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Hydrogeophysical imaging of deposit heterogeneity and groundwater chemistry changes during DNAPL source zone bioremediation

Chambers, J.E.; Wilkinson, P.B.; Wealthall, G.P.; Loke, M.H.; Dearden, R.; Wilson, R.; Allen, D.; Ogilvy, R.D.. 2010 Hydrogeophysical imaging of deposit heterogeneity and groundwater chemistry changes during DNAPL source zone bioremediation. Journal of Contaminant Hydrology, 118 (1-2). 43-61. 10.1016/j.jconhyd.2010.07.001

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Abstract/Summary

Robust characterization and monitoring of dense nonaqueous phase liquid (DNAPL) source zones is essential for designing effective remediation strategies, and for assessing the efficacy of treatment. In this study high-resolution cross-hole electrical resistivity tomography (ERT) was evaluated as a means of monitoring a field-scale in-situ bioremediation experiment, in which emulsified vegetable oil (EVO) electron donor was injected into a trichloroethene source zone. Baseline ERT scans delineated the geometry of the interface between the contaminated alluvial aquifer and the underlying mudstone bedrock, and also the extent of drilling-induced physical heterogeneity. Time-lapse ERT images revealed major preferential flow pathways in the source and plume zones, which were corroborated by multiple lines of evidence, including geochemical monitoring and hydraulic testing using high density multilevel sampler arrays within the geophysical imaging planes. These pathways were shown to control the spatial distribution of the injected EVO, and a bicarbonate buffer introduced into the cell for pH control. Resistivity signatures were observed within the preferential flow pathways that were consistent with elevated chloride levels, providing tentative evidence from ERT of the biodegradation of chlorinated solvents.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.jconhyd.2010.07.001
Programmes: BGS Programmes 2010 > Groundwater Science
Additional Keywords: GroundwaterBGS, Groundwater, Groundwater monitoring, Point source pollution
NORA Subject Terms: Earth Sciences
Related URLs:
Date made live: 09 Nov 2010 11:49
URI: http://nora.nerc.ac.uk/id/eprint/12030

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