Thesis Abstracts 2003
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Bioremediation of Hydrocarbon-Contaminated Soils at Canadian Forces Station Alert
By: Jason Mauchan MSc. (Environmental Science)
Supervisors: Dr. Kenneth Reimer and Dr. Barbara A. Zeeb
Abstract
Hydrocarbon fuel, predominantly diesel, constitutes the most prevalent type of contaminant at Canadian Forces Station (CFS) Alert, located at the northern tip of Ellesmere Island, Nunavut. Recent spills, as well as chronic inputs over the 50 years of station operations, have caused extensive contamination and have resulted in two distinct types of fuel-contaminated soils: ‘new spill’ soils and weathered soils. Unfortunately, remediation techniques at isolated northern sites, such as CFS Alert, are limited by accessibility and cold climates. Bioremediation, the use of microorganisms to destroy organic contaminants, is the one viable treatment option for the clean-up of hydrocarbon-contaminated soils at CFS Alert. The focus of this thesis was to treat contaminated soils, build upon previous high Arctic bioremediation studies, and implement a remediation strategy for previously contaminated as well as future spill areas.
Landfarm and biopile treatments were constructed to remediate diesel-contaminated soils. ‘New spill’ and weathered soils were successfully treated in landfarms that were periodically tilled. Blanket-insulated 35-m3 biopiles were effective at maintaining optimum temperatures.
Treatments were monitored over time for total petroleum hydrocarbons (TPH), carbon-scans, and microbial population counts. ‘New spill’ landfarms had limited TPH decreases after one summer and decreases of up to 94% after one year. Weathered soil landfarms had limited TPH decreases after one year and up to a 93% decrease after two years. Weathered soil biopiles had no discernible TPH decreases after two years. The carbon-scans indicated that, for the landfarms, the lighter-end hydrocarbons were preferentially being reduced over time. For the biopiles, the carbon-scans indicated that the light-end had been completely lost before one year of treatment. Microbial population counts for hydrocarbon-degraders indicated that generally over time there were increases for all treatment scenarios. Laboratory experiments confirmed that hydrocarbon contamination in Alert weathered soil is very persistent. Mineralization of dodecane occurred in previously uncontaminated soils but was inhibited by the presence of historical contamination.
