Investigators: Andreas Voegelin and Ruben Kretzschmar
Ph.D. Student: Olivier Jacquat
Long-term fate of Zn and Cd in soils of highly variable composition but with the same contamination history will be studied in this research project. During more than 50 years, these soils were contaminated with Zn and Cd from the runoff of galvanized power line towers.
The following objectives will be specifically addressed: a) Determination of the speciation of Zn and Cd in the soil matrix (X-ray absorption spectroscopy, selective sequential extraction) and in the soil solution (selective sequential batch extraction, column leaching experiments) and relate the metal speciation to soil properties (mineralogy, organic carbon, texture, acidity). b) Study the resistance of adsorbed Zn and Cd and metal-bearing mineral phases against cation exchange and soil acidification processes (selective sequential batch extraction, column leaching experiments). c) Evaluation of up-to-date adsorption models with respect to their performance in describing the Zn and Cd speciation on the soil surface and in solution and to develop methods to account for the formation of metal-bearing mineral phases. The results of this study will contribute to a more detailed qualitative understanding of the long-term fate of Zn and Cd in soils. This is the basis for an improved risk assessment and for the design of remediation stages.