INFLUENCE OF PEATLANDS ON THE ACIDITY OF LAKES IN NORTHEASTERN ALBERTA, CANADA

About a third of the lakes surveyed in the Birch Mountains Upland of n ortheastern Alberta, Canada, have pH below 7.0; 25% have alkalinities below 10 mg/L identifying them as acid-sensitive following criteria es tablished by the National Research Council of Canada (1981). Lakes in this region vary greatly as to surface area and depth. Watersheds also vary in area and in amount of peatland cover. Peatlands in the form o f peat plateaus and collapse scars, continental bogs, treed and open f ens, and shallow organic deposits cover over 50% of some watersheds. S urface water chemistries of these peatlands form three distinct classe s: bogs, poor fens and shallow organic deposits. The acidity of certai n lakes in this northern area is best explained by effects from high c over of Sphagnum-dominated peatlands in surrounding watersheds. Due to greater flow-through, poor fens appear to be more important than bogs in affecting the acidity of associated lakes.