Abiotic and Biotic Pathways in Chlorinated Solvent Natural Attenuation
ABSTRACT: Abiotic degradative pathways are often overlooked when evaluating natural attenuation at chlorinated solvent sites. Yet, at many sites, significant degradation of parent compounds such as 1,1,1-TCA, PCE and TCE is observed without the corresponding accumulation of daughter products, a sure indication of abiotic reactions. The problems in integrating abiotic processes into MNA are how to prove the existence of the abiotic pathways and how to apportion the degradation between biotic and abiotic pathways. Abiotic processes can be demonstrated and potentially quantified in four ways: plotting plume degradation patterns for the various chlorinated species, conducting mineralogical analyses, monitoring for unique reaction products, and finally, modifying and expanding microcosm study protocols to specifically examine abiotic reactions.