RADIOLOGICAL RISK OF NORM AND HEAVY METAL EXPOSURE IN SOIL OF MIRINGA, NORTH-EASTERN NIGERIA

Abstract

The observed low background radiation, as reported in the aerial survey of the Miringa community, does not always reflect low soil activity concentrations. Factors such as environmental dilution and shielding can significantly attenuate gamma radiation flux, potentially concealing high activity sources within the ground. Given the impact of rapid urbanization and agricultural expansion, a comprehensive ground-level assessment was conducted to establish a reliable public health baseline. Radionuclide activity concentrations, determined via NaI (Tl) scintillation detection, averaged 32.37, 56.82, and 241.27 Bq/kg for 226Ra, 232Th, and 40K, respectively. Heavy metal analysis using atomic absorption spectrometry revealed that while lead, zinc, manganese, and nickel remain within WHO safety margins, levels of arsenic, copper, chromium, and cadmium exceeded recommended thresholds. Cadmium exhibited the most significant contamination, exceeding safety limits by 341%. Ecological risk assessments identified cadmium and arsenic as the primary drivers of localized contamination. Although the average Pollution Load Index (0.94) classifies the area as unpolluted, localized enrichment of thorium and cadmium indicates emerging environmental and long-term health concerns. These findings underscore that ground-level monitoring is vital for precise environmental management and the protection of community health.