PHYSICAL AND CHEMICAL LIMNOLOGY OF NORTHERN BOREAL LAKES, WOOD BUFFALO NATIONAL-PARK, NORTHERN ALBERTA AND THE NORTHWEST-TERRITORIES, CANADA

Physical and chemical variables were measured in 35 lakes from Wood Bu ffalo National Park, northern Alberta and the Northwest Territories, C anada. Of these lakes, 22 were sinkholes, situated on limestone and gy psum, five were situated on the Canadian Shield and eight were shallow 'muskeg' lakes located on calcareous shales. All of the lakes were sm all to moderate in size. For each of the 35 lakes, 37 environmental va riables were measured. Principal component analysis (PCA) revealed tha t underlying geology strongly influenced limnic properties. Shield lak es were characterized by higher concentrations of Al and Fe, and lower pH values, specific conductivities and concentrations of ions such as , Ca, SO4, Li, Mg and Na, than either the sinkhole or the muskeg lakes . The muskeg lakes were differentiated from the sinkhole lakes by decr eased Secchi depth owing to higher concentrations of dissolved organic carbon (DOC) and greater productivity, as evidenced by high concentra tions of particulate organic carbon (POC) and chlorophyll a. Nitrogen (NH3 and NO2) was also notably higher at these sites. The 22 sinkhole lakes were further classified by the type of surrounding vegetation. S ix vegetation groups were recognized: (1)spruce; (2) pine; (3) mixed; (4) shrubs/poplar; (5) recently burned and (6) rocky. These vegetation groups largely reflect fire history, but also differences in soils an d drainage. Unlike geology, surrounding vegetation, and therefore rece nt fire history, generally had little influence on limnic properties. PCA showed that of the six vegetation groups, only the spruce lake gro up, which was characterized by high levels of DIG, was distinct.