Investigation of radioactivity in selected drinking water samples from Maryland

In 2004, levels of radioactivity exceeding federal drinking water standards were found by state laboratories in two separate areas of Maryland through gross alpha and beta screening measurements. It was desired to know which radionuclides were responsible for the activity and what effect water softener systems installed in individual households had on the mitigating problem. Non-destructive gamma-spectrometry and gross alpha-beta liquid scintillation measurements, as well as chemical separations followed by measurements of 222 Rn, 226 Ra and 228 Ra, uranium and thorium isotopes, 210 Po, and 210 Pb were carried out by National Institute of Standards and Technology (NIST). The results of the studies indicated disequilibrium among the decay products in the Th and U decay chains had a major influence on the radionuclide content. Unsupported 210 Po was found to be the predominant radionuclide in drinking water at one of the locations. Furthermore, the influence of the use of water softeners was found to be much more effective for radium than for uranium.