Integrated Assessment of Natural Radioactivity and Trace-Metal Enrichment in Lahj Soils Using HPGe, ICP-MS, and XRF

Abstract

This study reports the activity concentrations of 40K, 232Th, and 226Ra for 21 surface soil samples from Lahj Governorate, Yemen, with mean values of 714.5 Bq/kg, 30.7 Bq/kg, and 28.2 Bq/kg, respectively. Major-oxide analyses by XRF revealed SiO₂ contents between 60.5 % and 71.8 % and K₂O between 1.46 % and 3.23 %, and a near-perfect correlation (r = 0.99) was found between K₂O and 40K activity, confirming K-bearing minerals as primary hosts for 40K. Trace-oxide data (Cr₂O₃: 0.024–0.078 %, V₂O₅: 0.010–0.043 %, MnO: 0.051–0.169 %) were strongly associated with ICP-MS metal concentrations (Cr up to 776 ppm, V up to 431 ppm, Mn up to 1 127 ppm), indicating shared mineral phases. Integrating HPGe, ICP-MS, and XRF techniques provides a cohesive multi-method framework for assessing natural radioactivity and heavy-metal distributions in under-studied soils.