Uranium series disequilibria in ground waters from a fractured bedrock aquifer (Morungaba Granitoids--Southern Brazil): implications to the hydrochemical behavior of dissolved U and Ra.
Activity concentrations of dissolved (234)U, (238)U, (226)Ra and (228)Ra were determined in ground waters from two deep wells drilled in Morungaba Granitoids (Southern Brazil). Sampling was done monthly for little longer than 1 year. Significant disequilibrium between (238)U, (234)U and (226)Ra were observed in all samples. The variation of (238)U and (234)U activity concentrations and (234)U/(238)U activity ratios is related to seasonal changes. Although the distance between the two wells is short (about 900 m), systematic differences of activity concentrations of U isotopes, as well as of (234)U/(238)U, (226)Ra/(234)U and (228)Ra/(226)Ra activity ratios were noticed, indicating distinct host rock-water interactions. Slightly acidic ground water percolation through heterogeneous host rock, associated with different recharge processes, may explain uranium and radium isotope behavior.
Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226, CEP 05508-090 São Paulo, SP, Brazil.
Erika
E
Reyes
Leila S
LS
Marques
D001938:Brazil; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000379:methods*; D011886:Radon / Q000032:analysis*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive; D014501:Uranium; D011886:Radon