Dominant factors controlling variability in the ionic composition of West Greenland Lakes

Over 80 lakes were sampled between the ice margin and the coast in West Greenland between 66 and 67 degreesN and analyzed for their pH, alkalinity, conductivity, and tivity values < 150 muS cm(-1). There are, however, also saline lakes (2000-4000 muS cm(-1) NaHCO(3)/CO(3), and Mg HCO(3)/CO(3)-doniinated), mainly around the head of the fjord. The main control on lake chemistry in this area is evaporation as indicated by the fossil shorelines surrounding the saline lakes. The high concentrations of Na indicate extensive inputs from either weathering or from eolian transported silts (loess) derived from the sand outwash plains at the ice sheet margin. The pattern of cation dominance in the freshwater lakes is Ca > Mg > Na > K. Variability in the water chemistry and the dominant controls oil water chemistry were examined using PCA and RDA, respectively. There is a clear gradient in lake chemistry front west to east. This trend reflects the split between the dilute coastal lakes (with higher %Cl) and the saline lakes close to the head of the fjord. Altitude is also significant and probably reflects reduced Weathering rates at upland sites (similar to 500 m) with limited vegetation cover. A number of lakes had high SO(4) concentrations (maximum > 10,000 mu eq L(-1)) and were clearly influenced by local geology.