Measurements of dissolved and particulate 230Th and 232Th by thermal ionization mass spectrometry were made on samples collected from the Labrador Sea and the Denmark Strait and Iceland-Scotland overflow waters. The large-scale feature of low and invariant 230Th evident in deep waters of the Labrador Sea and previously observed in the deep northern Atlantic can be reproduced using a reversible scavenging model that includes the effect of ventilation. Advective transport also must be important in the redistribution of 230Th in other regions of the Atlantic and for other long-lived tracers, such as 231Pa, 26Al and 10Be.
Bibliographical noteFunding Information:
We wish to acknowledge the support ~otf he IOC, the Canadian government for use of the1C SS Hudson. the Captain and crew of the CSS H dson, Chief Scientist P.A. Yeats and the NSF for sp 1 nsoring the IOC cruises. We are grateful to R.F An erson, M.P. Bacon. W.S. Broecker, H.N. Edmon s and two anonymous reviewers for thorough and, 1 critical reviews. Lynn Hettinger corrected an e or in our original calculations. This work was fun ed by NSF grants OCE-9408945 to SBM and 0 1’ E-9203150, OCE-9402693. and EAR-94061 83 to RUE. &lKj
- Labrador Sea