Journal article
Multidimensional Investigation of Bedrock Heterogeneity/Unconformities at a DNAPL-Impacted Site
Ground water, Vol.55(4), pp.532-549
07/2017
DOI: 10.1111/gwat.12514
PMID: 28405963
Abstract
Organic solvent (i.e., dense nonaqueous phase liquid, DNAPL) migration in the subsurface is known to be extremely sensitive to geologic heterogeneity. There is often a focus on heterogeneity that results from changing depositional conditions over short spatial scales. Similar or even more extreme spatial heterogeneity can result postdeposition due to erosional processes. This study applies a synergistic approach based on a combination of high-resolution lithologic logs of continuous cores, borehole geophysical logs, surface electrical resistivity, and seismic refraction tomography models to assess spatial heterogeneity in a shallow bedrock sequence subject to multiple unconformities and contaminated with a mixture of organic chemicals. The persistence of DNAPL in the source zone and an associated dissolved-phase plume led to variable impacts on formation resistivity across the study site. Seismic refraction in combination with electrical resistivity tomography improved interpretation of highly irregular erosional boundaries by delineating sharp lateral transitions in lithologic composition near the source zone and across the dissolved-phase plume. Electrical resistivity was effective at differentiating between clean and mud-rich sandstones and their unconformable contact with an underlying dolostone. Geophysical measurements revealed eroded dolostone mounds encased by a network of younger mud-rich sandstones channelized by clean semi-lithified sand, all of which was buried beneath variable glacial drift. Our synergistic multidimensional approach resulted in the development of a detailed three-dimensional shallow bedrock geospatial model, which has led to an improved understanding of DNAPL migration and contaminant plume heterogeneity.
Details
- Title: Subtitle
- Multidimensional Investigation of Bedrock Heterogeneity/Unconformities at a DNAPL-Impacted Site
- Creators
- Colby M SteelmanJessica R Meyer - G360 Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, CanadaBeth L Parker - G360 Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
- Resource Type
- Journal article
- Publication Details
- Ground water, Vol.55(4), pp.532-549
- Publisher
- United States
- DOI
- 10.1111/gwat.12514
- PMID
- 28405963
- ISSN
- 0017-467X
- eISSN
- 1745-6584
- Grant note
- name: Natural Sciences and Engineering Research Council of Canada in the form of a Banting Fellowship; name: Industrial Research Chair, award: IRCPJ363783-06
- Language
- English
- Date published
- 07/2017
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983984518302771
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