Publications

No abstract available.

A method has been developed to establish steady state flow of water in an unsaturated soil sample spinning in a centrifuge. Theoretical analysis predicts moisture conditions in the sample that depend strongly on soil type and certain operating parameters. For Oakley sand, measurements of flux, water content, and matric potential during and after centrifugation verify that steady state...

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

The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded at a slow and nearly constant rate for at least 7 days. The rate of calcite

Modeling transport of reacting solutes in porous media often requires a choice between models based on the local equilibrium assumption (LEA) and models involving reaction kinetics. Direct comparison of the mathematical formulations for these two types of transport models can aid in this choice. For cases of transport affected by surface reaction, such a comparison is made possible by a...

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...

No abstract available.

No abstract available.

Anaerobic San Francisco Bay salt marsh sediments rapidly metabolized [14C]dimethylselenide (DMSe) to 14CH4 and 14CO2. Addition of selective inhibitors (2-bromoethanesulfonic acid or molybdate) to these sediments indicated that both methanogenic and sulfate-respiring bacteria could degrade DMSe to gaseous products. However, sediments taken from the selenium-contaminated Kesterson Wildlife...

The emphasis on harmful substances that may occur in potable waters has almost obscured the fact that important beneficial constituents are commonly present. The chemical substances in water that make positive contributions to human health act mainly in two ways: (i) nutritionally, by supplying essential macro and micro elements that the diet (excluding water) may not provide in adequate...

A new formula is presented for the analytical solution of the radial dispersion problem, which analyzes the dispersive transport of a tracer in radial flow from a recharge well. This formula is simpler than a solution presented by previous investigators, but the two solutions are shown to be equivalent. Because the analytical solution consists of an integral of an oscillatory function...