Determination of Uranium Concentrations and 234U/238U Isotopic Ratios in Plants and the Groundwater Used in Their Cultivation in an Area with High Background Radiation

Abstract

The weathering of rocks and soil causes uranium to collect in groundwater. In this article, we attempted to assess the activity concentrations of uranium and 234U/238U isotopic ratios in various groundwater samples and plants obtained from the Ha’il region, Saudi Arabia. The results showed that the concentrations of 238U ranged between 0.08 ± 0.04 and 1.11 ± 0.06 Bq L−1, with an average of 0.67 ± 0.05 Bq L−1. Activity concentrations of 234U ranged between 0.12 ± 0.01 and 2.2 ± 0.8 Bq L−1, with an average of 1.26 ± 0.11 Bq L−1. The international permissible limit of uranium in groundwater is 0.372 Bq L−1. The 234U/238U activity ratios in the collected groundwater samples ranged between 1.5 ± 0.09 and 2.49 ± 1.27 Bq L−1, with an average of 1.95 ± 0.52 Bq L−1. In fruit-bearing trees, the 234U/238U activity ratios were 1.57 ± 0.84, 2.58 ± 1.01, and 2.69 ± 0.95 Bq L−1 for lemon, fig, and narenj. In fruit-bearing shrubs, the 234U/238U activity ratios were 2.37± 0.69 and 2.68 ± 0.69 Bq L−1 for green pepper and eggplant. Our goal is to increase the understanding of the factors that govern uranium’s activity and isotopic composition to better understand its prospective utilization as a tracer in groundwater chemistry and hydrology, as well as the possibility of exploiting this area for irrigation. In this investigation area, the groundwater and plants were unfit for human consumption.