The study of metal speciation and the role of biogeochemical processes in metal distribution and cycling in lake sediments was carried out in remote lakes from the Huntsville and the Clyde Forks areas, Ontario and Kejimkujik Park, Nova Scotia, Canada. Based on geochemical data and sequential extraction results of trace elements from sediment cores of 20 lakes from the Huntsville region, Ontario, Canada, it was demonstrated that relative affinities to organic matter and mineral fractions (silicates) played an important role in the distribution of total metal values and hence in the shape of the metal concentration profiles. The importance of atmospheric and geological trace metal fluxes was studied by using sediment traps in two circum-neutral remote lakes, Lavant Long Lake and Perch Lake, in Lanark County, southeastern Ontario, Canada, to measure sedimentation rates, to quantify trace element fluxes from watershed and atmospheric sources, and to investigate the distribution of elements amongst component phases of the trapped sediments. The results of this study showed that local watershed sources were the dominant source of Hg, Cu, Al, Fe, Mn, Sb, in both lakes with ratio sometimes exceeding 9:1 (geogenic to atmospheric). The study of the effect of humic substances (HS) content and their transformation on their interaction with metals was carried out in three remote lakes: Lavant Long Lake, Perch Lake; and Big Dam Lake. HS transformation was demonstrated by the increase of HA aromaticity and the decrease of the E4/E6 ratio in Lavant Long Lake, by the increase of 13C resonance signal in the aromatic-C region (105--150 ppm) in Perch Lake, and by the gradual decrease of the HS content with depth in Big Dam Lake. A quantitative study of trace metal cycling between pore waters and sediments using the most comprehensive diagenetic models was carried out using a two-layer diagenesis model to account for the bioturbation zone and the zone below the bioturbation zone. Sulfate reducing bacteria (SRB) populations were determined in the three lakes using the most probable number (MPN) method. In the zone of bioturbation of Perch Lake, Co, Cu, and Hg predicted and observed concentrations in the pore waters were close. In Lavant Long Lake and for the rest of the elements in Perch Lake, trace metal concentrations predicted by the model were generally lower than the observed. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/9071 |
| Date | January 2001 |
| Creators | El Bilali, Larbi. |
| Contributors | Fortin, Danielle, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 211 p. |
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