Assessment of soil radon-driven natural radioactivity and associated radiation dose in Central-Eastern regions of Morocco using AlphaGUARD

Abstract

This study examines spatial variations in soil radon ( 222 Rn) levels across four zones of the Central-Eastern parts of Morocco (Tikajouine, Imilchil, Itzer, and Aït Ayach). The AlphaGUARD PQ2000 PRO instrument was employed to evaluate radon concentration, exhalation rate, emanation coefficient, and associated annual effective dose using standard equations to understand geogenic and radiological influences in the region. The highest radon levels were obtained in Itzer region compared to Tikajouine, Imilchil, and Aït Ayach, with values from 80.05 to 208.90 Bq/m 3 and average surface and mass exhalation rates of 35.86 mBq/m 2 /s and 58.59 mBq/kg/s, respectively. This is probably related to geological faults and hydrothermally altered zones that facilitate radon movement. The high emissions were reported in two samples, exceptionally in the Itzer region, suggesting possible natural radioactive mineralization in the area. Moreover, in the Aït Ayach region, followed by Itzer, the radon levels (63.21‒11.32 Bq/m 3 ; mean=89.77 Bq/m 3 ) and exhalation rates (25.87 mBq/m 2 /s; 37.86 mBq/kg/s), indicated a near-normal distribution of the obtained data. A one-way multivariate statistics (MANOVA) was used to determine statistically significant differences between the four regions. Further, Tukey’s HSD test showed that Itzer has a significantly higher radon potential than Imilchil, Tikajouine (p ≤ 0.003), and Aït Ayach (p ∼ 0.0025). The average annual effective dose for all regions ranged from 1.11 to 5.26 mSv/y, remaining below the occupational safe limits set by the International Commission on Radiological Protection. The results showed clear spatial variability due to geological and structural features of each region, however, indicating that radon levels do not pose significant radiological risks to the local population.