Date of Award
Program or Major
Doctor of Philosophy
Thomas P Ballestero
Petroleum contaminated soil exists at McMurdo Station in Antarctica. These soils were contaminated with historic releases of JP-8 jet fuel. Over time, there does not appear to have been significant reduction in the petroleum concentrations in these soils. This lack of reduction has been attributed to the extremely cold Antarctic environment and the lack of available moisture.
Cold temperatures and/or lack of moisture may not be the factors inhibiting biodegradation. Soil temperatures can exceed 20 degrees centigrade (°C) during the austral summer and melt water becomes available. However, the soil temperatures have also been reported to fluctuate rapidly. Swings of soil temperatures have ranged over a 25°C interval several times during a period of hours. Rapid changes in temperature may be most detrimental to microbial activity.
This research evaluated the biodegradation of petroleum contaminated Antarctic soil at a low stable temperature (7°C). It also evaluated temperature fluctuations. This was accomplished through experiments using contaminated soil from McMurdo Station, Antarctica.
The first experiment indicated that a statistically significant loss of petroleum hydrocarbons occurred at stable temperature. Approximately 440 mg/Kg of the starting average petroleum hydrocarbon concentration (38%) were lost by the 56th day of the experiment. Approximately 163 mg/Kg of was lost from the volatilization control reactors and 97 mg/Kg of from the fluctuating temperature reactors.
The second experiment showed a statistically significant 41% reduction of petroleum hydrocarbon concentrations at a stable temperature from a starting average concentration of approximately 13,000 to an ending average concentration of approximately 7,680 mg/Kg. Less than 650 mg/Kg was lost due to volatilization and approximately 333 mg/Kg from the fluctuating temperature reactors.
The bulk of the petroleum hydrocarbon loss was due to biotic processes, indicated by increased carbon dioxide in reactor effluent gas at stable temperature. The soils also showed significant growth of petroleum hydrocarbon-degrading microorganisms. No carbon dioxide above background concentrations was measured for the sterile, volatilization controls or the fluctuating temperature reactors. Therefore, it appears that temperature fluctuations have an inhibitory effect on biodegradation of petroleum hydrocarbons in Antarctic soils.
Leszkiewicz, Conrad George, "The effect of freeze /thaw temperature fluctuations on microbial metabolism of petroleum hydrocarbon contaminated Antarctic soil" (2001). Doctoral Dissertations. 22.