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Influence of reducing conditions on metallic elements released from various contaminated soil samples
Priscilla Pareuil1, Sonia Pénilla, Nursen Ozkan
1Université de Limoges, Groupement de Recherche Eau-Sol-Environnement, Faculté des Sciences & Techniques, Limoges, France.
Environmental Science & Technology
|November 6, 2008
Summary
Soil redox conditions significantly impact metallic element (ME) mobility. Decreasing redox potential dramatically increases ME solubilization, particularly affecting iron and manganese (oxy)hydroxides in contaminated soils.
Area of Science:
- Environmental Chemistry
- Soil Science
- Geochemistry
Background:
- Redox conditions are crucial for metallic element (ME) mobility in soils, yet are less studied than pH.
- Understanding ME behavior under varying redox potentials is vital for environmental risk assessment.
Purpose of the Study:
- To investigate the solubilization of metallic elements from contaminated soils under controlled reducing conditions.
- To determine the relationship between redox potential and ME mobilization in diverse soil types.
Main Methods:
- A batch method using sodium ascorbate solutions was employed to establish various reducing conditions.
- Four contaminated soil samples (A-D) with different origins and compositions were analyzed.
- Redox potential was systematically decreased from +410 mV to +10 mV.
Main Results:
- Metallic element mobilization significantly increased with decreasing redox potential within specific sensitive ranges for each soil sample.
- Sensitive redox potential ranges for mobilization varied between soil samples (e.g., 220-345 mV for soil A).
- High percentages of ME mobilization were observed (e.g., up to 59% for Zinc in soil B).
Conclusions:
- Redox potential is a critical factor controlling ME mobility in soils.
- The observed ME mobilization is likely due to the combined effects of decreasing redox potential and pH on iron and manganese (oxy)hydroxides.
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