238U and 232th isotopes in groundwater of Jordan: geological influence, water chemistry, and health impact

Abstract

An extensive pioneer study was conducted to determine the activity concentration of 238U and 232Th in 94 groundwater samples to examine the influence of geological formations on the activity concentrations of 238U and 232Th 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 238U and 232Th in groundwater were found to be 33 ± 5 mBq L−1 and 0.017 ± 0.002 mBq L−1, respectively. The highest mean of 238U and 232Th activity concentrations were found for lower Cretaceous geological formation, while Tertiary and Quaternary geological formations have the lowest mean 238U and 232Th activity concentration, respectively. The output of (ANOVA) and post hoc tests revealed the existence of significant influence of geological formations on 238U activity concentrations, while insignificant influence on 232Th 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 238U and 232Th in groundwater were found 1.143 μSv lower than recommended by WHO. The ingestion dose deduced is dominated by 238U of 99% where the average contribution from 232Th amounted to 1%. The results of the study will serve as a baseline data of 238U and 232Th activity concentrations in groundwater based on geological formations of Jordan.