Environmental isotopes isotope. For example, H (tritium) is a radioactive isotope of hydrogen. It decays into He with a half-life of ~12.3 years. By comparison, stable isotopes are more stable, decaying much more slowly and having much longer half-lives. Examples of stable isotopes are Sr and Sr. These isotopes of strontium have half-lives on the order of billions of years or are unmeasured because of how stable they are. On timescales that geologists and environmental scientists investigate, these isotopes are stable. Both of these types of isotopes are useful to scientists. Radioactive isotopes are generally more useful on shorter timescales, such as
Tritium be accredited to the mixing of runoff of freshwater from nearby lands due to large amounts found in coastal waters. Typically, lower concentrations were found between 35 and 45 degrees south latitude and near the equator. Results also indicated that (in general) tritium has decreased over the years (up to 1997) due to the physical decay of bomb tritium in the Indian Ocean. As for water vapor, the tritium concentration was approximately one order of magnitude greater than surface seawater concentrations (ranging from 0.46 to 1.15 Bq/liter). Therefore, the water vapor tritium is not affected by the surface seawater concentration;