ARCHIVED - Cleaning up the Arctic
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June 01, 2009— Montréal, Quebec
NRC is helping to clean up contaminated sites in the Arctic by harnessing naturally occurring soil bacteria.
Building on more than a decade of research, scientists at the NRC Biotechnology Research Institute (NRC-BRI) in Montréal are monitoring and enhancing the bioremediation of contaminated soils at Canadian Forces Station (CFS) Alert, Eureka and other communities in Nunavut.
Bioremediation involves the use of bacteria, fungi, plants or their enzymes to restore contaminated environments to a more pristine condition.
Soil contamination is very common in the Arctic. "Anywhere humans live, petroleum products are consumed," says Dr. Charles Greer, leader of the environmental microbiology group at NRC-BRI. "And any time this involves fuel transfer and storage, problems can arise. Leaks can occur because of pipeline breaks or simply due to the transfer of fuel from one vessel to another, because the valves and connections are subject to extreme temperature conditions. In the Arctic environment, these types of problems tend to occur more often than in temperate areas."
Arctic cleanup efforts rely heavily on local soil bacteria that have adapted to life at low temperatures. "Some bacteria can survive and grow at sub-zero temperatures," explains Dr. Greer. The soil bacteria of interest have "biodegradation pathways" — specialized enzymes that allow them to feast on fuel hydrocarbons, PCBs and other contaminants. "We have identified genes from these pathways, and are using gene tools to track and quantify how particular genes may change in frequency with time and with treatment," he says.
In the Arctic, the bioremediation of contaminated soils is limited by temperatures and nutrient levels. "For every 10 degree Celsius increase in temperature, an enzymatic reaction essentially doubles," says Dr. Greer. "Since a bacterium is essentially a bag of enzymes, its growth rate and metabolic function are temperature dependent. Also, there are limited nutrients available for soil bacteria because there is so little plant material and hence very little organic matter to break down."
At CFS Alert, NRC-BRI is helping the Department of National Defence clean up hydrocarbon-contaminated soils. To compensate for the low nutrient levels, "we're stimulating soil microorganisms with fertilizer and then monitoring the microbial population, including how it changes over time and how it changes in response to the addition of fertilizers," says Dr. Greer. "We're also monitoring the microbial population's degradation of specific hydrocarbons — namely compounds that are present in fuel — and measuring how their degradation activity responds to different treatments."
"In addition, we're looking at bacterial population indicators," he adds. "We're interested in how the overall microbial community in the soil responds to the initial contamination event and how it recovers during the course of the bioremediation."
Dr. Greer says cleanup efforts are going very well. "In some soil that we started treating in 2005, the bacterial population has eaten virtually all of the hydrocarbons that were initially present. We're now using this soil to mix with freshly contaminated soil that contains very low numbers of the same microbes. The idea is to get more 'catalysts' into the system by adding bacteria that are already growing and thriving."
In addition to their monitoring work, NRC-BRI researchers are studying the microbial diversity in various Arctic environments, including permafrost, to provide baseline data on indigenous bacterial communities as well as the potential impacts of pollution stress and global warming on their structure and function.
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