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 northeastern Alberta, Canada, have pH below 7.0; 25% have alkalinities below 10 mg/L identifying them as acid-sensitive following criteria established 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 of peat plateaus and collapse scars, continental bogs, treed and open fens, and shallow organic deposits cover over 50% of some watersheds. Surface water chemistries of these peatlands form three distinct classes: bogs, poor fens and shallow organic deposits. The acidity of certain lakes in this northern area is best explained by effects from high cover 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.