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Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario

Water Resources Research

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Abstract

Profiles of 4He in pore water were measured in clay aquitards in SW Ontario. The 4He distributions are consistent with groundwater velocities that are <6 mm yr-1, and thus diffusion is the dominant transport mechanism for 4He. Modeling indicates that the effective diffusion coefficient for 4He is 6.3 ?? 1.6 x 10 -6 cm2 s-1. Furthermore, the profiles are consistent with the internal release of 4He from aquitard sediments at a rate of 0.03-0.13 ??cc(STP) kg-1 yr-1. These rates are also consistent with laboratory release experiments and, on average, are 600 times greater than the production of 4He from U/Th decay. Modeling and the ratio of 21Ne to 4He within the sediments indicate that although the aquitards were deposited about 13 kA BP, the sediments released >70% of initial 4He for 50 to 60 kA prior to incorporation into the till.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario
Series title:
Water Resources Research
Volume
39
Issue:
12
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Water Resources Research