Radiological impact of radionuclides in Moroccan food crops under semiarid conditions

Abstract

Internal exposure to ionising radiation occurs predominantly through the consumption of contaminated crops, and evaluating soil-to-plant radionuclide transfer is essential for radiological risk assessment. This study investigated radionuclide activity concentrations, soil-to-plant concentration ratios (CRs), and the potential annual effective dose from food ingestion in a semiarid agricultural region. High-resolution alpha- and gamma-spectrometry (HPGe) was used to quantify ²¹⁰Po, ²³⁴Th, ²²⁶Ra, ²²⁸Th, ²²⁸Ra, ²¹⁰Pb, ⁴⁰ K, and ¹³⁷Cs in soil and in commonly consumed crops, including coriander, red pepper, potato, onion, pomegranate, cardoon, beet, tomato, and eggplant. The soil activities ranged from 16.37 to 39.59, 6.21 to 29.15, 4.84 to 26.26, 9.37 to 46.04, 10.10 to 51.04, 5.92 to 31.39, 107.21 to 434.20, and 1.15 to 2.98 Bq/kg for ²¹⁰Po,²³⁴Th, ²²⁶Ra, ²²⁸Th, ²²⁸Ra, ²¹⁰Pb, ⁴⁰ K, and ¹³⁷Cs, respectively. In plants, activity concentrations were generally lower, varying between 0.12–4.76 Bq/kg for ²¹⁰Po, 0.36–5.89 Bq/kg for ²²⁶Ra, 0.22–1.61 Bq/kg for ²²⁸Th, and 386.33–3265.53 Bq/kg for ⁴⁰ K, whereas ²³⁴Th, ²²⁸Ra, ²¹⁰Pb, and ¹³⁷Cs were mostly below the detection limits. The concentration ratios ranged from 0.01–0.14 for ²¹⁰Po, 0.02–0.43 for ²²⁶Ra, 0.01–0.17 for ²²⁸Th, and 1.02–20.03 for ⁴⁰ K, with elevated values observed in cardoon and eggplant. Correlation analysis highlighted strong interrelationships among radionuclides and demonstrated that transfer processes are controlled by soil physicochemical properties, particularly organic matter content, cation exchange capacity, and exchangeable cations. In contrast, carbonate content and salinity tend to restrict radionuclide mobility. These findings enhance understanding of radionuclide behaviour under semiarid climatic conditions and support improved radiological risk assessment and environmental protection strategies.