Geochronology in the South Florida Ecosystem and Associated Ecosystem Programs

In order to manage an ecosystem, it is imperative to define the rate at which ecologic, physical and chemical changes have occurred. The lack of historical records documenting ecological changes dictates that other methods are used to measure the rate of change. A common method of "dating" change is to measure the decay of naturally occurring radioactive nuclides.

The use of radioactive isotopes is founded on the known physical property of radioactive material, the half-life. A half-life of an isotope is the amount of time it takes for half of a given number of atoms to "decay" to another element. The age of objects that contain radioactive isotopes with known half-lives can be calculated by determining the percent of the remaining radioactive material. To use this method successfully certain other prerequisites must be met. These are: 1. the chemistry of the nuclide (element) is known; 2. Once the nuclide is incorporated into the substrate the only change is radioactive decay, and 3. in order to be useful, it is relatively easy to measure.