Large decadal-scale changes in uranium and bicarbonate in groundwater of the irrigated western U.S

Science of the Total Environment
By: , and 

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Abstract

Samples collected about one decade apart from 1105 wells from across the U.S. were compiled to assess whether uranium concentrations in the arid climate are linked to changing bicarbonate concentrations in the irrigated western U.S. Uranium concentrations in groundwater were high in the arid climate in the western U.S, where uranium sources are abundant. Sixty-four wells (6%) were above the U.S. EPA MCL of 30 μg/L; all but one are in the arid west. Concentrations were low to non-detectable in the humid climate. Large uranium and bicarbonate increases (differences are greater than the uncertainty in concentrations) occur in 109 wells between decade 1 and decade 2. Similarly, large uranium and bicarbonate decreases occur in 76 wells between the two decades. Significantly more wells are concordant (uranium and bicarbonate are both going the same direction) than discordant (uranium and bicarbonate are going opposite directions) (p < 0.001; Chi-square test). The largest percent difference in uranium concentrations occur in wells where uranium is increasing and bicarbonate is also increasing. These large differences occur mostly in the arid climate. Results are consistent with the hypothesis that changing uranium concentrations are linked to changes in bicarbonate in irrigated areas of the western U.S.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Large decadal-scale changes in uranium and bicarbonate in groundwater of the irrigated western U.S
Series title Science of the Total Environment
DOI 10.1016/j.scitotenv.2017.01.220
Volume 586
Year Published 2017
Language English
Publisher Elsevier
Contributing office(s) California Water Science Center
Description 9 p.
First page 87
Last page 95
Country United States