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The distribution of sea ice meltwater and meteoric water in the eastern Canadian Arctic has been studied by oxygen isotope techniques. The distribution pattern of sea ice meltwater is presented. A comparison of the relative amounts of sea ice meltwater and meteoric water in the surface layer shows that more than 25% of all the samples with sea ice input contained more sea ice input than meteoric input. Sea ice meltwater/meteoric water ratios as high as 4.7 have been observed. The depth of sea ice meltwater penetration varies from 50 m in Baffm Bay to 140 m in Lancaster Sound. Calculated sea ice thicknesses range from 0.5 to 4.5 m with a mean of 1.5 m, in good agreement with ice core data. The significance of sea ice meltwater for chemical, physical, and biological oceanography is briefly discussed. The principles and limitations of using oxygen isotopes to detect brines are discussed in the Baffm Bay setting. The isotopic compositions of possible source waters for Baffm Bay bottom water are examined. INTRODUCTION In arctic regions the composition of surface seawater is in-. fluenced by freshwater derived from both the melting of sea ice and the input of meteoric waters•precipitation, land runoff, and glacial melt. A full understanding of the chemistry and physics of such regions would require the knowledge of the spatial and temporal distributions of these low-salinity inputs. At the present time it is not possible to determine the individual contributions of each of these four sources in reducing the surface salinity and causing other surface layer changes. Stable isotope measurements can, however, distinguish between sea ice meltwater and the combined input of meteoric water from the other three sources. Redfield and Friedman [1969] showed that the D/H ratios of freshwaters derived from the melting of sea ice are substantially heavier (i.e., higher) than those derived from meteoric waters. Since 180/160 ratios behave in the same way [e.g., Craig, 1961], this distinction is equally well made by 180/•60 measurements. The isotopic difference between meteoric waters and seawater has long been recognized [Epstein and Mayeda, 1953]. However, freshwater derived from the melting of sea ice has an isotopic composition very similar to that of the seawater from which it was formed IRedfield and Friedman, 1969; O'Neil, 1968; Tan and Fraser, 1976]. It is therefore possible to use the oxygen isotope-salinity relationship to determine in situ concentrations of sea ice meltwater and meteoric water. Redfield and Friedman [1969] used D/H ratios to demonstrate the presence of sea ice meltwater in arctic surface waters. The present paper describes an 180/•60 study of the distribution of sea ice meltwater and meteoric water in the eastern Canadian Arctic based on samples collected in 1976 and 1977. This work extends that of Redfield and Friedman [1969] to a wider, more intensively sampled geographic area. Furthermore, we provide the first quantitative estimates of sea ice melt concentrations and their variations with depth and loca...

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Temperature, salinity, nutrient, tritium, and oxygen isotope data collected during the Lomonosov Ridge Experiment along a drift track between the Makarov and Fram Basins over the Lomonosov Ridge are presented. The relationship of these quantities to the processes that maintain the halocline, in particular to the production of more saline waters by addition of brines formed during the freezing of seawater, is described. The results support the idea that the wide continental shelves of the Arctic Ocean play an important role in maintaining the halocline. ß ß ß o ß ß ß ß Fig. 2. Salinity versus depth at LOREX station. Solid circles, profile 1' open circles, profile 2.

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