Publications

Reported solubility data for a synthetic scorodite and the techniques used to prepare the synthetic phase are questioned. (A.M. 70-838, 72-852)-J.A.Z.

Overall mass-transfer coefficients for the volatilization of ethylene dibromide from water were measured simultaneously with the oxygen absorption coefficient in a laboratory stirred tank. Coefficients were measured as a function of mixing conditions in the water for two windspeeds. The ethylene dibromide mass-transfer coefficient depended on windspeed; the ethylene dibromide liquid-film

Dissolution of synthetic strontianite-aragonite solid solutions was followed analytically to stoichiometric saturation using large solid to solution ratios in CO2-H2O solution at 25 and 76°C. The compositional dependence of the equilibrium constant was calculated from the composition of saturated (stoichiometric) solutions and used to calculate the activities and activity coefficients of...

Inductively coupled plasma mass spectrometry is employed in the determination of Ni, Cu, Sr, Cd, Ba, Ti, and Pb in nonsaline, natural water samples by stable isotope dilution analysis. Hydrologic samples were directly analyzed without any unusual pretreatment. Interference effects related to overlapping isobars, formation of metal oxide and multiply charged ions, and matrix composition...

Playa-lake basins of the Southern High Plains, Texas and New Mexico, may originate wherever water periodically can collect in a surficial depression. They expand, however, by hydrologic and geomorphic processes including (1) dissolution of lithologic carbonates by infiltrating water; (2) transport downward of fine-grained clastic and organic material by the infiltrating ground water...

A moving boundary problem which arises during transport with precipitation-dissolution reactions is solved by three different numerical methods. Two of these methods (one explicit and one implicit) are based on an integral formulation of mass balance and lead to an approximation of a weak solution. These methods are compared to a front-tracking scheme. Although the two approaches are...

Recent literature concerning the modeling of chemical reactions during transport in ground water is examined with emphasis on sorption reactions. The theory of transport and reactions in porous media has been well documented. Numerous equations have been developed from this theory, to provide both continuous and sequential or multistep models, with the water phase considered for both...

The ability to identify a formation mechanism for natural gas in a particular environment requires consideration of several geochemical factors when there are multiple sources present. Four primary sources of methane have been identified in Mono Lake. Two of these sources were associated with numerous natural gas seeps which occur at various locations in the lake and extend beyond its...

A spectrometric technique utilizing electrothermal vaporization (graphite furnace) and gas phase-multiple wavelength absorption with photodiode array detection is used to characterize crude oil.

A procedure for conducting adsorption studies at low suspended solid concentrations in natural waters (

Washed cell suspensions of Desulfovibrio desulfuricans subsp. aestuarii were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate...

The rate of Cd2+ sorption by a calcareous aquifer sand was characterized by two reaction steps, with the first step reaching completion in 24 hours. The second step proceeded at a slow and nearly constant rate for at least seven days. The first step includes a fast adsorption reaction which is followed by diffusive transport into either a disordered surface film of hydrated calcium...