Radionuclide Distribution and Hydrochemical Controls in Groundwater of the Nile Valley, Upper Egypt

Health and Environmental Implications

authored by

Khaled Ali, Zinab S. Matar, Clemens Walther, Khaled Salah El-Din, Shaban Harb, Mahmoud Kilany, Karem Moubark

Abstract

This study provides a comprehensive evaluation of naturally occurring radionuclides—radium-226 (²²⁶Ra), thorium-232 (²³²Th), and potassium-40 (⁴⁰K)—in groundwater systems across the Nile Valley regions of Upper Egypt, based on the analysis of 85 groundwater wells. Measured mean activity concentrations were 0.74 ± 0.3 Bq/L for ²²⁶Ra, 0.24 ± 0.1 Bq/L for ²³²Th, and 13 ± 4 Bq/L for ⁴⁰K, with ²²⁶Ra displaying low correlations with salinity indicators including chloride (Cl⁻), sodium (Na⁺), electrical conductivity (EC), and total dissolved solids (TDS). Notably, approximately 30% of sampled wells exceeded the World Health Organization (WHO) guidance level of 1 Bq/L for ²²⁶Ra, primarily in central and eastern zones influenced by elevated salinity and evaporite dissolution processes. Geospatial mapping combined with multivariate statistical analysis identified four principal components accounting for over 85% of total data variability, demonstrating that depth-dependent processes, including prolonged water–rock interaction and redox evolution, are the primary controls on ²²⁶Ra mobilization, with salinity-driven ion exchange as a secondary factor. Minor anthropogenic influences, potentially linked to agricultural activities in shallow aquifers, were also detected. Radiological risk assessment confirmed that calculated annual effective doses remain well within international safety limits (<1 mSv/year), although infants and children demonstrated relatively higher exposure levels due to increased water intake per unit body weight. Lifetime cancer risk estimates via ingestion pathways yielded values below 1 × 10⁻⁴, aligning with global health organization benchmarks and reinforcing the general safety of groundwater use in the region. The study highlights potential risks posed by saline groundwater to ancient monuments and archaeological sites, as the cycles of salt forming and breaking down might speed up damage to buildings made of limestone and sandstone. These findings establish a robust scientific foundation for future groundwater quality management and cultural heritage conservation efforts in the Nile Valley region of southern Egypt.

Organisation(s)

Centre for Radiation Protection and Radioecology

External Organisation(s)

South Valley University, Egypt
Umm Al Qura University

Type

Article

Journal

Water (Switzerland)

Volume

17

ISSN

2073-4441

Publication date

15.09.2025

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Biochemistry, Geography, Planning and Development, Aquatic Science, Water Science and Technology

Sustainable Development Goals

SDG 3 - Good Health and Well-being

Electronic version(s)

https://doi.org/10.3390/w17182730 (Access: Open)