14C distribution in the Atlantic Ocean

Abstract

The amount of 14C produced by nuclear bomb testing that entered the Atlantic Ocean by late 1972 was 1.71×10−8 μmol/cm2 of ocean surface area for the west Atlantic (36°S–45°N) and 1.18×10−8 μmol/cm2 for the east Atlantic (50°S–28°N) Geochemical Ocean Sections Study stations. There are strong latitudinal differences in the integrated amount of bomb 14C content in Atlantic waters. Bomb‐produced 14C is mostly encountered near the center of the large mid‐latitude gyres, whereas the equatorial region has a lower 14C inventory. The average ocean wide vertical distribution of bomb 14C in the Atlantic can be explained by a vertical eddy diffusion coefficient of 4.0 cm2/s in the surface mixed layer plus thermocline gyre reservoirs. The average 14C activity per unit area measured in the Atlantic yields an CO2 exchange rate of 23 mol/m2 yr, which is equivalent with an atmospheric CO2 residence time of 6.8 years.