Pre-Bomb Radiocarbon Variability Inferred from a Kenyan Coral Record

Abstract

We report results from AMS radiocarbon measurements (Delta-14C) in corals recovered off the coast of Kenya. Bimonthly samples which span the pre-bomb era average -51 per mil (+/3.7; n=43), when age and Suess effect are corrected, and over the time of interest (1946-1954) do not exhibit any discernible seasonality. Relative to regional pre-bomb Delta-14C values in the western Indian Ocean, our results indicate 14C enrichment off the coast of Kenya. Furthermore, the absence of a distinct subannual Delta-14C signal suggests that open and coastal upwelling is negligible off the coast of Kenya. Unlike pre-bomb values south of the equator near Seychelles and Madagascar, our pre-bomb value are enriched by more than 10 per mil. The enrichment of pre-bomb Kenyan Delta-14C values relative to sites around Mauritius, northern Madagascar and Seychelles, suggest that the influence of depleted Delta-14C water transported in the SEC is limited to regions south of 3 to 4 degrees S.