SEA-ICE AND OXYGEN ISOTOPES IN FOXE BASIN, HUDSON-BAY, AND HUDSON STRAIT, CANADA

The summer distribution of sea ice meltwater and river runoff and the surface circulation in Fore Basin, Hudson Bay, and Hudson Strait have been studied by oxygen isotope techniques. On the basis of oxygen isot ope and salinity relationships, the reduction of surface salinity in s ummer in Fore Basin is predominantly due to sea ice meltwater. River r unoff and sea ice meltwater contribute equally to the summer surface l ayer in northern Hudson Bay. The isotopic data clearly show the flow o f Fore Basin water through Roes Welcome Sound into northwestern Hudson Bay, but no evidence for this outflow is found in the passages connec ting Hudson Bay and Hudson Strait. Oxygen isotopes indicate that recen t river runoff is concentrated in a narrow band along the south side o f Hudson Strait. The wide variety of relationships between oxygen isot ope ratios and salinity is explained by the known ice dynamics and the seasonal variability predicted from ice melting and freezing models.