title: Methods for using argon-39 to age-date groundwater using ultra-low-background proportional counting.
abstract: Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years,39Ar fills an intermediate age range gap (50-1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. We present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA. Electronic address: Emily.Mace@pnnl.gov.
authors.forename: Emily
authors.initials: E
authors.lastname: Mace
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Aalseth
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Brandenberger
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Day
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Hoppe
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Humble
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Keillor
authors.affiliation: U.S.G.S. California Water Science Center, 4165 Spruance Rd., San Diego, CA 92140, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Kulongoski
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Cory
authors.initials: C
authors.lastname: Overman
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Panisko
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Allen
authors.initials: A
authors.lastname: Seifert
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Signe
authors.initials: S
authors.lastname: White
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Wilcox Freeburg
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, MSIN J4-65, Richland, WA 99352, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Williams
keywords: Age-dating; Argon-39; Groundwater; Proportional counting; Ultra-low-background