Significance of the distribution of bomb-produced radiocarbon in the ocean

The pattern of global water column inventories of bomb-produced radiocarbon suggests that a sizable portion of the bomb radiocarbon that entered the Antarctic, the northern Pacific, and the tropical oceans has been transported to the adjacent temperate regions. Models of lateral transport of surface water in the Atlantic, Indian, and Pacific Oceans are designed on the basis of this distribution pattern. Upwelling of bomb-radiocarbon-free water from below takes place in the Antarctic, the northern Pacific, and the tropical regions; and downwelling of surface water occurs in the temperate oceans and in the northern Atlantic. Uptake of excess CO2 by these models is calculated using the observed Mauna Loa pCO2 record as an input function. Results indicate that 35 percent of fossil fuel CO2 is taken up by these model oceans during the period 1958-1980. Considering the observed airborne fraction of 0.55, it appears that about 10 percent of the global fossil fuel CO2 is still missing. 24 refs., 5 tabs