Natural Attenuation Processes: A New Understanding
SERDP has selected a suite of projects to examine the impact of several natural processes on the fate and transport of contaminants in groundwater. Ultimately, the goal of this combined research effort is to quantify the long term impacts of natural processes on contaminants in groundwater and to estimate the resulting contaminant attenuation rate. Seven projects were selected for funding and will be initiated over the next few months.
Three researchers will be focused on issues associated with low permeability zones. Under SERDP project ER-2529, Dr. Bob Borden and his team from Solutions IES, will be working on developing methods to better characterize and model the mass transfer of contaminants between higher and lower mobility zones and its impact on the long-term release of contaminants in groundwater. Dr. Charles Werth from the University of Texas at Austin will seek to quantify the biotic and abiotic attenuation mechanisms that impact the fate of trichloroethene (TCE) within and at the boundaries of low permeability zones comprised of clays and silts under SERDP project ER-2530. The third project, ER-2533, is being led by Dr. Richelle Allen-King at the University at Buffalo and will focus on developing a field method capable of concurrently quantifying site-specific chlorinated volatile organic compound diffusion and degradation rates and sorption coefficients in low permeability zones.
Dr. Michelle Scherer from the University of Iowa will lead SERDP project ER-2532, applying a new conceptual framework based on solid-state mineral chemistry to understand biologically mediated abiotic degradation (BMAD) of tetrachloroethene (PCE) and TCE by magnetite, iron (Fe) sulfides, and Fe-bearing clays. While it has been long suspected that these minerals play an important role in BMAD of chlorinated solvents, BMAD performance has not been predictable or reproducible at the field scale, or even at the more controlled laboratory scale.
Three limited scope projects also were selected to improve our understanding of natural attenuation processes. Limited scope projects are high risk, proof-of-concept projects that are conducted within approximately one year. Dr. Paul Hatzinger of CB&I Federal Services will be evaluating the role of acidophilic methanotrophs in the natural attenuation of chlorinated ethenes in low pH aquifers under SERDP project ER-2531. Novel in situ sensors based on nuclear magnetic resonance (NMR) will be developed under SERDP project ER-2534, led by Dr. Julie Konzuk from Geosyntec Consultants. These sensors will be capable of providing improved temporal and spatial monitoring of natural attenuation processes in order to improve current monitoring practices and reduce long-term monitoring costs. Under SERDP project ER-2535, Mr. Peter Bennett from Haley & Aldrich will be developing a method for performing compound-specific isotope analysis (CSIA) on low levels of 1,4-dioxane in groundwater.
Summaries of the research projects discussed above can be found at the SERDP and ESTCP web site. In addition, all reports originating from these efforts will be available to download at the project web pages. Please contact the Environmental Restoration Program Manager if you have additional questions about this research area.