Radiocarbon in Dissolved Organic Carbon and Inorganic Carbon in the Pacific Ocean

Ellen R M Druffel1, Sheila Griffin2, Ning Wang3,4, Christian Blair Lewis5, Noreen Garcia6, Niels Hauksson5, Ann P McNichol7, Robert M Key8 and Brett Walker9, (1)University of California Irvine, Department of Earth System Science, Irvine, CA, United States, (2)University of California Irvine, Irvine, CA, United States, (3)Nanjing University, Nanjing, China, (4)Chinese Academy of Sciences, State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry,, Beijing, China, (5)University of California Irvine, Earth System Science, Irvine, CA, United States, (6)University of California Irvine, Irvine, United States, (7)Woods Hole Oceanographic Institution, Geology and Geophysics, Woods Hole, MA, United States, (8)Princeton Univ, Princeton, NJ, United States, (9)University of Ottawa, Department of Earth and Environmental Sciences, Ottawa, ON, Canada
Abstract:
We report dissolved organic carbon (DOC) ∆14C and δ13C values in seawater collected from meridional sections of the central (P16) and east (P18) Pacific Ocean. Surface DOC ∆14C values are low in equatorial and polar regions where upwelling occurs, and high in subtropical regions dominated by downwelling. A core feature of these data is that 14C aging of DOC and dissolved inorganic carbon (DIC) in Antarctic Bottom Water are equivalent. We conclude that DOC ages in bottom water as it flows northward, similar to that of DIC. This is in contrast to 14C aging of DOC and DIC in other water masses of the deep ocean. We also observe minimum Δ14C values (−550‰ to −585‰) between the depths of 2,000 and 3,500 m, indicating that there are sources of ancient carbon or utilization of young carbon in the deep ocean.