Salinity and Isotope Analysis of Some Multi-Year Landfast Sea-Ice Cores, Northern Ellesmere Island, Canada

The salinity and isotope ( 18 O, 3 H) content of multi-year landfast sea-ice (MLSI) cores from northern Ellesmere Island, Canada, are examined. Salinity ranges from 0.01‰ to 4.54‰, and δ 18 O ranges from −23.8‰ to +0.7‰. Salinity and δ 18 O are linearly related, and tritium values generally exceed natural background levels. The results are evidence of ice growth associated with fresh-water / sea-water stratification below the ice. Salinity variations are cyclic and indicate a mean annual bottom accretion rate of 0.33–0.5 m a −1 . Rather than signifying downward percolation of melt water from the surface, the ice δ values are a proxy measure of variations in salinity and 18 O content of the water below the ice. Annual salinity layers are preserved in the absence of significant brine movement and ice deformation. The fast-ice environment appears to favour the maintenance of water stratification and growth of annual layers. It is suggested that ice growth in this environment is somewhat independent of thermodynamic sea-ice growth models; instead, ice growth by a double-diffusion process might account for the growth of MLSI beyond thicknesses normally encountered in undeformed multi-year pack-ice floes.