Distribution of Radiocarbon in the Southwestern North Pacific

Abstract

Radiocarbon measurements in seawater samples taken at six stations in the southwestern North Pacific visited during the International Atomic Energy Agency (IAEA) 1997 Pacific Ocean Expedition were carried out at the accelerator mass spectrometry (AMS) facility of the Japan Atomic Energy Research Institute (JAERI). Three stations were located close to GEOSECS stations, and three were in the vicinity of Bikini and Enewetak Atolls, which may be influenced by former nuclear weapons testing. Compared with the GEOSECS data (1973), our results show an increase of 14C in intermediate waters. Furthermore, it is estimated that bomb-produced 14C inventories in the water column have increased by more than 20% during the last 24 years. However, vertical profiles of Δ14C at the stations near Bikini and Enewetak Atolls show a similar general trend to those found in other stations.