TITLE:
Assessment of Radon Gas, Heavy Metals, and Physicochemical Parameters in Groundwater of Al-Qassim Region, Kingdom of Saudi Arabia
AUTHORS:
Ruaa Kh Aldhahyan, Khalda T. Osman, Ahmed Ayad Alharbi, Aiyeshah Alhodaib
KEYWORDS:
Radon, Groundwater, Health Risks, The Physicochemical Parameters
JOURNAL NAME:
Open Access Library Journal,
Vol.12 No.9,
September
8,
2025
ABSTRACT: In this study the radon-222 (222Rn) concentrations for the groundwater quality in selected area of Saudi Arabia—AL Qassim is measured beside the physicochemical parameters (pH, total dissolved solids [TDS], and electrical conductivity [EC]), and heavy metal content. Eight groundwater samples were analyzed using advanced techniques, including the RAD7 detector with the RAD-H2O accessory for radon detection, EZ9909SP water quality testing, and inductively coupled plasma mass spectrometry (ICP-MS) for heavy metal content. The results showed that radon concentrations ranged between 0.0536 and 0.0729 Bq/L with mean 0.064 Bq/L. This remained within the WHO limits of 100 Bq/L and the US Environmental Protection Agency limits of 11 Bq/L. All annual effective doses, both ingested and inhaled, were below the WHO and European Commission safety threshold of 0.1 mSv/yr. Chemical and physical parameters were within acceptable limits: pH values ranged from 6.84 to 7.57, with mean 7.31, total dissolved solids (TDS) values ranged from 695 to 4240 mg/L with mean 1943.13 mg/L, and electrical conductivity (EC) values ranged from 1398 to 8450 (μs/cm), with mean 3879.63 (μs/cm). As for heavy metals, most elements—including mercury, copper, zinc, and lead—were below the limit of quantification (LOQ) in all samples. However, nickel (Ni) was detected in three samples, with concentrations ranging from 0.16 to 0.34 µg/L, with an average of 0.24 µg/L. These values indicate that the water is safe and not significantly affected by contamination from this element. Using the Pearson correlation coefficient calculated via Microsoft Excel, the relationship between radon concentration (Rn222) and selected water quality parameters was evaluated. The results revealed a weak positive correlation (r = 0.28416) between radon and pH, indicating a slight tendency for radon levels to increase with higher pH values. In contrast, moderate to strong negative correlations were observed with both total dissolved solids (TDS) (r = −0.6506) and electrical conductivity (EC) (r = −0.6521). Notably, a very strong positive correlation (r = 0.9969) was found between radon and nickel concentrations, based on three samples, indicating an almost proportional relationship.