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Deglacial water-table decline in Southern California recorded by noble gas isotopes

December 16, 2019

Constraining the magnitude of past hydrological change may improve understanding and predictions of future shifts in water availability. Here we demonstrate that water-table depth, a sensitive indicator of hydroclimate, can be quantitatively reconstructed using Kr and Xe isotopes in groundwater. We present the first-ever measurements of these dissolved noble gas isotopes in groundwater at high precision (≤0.005‰ amu−1; 1σ), which reveal depth-proportional signals set by gravitational settling in soil air at the time of recharge. Analyses of California groundwater successfully reproduce modern groundwater levels and indicate a 17.9 ± 1.3 m (±1 SE) decline in water-table depth in Southern California during the last deglaciation. This hydroclimatic transition from the wetter glacial period to more arid Holocene accompanies a surface warming of 6.2 ± 0.6 °C (±1 SE). This new hydroclimate proxy builds upon an existing paleo-temperature application of noble gases and may identify regions prone to future hydrological change.

Citation Information

Publication Year 2019
Title Deglacial water-table decline in Southern California recorded by noble gas isotopes
DOI 10.1038/s41467-019-13693-2
Authors Alan M. Seltzer, Jessica Ng, Wesley R. Danskin, Justin T. Kulongoski, Riley Gannon, Martin Stute, Jeffery P. Severinghaus
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Communications
Index ID 70225713
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center