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Updated: Feb 15, 2026

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Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix
Published on: June 12, 2015
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Evidence of rock matrix back-diffusion and abiotic dechlorination using a field testing approach
Charles E Schaefer1, David R Lippincott2, Harald Klammler3
1CDM Smith, 110 Fieldcrest Avenue, #8, 6(th) Floor, Edison, NJ 08837, United States.
Journal of Contaminant Hydrology
|February 4, 2018
Summary
Contaminant rebound in fractured rock was studied after flushing. Matrix back-diffusion, supported by isotopic data, was identified as the primary mechanism driving contaminant resurgence.
Area of Science:
- Environmental Science
- Geochemistry
- Hydrogeology
Background:
- Fractured rock formations are susceptible to groundwater contamination.
- Chlorinated ethenes like trichloroethene (TCE) and cis-1,2-dichloroethene (DCE) are common persistent organic pollutants.
- Understanding contaminant behavior in fractured rock is crucial for effective remediation.
Purpose of the Study:
- To investigate contaminant rebound in fractured rock after hydraulic flushing.
- To assess the role of matrix back-diffusion in contaminant resurgence.
- To evaluate the utility of isotopic analysis and modeling in understanding contaminant fate.
Main Methods:
- In situ field demonstration in fractured rock.
- Hydraulic flushing of TCE and DCE using a bedrock well pair.
- Monitoring contaminant concentrations over 151 days.
- Application of a matrix back-diffusion screening model.
- Analysis of carbon isotopic ratios.
Main Results:
- Observed contaminant rebound of TCE and DCE after flushing.
- Matrix back-diffusion model reasonably predicted TCE rebound magnitude.
- Shift in TCE:DCE ratio and carbon isotopic enrichment indicated dual biotic and abiotic dechlorination.
- Isotopic data and modeling confirmed matrix back-diffusion as the rebound mechanism.
Conclusions:
- Matrix back-diffusion is a significant mechanism for contaminant rebound in fractured rock.
- Bench-scale determined rock matrix parameters are applicable in field demonstrations.
- Carbon isotopic enrichment serves as evidence for abiotic dechlorination in rock matrices.
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