Student Abstracts: Environmental Science at LBNL

Evaluation of Chemical Transport in Soil Using Multimedia Environmental Fate Modeling.

Kirsten Enoch (San Francisco State University, San Francisco, CA 94132) Deborah Bennett and Thomas McKone (Lawrence Berkeley National Laboratory, Berkeley, CA 94720)

Multimedia environmental models are used to understand the fate and transport of chemicals in multiple environmental media such as air, water, vegetation, soil, and sediment. Understanding the behavior of chemicals in the environment allows for the assessment of possible adverse effects on human and ecological health. Some multimedia fate models use the fugacity concept to describe the behavior of chemicals in environmental media. Multimedia models, such as CalTOX, are available for public use in order that exposure rates can be determined for populations in all areas. As one of the updates, a new user-friendly interface will be added to CalTOX. Recent research has provided new equations for the behavior of chemicals in soil and for chemical, landscape, and exposure factor data that will be added to CalTOX. These changes are assessed using four case studies: benzene, methyl tertiary butyl ether (MTBE), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and benzo(a)pyrene. The CalTOX model produced similar data when compared to the collected data. Bioturbation was found to be an important factor in the new soil algorithms.

Grassland Water District Real-Time Water Quality Management and Panoche Drainage District Algal-Bacterial Selenium Removal System.

Adele Gelvin (Northeastern Junior College, Sterling, Colorado 80751). Nigel Quinn (Lawrence Berkeley National Laboratory, Berkeley, California 94720). Water quality is a common environmental concern that scientists are working to improve. Two current projects being conducted in the San Joaquin Valley of California are the Grassland Water District Real-Time Water Quality Management project and the Panoche Drainage District Algal-Bacterial Selenium Removal System project. The Grassland Water District project focuses on the concentration of salinity in the 90,000-acre wetland area and the amount that is released to the San Joaquin River in the spring. The high salinity is a problem for farmers in the early spring irrigation because the salinity interferes with water uptake by the plant which causes poor germination and growth, resulting in poor production. Panoche Drainage District Algal-Bacterial Selenium Removal System utilizes algae and bacteria to reduce nitrate and selenate found in tile drainage water. The project incorporates two pilot systems to determine the most effective and cost efficient system in which a larger plant can be built. The nitrate is a problem because it influences unwanted algae growth in the canals. The selenate poses a threat to waterfowl and their offspring by acting as a teratagen. My role was to create a web page explaining the importance, location, and nature of each project. I also created a newsletter for the Panoche Drainage District.

Electrokinetics in the Bioremediation of Soil Contaminated with Nitroaromatics.

Stacy A. Green (The Ohio State University, Columbus, Ohio, 43210) John Kerr (Lawrence Berkeley National Laboratory, Berkeley, California, 94720).

Through years of use as pesticides, in industry, and in the manufacture of munitions, nitroaromatics have contaminated the world’s soil and groundwater. Recognized as priority pollutants, these compounds are known carcinogens and cause damage to the blood and to other internal organs. In the natural environment, small amounts of these substances can be broken down naturally into harmless, inorganic compounds and minerals. If the nitroaromatics are not fully degraded, however, they are converted into even more dangerous intermediates. When found in large concentrations, this is most often the case. Bioremediation is the most effective means of cleaning up nitroaromatics. Because the process uses microorganisms and is carried out on site, it is more efficient and costs less than the alternative dig-and-incinerate method. Electrokinetics enhances bioremediation by using electricity to deliver nutrients, water, and heat to the microorganisms. The application of electrokinetics is shown to have increased the rate of bacterial growth. When the microbial community grows, the rate of remediation is increased. Currently, only two countries worldwide, the United States and Germany, have assessed their levels of nitroaromatic contamination. Estimates indicate, however, that the levels of contamination elsewhere are high, making remediation of nitroaromatics an important global issue.

Polynuclear Aromatic Hydrocarbons in situ bioremediation treatability test; focus on contaminant disappearance by HPLC analysis.

Jessica Montañez1, Loyda Méndez1, Sadhana Chauhan2, Terry C. Hazen2. 1University of Puerto Rico Mayagüez Campus, Mayagüez Puerto Rico, 2Ernest Orlando Lawrence Berkeley National Laboratory.

