Impacts of an Ethanol-Blended Fuel Release on Groundwater and Fate of Produced Methane: Simulation of Field Observations

[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

Determining the Temporal and Spatial Variability of Biomass Productivity in a Pilot-scale Algal Resource Recovery Unit Treating Agricultural Wastewater

Idaho dairy cows produce an estimated 3 million tons of dry manure annually; each ton contains 4.5 kg of nitrogen (N) and 0.82 kg of phosphorous (P). Excess application of manure as crop fertilizer can contaminate aquifers and surface water due to leeching of N and P. We constructed three replicate Algal Resource Recovery Units (ARRU) at the University of Idaho dairy facility in Moscow, ID to test their utility to manage nutrients and produce algal biomass as a secondary commodity. Each ARRU was inoculated with a mixture of algal cultures consisting of Chlorella vulgaris, Scenedesmus obliquus, and Synechococcus leopoliensis, as well as a consortium of algae species obtained from the Boise River and received one of 3 treatments A) lagoon waste water; B) 100% effluent from a polyhydroxyalkanoate reactor effluent (PHAE); or C) a mixture of 90% PHAE and 10% anaerobic digester effluent (ADE). Daily Nitrogen and Phosphorus removal were 83.6%, 82%, and 83.7% N removal and 96.6%, 86%, and 95.8% P removal for treatments A, B, and C, respectively. Biomass productivity was 10.37, 19.13, and 18.9 g/m2/day for each treatment. Algal growth and nutrient removal rates are being evaluated for nutrient management and as secondary commodities

Effect of Ethanol on Microbial Community Structure and Function During Natural Attenuation of Benzene, Toluene, and \u3cem\u3eo\u3c/em\u3e-Xylene in a Sulfate-reducing Aquifer

Ethanol (EtOH) is a commonly used fuel oxygenate in reformulated gasoline and is an alternative fuel and fuel supplement. Effects of EtOH release on aquifer microbial ecology and geochemistry have not been well characterized in situ. We performed a controlled field release of petroleum constituents (benzene (B), toluene (T), o-xylene (o-X) at ∼1–3 mg/L each) with and without EtOH (∼500 mg/L). Mixed linear modeling (MLM) assessed effects on the microbial ecology of a naturally sulfidic aquifer and how the microbial community affected B, T, and o-X plume lengths and aquifer geochemistry. Changes in microbial community structure were determined by quantitative polymerase chain reaction (qPCR) targeting Bacteria, Archaea, and sulfate reducing bacteria (SRB); SRB were enumerated using a novel qPCR method targeting the adenosine-5′-phosphosulfate reductase gene. Bacterial and SRB densities increased with and without EtOH-amendment (1−8 orders of magnitude). Significant increases in Archaeal species richness; Archaeal cell densities (3–6 orders of magnitude); B, T, and o-X plume lengths; depletion of sulfate; and induction of methanogenic conditions were only observed with EtOH-amendment. MLM supported the conclusion that EtOH-amendment altered microbial community structure and function, which in turn lowered the aquifer redox state and led to a reduction in bioattenuation rates of B, T, and o-X

Fluorescent Particles Comprising Nanoscale ZnO Layer and Exhibiting Cell-Specific Toxicity

Multifunctional smart nanostructures are disclosed that include fluorescein isothiocyanate (FITC)-encapsulated SiO2 core-shell particles with a nanoscale ZnO finishing layer, wherein an outer ZnO layer is formed on the SiO2-FITC core. These ~200 nm sized particles showed promise toward cell imaging and cellular uptake studies using the bacterium Escherichia coli and Jurkat cancer cells, respectively. The FITC encapsulated ZnO particles demonstrated excellent selectivity in preferentially killing Jurkat cancer cells with minimal toxicity to normal primary immune cells (18% and 75% viability remaining, respectively, after exposure to 60 μg/mL) and inhibited the growth of both gram-positive and gram-negative bacteria at concentrations .gtoreq.250-500 μg/mL (for Staphylococcus aureus and Escherichia coli, respectively). These results indicate that the FITC encapsulated multifunctional particles with nanoscale ZnO surface layer can be used as smart nanostructures for particle tracking, cell imaging, antibacterial treatments and cancer therapy

