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Dissolved Solute Sampling Across an Oxic-Anoxic Soil-Water Interface Using Microdialysis Profilers
Published on: March 24, 2023
Insights into colloid-mediated trace element release at the soil/water interface
Mathieu Pédrot1, Aline Dia, Mélanie Davranche
1CNRS-UMR 6118, Géosciences Rennes, University of Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France. mathieu.pedrot@univ-rennes1.fr
Journal of Colloid and Interface Science
|June 17, 2008
Summary
Organic and inorganic colloids mobilize trace elements in soils and waters, influenced by environmental factors. Humic substances, particularly humic acids, are key carriers for many insoluble trace elements and rare earth elements, controlling their transport and speciation.
Area of Science:
- Environmental Chemistry
- Soil Science
- Geochemistry
Background:
- Colloids significantly influence trace element mobility in soil and aquatic systems.
- Environmental factors like pH and redox potential control colloidal mobilization.
Purpose of the Study:
- To investigate colloid-mediated trace element mobilization at the soil/water interface over time.
- To identify the roles of different organic compounds and colloidal phases in trace element transport.
Main Methods:
- Soil column experiments using percolating synthetic solutions.
- Ultrafiltration of percolated solutions to separate colloidal phases.
- Measurement of dissolved organic carbon and trace element concentrations in separated phases.
Main Results:
- Organic compounds were classified by aromaticity and molecular weight (microbial metabolites, fulvic acids, humic acids).
- Trace elements were grouped based on their association with colloidal phases: truly dissolved, intermediate, and organically bound.
- Fulvic acids primarily carried Cu, Cd, Co, and Ni; humic acids, especially those with iron nanoparticles, mobilized insoluble elements like Pb, Ti, U, and rare earth elements (REE).
Conclusions:
- Humic substances are crucial for the colloidal transport of insoluble trace elements, either directly binding them or stabilizing carrier phases like iron nanoparticles.
- Humic substances significantly control REE speciation and fractionation patterns, with the humic substance/metal ratio being a key factor.
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