238U and 232Th isotopes in groundwater of Jordan: Geological influence, water chemistry, and health impact. (May 2020) - Alomari, Ahmad Hussein
Abstract: An extensive pioneer study was conducted to determine the activity concentration of 238 U and 232 Th in 94 groundwater samples to examine the influence of geological formations on the activity concentrations of 238 U and 232 Th and to investigate a relationship with the major chemical elements in groundwater. The study also aims to estimate the annual effective dose and health impact due to the intake of these radionuclides in the groundwater of Jordan. The mean activity concentrations of 238 U and 232 Th in groundwater were found to be 33 ± 5 mBq L −1 and 0.017 ± 0.002 mBq L −1, respectively. The highest mean of 238 U and 232 Th activity concentrations were found for lower Cretaceous geological formation, while Tertiary and Quaternary geological formations have the lowest mean 238 U and 232 Th activity concentration, respectively. The output of (ANOVA) and post hoc tests revealed the existence of significant influence of geological formations on 238 U activity concentrations, while insignificant influence on 232 Th activity concentrations was found in the groundwater of Jordan. The groundwater of Jordan was dominated by HCO3 −1, Cl −1, Ca +2, and Na +1 . The mean annual effective dose due to the ingestion of radionuclides 238 U and 232 Th in groundwater were found 1.143 μSv lower than recommended by WHO. The ingestion dose deduced is dominated by 238 U of 99% where the average contribution from 232 Th amounted to 1%. The results of the study will serve as a baseline data of 238 U and 232 Th activity concentrations in groundwater based on geological formations of Jordan. Highlights: The activity concentrations of 238 U and 232 Th in groundwater of Jordan are below recommended by WHO. The highest mean activity concentration of 238 U and 232 Th were found for lower Cretaceous geological formation. Geological formations significantly influence 238 U, while no influence on 232 Th activity concentration was found. The health impact due to intake 238 U and 232 Th in groundwater of Jordan found lower than the global average.