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GW age determination graphicsite guide button
   The age of ground water is defined as the time since the environmental tracer or isotope (CFCs, tritium, etc.) was isolated from the atmosphere by recharge to the ground-water system. The VAS study used five different techniques to determine the age of ground water.

 
GW age determination table heading

 

 Environmental tracer/
isotope

 Age range
(years)

 Laboratory
  age determinationCFC button 0 to 60  USGS, National Research Program
CFC Laboratory
Reston, VA
  tritiumtritium button 0 to 50  USGS, National Research Program
Low-Level 3H Laboratory
Menlo Park, CA
  tritiumtritium-helium button 0 to 30   Lamont-Doherty Earth Observatory
Columbia University, NY
sulfur hexafluoridesulfur hexaflouride button 0 to 30 USGS, National Research Program
SF6 Laboratory
Reston, VA
  Carbon 14carbon 14 button 1,000 to 30,000  Environmental Isotope Laboratory
 Department of Earth Sciences
 University of Waterloo
Waterloo, Ontario
Canada

Rafter Radiocarbon Laboratory
Institute of Geological and Nuclear Sciences, Ltd.
Lower Hutt, New Zealand

 
Last Updated on 2/4/2002
By David L. Nelms
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URL http://va.water.usgs.gov/va123/3age.html
Last update: 09/15/04 12:54