Dating of groundwater with 85Kr, 39Ar, and 81Kr
Abstract
The noble gas radioisotopes 85Kr, 39Ar, and 81Kr are ideal tracers for environmental water and ice samples. Together with 14C, they cover an age range from a few years to 1.3 million years. 81Kr-dating, a concept pursued over the past five decades has become available recently to the earth science community at large due to the development of the Atom Trap Trace Analysis (ATTA) method [1,2]. In order to meet the increasing demands from the earth science community, we have established a new laboratory dedicated to radiokrypton and radioargon dating. For 85Kr- and 81Kr -dating, we can measure samples as small as 1-2 μL STP of Kr gas, which is contained in about 10-20 kg of water or ice. This allows us to perform radiokrypton dating not only on groundwater but also on glacier ice and ocean water. A setup for 39Ar is currently been commissioned requiring a sample size of 1-2 mL STP of argon, corresponding to a few kg of water or ice. Here, we will present our latest developments on radiokrypton and radioargon dating, including ATTA systems, degassing devices for groundwater, purification systems for dual krypton/argon output as well as examples of groundwater studies in semi-arid regions. [1] Z.-T. Lu, Tracer applications of noble gas radionuclides in the geosciences, Earth-Science Reviews 138, 196-214, (2014) [2] W. Jiang et al., An atom counter for measuring 81Kr and 85Kr in environmental samples. Geochim. Cosmochim. Acta 91, 1-6, (2012) http://atta.ustc.edu.cn/en-us/events/attaprimer.html
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- April 2019
- Bibcode:
- 2019EGUGA..21.3279G