Determining the extent of biodegradation of fuels using the diastereomers of acyclic isoprenoids.

Improved testing and remediation procedures for sites contaminated with petroleum hydrocarbons are a priority in remote cold regions such as Antarctica, where costs are higher and remediation times are longer. Isoprenoid/n-alkane ratios are commonly used to determine the extent of biodegradation at low levels but are not useful once the n-alkanes have been removed. This study demonstrates how the diastereomers of the acyclic isoprenoids can be used to determine the extent of biodegradation in moderately biodegraded fuel in soils from a bioremediation trial at Casey Station, Antarctica.

Using real-time PCR to assess changes in the hydrocarbon-degrading microbial community in Antarctic soil during bioremediation.

A real-time polymerase chain reaction (PCR) method to quantify the proportion of microorganisms containing alkane monooxygenase was developed and used to follow changes in the microbial community in hydrocarbon-contaminated Antarctic soil during a bioremediation field trial. Assays for the alkB and rpoB genes were validated and found to be both sensitive and reproducible (less than 2% intrarun variation and 25-38% interrun variation). Results from the real-time PCR analysis were compared to analysis of the microbial population by a culture-based technique [most probable number (MPN) counts].

Fertilization stimulates anaerobic fuel degradation of antarctic soils by denitrifying microorganisms.

Human activities in the Antarctic have resulted in hydrocarbon contamination of these fragile polar soils. Bioremediation is one of the options for remediation of these sites. However, little is known about anaerobic hydrocarbon degradation in polar soils and the influence of bioremediation practices on these processes.

Investigation of evaporation and biodegradation of fuel spills in Antarctica: II-extent of natural attenuation at Casey Station.

In many temperate regions, fuel and oil spills are sometimes managed simply by allowing natural degradation to occur, while monitoring soils and groundwater to ensure that there is no off-site migration or on-site impact. To critically assess whether this approach is suitable for coastal Antarctic sites, we investigated the extent of evaporation and biodegradation at three old fuel spills at Casey Station. Where the contaminants migrated across frozen ground, probably beneath snow, approximately half the fuel evaporated in the first few months prior to infiltration at the beginning of summer.

Investigation of evaporation and biodegradation of fuel spills in Antarctica. I. A chemical approach using GC-FID.

Little effort has been devoted to differentiating between hydrocarbon losses through evaporation and biodegradation in treatability studies of fuel-contaminated Antarctic soils. When natural attenuation is being considered as a treatment option, it is important to be able to identify the mechanism of hydrocarbon loss and demonstrate that rates of degradation are sufficient to prevent off-site migration. Similarly, where complex thermally enhanced bioremediation schemes involve nutrient addition, water management, air stripping and active heating, it is important to appreciate the relative roles of these mechanisms for cost minimisation.

Effects of temperature on mineralisation of petroleum in contaminated Antarctic terrestrial sediments.

Although petroleum contamination has been identified at many Antarctic research stations, and is recognized as posing a significant threat to the Antarctic environment, full-scale in situ remediation has not yet been used in Antarctica. This is partly because it has been assumed that temperatures are too low for effective biodegradation. To test this, the effects of temperature on the hydrocarbon mineralisation rate in Antarctic terrestrial sediments were quantified.