Thursday, July 30, 2009 - 10:00 AM
S145

Innovations in “in-situ” Bioremediation of Organic Compounds

Michael J. Barcelona, Department of Chemistry, Western Michigan University, Kalamazoo, Kalamazoo, MI 49008

Sources of organic contaminants are widespread and seldom removed or isolated to prevent further contamination of ground water.  This is especially true at sites at which monitored natural attenuation (MNA) approaches have been chosen as a remedy.  MNA presumes that sorption, dilution, or natural microbial degradation will reduce contaminant concentrations and also the risk of exposures.  In these cases, monitoring of the contaminant plume for parent compound concentrations is conducted over time with little attention to the microbial processes or geochemical conditions which support bioremediation.  If one were to apply the results of recent research on microbial degradative pathways and metabolite formation it would be possible to make far better decisions on whether MNA approaches are effective and protective of human health and the environment.  For example, depending on subsurface redox conditions, toluene can be degraded to ethylbenzyl alcohol, phenol, toluene-2,3 diol, or benzoic acid.  These metabolites differ substantially in their aqueous solubility, mobility, sorptive properties and potential toxicity.  The consideration of these “second order” contaminants should be incorporated into remedial decision-making.  Further examples of diverse metabolites of common contaminants will be provided from the literature.