Radiocarbon measurements in South Pacific Ocean waters in the vicinity of the subtropical convergence zone.

Abstract

Radiocarbon distribution profiles have been measured along three transects in the southern Pacific, two east of New Zealand and one east of Tasmania. Use of accelerator mass spectrometry (AMS), with its small-sample-size capability, made it possible to sample near-surface waters with a depth resolution of a few tens of meters. Sampling of deeper water was guided by salinity and temperature data transmitted by a CTD probe. In the case of measurements taken over the Chatham Rise, east of New Zealand, the radiocarbon profiles are highly structured, and can be correlated with known circulation patterns in this region. The other two sets of data are less influenced by the local bathymetry, and show profiles more typical of the deep ocean. The results will be discussed in terms of the rate of penetration of bomb-radiocarbon they imply, and their significance for ocean-atmosphere exchange of carbon-dioxide.