Chemistry of radioactive dating
Radioactive isotopes of radium, thorium, and uranium, for example, are found naturally in rocks and soil.Uranium and thorium also occur in trace amounts in water.Some of these are found in nature; the rest are produced artificially as the direct products of nuclear reactions or indirectly as the radioactive descendants of these products.Each “parent” radioactive isotope eventually decays into one or at most a few stable isotope “daughters” specific to that parent. Some radioactive isotopes are present as terrestrial radiation.In nuclear medicine, tracer radioisotopes may be taken orally or be injected or inhaled into the body.The radioisotope circulates through the body or is taken up only by certain tissues.Scientists have concluded that very little change has occurred in the ratio of Carbon-12 to Carbon-14 isotopes in the atmosphere meaning that the relationship between these two should be very similar to how they remain today.
Organic materials typically contain small amounts of radioactive carbon and potassium.
Cosmic radiation from the Sun and other stars is a source of background radiation on Earth.
Other radioactive isotopes are produced by humans via nuclear reactions, which result in unstable combinations of neutrons and protons.
The carbon isotope is when absorbed by plants through photosynthesis and consumed by animals.
Due to the way the sunlight reacts with the atmosphere, it is also taken in by respiration.