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A Porous Flow Model for Steady State Transport of Radium in Groundwater
Author(s) -
Davidson M. R.,
Dickson B. L.
Publication year - 1986
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/wr022i001p00034
Subject(s) - aquifer , radium , limiting , groundwater , uranium , radionuclide , isotope , tracer , geology , groundwater flow , hydrology (agriculture) , soil science , environmental science , chemistry , geotechnical engineering , radiochemistry , physics , nuclear physics , mechanical engineering , engineering
The quasi‐steady variation of uranium and radium isotopes from the decay of 238 U, 235 U, and 232 Th has been determined along an idealized, one‐dimensional aquifer which is a distributed source of activity and from which the transfer of radionuclides to solution occurs by alpha recoil and chemical exchange. The model includes the effects of dispersive flow and retardation by adsorption. The importance of these effects on the variation of U and Ra activity ratios along the model aquifer is shown. Predicted limiting activity ratios (for large flow times) of 226 Ra/ 223 Ra, 224 Ra/ 228 Ra, and 226 Ra/ 228 Ra are 21.4, 1.5, and (∼1.7–2.0) (U/Th) s , respectively (where (U/Th) s is the activity ratio 238 U/ 232 Th in the aquifer rocks), although in many cases, an aquifer may not be long enough for the ratios involving 226 Ra to achieve their limiting values.