Radiocarbon in Seawater and Organisms from the Pacific Coast of Baja California

Abstract

Radiocarbon was measured in dissolved inorganic carbon (DIC) and living organisms collected off the west coast of Baja California in October 1980. Samples from three locations were examined. Δ14C of DIC at the southernmost station was higher than those further north, which reflects reduced upwelling in the southern region. Crabs and anchovies had Δ14C values significantly lower than surface DIC Δ14C, indicating the incorporation of ‘older', sediment-derived carbon sources from their diets. Comparisons are made between our DIC Δ14C measurements and those obtained during other cruises and at a coastal site, from 1959 through 1987. Two distinct time histories of DIC Δ14C are apparent for the post-bomb period: 1) a lower Δ14C curve for sites close to the coast influenced by enhanced coastal upwelling; and 2) a higher Δ14C curve for sites further offshore within the California Current.