Assessment of radioactive nuclides and heavy metals in soil and drink water in Lahij city, Yemen

This study was conducted in Lahij city, Yemen, to evaluate the concentrations and potential health risks of natural radioactive nuclides and heavy metals in soil and drinking water. A total of 21 soil samples and 17 water samples were collected from various locations. A high-purity germanium gamma detector HPGe was used to measure the concentrations of ⁴⁰K, ²³²Th, and ²²⁶Ra in all samples, along with the concentrations of heavy metals. In soil samples, the average concentrations of ⁴⁰K, ²³²Th, and ²²⁶Ra were 731.5, 30.7, and 28.16 Bq kg^-1, respectively. While some samples showed higher than permissible levels for ²²⁶Ra and ²³²Th, the overall average remained within acceptable limits. However, ⁴⁰K levels were almost twice the recommended global limits. In water samples, the average concentrations of these nuclides were 5.38, 0.73, and 0.66 Bq L^-1, all within the global safety limits. Radiological risk assessments for soil indicated an average radium equivalent activity (Ra_eq) of 124.4 Bq kg^-1, absorbed dose rate in air of 59.9 nGy h^-1, annual effective dose rate of 0.07 mSv y^-1, outdoor excess lifetime cancer risk (ELCR) of 0.26 × 10^-3, and annual gonad equivalent dose (AGED) of 336.6 mSv y^-1. Risk indices, including the activity concentration index (I_γ), external hazard index (H_ex), and internal hazard index (H_in), averaged 0.48, 0.34, and 0.41, respectively, all below global limits except for AGED, which slightly exceeded the recommended level. For drinking water, the total ingestion dose was calculated for different age groups. The average doses for infants, children, and adults were 0.15, 0.27, and 0.19 mSv y^-1, respectively. The doses for children and adults exceeded the permissible limits, while those for infants were within safe levels. Heavy metal concentrations were measured in all samples, and the Hazard Quotient (HQ) was calculated. In soil samples, HQ values for all metals >1, indicating potential health risks. In water samples, HQ values were also >1 for all metals except vanadium (V) and iron (Fe). To reduce the dangers associated with radioactive nuclides and heavy metals, regular monitoring and cleanup are crucial, and further research is needed to understand contamination sources and long-term health impacts.