EVALUATION OF THE PHYSICAL, CHEMICAL, AND RADIOACTIVITY PROPERTIES OF SURFACE SOIL IN MAMUJU REGENCY, WEST SULAWESI, AS THE HIGHEST NATURAL RADIATION AREA IN INDONESIA

• Main Author: Rahmansyah Amir Abdullah, Adi
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87834
• Institution: Institut Teknologi Bandung

This study evaluates the physical, chemical, and radioactivity characteristics of surface soil in Mamuju Regency, West Sulawesi, which has the highest natural radiation levels in Indonesia. The research aims to identify the enrichment mechanisms of uranium (U), thorium (Th), and potassium (K) through geochemical and mineralogical analysis. A total of 21 soil samples were analyzed using X-ray fluorescence (XRF) method to determine elemental composition, X-ray diffraction (XRD) method for mineral identification, as well as pH and soil fraction analysis. The results indicate that weathering and lateritization play a significant role in the enrichment of U and Th, particularly in low-pH clay-rich soils, while K enrichment is more dominant in high-pH sandy soils. Radioactivity measurements using a High-Purity Germanium (HPGe) Gamma Spectrometer recorded average activity levels of 648±15 Bq/kg (²²?Ra), 1370±29 Bq/kg (²³²Th), and 642±16 Bq/kg (??K), exceeding the global average. The ambient dose equivalent, measured using a NaI(Tl) Scintillator and a Geiger Muller Counter (GMC), recorded average values of 454.78 nSv/h and 768.82 nSv/h, respectively, both classified as high. The calculation of the annual outdoor effective dose reached 1.36 mSv (GMC) and 0.36 mSv (NaI(Tl)), significantly surpassing the global average. These findings confirm that Mamuju is classified as a High Natural Background Radiation Area (HNBRA).