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Future Use of Tritium in Mapping Pre‐Bomb Groundwater Volumes

Future Use of Tritium in Mapping Pre‐Bomb Groundwater Volumes The tritium input to groundwater, represented as volume‐weighted mean tritium concentrations in precipitation, has been close to constant in Tucson and Albuquerque since 1992, and the decrease in tritium concentrations at the tail end of the bomb tritium pulse has ceased. To determine the future usefulness of tritium measurements in southwestern North America, volume‐weighted mean tritium levels in seasonal aggregate precipitation samples have been gathered from 26 sites. The averages range from 2 to 9 tritium units (TU). Tritium concentrations increase with site latitude, and possibly with distance from the coast and with site altitude, reflecting local ratios of combination of low‐tritium moisture advected from the oceans with high‐tritium moisture originating near the tropopause. Tritium used alone as a tool for mapping aquifer volumes containing only pre‐bomb recharge to groundwater will become ambiguous when the tritium in precipitation at the end of the bomb tritium pulse decays to levels close to the analytical detection limit. At such a time, tritium in precipitation from the last one to two decades of the bomb pulse will become indistinguishable from pre‐bomb recharge. The threshold of ambiguity has already arrived in coastal areas with a mean of 2 TU in precipitation and will follow in the next three decades throughout the study region. Where the mean tritium level is near 5 TU, the threshold will occur between 2025 and 2030, given a detection limit of 0.6 TU. Similar thresholds of ambiguity, with different local timing possible, apply globally. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ground Water Wiley

Future Use of Tritium in Mapping Pre‐Bomb Groundwater Volumes

Eastoe, C.J.; Watts, C.J.; Ploughe, M.; Wright, W.E.
Ground Water , Volume 50 (1) – Jan 1, 2012
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References (17)

Publisher
Wiley
Copyright
© 2011, The Author(s). Ground Water © 2011, National Ground Water Association
ISSN
0017-467X
eISSN
1745-6584
DOI
10.1111/j.1745-6584.2011.00806.x
pmid
21361928
Publisher site
See Article on Publisher Site

Abstract

The tritium input to groundwater, represented as volume‐weighted mean tritium concentrations in precipitation, has been close to constant in Tucson and Albuquerque since 1992, and the decrease in tritium concentrations at the tail end of the bomb tritium pulse has ceased. To determine the future usefulness of tritium measurements in southwestern North America, volume‐weighted mean tritium levels in seasonal aggregate precipitation samples have been gathered from 26 sites. The averages range from 2 to 9 tritium units (TU). Tritium concentrations increase with site latitude, and possibly with distance from the coast and with site altitude, reflecting local ratios of combination of low‐tritium moisture advected from the oceans with high‐tritium moisture originating near the tropopause. Tritium used alone as a tool for mapping aquifer volumes containing only pre‐bomb recharge to groundwater will become ambiguous when the tritium in precipitation at the end of the bomb tritium pulse decays to levels close to the analytical detection limit. At such a time, tritium in precipitation from the last one to two decades of the bomb pulse will become indistinguishable from pre‐bomb recharge. The threshold of ambiguity has already arrived in coastal areas with a mean of 2 TU in precipitation and will follow in the next three decades throughout the study region. Where the mean tritium level is near 5 TU, the threshold will occur between 2025 and 2030, given a detection limit of 0.6 TU. Similar thresholds of ambiguity, with different local timing possible, apply globally.

Journal

Ground Water – Wiley

Published: Jan 1, 2012

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