| Project Title |  |
| Project
B4: Chemical speciation of metals in fresh waters, atmospheric precipitation, and
other liquid/solid environmental media.
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| Research Team | |
| C.L. Chakrabarti,
Carleton Univ. Email: chuni_chakrabarti@carleton.ca Tel: 613-520-7400 D. Grégoire,
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| Project Summary | |
| The first objective of this project is to determine the environmental factors that control the release of humic-bound trace metals as free metal ions (which are widely reported to be bioavailable and toxic) in freshwaters. This goal is important, as humic substances are ubiquitious in the aquatic and the terrestrial environment. A second important goal is to develop new techniques for determination of speciation parameters: dissociation rate coefficient (which is a measure of the chemical reactivity), diffusion coefficient (which is a measure of the mobility), and stability constant (which is a measure of the equilibrium availability of free metal ions. Investigation into the competitive binding of metal ions revealed the crucial role of major cations, Ca2+ and Mg2+ in the release of humic-bound target metal nickel as free Ni2+ ion. Also, recently developed techniques for metal speciation were explored in synthetic solutions: Adsorptive Cathodic Stripping Voltammetry and Rotating Disk Electrode Voltammetry/Anodic Stripping Square Wave Voltammetry to determine free-metal ion concentrations in soil solutions and in soil samples. | |