Quantification of in situ polycyclic aromatic hydrocarbon biodegradation at a petroleum contaminated site

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.A major difficulty in applying bioremediation to field sites is the quantification ofin situ bioremediation. This study is based on the hypothesis that molecular markers can be used to quantify in situ biodegradation. By using concentrations of two different markers, a ratio can be formed which will quantify the level and degree of biodegradation, given that one marker is used as a conservative mass tracer. This research was conducted to evaluate in situ biodegradation of polycyclic aromatic hydrocarbons (PAHS) at a Bunker C contaminated soil. The effectiveness of EPA Seal Beach treatment with a consortium of biosurfactant bacteria in relation of a control is compared. using an EPA Seal Beach consortium of biosurfactant organisms in relation to PAH degradation. Also the use of 17a 21 b hopane as an internal mass balance indicator is compared to a high molecular weight PAH benzo(gh/)perylene and to some alkylated homologous. Different ratios of molecualr markers are tested. Linear regression is performed to determine the coefficients for the slope and the intercept. The slope of the equation determines any change in the ratio of molecular Markers. Statistical tests are performed to analyze the significance of the slope for each fertilizer and control areas. Non normalized PAH concentrations over time show high variability due to the large spatial heterogeneity of the oil content in the soil. Normalizing the data by using ratios of molecular markers decreases the PAH concentration variability in the samples. Some of the PAH/hopane ratios show statistically significant decreases over time for the control plots. Half-life constants calculated from these ratios, assuming first-order degradation, seem to be unrealistic estimates for biodegradation in these samples. Total ion chromatograms from each of the samples from both areas illustrate a highly weathered oil, that did not markedly change over the 1 1 weeks of the experiment, indicating little or no biodegradation. Bioavailability is important for biodegradation to occur. Low bioavailability may account for the lack ofbioremediation at this site