Premium
Radon in groundwater: A tool to assess infiltration from surface waters to aquifers
Author(s) -
Hoehn E.,
Von Gunten H. R.
Publication year - 1989
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr025i008p01795
Subject(s) - radon , groundwater , aquifer , infiltration (hvac) , hydrology (agriculture) , tracer , environmental science , surface water , geology , groundwater discharge , soil science , radium , groundwater flow , geotechnical engineering , environmental engineering , geography , chemistry , radiochemistry , physics , quantum mechanics , meteorology , nuclear physics
We measured the concentrations of natural 222 Rn (half‐life 3.8 days) in groundwater at three sites in Switzerland; here groundwater is recharged mainly by river water. Upon infiltration and movement in the ground, the radon concentration in the water increases by more than two orders of magnitude to reach a steady state. This increase was found at two of the three sites. At the site of main interest, we used the ingrowth of radon between the river and nearby observation wells to estimate groundwater residence times of up to about four half lives. We assumed that the ingrowth of radon can be described by the growth law of radioactivity, that the progenitors of radon ( 226 Ra, 238 U) are homogeneously distributed in the aquifer, and that the freshly infiltrated water is not mixed significantly with older groundwater. A linear regression through the data at the site of main interest yielded an average flow velocity of 4.6 m −1 , which confirms earlier tracer observations. Radon accumulates to higher concentrations, when the top soil layer is frozen or exhibits a high moisture content. During these conditions the radon data cannot be used for dating purposes.