Observations from the the Somov during the US-USSR Weddell Polynya expedition show that the mixed layer blow the sea ice just prior to the austral spring retreat in the 60 S Greenwich meridian region has an oxygen content of 7.4 ml/1. This is 86% of full oxygen saturation, representing an oxygen deficit, relative to full saturation, of 1.1 m1/1. The source of this deficit is believed to be a consequence of oxygen-poor (4.5 m1/1) Weddell Deep Water (WDW) entrainment by the winter mixed layer. Assuming effective cutoff of ocean-atmosphere oxygen exchange by the nearly complete snow and sea ice cover with do not impact of oxygen content as a result of biological factors, a mixing ratio of 1:3 for WDW to ''beginning of winter'' surface water is required to explain the end-of-winter mixed-layer oxygen content. Accompanying the WDW transfer into the mixed layer is heat transfer of approximately 7¿103 cal/cm2 (2.9¿108 J/m2) during the five winter monts of sea ice coverage as well as salt transfer, which requires 34 cm of fresh water to produce typical mixed-layer salintiy. During the seven ice-free months when entrainment is expected to be minor diffusive heat and salt flux continues. A mean annual heat flux of 12 W m3 is suggested, with an annual demand for freshwater of 46 cm/yr. Consideration of the winter period salintiy budget indicates not sea ice melting of 20 cm, which can be attributed to regional convergence of sea ice. The remaining freshwater is derived from excess predicipation and possibly iceberg melt. Oxygen undersaturation of the winter surface water suggests slightly less potential for abyssal water ventilation than might be expected from a fully saturated condition.