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Ionic strength reduction and flow interruption enhanced colloid-facilitated Hg transport in contaminated soils
Yingjia Zhu1, Lena Q Ma2, Xiaoling Dong1
1Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
Journal of Hazardous Materials
|December 10, 2013
Summary
Reducing ionic strength and interrupting flow significantly increased colloidal mercury (Hg) release from contaminated soils. Organic matter in colloids acts as a key carrier for mercury transport.
Area of Science:
- Environmental Science
- Geochemistry
- Soil Science
Background:
- Mercury (Hg) contamination in soils poses environmental risks.
- Understanding mercury transport mechanisms is crucial for remediation.
- Colloidal particles can mobilize contaminants in soil leachate.
Purpose of the Study:
- To investigate the impact of ionic strength reduction and flow interruption on colloidal mercury release.
- To identify the role of soil organic matter and other fractions in mercury transport.
- To determine the primary carriers of mercury in leachate under altered flow conditions.
Main Methods:
- Column leaching experiments were conducted on two mercury-contaminated soils.
- Ionic strength was reduced from 5mM to 0.05mM.
- Flow interruption (7 days) was simulated; leachate was analyzed for colloidal mercury, organic matter, and iron.
Main Results:
- Both ionic strength reduction and flow interruption substantially increased colloidal mercury release (44-48% of total released Hg).
- Peak colloidal mercury concentrations (27.8 and 360 μg/L) were observed after flow interruption.
- Colloidal organic matter and iron concentrations correlated with colloidal mercury, indicating their role as carriers.
Conclusions:
- Colloidal organic matter is a significant carrier for mercury transport in soils, particularly under reduced ionic strength and flow interruption.
- Altered hydrological conditions can enhance the mobilization of mercury-bound colloids.
- Findings highlight the importance of considering colloidal transport in mercury-contaminated site assessments and management.
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