Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3746
Biogeochemistry: Hexadecane decay by methanogenesis
The potential for the biological conversion of long-chain saturated hydrocarbons to methane under anaerobic conditions has been demonstrated by using an enrichment culture of bacteria to degrade pure-phase hexadecane. The formation of methane in hydrocarbon-rich subsurface zones could be explained if a similar conversion of long-chain alkanes to methane were to take place in subsurface environment
Authors
Robert T. Anderson, Derek R. Lovely
Silica-coated titania and zirconia colloids for subsurface transport field experiments
Silica-coated titania (TiO2) and zirconia (ZrO2) colloids were synthesized in two sizes to provide easily traced mineral colloids for subsurface transport experiments. Electrophoretic mobility measurements showed that coating with silica imparted surface properties similar to pure silica to the titania and zirconia colloids. Measurements of steady electrophoretic mobility and size (by dynamic ligh
Authors
Joseph N. Ryan, Menachem Elimelech, Jenny L. Baeseman, Robin D. Magelky
Importance of the Mississippi River Basin for investigating agricultural–chemical contamination of the hydrologic cycle
This special issue is devoted to recent and ongoing research relating to the fate and transport of agricultural chemicals in the Mississippi River Basin by the US Geological Survey Toxic Substances Hydrology (Toxics) Program. The Mississippi River Basin drains approximately 3 200 000 km2 representing 41% of the United States. This is the largest river in the United States and the third largest in
Authors
Dana W. Kolpin
Occurrence and load of selected herbicides and metabolites in the lower Mississippi River
Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991–1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general, were prese
Authors
Gregory M. Clark, Donald A. Goolsby
Evaluation and application of the transient-pulse technique for determining the hydraulic properties of low permeability rocks: Part 2: Experimental application
In Part 1 of this study, the general solution to the transient-pulse test (Hsieh et al. 1981) was extended to evaluate quantitatively the transient variations in hydraulic head and the corresponding distributions of hydraulic gradient within a test specimen. In addition, the conditions and the validity of using the expression proposed by Brace et al. (1968) to compute the low permeability of a roc
Authors
M. Zhang, M. Takahashi, R. Morin, T. Esaki
Influence of dissimilatory metal reduction on fate of organic and metal contaminants in the subsurface
Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination, or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and
Authors
Derek R. Lovely, Robert T. Anderson
Using OTIS to model solute transport in streams and rivers
Solute transport in streams and rivers is governed by a suite of hydrologic and geochemical processes. Knowledge of these processes is needed when assessing the fate of contaminants that are released into surface waters. The study of solute fate and transport often is aided by solute transport models that mathematically describe the underlying processes. This fact sheet describes a model that cons
Authors
Robert L. Runkel
Enrichment of Geobacter species in response to stimulation of Fe(III) reduction in sandy aquifer sediments
Engineered stimulation of Fe(III) has been proposed as a strategy to enhance the immobilization of radioactive and toxic metals in metal-contaminated subsurface environments. Therefore, laboratory and field studies were conducted to determine which microbial populations would respond to stimulation of Fe(III) reduction in the sediments of sandy aquifers. In laboratory studies, the addition of eith
Authors
O.L. Snoeyenbos-West, K.P. Nevin, R. T. Anderson, D.R. Lovely
Development of a pore network simulation model to study nonaqueous phase liquid dissolution
A pore network simulation model was developed to investigate the fundamental physics of nonequilibrium nonaqueous phase liquid (NAPL) dissolution. The network model is a lattice of cubic chambers and rectangular tubes that represent pore bodies and pore throats, respectively. Experimental data obtained by Powers [1992] were used to develop and validate the model. To ensure the network model was re
Authors
Leslie A. Dillard, Martin J. Blunt
Nitrogen biogeochemistry and surface-subsurface exchange in streams
No abstract available.
Authors
John H. Duff, Frank J. Triska
Can contaminant transport models predict breakthrough?
A solute breakthrough curve measured during a two-well tracer test was successfully predicted in 1986 using specialized contaminant transport models. Water was injected into a confined, unconsolidated sand aquifer and pumped out 125 feet (38.3 m) away at the same steady rate. The injected water was spiked with bromide for over three days; the outflow concentration was monitored for a month. Based
Authors
Wei-Shyuan Peng, Duane R. Hampton, Leonard F. Konikow, Kiran Kambham, Jeffery J. Benegar
Advances in the hydrogeochemistry and microbiology of acid mine waters
The last decade has witnessed a plethora of research related to the hydrogeochemistry and microbiology of acid mine waters and associated tailings and waste-rock waters. Numerous books, reviews, technical papers, and proceedings have been published that examine the complex bio-geochemical process of sulfide mineral oxidation, develop and apply geochemical models to site characterization, and chara
Authors
D. Kirk Nordstrom