| Summary: | The control exerted by underlying geological formations, topography and time in governing physico-chemical variability of shallow waterbodies is documented for Schefferville. Nouveau-Quebec and Igloolik Island, N.W.T. The highly resistant siliceous bedrock of the Labrador Trough in the Schefferville area produced very dilute surface waters with more or less equivalent concentrations of major cations. Dolomitic limestone and dolostone on Igloolik Island resulted in highly mineralized surface waters dominated by Ca$ sp{2+}$, Mg$ sp{2+}$ and HCO$ sb3 sp-$, with contributions by Na$ sp+$ and Cl$ sp-$ increasing with coastal proximity. Sediments from the Schefferville area possessed low concentrations of Ca and Mg indicative of noncarbonate bearing substrate, contrasting to the calcareous nature of the sediments from Igloolik Island. Sediment concentrations of Al, Fe and Mn from the Schefferville area were elevated compared to sediment concentrations on Igloolik Island. The disparity in trace metal concentrations in sediments between the two study areas is attributed to the enrichment of these elements in the Labrador Trough, as well as the general trace metal dilution encountered in limestone and dolostone. Principal Component Analysis with Varimax Rotation for surface waters of Igloolik Island revealed four factors accounting for 98% of the total variance confirming controls exerted by sea-salt spray and lithological substrate in moderating surface water chemistry. Differential rates of weathering at certain sites on Igloolik Island are suggested by dissimilar factor loading scores.
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