• Ages of groundwater in Israel

Objective

An integrative knowledge of water residence time can give insight into the behavior of aquifers. We apply and further develop the newly available tracers, 81Kr and 85Kr, to determine the residence time of groundwater.

Technical Approach

In order for the new tracers to become more reliable and widely available, we improve the sample preparation efficiency and the measurement accuracy of Atom Trap Trace Analysis (ATTA).

Accomplishments

  • Apparatus for gas extraction in the field and Kr purification in the lab were developed and successfully deployed
  • Calibration and laser tuning methods for ATTA improved the measurement reliability
  • Groundwater samples acquired from Israel are currently being analyzed

Next Steps

A second field sampling campaign in FY2015; further technical developments in the labs of Argonne and UChicago.

Impact

The acquired 81Kr ventilation age ranged up to 236 ka, recharged from Sinai Desert. The long ventilation ages of these groundwater samples suggest that it followed the pronounced groundwater flow trajectory within the Nubian Sandstone aquifer from the Sinai Desert toward the Dead Sea. The oldest sample provides a rough estimate of flow rate to be 1.7 m/year for a straight trajectory.