Stable isotopes of hydrogen, carbon, nitrogen and oxygen are present in significant amounts in all the natural materials. However, their abundances are not invariant. The natural variations in stable isotopes of a given element can arise due to many factors and some of these are tractable through theoretical calculations. The change in isotope content of an element from one phase/compound to another is termed as fractionation. There are two basic mechanisms of fractionation—kinetic and equilibrium which can be linked to the nature of the associated reactions.The variations in the natural materials can be used to trace the processes undergone by these systems. Various environmental issues like pollution, global warming, changes in ocean productivity, tracing pathways of carbon cycle etc., can be addressed by measurement of the stable isotope ratios in the relevant materials. This talk will give an introduction to this subject as well as discuss some recent discoveries in this area.
