Investigation of the Effect of Protons Produced by Radon and Its Progeny on the pH Level in Water Using Monte Carlo and Experimental Methods

This study investigates the impact of radon and its radioactive progeny concentration on variations in water pH. Given that water pH is a function of proton concentration, and considering the potential for interactions between radon’s alpha particles (and those of its progeny) with hydrogen/oxygen nuclei in water to generate protons and other charged species, this process is hypothesized to affect water pH levels.

Initially, we employed the Geant4 toolkit to compute the probability of proton production resulting from the interaction of radon alpha particles and their decay progeny within the drinking water of Mahan City. Subsequently, utilizing this calculated probability, we determined the corresponding proton generation rate for a radon concentration of 1 kBq/m³ in the water. Ultimately, we established the correlation between radon concentration and pH alterations based on empirical data. Both our simulation results and experimental findings demonstrated a linear relationship between pH change (ΔpH) and radon concentration (C), which can be expressed as ΔpH = 0.0017C. where C denotes the radon concentration in kBq/m³. This formula exhibits a high degree of agreement with the experimental data, exceeding 99% consistency.

The observed increase in pH associated with radon presence contributes to elevated water alkalinity, potentially conferring beneficial effects on human health. Furthermore, the interaction of radon alpha particles and their decay products with water constituents leads to the production of a spectrum of secondary particles, including ¹⁸O, ¹⁶O, ²¹Ne, ²²Ne, gamma photons, positrons, and neutrons. The production probability of these secondary particles is contingent upon the energy of the incident alpha particles. Notably, 6-MeV alpha particles originating from ²¹⁸Po exhibit a higher probability of inducing proton generation and the formation of other secondary particles compared to alternative alpha particle energies.

In summary, this research elucidates that elevated radon and progeny concentrations in Mahan City’s water supply correlate with increased pH levels. This augmentation in pH is not considered detrimental to public health and may even present certain advantages.