| Project Title |  |
| Project
A4: Geochemical mobility of metals in surface sediments:
Influence of sediment diagenesis.
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| Research Team | |
| R. Carignan,
Univ. de Montréal. Email: carignan@ere.umontreal.ca Tel: 514-343-7239
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| Project Summary | |
| The objective
of this project is to determine to what extent and under what
circumstances lake sediments can provide useful historical records of
trace-metal loadings from the atmosphere. The approach is to compare
sediment metal profiles between sites exposed to atmospheric
deposition of anthropogenic metals with those obtained in remote sites
receiving negligible amounts of airborne metals. Three undisturbed
lakes (considered to be exposed to moderate levels of atmospheric
pollution) at Haute-Mauricie have been selected and duplicate cores
taken. Porewater samplers for various analyses were installed and
removed. Cores were sectioned and freeze-dried for analysis. Lakes at
a remote site (Sept-Iles), which are chemically similar to the Haute-Mauricie
lakes, were identified and fieldwork will be conducted in July 2000.
Results from Haute-Mauricie lakes show that there are no signs of
bioturbation. Pb demonstrates no post-depositional mobility, while Cs
and dissolved Hg profiles indicate substantial mobility of these
elements. Porewater sampler and sediment solids analysis will be
completed in March 2000.
Method development for in situ measurements of labile trace metals show that the technique of Diffusion Gradients in Thin Films is not useful for measuring trace metal species in lakes with low cation concentrations. |
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