October 2013    Print this article

Reanalysis of lake-bottom sediments in Québec: Completed.

Charles Maurice
Ministère des Ressources naturelles

The reanalysis of lake-bottom sediment samples taken between 1973 and 1997 is now complete. Under the reanalysis program, launched in 2008 by the Ministère des Ressources naturelles, more than 50 chemical elements were analyzed from each sample. The analyses were carried out by inductively coupled plasma mass spectrometry (ICP-MS) following partial dissolution in aqua regia. Results were obtained for elements that had not previously been analyzed, and in the case of previously-analyzed elements, the detectable limits were better and the results were more accurate. The program therefore ends with the publication of more than 2,600 new sediment analyses from lakes in the Superior Province, north-west of the Caniapiscau Reservoir and south-west of the Opinaca Reservoir (see diagram). The new data are available in SIGEOM as of today.

Two new surveys now underway

In addition, sediment samples continue to be collected from lakes in poorly-documented or undocumented regions of Québec, through two surveys. The Abitibi-Est survey (-a- in the diagram) covers the Caopatina Strip, the Urban-Barry Belt and the Attic complex in the extreme south-eastern portion of the Abitibi Subprovince. So far, this sector has been only partially covered by till and runoff sediment surveys. Unlike the rest of the Abitibi Subprovince, this region contains very little clay. The North-East Mistassini Lake project (-b- in the diagram) is being carried out in the only other sector of Northern Québec for which no lake sediment analyses are available. The target sampling density for both surveys is one sample per six square kilometres. The samples from these new surveys are currently being analyzed and the results should be published in March 2014.

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Diagram Key
Sediment samples from lakes in Québec analyzed using ICP-MS for more than 50 elements. In yellow: more than 119,000 samples, in orange: 2,600 samples available as of today (1- project 1983050; 2- project 1995004). The red polygons show the surveys currently underway.

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