Nuclear weapons testing brought about a reaction that simulated atmospheric production of carbon 14 in unnatural quantities.
The carbon 14 produced reacts with oxygen atoms in the atmosphere to form carbon dioxide.This carbon dioxide is no different from those produced by carbon 12 and carbon 13; hence, carbon dioxide with carbon 14 has the same fate as those produced with the other carbon isotopes.The change in global radiocarbon levels brought about by human activities necessitated the use of a reference standard for carbon 14 dating. National Bureau of Standards had been adopted as standard for radiocarbon dating.Radiocarbon dating needed an organic material that was not contaminated with carbon 14 from fossil fuel burning or nuclear weapons testing. Its radiocarbon content was theoretically the same as a wood sample grown in AD 1950, the zero point of the radiocarbon timescale used in quoting carbon dating results.The World Ocean Circulation Experiment from 1990 to 2002 obtained radiocarbon measurements from dissolved inorganic carbon.
Reidar Nydal and Knut Lovseth have made radiocarbon measurements in atmospheric carbon dioxide from the northern and southern hemispheres from 1962 to 1993.The Geochemical Ocean Section Study analyzed ocean water samples from the Atlantic, Pacific, Indian, and Mediterranean Oceans and mapped the presence of bomb carbon.Results of the study have enabled modelers to analyze the pathway of radiocarbon and its exchange and residence times.The other assumption is the corollary of the first; the biosphere has the same overall concentration of radiocarbon as the atmosphere due to equilibrium.Radiocarbon’s entry into the global carbon cycle starts in the atmosphere where it is formed by the interaction of neutrons produced by cosmic rays with nitrogen atoms.The level of bomb carbon was about 100% above normal levels between 19.