Isotopic uranium activity ratios in California groundwater

• Published in: Journal - American Water Works Association Vol. 91; no. 4; pp. 171 - 185
• Main Authors: Wong, Carolyn T., Okamoto, Howard S., Milea, Alexis M., Perera, S. Kusum, Baumann, Frank J.
• Format: Journal Article
• Language: English
• Published: Denver, CO American Water Works Association 01-04-1999
• Subjects: Analysis methods; Applied sciences; Average linear density; Compliance; Conversion Factors; Correlations; Drinking water; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental protection; Equilibrium; Exact sciences and technology; Fall lines; Groundwater; Groundwaters; Hydrogeology; Hydrology. Hydrogeology; Isotopes; Lasers; Measurement techniques; Natural water pollution; Pollution; Pollution, environment geology; Potable water; Public health; Radioactive decay; Regulations; Reimbursement; Sampling; Surface water; Toxicity; Uranium; USA, California; Water treatment and pollution; California; United States; North America; America; Natural origin pollution; Actinide; Chemical analysis; Uranium; Measurement result; Water pollution; Measurement method; Radioisotope; Comparative study; Ground water
• ISSN: 0003-150X; 1551-8833
• DOI: 10.1002/j.1551-8833.1999.tb08623.x

Uranium, a kidney toxicant and a radioactive material, is present at elevated concentrations in groundwater in some states. In 1991 the US Environmental Protection Agency proposed a maximum contaminant level (MCL) for uranium in drinking water off 20 µg/L or 30 pCi/L (1.1 Bq/L). In 1992 California adopted an MCL of 20 pCi/L (0.74 Bq/L). Because California regulations permit analysis of uranium by either mass cur radiochemical techniques, a reliable factor that converts values from mass to activity is required to determine compliance with the California MCL and any future federal MCL. The conversion factor for groundwater may differ markedly from that of the natural crustal abundance of uranium. This study compared values determined by three mass measurement techniques and two radiochemical techniques. It is suggested that a conversion factor of 0.79 pCi/µg be used to determine compliance with the California MCL.