Advancing environmental monitoring: A comparative analysis of sequential radiochemical methods for precise alpha-particle spectrometry analysis of 241Am in soil and marine sediment samples

Environmental monitoring of alpha-emitting radionuclides is crucial for assessing the long-term impacts of nuclear activities and understanding ecosystem dynamics. Thus, long-term marine environmental monitoring needs a precise analytical method for determining isotopes in sediment and soil samples. Because 241Am is the first decay product of 241Pu, its activity in the environment will grow during the next 50 years. This study aims to compare and evaluate different sequential radiochemical methods for 241Am analysis, focusing on their precision and accuracy, to establish a more rapid, refined and reliable approach for environmental monitoring. Four radiochemical methods for 241Am determination in soil and marine sediment samples were compared using alpha-particle spectrometry. This sensitive technique plays a key role in quantifying low-level radioactive contaminants in sediment and soil samples. The procedure was optimised using reference materials prepared by IAEA: sediment (IAEA-300, IAEA-384 and IAEA-385) and soil (IAEA-327 and IAEA-375), and digestion, radiochemical separation, and purification on anion exchange resin (AG 1X8) and chromatographic resins (UTEVA, TRU) were used. The effectiveness of the Ca-oxalate precipitation method for iron removal was also evaluated. We used microcoprecipitation on neodymium fluoride (NdF3) to prepare measurement sources. As a significant outcome, we suggested the potential exclusion of co-precipitation (method D) in the determination of the 241Am isotope in sediment and soil samples. This recommendation aligns with our goal of developing a precise sequential radiochemical method for alpha-particle spectrometry. Our approach offers a valuable and optimised tool for monitoring the environmental impact of nuclear activities and accidents, particularly in marine ecosystems.