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Kinetic metal release from competing processes in aquifers
Lindsay A Bearup1, Alexis K Navarre-Sitchler, Reed M Maxwell
1Civil and Environmental Engineering Department, Hydrologic Science and Engineering Program, Water Modeling Center Colorado School of Mines 1500 Illinois Street Golden, Colorado 80401, United States.
Environmental Science & Technology
|May 17, 2012
Summary
Understanding groundwater metal release requires considering kinetic metal-desorption and mineral-dissolution. This study found desorption kinetics influence release up to two years, while dissolution is relevant for most groundwater residence times.
Area of Science:
- Geochemistry
- Environmental Science
- Hydrogeology
Background:
- Realistic groundwater modeling necessitates understanding the time scales of kinetic metal-desorption and mineral-dissolution processes.
- These kinetic mechanisms significantly influence metal release into groundwater systems.
Purpose of the Study:
- To determine the relevant time scales for kinetic metal-desorption and mineral-dissolution in groundwater.
- To provide constraints for incorporating these kinetic processes into groundwater transport models.
Main Methods:
- Compiled metal-desorption and mineral-dissolution rate constants from existing literature.
- Applied the Damköhler number analysis to calculate residence times where kinetic formulations are significant.
- Investigated competitive desorption and dissolution for an illustrative metal using geochemical models.
Main Results:
- Metal-desorption kinetics can be influential at groundwater residence times up to approximately two years, varying by metal and conditions.
- Kinetic mineral-dissolution is relevant across nearly all groundwater modeling residence times, contingent on mineral properties and availability.
- Total metal concentrations can be sensitive to mineral dissolution rate variations, even when desorption dominates release.
Conclusions:
- Kinetic metal-desorption and mineral-dissolution are critical factors in groundwater metal release modeling.
- The Damköhler number analysis provides essential insights into the temporal relevance of these processes.
- This research offers valuable constraints for enhancing the accuracy of groundwater transport models.
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