MEASUREMENT OF RADIOACTIVITY IN ARIZONA GROUNDWATER USING IMPROVED ANALYTICAL TECHNIQUES FOR SAMPLES WITH HIGH DISSOLVED SOLIDS

Radiochemical analyses of 667 samples collected over the 5-y period 19 89 to 1993 indicate that approximately 2% of Arizona drinking water su pplies from groundwater sources violate current regulatory standards. About 1% of the population is affected. The 1996 change in regulatory requirements will bring some Arizona water systems into compliance thr ough Ra-226 limit relaxation, while others will become noncompliant du e to new limits on uranium levels. Maximum concentrations in Arizona o f adjusted gross alpha, gross beta, and Ra-226 activities are higher t han levels found in the U.S. Environmental Protection Agency's nationa l survey. Sampling results show a correlation between radionuclide con centration and localized geology. Improved radiochemical methods are d escribed that result in greater accuracy and sensitivity for samples h igh in dissolved solids, as are typical in Arizona.