234U/230TH Ratio as an Indicator of Redox State, and U, TH, and RA Behavior in Briney Aquifers

Abstract

AbstractThe 234U/230Th ratio serves as an in-situ indicator of the redox state in groundwater aquifers. The higher this ratio, the more U there is in the +6 valance state and thus a less reducing environment. Radium sorption is retarded in the shallow aquifer and is dependent on the CaSO4 content and the redox state. Relative to Ra, U and Th are highly sorbed. The total retardation factor for Th is ∼1400 and mean sorption time for 228Th is ∼10 days in the shallow zone. The desorption rate of Ra is significantly slower in the shallow than in the deep aquifer. There is no effect of colloids in brines.