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Colloid retention mechanisms in single, saturated, variable-aperture fractures
S N Rodrigues1, S E Dickson, J Qu
1McMaster University, Hamilton, ON, Canada. Sandrina.Rodrigues@gmail.com
Water Research
|November 7, 2012
Summary
Fractured aquifers retain more contaminants than previously thought. Key factors influencing contaminant transport include fracture aperture, matrix properties, and flow rate, with attachment being a primary retention mechanism.
Area of Science:
- Environmental Science
- Hydrogeology
- Geosciences
Background:
- Conventional methods for fractured aquifer characterization are insufficient, leading to uncertainties in contaminant transport assessment.
- Recent studies suggest fractured rocks possess greater particulate removal capabilities than traditionally acknowledged.
Purpose of the Study:
- To quantify the retention of Escherichia coli RS2-GFP in natural, saturated, variable-aperture fractures.
- To elucidate the relationship between contaminant retention mechanisms, fracture aperture characteristics, and flow rate.
Main Methods:
- Conducted conservative solute and E. coli RS2-GFP tracer experiments in single, natural fractures.
- Utilized a non-destructive method to determine the coefficient of variation of aperture (COV(S)) as a surrogate measure.
- Analyzed the influence of mean aperture, matrix properties, COV(S), and flow rate on particulate recovery.
Main Results:
- Fracture aperture field characterization is crucial for understanding contaminant fate and transport.
- Mean aperture, matrix properties, COV(S), and flow rate significantly impact particulate recovery.
- Attachment was identified as a more dominant retention mechanism than straining under the tested conditions.
- The primary retention mechanism within a fracture is dependent on the specific discharge.
Conclusions:
- Improved characterization of fractured aquifers requires understanding aperture field properties.
- Findings will aid in developing better tools for aquifer characterization and contaminant remediation strategies.
- The study highlights the potential to manipulate retention mechanisms for specific applications in fractured aquifer management.
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