A long-lived radioactive isotope of chlorine, , having seventeen protons and nineteen neutrons, and a half-life of 3x10 years; it can be used to date samples of groundwater. Chlorine is an isotope of chlorine. Chlorine has two stable isotopes and one radioactive isotope: the cosmogenic isotope 36Cl. In the top meter of the lithosphere, 36Cl is generated primarily by thermal neutron activation of 35Cl and spallation of 39K and 40Ca. In the subsurface environment, muon capture by 40Ca becomes more important.
Chlorine-36 dating of deep groundwater from northern Sahara
Skip to search form Skip to main content. Moysey and L. Natural production of the radionuclide chlorine 36Cl has provided a valuable tracer for groundwater studies.
Groundwater dating is an important step in understanding how much groundwater will be available over the long term, especially important at a time when drought is diminishing above-ground fresh water resources in the U. The process involves using isotopes in groundwater to calculate just how long the water has been in the subsurface, comparable to how archeologists use carbon dating with fossils. So knowing the age of aquifers would give you an idea of how long it took and how valuable that resource is. Using what he calls first-of-its-kind equipment in his lab, Lu is able to determine the age of such old groundwater by quantifying the concentration of krypton isotopes in a given groundwater sample.