DISTRIBUTION OF TH-230 IN THE LABRADOR SEA AND ITS RELATION TO VENTILATION

Measurements of dissolved and particulate Th-230 and Th-232 by thermal ionization mass spectrometry were made on samples collected from the Labrador Sea and the Denmark Strait and Iceland-Scotland overflow wate rs. The large-scale feature of low and invariant Th-230 evident in dee p waters of the Labrador Sea and previously observed in the deep north ern Atlantic can be reproduced using a reversible scavenging model tha t includes the effect of ventilation. Advective transport also must be important in the redistribution of Th-230 in other regions of the Atl antic and for other long-lived tracers, such as Pa-231, Al-26 and Be-1 0. (C) 1997 Elsevier Science B.V.