The transfer between the ocean shallow layer and the large reservoir of bicarbonates in the ocean depths occurs at a limited rate.--or rather, its relative absence—is therefore used to determine the relative contribution (or mixing ratio) of fossil fuel oxidation to the total carbon dioxide in a given region of the Earth's atmosphere.
Dating a specific sample of fossilized carbonaceous material is more complicated.
One of the frequent uses of the technique is to date organic remains from archaeological sites.
Plants fix atmospheric carbon during photosynthesis, so the level of C level for the calculation can either be estimated, or else directly compared with known year-by-year data from tree-ring data (dendrochronology) up to 10,000 years ago (using overlapping data from live and dead trees in a given area), or else from cave deposits (speleothems), back to about 45,000 years before the present.
Carbon dioxide also dissolves in water and thus permeates the oceans, but at a slower rate.
has been estimated to be roughly 12 to 16 years in the northern hemisphere.
When cosmic rays enter the atmosphere, they undergo various transformations, including the production of neutrons.
The resulting neutrons ( but attempts to directly measure the production rate in situ were not very successful.
The different isotopes of carbon do not differ appreciably in their chemical properties.
Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California.