C-14 IN AIR OVER THE ARABIAN SEA

Global monitoring of radiocarbon in atmospheric CO2 began during the m id fifties to determine the time scales of exchange of radiocarbon (an d CO2) between the atmosphere and other terrestrial reservoirs, The di stribution of natural radiocarbon in the environment was perturbed sig nificantly during the 1960s through injection of C-14 from nuclear wea pon tests, This 'bomb C-14' has proved to be an excellent tracer to ch aracterize and quantify CO2 exchange between various reservoirs, We ha ve measured radiocarbon activity of marine air over the central and ea stern Arabian sea during 1993-95. The mean Delta(14)C values are 121+/ -6, 116+/-6 and 105+/-5 parts per thousand respectively for these thre e years, These values, in conjunction with those reported in the liter ature for troposphere for the decades of 60s through 80s, show that th e C-14 activity in the tropospheric air has been decreasing exponentia lly with an e-folding time of similar to 16 years.