This study investigates the natural radioactivity in 500 soil samples collected across Binh Phuoc Province, Vietnam, a region characterized by basalt formations and bauxite mining. Activity concentrations of 226 Ra, 232 Th, 40 K, and 137 Cs were measured using gamma spectrometry, with spatial distributions mapped at a 1:60,000 scale using a QGIS software. Results revealed 226 Ra ranging from 5.88 to 63.17 Bq.kg −1 , 232 Th from 17.78 to 117.33 Bq.kg −1 , 40 K from 111.42 to 1019.90 Bq/kg, and negligible 137 Cs of about 0.26 Bq.kg −1 . Radiological hazard indices, including radium equivalent activity (Ra eq : 117.42 Bq.kg −1 ) and external hazard index (Hex: 0.317), remained below international thresholds of 370 Bq.kg −1 and 1, respectively, indicating low environmental risk. Driven by a high sampling density (approximately 1 sample per 14 km 2 ), the detailed geographic information systems (GIS) maps provide the first high-resolution baseline for naturally occurring radioactive materials (NORM) monitoring and support bauxite mining management as well as agricultural safety assessments in southeastern Vietnam. This research contributes significant data to the limited literature on natural radioactivity in Southeast Asian soils. • High-density survey of 500 soil samples across Binh Phuoc Province were collected. • The activity concentrations of 226 Ra, 232 Th, and 40 K were measured and spatially analyzed. • GIS maps revealed a north-south gradient with hotspots appearing in southern districts of Binh Phuoc. • The external hazard index of 0.317 well below international safety limits. • The study provides essential baseline data for environmental monitoring and land-use planning in Binh Phuoc Province.
Tran et al. (Wed,) studied this question.