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. Δ 14 C of DIC at the southernmost station was higher than those further north, which reflects reduced upwelling in the southern region. Crabs and anchovies had Δ 14 C values significantly lower than surface DIC Δ 14 C, indicating the incorporation of ‘older', sediment-derived carbon sources from their diets. Comparisons are made between our DIC Δ 14 C measurements and those obtained during other cruises and at a coastal site, from 1959 through 1987. Two distinct time histories of DIC Δ 14 C are apparent for the post-bomb period: 1) a lower Δ 14 C curve for sites close to the coast influenced by enhanced coastal upwelling; and 2) a higher Δ 14 C curve for sites further offshore within the California Current.