ABSTRACT. AMS radiocarbon results from the World Ocean Circulation Experiment in the Pacific Ocean show dramatic changes in the inventory and distribution of bomb-produced 14C since the time of the GEOSECS survey (8/73-6/74). Near-surface Δ14C values for the eastern portion of both the northern and southern subtropical gyres decreased by 25-50%o, with the change being greater in the north. Equatorial near-surface values have increased by ca. 25%o. Changes in the 250-750-m depth range are dramatically different between the northern and southern basins. The intermediate and mode waters of the southern basin have increased by as much as 75%o since GEOSECS. Waters of similar density in the northern hemisphere are not exposed to the Southern Ocean circulation regime and are significantly less ventilated, showing maximum changes of ca. 50%o.
[Radiocarbon Volume 38, Number 3, 1996]