Minimally disturbed intact bedrock cores were collected under anaerobic conditions. Diffusion of TCE both parallel and normal to bedding was measured, and abiotic reaction with ferrous minerals was measured. Results showed that diffusion perpendicular to bedding was up to 5-times greater than diffusional flux parallel to bedding. SEM imaging showed that the observed differences in diffusion correlated with differences in the porosity measured for each orientation. Reaction with ferrous minerals also was observed. Substantial levels of reduced gases (acetylene, ethene, and ethane) were generated from all of the rock types investigated. First order TCE degradation rate constants were on the order of 10-8 s-1. Measured reaction rates were correlated to the available ferrous iron content. Based on the diffusion length scale likely encountered in situ, the reaction rates observed in the laboratory suggest that abiotic reaction between TCE and the rock matrices will have a significant impact on natural attenuation.

Diffusion and reaction of trichloethene in rock matrices: Impacts on groundwater quality

243rd National Meeting (2012)

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