Determination of 241Am in Environmental Samples: A Review

Vertical distribution of 241Am in the southern Baltic Sea sediment profiles

The contamination of the Baltic Sea with radioactive substances occurred due to the global fallout of atmospheric nuclear weapon tests and the Chernobyl disaster. The knowledge of 241Am in the sediments of the Baltic Sea is limited. Thus, this study aimed to determine 241Am in sediment cores collected from the southern Baltic Sea. Time-based distributions were derived from age-depth profiles using the 210Pb dating method and further corroborated by 137Cs profiles. The activities of 241Am were measured by alpha spectrometry after radiochemical purification. The results show divergences in the concentrations of 241Am at the local level, varying from 0.017 ± 0.001 Bq·kg-1 at the Gotland Basin station to 3.19 ± 0.23 Bq·kg-1 in the Gdańsk Basin. These findings enhance our understanding of the radioactive contamination levels in the Baltic Sea and serve as a crucial reference dataset for future assessments and management strategies to mitigate the environmental impact of radionuclides in the region.

Determination of ultra-trace level 241Am in marine sediment and seawater by combining TK200-TK221 tandem-column extraction chromatography and SF ICP-MS

Sound strategies for marine chemical monitoring call for measurement systems capable of producing comparable analytical results with demonstrated quality. This work presents the development and validation of a new analytical procedure for the determination of the 241Am mass fraction in marine sediment and seawater samples at low levels. The procedure includes a tandem-column extraction chromatography for separation of 241Am and sector field-inductively coupled plasma mass spectrometry (SF ICP-MS) for its determination. The separation is based on the application of two new extraction resins, TK200 and TK221. The acid leaching method was employed for the pre-treatment of marine sediments, while Fe(OH)3 co-precipitation was used for Am pre-concentration in seawater samples. The extraction behaviors of Am on TK221 resins in the different acidic mediums were investigated. The removal capabilities of the tandem TK200-TK221 columns for the 241Am in the presence of interfering elements including Pu, Pb, Hg, Bi, Tl, Pt, Hf, U, and Th were carefully investigated and the corresponding decontamination factors (DFs) estimated to be in the range from 104 to 106. The main interfering element Pu was efficiently removed with a DF of about 6 × 105. Matrix rare earth elements (REEs) in marine sediments were further removed by the application of TEVA resins. 241Am mass fraction was quantified by the application of external calibration and SF ICP-MS. Following the recommendations of the ISO/IEC 17025 guidelines, the validation of the analytical procedure was accomplished by executing it on the certified reference material (CRM) IAEA-385 (marine sediment) and the seawater IAEA-443 reference materials (RM). The obtained results showed that 241Am mass fractions were accurately determined in both reference samples, with excellent reproducibility (2.1 % and 7.6 %) and low LODs (0.4 fg g-1 and 0.2 fg g-1). The relative expanded uncertainties (k = 2) obtained were 17.1 % and 29.0 %, respectively. The overall analytical times for the application of the proposed procedure on the marine sediment and seawater samples were evaluated to be only about 9 h and 6.5 h, respectively. It shows great advantages for its potential applications for emergency monitoring of 241Am contamination in the marine environment.