courtesy of Apollo 17!

Earth, The Water Planet

The stable isotopes of oxygen and hydrogen (the elements constituting 100% of water molecules!) serve as sensitive tracers of Earth's water cycle.   Stable isotope data, integrated with other geochemical tracers (e.g., tritium, strontium isotopes, water solute chemistry), have been increasingly applied in assessments of modern water resources, affording complex modeling of local-to-global scale precipitation patterns and climatic variation, and detailed study of groundwater sources, movement, and contamination.  Isotopic data for waters and hydrous minerals (e.g., clays, micas) also yield insight into deeper-Earth hydrogeology, allowing us to trace the volatiles emitted by active volcanoes and examine the roles of Earth's hydrosphere in plate tectonics.
 

Understanding Earth's (near-surface) Water Cycle

It is extremely important that we fully understand the cycling of water on Earth, as the vitality of the hydrosphere is obviously intimately linked to that of the biosphere.  In particular, we have learned that Earth's precious freshwater reservoirs are finite and directly impacted by human activities.  Stable isotope data will continue to figure prominently in attempts to model global and more local water budgets, strategize the more efficient use of our freshwater reservoirs, and understand, even predict, short-term climatic variation.

courtesy of IAEA/GNIP

Some Sources of Background Information on Stable Isotopes and Their Applications in Hydrogeological Studies

1. A brief, easy-to-read description of the utility of O and H isotopes in studies of Earth's water cycle can be found at the GNIP (Global Network for Isotopes in Precipitation) website (click here).

2. I. Clark and P. Fritz's on-line text ("Environmental Isotopes in Hydrology") provides excellent, more detailed background on aspects of the applications of stable (and other) isotopes in hydrologic studies (click here).  Then click on "Table of Contents".

Click on globe for Main LIHS Page