Radiological sampling and analytical methods for National Primary Drinking Water Regulations.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Radiochemistry

Background:

• National Interim Primary Drinking Water Regulations require radiological sampling and analysis.
• Current screening methods for radium and uranium may not accurately reflect contaminant levels.

Purpose of the Study:

• Evaluate current radiological sampling and analysis procedures.
• Identify problems and recommend changes to the U.S. Environmental Protection Agency (EPA) Office of Drinking Water program.

Main Methods:

• Review of analytical screening schemes, sample handling, and method selection.
• Assessment of data reliability and identification of future analytical needs.
• Discussion of alternative analytical approaches for radium and uranium.

Main Results:

• The primary issue is using gross alpha-particle activity and 226Ra to predict 228Ra, as levels can be unrelated in some aquifers.
• Compliance measurements for gross alpha-particle activity minus Ra, Rn, and U rely on chemical U analysis, assuming isotopic equilibrium which is not always valid.

Conclusions:

• Alternative analytical methods are needed to accurately determine 228Ra levels and ensure compliance with maximum contaminant levels (MCLs).
• Radiometric uranium analysis is necessary for groundwaters with known disequilibrium between 238U and 234U.
• Further studies on analytical uncertainties, sampling, and sample maintenance are recommended, along with incorporating methods for additional radionuclides.