Carbon dating system accuracy
In order to ascertain the ages of samples which were formed in equilibrium with different reservoirs to these materials, it is necessary to provide an age correction.Implicit in the Conventional Radiocarbon Age BP is the fact that it is not adjusted for this correction.Thus, it dilutes the activity of the lake meaning that the radioactivity is depleted in comparison to 14C activity elsewhere.
A CRA is derived using an age calculation based upon the decay corrected activity of the absolute radiocarbon standard (1890 AD wood) which is in equilibrium with atmospheric radiocarbon levels (as mentioned previously, 1890 wood is no longer used as the primary radiocarbon standard, instead Oxalic Acid standards I and II were correlated with the activity of the original standard).The volcanic effect has a limited distance however. (1980) found that at 200 m away from the source, plants yielded an age in agreement with that expected.They suggested that the influence of depleted CO2 declined rapidly with increasing distance from the source.The effect of this has been to almost double the amount of C14 activity in terrestrial carbon bearing materials (Taylor, 1987).
De Vries (1958) was the first person to identify this 'Atom Bomb' effect.Reservoir corrections for the world oceans can be found at the Marine Reservoir Correction Database, a searchable database online at Queen's University, Belfast and the University of Washington.