| 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
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| Project Summary | |
| Currently, there exists no
technique that can identify and quantify "free-metal ions" and other metal
species at concentrations that are relevant for environmental studies, i.e. at 10-7 -->
10-12 M and lower. The most promising techniques that are now available do not measure
"free-metal ions" unequivocally - they measure labile or diffusible species,
which are mixtures of "free-metal ions" and other small metal complexes. We
propose to replace current operationally-defined categories with speciation parameters
based on measurement of the characteristic times of the processes themselves, such as,
dissociation rate constants (which are a quantitative measure of the chemical reactivity,
namely, the rate of dissociation of metal complexes to form "free metal ions")
for a first-order (or pseudo-first-order) dissociation of the metal complex, diffusion
coefficients (which are a quantitative measure of the mobility of the metal complex), and
conditional stability constants (which are a quantitative measure of the thermodynamic
drive of the metal complex to generate "free-metal ions" under the particular
environmental conditions).
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