Remote sensing of radioactive alteration zones using Sentinel-2 and SPAD chlorophyll measurements in Mamuju, Indonesia

Authors

  • Nuraisyiah Pertiwi Kamsir ITB University
  • Asep Saepuloh ITB University
  • Very Susanto ITB University
  • Eka Djatnika Nugraha The National Research and Innovation Agency of Indonesia (BRIN)

DOI:

https://doi.org/10.17794/rgn.2026.3.14

Keywords:

Sentinel-2, Red Edge Vegetation Index (REVI), SPAD chlorophyll, Radioactive mineralization, Mamuju

Abstract

This study investigates natural radioactive mineralization (uranium–thorium) in Mamuju, West Sulawesi, particularly within the fault-controlled Adang Volcanics, an area known for anomalous natural radiation. The objective was to evaluate vegetation stress as a proxy for radioactive mineralization by integrating satellite data and field validation. We processed Sentinel-2A data using band ratios (4/2 iron oxide, 4/3 ferric iron, 11/12 clay) and false colour composites to delineate alteration zones. The Red Edge Vegetation Index (REVI; B3, B4, B6) was calculated to detect vegetation stress. Fieldwork in December 2023 collected 68 SPAD chlorophyll measurements from ferns, interpolated with inverse distance weighting, and compared with independent radiation dose rates. The results show a strong correlation between REVI and SPAD (R² = 0.76), confirming the sensitivity of red-edge bands to chlorophyll variability. SPAD values decreased significantly in high-radiation zones, showing a strong negative correlation with dose rate (R² = 0.90). Values of 4–40 were typical in anomalous radiation areas, while >40 characterized lower exposure. Vegetation stress anomalies and satellite-derived Chlorophyll Index overlapped spatially with alteration zones and were concentrated in the Adang Volcanics along structural controls. Species differences among ferns indicated varied sensitivity to radiation. This integrated approach demonstrates the effectiveness of Sentinel-2 alteration composites, REVI, and SPAD validation as a rapid, low-cost framework for early exploration of radioactive minerals while also contributing to environmental radiation hazard assessment. 

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Published

2026-05-15

Issue

Vol. 41 No. 3 (2026): No. 79

Section

Other sciences and contributions

License

Copyright (c) 2026 Nuraisyiah Pertiwi Kamsir, Asep Saepuloh, Very Susanto, Eka Djatnika Nugraha

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How to Cite

Kamsir, N. P., Saepuloh, A., Susanto, V., & Nugraha, E. D. (2026). Remote sensing of radioactive alteration zones using Sentinel-2 and SPAD chlorophyll measurements in Mamuju, Indonesia. Rudarsko-geološko-Naftni Zbornik, 41(3), 207-218. https://doi.org/10.17794/rgn.2026.3.14