Publications

If the primordial atmosphere was reducing, then the first microbial ecosystem was probably composed of anaerobic bacteria. However, despite the presence of an oxygen-rich atmosphere, anaerobic habitats are important, commonplace components of the Earth's present biosphere. The geochemical activities displayed by these anaerobes impact the global cycling of certain elements (e.g., C, N, S...

Preliminary results from New York, New Jersey, Connecticut, Florida, Nebraska, and Colorado indicate that regional ground-water quality has been affected by human activities. The frequencies of detection of volatile organic compounds and some trace elements were larger in ground water underlying urban or industrial areas in comparison to undeveloped areas. Ground water in agricultural...

A field study approach is proposed for reliably estimating hydraulic gradients in subregions within a region of variable-salinity ground water. It is based upon Hubbert's concept about the kind of density distributions that are required for ground water to have a potential. The approach consists of dividing a region of variable-salinity ground water into subregions with constant density

Organic liquids inadvertently spilled and then distributed in the unsaturated zone can pose a long-term threat to ground water. Many of these substances have significant volatility, and thereby establish a premise for contaminant removal from the unsaturated zone by inducing advective air-phase transport with wells screened in the unsaturated zone. In order to focus attention on the...

Saturation indices computed with WATEQ4F chemical analyses from a groundwater in crystalline bedrock and a surface water receiving acid mine drainage are frequently at or above saturation with respect to calcite, fluorite, barite, gibbsite and ferrihydrite. Deep granitic groundwaters from Stripa, Sweden, are supersaturated with respect to calcite and fluorite. Acid mine waters from the...

Increased solubility of quartz and mobilization in contaminated groundwater due to the complexation with dissolved organic acids has been recently proposed [Bennett and Siegel, Nature 326, 684–686 (1987)]. Using laser Raman and Fourier transform infrared spectroscopies, we have examined mixed solutions of oxalic and silicic acids at near neutral pH in the tenth molar concentration ranges...

A simultaneous calorimetric and potentiometric technique has been developed for measuring the thermodynamics of proton binding to mineral oxides in the presence of a supporting electrolyte. Modifications made to a commercial titration calorimeter to add a combination pH electrode and maintain an inert atmosphere in the calorimeter reaction vessel are described. A procedure to calibrate

Appraisal of ground water contaminated by organic substances raises problems of difficult sample collection and timely chemical analysis. High-performance liquid chromatography was evaluated for on-site determination of specific organic contaminants in ground water samples and was used at three study sites. Organic solutes were determined directly in water samples, with little or no...

Chemical and biological processes have important roles in the transport and cycling of trace elements in natural waters, but their complex interactions are often not well understood. Trace-element concentrations may, for example, be controlled by adsorption-desorption reactions at mineral surfaces, with the equilibrium strongly influenced by pH. Variations in pH due to photosynthetic...

Characteristics of an obligately methylotrophic coccoid methanogen (strain GS-16) previously isolated from estuarine sediment are described. Growth was demonstrated on dimethyl sulfide (DMS) or trimethylamine (TMA), but not on methane thiol, methane thiol plus hydrogen, dimethyl disulfide, or methionine. DMS-grown cells were able to metabolize DMS and TMA simultaneously when inoculated...

Water solubility enhancements of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT) and 1,2,3-trichlorobenzene (TCB) by aqueous surfactants below and above their critical micelle concentrations (CMCs) have been studied at room temperature with the following surfactants: Triton X-100, Triton X-114, Triton X-405, Brij 35, sodium dodecyl sulfate, and cetyltrimethylammonium bromide. While...

Injection of liquid waste into a highly transmissive, saltwater-bearing, fractured dolomite underlying the city of St. Petersburg, Florida, provided an opportunity to study density-dependent flow associated with two miscible and density-different liquids. The injection zone was 98 m thick with a radial hydraulic conductivity of 762 m/d and a vertical hydraulic conductivity of 152 m/d...