Parameter Tree:
EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > RADIOISOTOPES

Definition:
Any radioactive form of a chemical element, having the same atomic weight
as that element (i.e. same number of protons), but a different number of
neutrons. Used in a variety of oceanic applications such as dating and
movement of water masses.  


Reference:
Adapted from: Webster's College Dictionary. 1991. Random House.