The activity concentrations of 222Rn and corresponding health risk in groundwater samples from basement and sandstone aquifer; the correlation to physicochemical parameters

• The highest concentration of U and 222Rn was found to be in the basement aquifer.
• A 57% of the groundwater samples were above the USEPA recommended value.
• Mean annual effective dose for ingestion was 24 times the world average.
• Mean annual effective dose for inhalation was 23 times the world.
• Strong relationship between 222Rn with concentration of U in the basement aquifer.

This study aims to evaluate the activity concentrations of 222Rn and to assess the corresponding health risk in groundwater samples obtained in Juban District, Ad Dali’ Governorate, Yemen. The measurements were performed by RAD 7 radon detector manufactured by DURRIDGE COMPANY Inc. The activity concentrations of 222Rn ranged from 1.0±0.2 Bq l−1 to 896.0±0.8 Bq l−1. 57% of the groundwater samples were above the US Environmental Protection Agency (USEPA) recommended value for Rn in water. Induced coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of uranium in groundwater samples. The measured concentration of U ranged from 0.33±0.01 μg l−1 to 24.6±0.6 μg l−1. The results were comparable to internationally recommended values. The highest concentration of U and 222Rn were found to be in the basement aquifer, while the lowest concentrations of both radionuclides were in the sandstone aquifer. High concentrations of Rn are found along fault zones. The relationship between the activity concentration of 222Rn, concentration of U and physicochemical parameters were investigated. The results showed a very strong relationship between activity concentrations of 222Rn with concentrations of U and the salinity of water.