Publications

Simulation of transport affected by heterogeneous or homogeneous reversible reactions requires a choice between local equilibrium-based and kinetics-based models. The error associated with the use of equilibrium-based models is equivalent to the error of neglecting certain mathematical terms in the governing kinetics-based transport equations. Identification and evaluation of these kinetically inf

The possibility that microorganisms are catalyzing the ongoing reduction of Fe(III) in the sediments of deep (20-250 m) aquifers was investigated. Acetate-oxidizing, Fe(III)-reducing bacteria were recovered from deep subsurface sediments, but only from sediments in which it appeared that Fe(III) reduction was the terminal electron-accepting process for oxidation of organic matter. The Fe(III)-redu

The design and application of a hollow-fiber tangential-flow filtration device has been used to concentrate bacteria and suspended particles from large volume surface water and groundwater samples (i.e., hundreds of liters). Filtrate tlux rates (4–8 L min−1) are equal to or faster than those of other devices that are based on continuous flow centrifugation and plate and frame filtration. Particle

The transformation of benzene and a series of alkylbenzenes was studied in anoxic groundwater of a shallow glacial-outwash aquifer near Bemidji, Minnesota, U.S.A. Monoaromatic hydrocarbons, the most water-soluble components of crude oil, were transported downgradient of an oil spill, forming a plume of contaminated groundwater. Organic acids that were not original components of the oil were identi

The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for the

This report presents data on the sorption of trichloroethene (TCE) vapor to vadose-zone soil above a contaminated water-table aquifer at Picatinny Arsenal in Morris County, NJ. To assess the impact of moisture on TCE sorption, batch experiments on the sorption of TCE vapor by the field soil were carried out as a function of relative humidity. The TCE sorption decreases as soil moisture content inc

The Mississippi River and its tributaries drain extensive agricultural regions of the Mid-Continental United States. Millions of pounds of herbicides are applied annually in these areas to improve crop yields. Many of these compounds are transported into the river from point and nonpoint sources, and eventually are discharged into the Gulf of Mexico. Studies being conducted by the U.S. Geological

Distributions in time and space of Ag, Cd, Cr, Cu, Pb and Zn were determined in fine-grained sediments and in the filter-feeding bivalve Corbicula sp. of Suisun Bay/delta at the mouth of the Sacramento and San Joaquin Rivers in North San Francisco Bay. Samples were collected from seven stations at near-monthly intervals for 3 years. Aggregated data showed little chronic contamination with Ag, Zn a

The Mississippi River and its tributaries drain extensive agricultural regions of the midcontinental United States, where large amounts of herbicides are applied as weed control agents on crops such as corn and soybeans. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries, representing a 1930-km river reach, have confirmed that several

Topographically closed basins may be hydrologically open as a result of seepage losses to underlying or surrounding ground-water systems. In such cases, these losses can have a substantial control over the suite and the thicknesses of evaporite minerals formed in the basin. The ratio of ground-water outflow to inflow (flux ratio) in hydrologically open basins is as important in determining the min

Quantitative and semiquantitative analyses of dissolved trace metals are reported for designated sampling sites on the Mississippi River and its main tributaries utilizing depth-integrated and width-integrated sampling technology to collect statistically representative samples. Data are reported for three sampling periods, including: July-August 1987, November-December 1987, and May-June 1988. Con

The mineral surface of Wyoming bentonite (clay) was modified by replacing inorganic ions by each of 10 quaternary ammonium compounds, and tetrachloromethane sorption to the modified sorbents from water was studied. Tetrachloromethane sorption from solution to clay modified with tetramethyl-, tetraethyl-, benzyltrimethyl-, or benzyltriethylammonium cations generally is characterized by relatively h