Dissolved gases in the milk river aquifer, Alberta, Canada

Andrews, J.N.; Drimme, R.J.; Loosli, H.H.; Hendry, M.J. (1991). Dissolved gases in the milk river aquifer, Alberta, Canada. Applied geochemistry, 6(4), pp. 393-403. Pergamon 10.1016/0883-2927(91)90039-R

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Geochemical relations between the noble gases,40Ar/36Ar ratio, N2 and CH4 contents of groundwaters from the Milk River aquifer, Albert, Canada, have been investigated. The CH4 contents for many of the groundwaters are several times their N2 contents and cause degassing to occur as the hydrostatic pressure decreases during their ascent in the wells. Recharge temperatures, derived for those groundwaters that were not degassed, indicate that the youngest groundwaters were recharged under cooler climatic conditions than prevailed during earlier recharge. This conclusion is supported by the stable isotope compositions of the groundwater. The4He concentration in the groundwater varies with depth according to the theoretical concentration/depth profile for accumulated radiogenic4He in the aquifer and its adjacent shales. The corresponding flux of4He to the atmosphere is <2% of the total crustal4He production rate. Excess radiogenic40Ar is associated with CH4 and both gases originated within the adjacent shales. The CH4 is biogenic and was produced in an aqueous environment which ranged from marine to freshwater as the connate fluids in these marine shales were replaced. The degassing process has been modelled to explain the residual dissolved gas contents of the groundwater and to show that the CH4/N2 ratio in situ was ∼12.

Item Type:	Journal Article (Original Article)
Division/Institute:	08 Faculty of Science > Physics Institute > Climate and Environmental Physics
UniBE Contributor:	Loosli, Heinz Hugo
Subjects:	500 Science > 530 Physics
ISSN:	0883-2927
Publisher:	Pergamon
Language:	English
Submitter:	BORIS Import 2
Date Deposited:	15 Sep 2021 10:07
Last Modified:	05 Dec 2022 15:52
Publisher DOI:	10.1016/0883-2927(91)90039-R
URI:	https://boris.unibe.ch/id/eprint/158563