Chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), are one of the most prevalent pollutants at hundreds of Department of Defense (DoD) sites, and remain among the most difficult to remediate despite years of intense research and development. Biological degradation of PCE and TCE has been studied in some detail, however, there is still a significant knowledge gap in the understanding of how abiotic processes contribute to the degradation of PCE and TCE, in particular the formation of reactive mineral phases through biologically mediated pathways.
Dr. Michelle Scherer from the University of Iowa and her team led a SERDP funded project that studied the application of a new conceptual framework based on solid-state mineral chemistry to understand biologically mediated abiotic degradation (BMAD) of 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.
Study results have significantly improved the understanding of pathways and factors controlling abiotic degradation of PCE and TCE as well as provided an evaluation of aquifer properties used as indicators for BMAD rates and products in PCE and TCE plumes and identified strategies to accelerate the BMAD processes. These findings helped to establish a framework that can be used by DoD site managers to predict the likelihood of natural attenuation and advance the design of enhanced natural attenuation technologies.
For this significant work, Dr. Scherer and her team received the 2018 SERDP Project-of-the-Year Award for Environmental Restoration for their project titled Biologically Mediated Abiotic Degradation of Chlorinated Ethenes: A New Conceptual Framework.