Aquatic sediments are ultimate receptors of many halogenated contaminants, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and chlorinated pesticides. Sediment treatment is currently limited primarily to dredging with ex situ treatment or sequestration and new methods are needed for in situ containment and degradation of contaminants. Although microbially mediated reductive dehalogenation of organohalides is well established, methods for treating aquatic sediments contaminated with organohalide mixtures are not yet readily available. The overall objective of this project is to stimulate anaerobic biological dechlorination, which offers the most promising approach towards eventual detoxification and complete degradation of halogenated contaminant mixtures. The project focuses on developing stimulatory amendment mixtures (e.g., bioaugmented dechlorinating bacteria, organic electron donors and halogenated co-amendments) to sediments and their placement method in conjunction with capping. Molecular tools to monitor dehalogenating bacteria are being developed and refined for use to assess the effectiveness of the remediation treatments. The technology development will be coupled with model frameworks to provide an understanding of the impacts of stimulated in situ bioremediation on contaminant redistribution and transformation product fate.
Results from micro- and mesocosm experiments indicate that the Anacostia River, Kearny Marsh, and Kymijoki River sediments contain diverse populations of dehalogenating microorganisms. We have refined and optimized a suite of molecular tools for rapid high-throughput detection, enumeration and diversity characterization of bacterial populations that reductively dehalogenate the target organohalides. Although Dehalococcoides species are the most likely candidates for PCDD/F and PCB dechlorination, there are other Chloroflexi-like microorganisms that have been shown to be active in the dechlorination. Active dechlorinating populations are present in these sediments and biostimulation may enhance the activity of both native Dehalococcoides and bioaugmented Dehalococcoides species. We have shown in micro- and mesocosm studies with different contaminated sediments that the addition of halogenated co-amendments might be one tool to enhance dechlorination of PCBs and PCDD/Fs in historically contaminated sediments. The enhanced dechlorination correlates with increased numbers of dehalorespirer populations and reductive dehalogenase genes, supporting our hypothesis that the halogenated co-substrates enhance dechlorination of historic pollutants by supporting growth and activity of dehalogenating bacteria. A combined bioaugmentation/biostimulation approach may thus be feasible for the bioremediation of sediments contaminated with PCBs and PCDD/Fs.
Researchers: Joong-Wook Park, Duong Minh Vien, Hui Liu and Francis Ortega
Publications:
Ahn Y-B, Liu F, Fennell DE, Häggblom MM (2008) Biostimulation and bioaugmentation to enhance dechlorination of polychlorinated-p-dioxins in contaminated sediments. FEMS Microbiology Ecology 66:271-281.
Ahn Y-B, Häggblom MM. Kerkhof LJ (2007) Comparison of anaerobic microbial communities amended with halogenated compounds to enhance dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin in estuarine sediments. FEMS Microbiol Ecol. 61:362-371.
Ahn Y-B, Häggblom MM, Fennell DE (2005) Co-amendment with halogenated compounds enhances anaerobic microbial dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin and 1,2,3,4-tetrachlorodibenzofuran in estuarine sediments. Environ. Toxicol. Chem. 24:2775-2784.
Häggblom MM, Fennell DE, Ahn Y-B, Ravit B, Kerkhof LJ (2006) Anaerobic dehalogenation of halogenated organic compounds: Novel strategies for bioremediation of contaminated sediments. In: Twardowska I, Allen HE, Häggblom MM (eds) Viable Methods of Soil and Water Pollution Monitoring, Protection and Remediation, Springer, pp. 505-521.
Fennell DE, Nijenhuis I, Wilson SF, Zinder SH, Häggblom MM (2004) Dehalococcoides ethenogenes strain 195 reductively dechlorinates diverse chlorinated aromatic pollutants. Environ. Sci. Technol. 38:2075-2081.
Häggblom MM, Ahn Y-B, Fennell DE, Kerkhof LJ, Rhee SK (2003) Anaerobic dehalogenation of organohalide contaminants in the marine environment. In: Laskin AI, Gadd GM, Bennett J (eds) Advances in Applied Microbiology 53:61-84. Elsevier Science, San Diego.
Funding:
Department of Defense Strategic Environmental Research and Development Program (SERDP)
Collaborators:
Donna E. Fennell, Rutgers, Department of Environmental Sciences
http://envsci.rutgers.edu/~fennell/Fennell/
Lisa Rodenburg, Rutgers, Department Environmental Sciences
http://envsci.rutgers.edu/php/totten.html
Lee Kerkhof, Rutgers, Institute of Marine and Coastal Sciences
http://marine.rutgers.edu/main/IMCS-People-Details/People-Details-Lee-J.-Kerkhof.html
Kevin Sowers, University of Maryland Biotechnology Institute, Center for Marine Biotechnology
http://www.umbi.umd.edu/comb/faculty-directory/sowers/index.php