Polynuclear Aromatic Hydrocarbons (PAHs) including Benzo(a)pyrene (BaP) are hydrocarbons containing two or more fused benzene rings. They are mostly found in the emissions from burned plant and petroleum products. One of the sites contaminated with PAHs is the United States Navy Base, Site 25 Parcel 182 at Alameda, CA. Biosparging, a bioremediation technique, is being considered for use at this site. This approach will allow the injection of air, methane, phosphorus and nitrogen to stimulate the indigenous microorganisms in the soil to increase their densities and degrade the PAHs. To establish that BaP in the soil at this site can be degraded by this technique, a treatability study is being done. Soil with no known pollution history was spiked with 10 ppm of BaP. These BaP and soil mixtures were amended with 10% methane (CH₄), 1% nitrous oxide (N₂O) and 1% triethyl phosphate (TEP). The total amount of CO₂ and CH₄ produced as a degradation product was quantified by gas chromatography (GC). Soil samples were extracted with acetone by vortex and sonication techniques. BaP recovery was quantified by High Performance Liquid Chromatography (HPLC). Vortexing was shown to be the best extraction method; however, the percent of extraction was low due to high BaP absorption to the soil. BaP concentrations decreased in every sample that contained CH₄, except for those amended with N₂O + CH₄ + TEP because it had a leakage. Unamended and CH₄ samples showed increases in biomass and microbial diversity in contrast with the amended samples, which showed low microbial density.

MTBE Remediation Via Co-Metabolic Degradation.

NICOLE PORTLEY (Boston College, Chestnut Hill, MA 02467) WILLIAM STRINGFELLOW (Lawrence Berkeley National Laboratory, Berkeley 94610)

Methyl tert-butyl ether (MTBE), an oxygenate and gasoline additive, is a prevalent water pollutant in California. The first objective in this project was to learn basic microbiology techniques. These techniques were then applied to test the hypothesis that strains of bacteria may be able to degrade MTBE co-metabolically while receiving primary nutrition from another gasoline component. Bacteria strains were isolated and cultured from a field sample where MTBE degradation was quantifiably taking place. These bacteria were streaked upon a single-source media with iso-pentane, hexane, or octane as a carbon source. Thus, the bacteria were separated by their ability to live on certain hydrocarbons. Several cultures were tested via gas chromatography for MTBE degradation. Evidence shows that iso-pentane sustained bacteria are the best MTBE degraders.

Detection of Groundwater Contaminants by Propagation of Seismic Waves.

SHRAVANTHI REDDY and Dr. Ernest Majer (Mentor Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA)

Propagation of seismic waves was used for the detection of contaminants known as DNAPL’s, specifically PCE, a cleaning solvent that is now contaminating ground aquifers. Velocity analysis of the waves proved to be a useful technique for determining the presence of the contaminant in water-saturated sand and clay, in a tank sized model of a ground aquifer. Velocities of the waves decreased by as much as 5% in the presence of PCE. Amplitudes of the waves were also effected, experiencing significant attenuation in the presence of the contaminant. These techniques for detection of contaminants may be useful for more efficient remediation of groundwater aquifers.

Energy Efficient Fixtures for Real World Applications

Laura Schloss (Gonzaga University, Spokane, WA 99258) Michael Siminovitch and Jeffrey Mitchell (Lawrence Berkeley National Laboratory, Berkeley, CA 94720).

Improving energy efficient light fixtures is the primary goal of the Energy Efficient Lighting Laboratory. Various photometric techniques are implemented as a crucial element for the designing of energy efficient lighting technology. Currently, instruments such as a Gonio-Photometer and an Integrating Sphere are used for testing fixtures and bare lamps. A Downlight Integrating Chamber was built at minimal cost and will ultimately be capable of testing downlight fixtures for a greater variety of applications than current methods being used. Fixture controls are another important element of saving energy. A modified occupancy sensor was installed on the lighting system of a beverage machine which dims the machine’s lights when no one is around. This Energy Smart technology saves energy without compromising the marketing technique of beverage machine companies. Using the energy efficient technology described herein will benefit the E.P.A. regulatory system, improve production for lighting manufacturers, improve marketing for beverage machine companies, and save millions of dollars in energy consumption.

Digital Inverse Modeling of Multiphase Flow Through Porous Medium.

Robert Reichenbach (Hope College, Holland, Michigan 49423) Liviu Tomutsa, Stefan Finsterle (Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720).