An application of the inverse hyperbolic sine Tobit model
A nonnormal and heteroscedastic Tobit model is used to determine the primary factors that affect nitrate concentrations in near-surface aquifers, using data from the U.S. Geological Survey collected in 1991. Both normality and homoscedasticity of errors are rejected, justifying the use of a nonnormal and heteroscedastic model. The following factors are found to have significant impacts on nitrate
Authors
Steven T. Yen, Shiping Liu, Dana W. Kolpin
Two-dimensional advective transport in ground-water flow parameter estimation
Nonlinear regression is useful in ground-water flow parameter estimation, but problems of parameter insensitivity and correlation often exist given commonly available hydraulic-head and head-dependent flow (for example, stream and lake gain or loss) observations. To address this problem, advective-transport observations are added to the ground-water flow, parameter-estimation model MODFLOWP using
Authors
E.R. Anderman, M. C. Hill, E. P. Poeter
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