As soon as a plant or animal dies, they cease the metabolic function of carbon uptake; there is no replenishment of radioactive carbon, only decay.
There is a useful diagrammatic representation of this process given here Libby, Anderson and Arnold (1949) were the first to measure the rate of this decay.
The rapidity of the dispersal of C14 into the atmosphere has been demonstrated by measurements of radioactive carbon produced from thermonuclear bomb testing.
14C also enters the Earth's oceans in an atmospheric exchange and as dissolved carbonate (the entire 14C inventory is termed the carbon exchange reservoir (Aitken, 1990)).
Founded in 2002 by Nobel Laureate Carl Wieman, the Ph ET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations.
Ph ET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.
There are three principal isotopes of carbon which occur naturally - C12, C13 (both stable) and C14 (unstable or radioactive).
These isotopes are present in the following amounts C12 - 98.89%, C13 - 1.11% and C14 - 0.00000000010%.
Libby of the University of Chicago in immediate post-WW2 years.
Libby later received the Nobel Prize in Chemistry in 1960: (From Taylor, 1987).
A wide range of nuclear techniques are used by archaeologists to determine the age of items.
Artefacts such as the Shroud of Turin, the Dead Sea Scrolls and Charlemagne’s Crown can be dated, and their authenticity verified, using nuclear techniques.
Nuclear techniques can also be used to determine the origins of an item and even the production process used.