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 × 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 μcc(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
DOI 10.1029/2002WR001797
Volume 39
Issue 12
Year Published 2003
Language English
Publisher American Geophysical Union
Description Article 1331; 12 p.