226Ra and 228Ra in Water Supplies

An early objective of this study was to develop a method for predicting the concentration of radium in well waters based on the well's location, the details of its construction, and the geological structures it penetrates. However, as in Aurora, Ill., 226Ra concentrations ranging from 3.8 to 18 pCi/L were found for wells of nearly identical construction located within relatively short distances from each other. Even larger deviations were found for comparisons among cities. The 228Ra concentration was determined in 140 of these samples and ranged from 0.3 to 32 pCi/L. Data obtained by other investigators in Iowa put the median 228Ra to 226Ra ratio at 0.64. Regression analysis, however, does not suggest any meaningful correlation of 228Ra and 226Ra. Because high concentrations of 228Ra have been found in areas with low 226Ra concentrations and 228Ra is not detected by gross‐alpha analysis, it appears that a large‐scale survey of 228Ra in water is needed.