VARIABILITY OF DISSOLVED INORGANIC RADIOCARBON AT A SURFACE SITE IN THE NORTHEAST PACIFIC OCEAN

Abstract

We report radiocarbon measurements of dissolved inorganic carbon (DIC) in surface water samples collected daily during 12 cruises to Station M in the northeast Pacific off central California. Individual surface Delta(14)C values ranged from 22 parts per thousand to 70 parts per thousand over 10 yr. Variability of average cruise values is highest during winter likely due to increased mixing. A general decrease of Delta(14)C values was observed at a rate of about 3 parts per thousand per year between 1994 and 2004, about half of that in atmospheric CO(2) during this period (Levin and Kromer 2004). The Delta(14)C results ranged from 2-18 parts per thousand during individual cruises and were often significantly larger than the total uncertainty for individual measurements (+/- 3.9 parts per thousand). This indicates that a single Delta(14)C result from a surface site is not sufficient to capture the true variability of Delta(14)C in the surface ocean.