Assessing radiation dosimetry for microorganisms in naturally radioactive mineral springs using GATE and Geant4-DNA Monte Carlo simulations
Résumé
Mineral springs in Massif Central, France can be characterized by higher levels of natural radioactivity in comparison to the background. The biota in these waters is constantly under radiation exposure mainly from the α-emitters of the natural decay chains. This study proposes to apply for the first time micro- and nanodosimetric approaches and tools to evaluate the dose received by microorganisms living in naturally radioactive ecosystems. We focus on the impact of the dominant radioelements, 226Ra in the sediments and 222Rn dissolved in the water of the mineral springs, and on diatoms, microalgae displaying an exceptional abundance of teratological forms in the most radioactive springs studied in Auvergne. Our results show that the dose rates are significant and comparable to the threshold suggested for the protection of the ecosystems. They also offer a first evaluation of the radiation induced DNA damage on these species. Our study confirms the significant mutational pressure from natural radioactivity to which microbial biodiversity has been exposed since Earth origin in hydrothermal springs.
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