Dairy Wastewaters for Algae Cultivation, Polyhydroxyalkanote Reactor Effluent Versus Anaerobic Digester Effluent

Nutrients in dairy wastewaters can be remediated through assimilation into algal biomass. Anaerobically digested manure creates an effluent (ADE) that is useful for algal cultivation while alternate processing of manure through a polyhydroxyalkanoate reactor generates a distinct effluent (PHAE), not previously characterized for algal cultivation. Each effluent was evaluated for growth rate, biomass production, and nutrient recovery using type algae species Chlorella vulgaris. Growth rates were elevated in 5, 10, and 20 % dilutions of PHAE (0.59, 0.53, 0.42 days−1) compared to equal concentrations of ADE (0.40, 0.36, 0.37 days−1). In addition, the growth phase lasted up to twice as long for PHAE, resulting in a fourfold higher stationary phase algal concentration (cells∙mL−1) compared to ADE. Growth in ADE was limited by specific inhibitory properties: high concentrations of dissolved organic matter, ammonia, and elevated bacterial load. Maximum nutrient removal rates for ADE and PHAE were 0.95 and 3.46 mg·L−1·day−1 for nitrogen and 0.67 and 0.04 mg·L−1·day−1 for phosphorus, respectively. Finally, biomass derived from PHAE was higher in lipids (11.3 % versus 7.2 %) and thus has a greater potential as a feedstock for biofuel compared to ADE

Spatial and Temporal Dynamics of Dissolved Oxygen Concentrations and Bioactivity in the Hyporheic Zone

Dissolved oxygen (DO) concentrations and consumption rates are primary indicators of heterotrophic respiration and redox conditions in the hyporheic zone (HZ). Due to the complexity of hyporheic flow and interactions between hyporheic hydraulics and the biogeochemical processes, a detailed, mechanistic, and predictive understanding of the biogeochemical activity in the HZ has not yet been developed. Previous studies of microbial activity in the HZ have treated the metabolic DO consumption rate constant (KDO) as a temporally fixed and spatially homogeneous property that is determined primarily by the concentration of bioavailable carbon. These studies have generally treated bioactivity as temporally steady state, failing to capture the temporal dynamics of a changeable system. We demonstrate that hyporheic hydraulics controls rate constants in a hyporheic system that is relatively abundant in bioavailable carbon, such that KDO is a linear function of the local downwelling flux. We further demonstrate that, for triangular dunes, the downwelling velocities are lognormally distributed, as are the KDO values. By comparing measured and modeled DO profiles, we demonstrate that treating KDO as a function of the downwelling flux yields a significant improvement in the accuracy of predicted DO profiles. Additionally, our results demonstrate the temporal effect of carbon consumption on microbial respiration rates

Gateway Scholarships in Biological Sciences: Year 4 Annual Report

This report summarizes grant activities, progress toward goals, and broader impacts of the Gateway Scholars Program in the Boise State Department of Biological Sciences during the 2020-21 academic year

Use of Microcalorimetry to Determine the Costs and Benefits to Pseudomonas Putida Strain KT2440 of Harboring Cadmium Efflux Genes

A novel microcalorimetric approach was used to analyze the responses of a metal-tolerant soil bacterium (Pseudomonas putida strain KT2440) to metal resistance gene deletions in cadmium-amended media. As hypothesized, under cadmium stress, the wild-type strain benefited from the resistance genes by entering the exponential growth phase earlier than two knockout strains. In the absence of cadmium, strain KT1, carrying a deletion in the main component (czcA1) of a Cd/Zn chemiosmotic efflux transporter (CzcCBA1), grew more efficiently than the wild type and released similar to 700 kJ (per mole of biomass carbon) less heat than the wild-type strain, showing the energetic cost of maintaining CzcCBA1 in the absence of cadmium. A second mutant strain (KT4) carrying a different gene deletion, Delta cadA2, which encodes the main Cd/Pb efflux transporter (a P-type ATPase), did not survive beyond moderate cadmium concentrations and exhibited a decreased growth yield in the absence of cadmium. Therefore, CadA2 plays an essential role in cadmium resistance and perhaps serves an additional function. The results of this study provide direct evidence that heavy metal cation efflux mechanisms facilitate shorter lag phases in the presence of metals and that the maintenance and expression of tolerance genes carry quantifiable energetic costs and benefits