Return to search

Mechanisms regulating sulfate movement in some podzols from Quebec

The reaction of sulfate with six podzolic horizons of the Southern Laurentians (Quebec) was investigated using batch reaction techniques. It was demonstrated that sulfate sorption increased with decreasing solution pH to a maximum sorption capacity at around pH 4.0; below this pH retention decreased. This drop in sorption capacity was related to the partial dissolution of Al surface coatings. Indeed, the amount of native sulfate and the maximum sorption during the experiment were positively correlated (R$ sp2$ = 0.982, 0.800) with the oxalate extractable Al content of these forested soils. In all six horizons, the increase in sulfate sorption as a function of equilibrium sulfate concentration was best described by the Gunary equation. Kinetic experiments showed the presence of two major stages in both sorption and desorption reactions with an initial quick change (first 6 h) in solution concentration being followed by a second step where the reactions between sulfate and the soil matrix were much slower. The time-dependence of these reactions emphasized the appropriateness of kinetic equation in describing field situations. Moreover, kinetics studies performed under highly acidic conditions demonstrated that the amount of sulfate sorbed decreased with time after an initial sorption step due to the partial dissolution of Al surface materials. Thermodynamic calculations further suggested the subsequent precipitation of jurbanite. It was then concluded that surface dissolution and mineral formation should be considered in the interpretation of results obtained from experiments aimed at determining the effect of pH on sulfate retention.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.75774
Date January 1988
CreatorsCourchesne, François
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageDoctor of Philosophy (Department of Renewable Resources.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 000725417, proquestno: AAINL46168, Theses scanned by UMI/ProQuest.

Page generated in 0.0017 seconds