Comparative Use of Two Radiometric Techniques for Determining Radium Activity in Simulated Surface Waters to Assess Method Suitability

Abstract

Although rapid and routine radiochemical methods are readily available for most radionuclides, methods for low-level ²²⁶Ra analysis remain limited, time-consuming, and primarily designed for assessing drinking water quality. Monitoring radium levels in environmental waters with diverse matrices and varying mineral compositions requires further understanding of the matrix effect on the analytical method. This study aims to explore these effects to ensure robust analytical methods capable of accurate measurements are achieved despite potential interferences from elevated mineral water components. This study presents a fast radio-analytical method for determining ²²⁶Ra activity concentration in natural surface water sources, utilizing two radiometric techniques, alpha spectrometry and liquid scintillation counting. The aim is to evaluate the suitability of each technique given the variations in natural water matrices resulting from industrial effluent releases. This study was specifically aimed to identify effects on sample dissolution and the quality of the source required to obtain high-resolution alpha spectrum at high chemical recovery for accurate concentration determination. In addition, another radiometric technique was implemented for measurement to compare the results obtained from alpha spectrometry. Simulated natural water samples with different mineral contents and concentrations were analyzed using both radiometric techniques to assess their suitability with regards to matrix effect. The study concludes that both alpha spectrometry and liquid scintillation counting (LSC) can be effective for determining ²²⁶Ra concentrations in environmental surface water samples, with some exceptions where high amounts of certain minerals are present in the sample. Both techniques exhibit high tolerance for magnesium, sodium, and calcium levels in the sample, but lower tolerance for barium and iron. This research provides guidance for accurately determining ²²⁶Ra concentrations in various environmental surface water or effluent samples. It also highlights the importance of evaluating mineral water content, resin capacity, and being aware of self-adsorption effects to achieve accurate measurements of ²²⁶Ra for samples with complex matrix. Although alpha spectrometry is generally the preferred technique for the determination of alpha emitters due to its lower detection limit, the LSC technique, particularly after radiochemical separation, can be advantageous for samples with higher mineral content, such as calcium, since it does not suffer from poor source quality due to self-adsorption effects.