Showing papers by "Barbara A. Bekins published in 2013"
TL;DR: A reactive transport model was developed to understand processes controlling the fate of ethanol and BToX and suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfates in the aquifer.
Abstract: [1] In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (no-ethanol lane) and BToX plus ethanol (with-ethanol lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BToX. The model was calibrated to the extensive field data set and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea. The benzene plume was about 4.5 times longer in the with-ethanol lane than in the no-ethanol lane. Matching this different behavior in the two lanes required inhibiting benzene degradation in the presence of ethanol. Inclusion of iron reduction with negligible growth of iron reducers was required to reproduce the observed constant degradation rate of benzene. Modeling suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfate in the aquifer. Matching of methane data required incorporating initial fermentation of ethanol to acetate, methane loss by outgassing, and methane oxidation coupled to sulfate and iron reduction. Simulation of microbial growth using dual Monod kinetics, and including inhibition by more favorable electron acceptors, generally resulted in reasonable yields for microbial growth of 0.01–0.05.
13 citations
TL;DR: Petroleum fingerprinting is an invaluable tool in forensic geochemistry as mentioned in this paper, which can provide information about processes in the environment that impact oils such as weathering and microbial degradation, and can be used to evaluate organic matter that contributed to oils, and classify oils with regard to the geological framework of their source.
12 citations
01 Jan 2013
TL;DR: Borehole logs from the northern Barbados accretionary prism show that the plateboundary decollement initiates in a low-density radiolarian claystone, but in a patchy manner.
Abstract: Borehole logs from the northern Barbados accretionary prism show that the plateboundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a threedimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch. on January 19, 2013 geology.gsapubs.org Downloaded from