OXYGEN-ISOTOPE STUDY OF WATER MASSES IN THE PRINCESS-ELIZABETH TROUGH, ANTARCTICA

Data from a hydrographic survey located in the Princess Elizabeth Trou gh, near the Antarctic continent (63-65 degrees S, 85 degrees E) are p resented and discussed. This region is covered by sea-ice for most of the year with the ice-edge retreating to the southern edge of the Trou gh during summer. Water samples were collected during the Austral summ er, February 1993, to determine the ratio of the oxygen-18 to oxygen-1 6 isotope, delta(18)O. Four water bodies are characterised by their te mperature, salinity and delta(18)O properties, Surface Water (0.0-1.2 degrees C, 33.1-34.0, -0.39 parts per thousand), Winter Water (-1.7 de grees C, 34.4, -0.39 parts per thousand), Warm Deep Water (2.0 degrees C, 34.69, 0.02 parts per thousand) and Bottom Water (-0.43 degrees C, 34.669, -0.25 parts per thousand). The Bottom Water is warmer, saltie r and heavier isotopically than Weddell Sea Bottom Water (-0.9 degrees C, 34.65, -0.29 parts per thousand); and has T-S properties close to that of classical Antarctic Bottom Water (-0.4 degrees C, 34.66). This Bottom Water is isotopically distinct from the Weddell Sea derived Bo ttom Water that Ventilates the Indian ocean through the Kerguelen-Croz et gap. A mechanism for local formation of the Bottom Water involving freezing of Surface Water and entrainment of Warm Deep Water is descri bed.