WOCE AMS RADIOCARBON .1. PACIFIC-OCEAN RESULTS (P6, P16 AND P17)

AMS radiocarbon results from the World Ocean Circulation Experiment in the Pacific Ocean show dramatic changes in the inventory and distribu tion of bomb-produced C-14 since the time of the GEOSECS survey (8/73- 6/74). Near-surface Gamma(14)C values for the eastern portion of both the northern and southern subtropical gyres decreased by 25-50 parts p er thousand, with the change being greater in the north. Equatorial ne ar-surface values have increased by ca. 25 parts per thousand. Changes in the 250-750-m depth range are dramatically different between the n orthern and southern basins. The intermediate and mode waters of the s outhern basin have increased by as much as 75 parts per thousand since GEOSECS. Waters of similar density in the northern hemisphere are not exposed to the Southern Ocean circulation regime and are significantl y less ventilated, showing maximum changes of 50 parts per thousand.