¹⁴C in air over the Arabian Sea

Abstract

Global monitoring of radiocarbon in atmospheric CO₂ began during the mid fifties to determine the time scales of exchange of radiocarbon (and CO₂) between the atmosphere and other terrestrial reservoirs. The distribution of natural radiocarbon in the environment was perturbed significantly during the 1960s through injection of ¹⁴C from nuclear weapon tests. This 'bomb ¹⁴C has proved to be an excellent tracer to characterize and quantify CO₂ exchange between various reservoirs. We have measured radiocarbon activity of marine air over the central and eastern Arabian sea during 1993-95. The mean A ¹⁴C values are 121 ±6, 116 ±6 and 105±5%o respectively for these three years. These values, in conjunction with those reported in the literature for troposphere for the decades of 60s through 80s, show that the ¹⁴C activity in the tropospheric air has been decreasing exponentially with an e-folding time of -16 years.