ON THE USE OF CARBON-TETRACHLORIDE AS A TRANSIENT TRACER OF WEDDELL SEA DEEP AND BOTTOM WATERS

Antarctic bottom waters have long been known to be a mixture of Circum polar Deep Water and Shelf Water. Recent observations show that in the Antarctic bottom waters of the Scotia Sea and northern Weddell Sea, t he ratios of carbon tetrachloride (CCl4) to chlorofluorocarbons (CFC-1 1, 12) are inconsistent with the ratios observed in the surface layer of the Weddell Sea. This is the result of a deficit of CCl4 in the bot tom waters, and renders the compound unsuitable for use as a transient tracer from which apparent ages can be derived directly. The summer n ear-surface temperature minimum of Antarctic Surface Water exhibits a similar inconsistency, demonstrating that CCl4 can be removed from col d waters with high oxygen levels, probably through a biological proces s. It is inferred that Shelf Water features a similar CCl4 deficit whi ch is transferred to the new Antarctic bottom waters upon formation, a ccounting for the observed deep CCl4 deficit.