WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2004OH10B
Title: Rapid Characterization of PCB Contaminated Sediments toward Effective Enhanced Remediation
Project Type: Research
Focus Categories: Sediments, Surface Water, Toxic Substances
Keywords: sediments, PCBs, remediation, microbiology
Start Date: 03/01/2004
End Date: 02/28/2005
Federal Funds: $25,000
Non-Federal Matching Funds: $61,655
Congressional District: 9th District; Lucas County, OH
Point and non-point pollutant discharges combined with urban and agricultural runoff have resulted in major surface water contamination issues in the Great Lakes region. Many of the contaminants (e.g., polychlorinated biphenyls (PCBs), heavy metals) released accumulate in underlying sediments. Contaminated sediments have been identified as a major problem in 42 out of 43 Great Lakes Areas of Concern (AOCs) by the US/Canada International Joint Commission (IJC) including the Maumee River AOC in Northwest Ohio. In the Maumee River AOC, PCBs have been identified as a contaminant of concern due to discharges from industrial facilities and leaky landfills. Chlorinated aromatic compounds are considered priority pollutants in sediments because they are persistent, bioaccumulative and generally toxic contaminants. For reduction of the human and ecological risks associated with sediment contamination, enhanced recovery strategies, designed to stimulate natural fate pathways, may be preferred to conventional approaches (e.g., sediment removal and storage) which are labor intensive and may be cost-prohibitive in many locations. Diffusion of low (nano- to micromolar) concentrations of hydrogen in sediment matrices has been shown to increase electron fluxes and enzyme activity in reducing environments, resulting in the stimulation of microbial respiratory activity, and consequential dechlorination processes. However, limited information is available on design parameters for field application.
In this research, sediments from the Maumee River will be collected and characterized. Rapid sediment characterization will include physical evaluation (total organic carbon; total/volatile solids), microbial assessment (enumeration and activity assessment), and screening of PCB concentration. In addition, sediment-eluted microorganisms will be evaluated based on their demonstrated response to hydrogen-based activity enhancement. Three samples with distinct characteristics (historical PCB levels) will be selected, based on their amenability to microbial enhancement, for incubation studies with Maumee River water and hydrogen donors (fermentable substrates) in an anaerobic glove-box for up to six months. The data will be interpreted by plotting reaction endpoints (PCB loss) against relevant sediment characteristics.
The overarching goal of this proposed research is to develop a rapid characterization (physical-chemical-microbiological) protocol for determining the efficacy of hydrogen-enhanced remediation of PCB-contaminated sediments. The following specific objectives will be addressed: (i) sediment sample collection from the Maumee River; (ii) sediment sample characterization (physical-chemical-microbiological); (iii) identification of candidate sediments based on demonstrated response to hydrogen-based enhanced remediation; (iv) incubation studies to determine the efficacy of a hydrogen-based remediation strategy targeted at historical PCB contamination in selected sediments. The sediment characterization protocol will be utilized to establish relationships between sediment characteristics and dechlorination response to hydrogen enhancement in bench-top sediment slurry incubation studies. This treatment technology may be applicable to contaminated sediments in-situ or in confined disposal facilities.