The emission of trace metals (TMs) into boreal forest regions of the northern hemisphere is an important environmental issue due to their potential detrimental impacts on these sensitive ecosystems. One of the foremost factors controlling metal cycling is the chemistry of the overlying organic forest floor of the forest soil. In this thesis we examine the chemistry of forest floor horizons of podzolic soils. Our goal is to improve our ability to predict the partitioning of metals between the soil solid and solution phases. / We developed a standard protocol to produce solutions that resemble lysimeter solutions from podzolic soils using air-dried samples. We hypothesized that the stabilization point of the electrical conductivity (EC) of the soil solution is indicative of the point in which soluble salts and organic material precipitated during sampling and storage are removed from the soil particle surfaces. Solutions produced by leaching the soils, once the EC of wash solutions had stabilized, were comparable to lysimeter solutions from the area where samples were collected with respect to the concentrations of divalent cations, pH, EC and dissolved organic carbon (DOC). The applicability of this procedure to trace metal partitioning in forest floors was explored. Laboratory extractions produced partition coefficients (log Kd) similar to observed lysimeter solutions ranging from 3.4 to 3.9 for Cd, 3.4 to 3.9 for Cu, 3.4 to 4.1 for Ni, 4.1 to 5.2 for Pb and 3.2 to 3.5 for Zn. According to a semi-mechanistic regression model based on observed lysimeter concentrations, the metal concentrations in solution were appropriate relative to known factors that influence metal partitioning in soils: pH, the concentrations of total metals and DOC. / While chemical characteristics of soils have been consistently observed to play important roles in the partitioning and toxicity of metals we wished to place the importance of the chemical characteristics of soil on mobility and toxicity in context. We interpreted field data that had been collected from transects established with distance from two point source emitters in Rouyn PQ, and Sudbury ON. Canada find developed equations that predict dissolved metal concentrations from total metal concentrations, soil pH, soil organic matter (SOM), and DOC contents. We integrated these equations into a simple box model that calculates changes in the concentration of metals in the organic and upper mineral horizons and includes a loop for vegetative return of metals to the forest floor.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85575 |
| Date | January 2005 |
| Creators | MacDonald, James Douglas |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002227120, proquestno: AAINR12895, Theses scanned by UMI/ProQuest. |
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