River Kymijoki in southern Finland is highly contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), which mainly originate from the production of wood preservatives until the 1980s. These compounds are of major concern due to their extreme toxicity and high resistance to microbial degradation and the Kymijoki River is a notable source of PCDD/Fs into the Gulf of Finland which seriously affects fisheries in the Baltic. Microbial reductive dechlorination of PCDD/Fs in sediments is an important environmental process, because it has the potential of decreasing the toxicity of PCDD/Fs if lateral chlorines are removed. Dechlorination may also be advantageous because lesser chlorinated congeners of PCDD/Fs are more susceptible to subsequent aerobic degradation. However, little is known about the anaerobic microorganisms that mediate reductive dechlorination of PCDD/Fs, nor which populations are active in contaminated sediments.
The project builds on our prior work demonstrating the potential for enhancing microbial dehalogenation activity in contaminated sediments. Our preliminary studies indicate that sediments from Kymijoki River contain active populations of native dechlorinating bacteria with potential for dechlorination of the historical PCDFs contaminants. Importantly, dechlorination at lateral substituted positions of historical PCDFs, would result in detoxification of contaminated sediments. The overall objectives of the project are to assess the potential for anaerobic microbial dechlorination of PCDD/Fs in sediments of River Kymijoki. The anticipated result of the research is an understanding of the microbial in-sediment processes involved in dechlorination of PCDD/F contaminants. Specifically, we will gain information on the potential for using of microbial dechlorination for bioremediation and detoxification of Kymijoki River sediments. This information is pivotal for assessing long-term treatment options and will lay the foundation for development of effective treatment technologies.
The project is a collaborative effort between the University of Helsinki Department of Ecological and Environmental Sciences, the Finnish Environment Institute (SYKE) and Rutgers University.
Researchers: Hui Liu, Sanna Kuokka and Joong-Wook Park
Funding: Maj and Tor Nessling Foundation
Collaborators:
Anna-Lea Rantalainen, University of Helsinki, Department of Ecological and Environmental Sciences
http://www.helsinki.fi/ecology/info/annalearantalainen.htm
Timo Kairesalo, University of Helsinki, Department of Ecological and Environmental Sciences
http://www.helsinki.fi/ecology/homepage/kairesal/
Matti Verta, Finnish Environment Institute (SYKE)
http://wwwp.ymparisto.fi
