Impact of Air Pollutant Mixtures on Forest Vegetation and Soils

This report describes both the accomplishments to date and the long-term plans of the joint project between the Toxic Substances Program of the Canadian Forestry Service and the Research Management Division of Alberta Environment. No evidence of impact on jack pine physiology was found when concentrations of the dominant pollutants from Oil Sands operations equivalent to 104 years of soluble disposition were added to intact soil cores. Evidence indicates that the surface litter layer or LFH horizon plays a dominant role in protecting both the mineral soil and established plants from pollutant effects either through an improved nutrient balance or by complexing the pollutants. Several major cations increase in solubility with the addition of SO4 and nutrient depletion may occur in field situations. Metal pollutants did not enhance the solubility of cations as has been reported elsewhere. The lichen Evernia mesomorpha responded to S02 at lower levels than reported elsewhere and demonstrated that it was indeed sensitive to this pollutant. Further work is required to clarify the response of this lichen's physiology and sulphur uptake during fumigation with S02.