Ali Khaled, Abbady Abd El-Basset, Abu-Taleb Ahmed, Harb Shaban
Physics Department, Faculty of Science, South Valley University, Qena, Egypt.
Sci Rep. 2025 Jul 18;15(1):26115. doi: 10.1038/s41598-025-09342-y.
This study investigates the distribution, transfer, and potential ecological risks of naturally occurring radioactive materials, including radon-222 (Rn), radium-226 (Ra), thorium-232 (Th), and potassium-40 (K), in the aquatic ecosystem of Nasser Lake, Egypt. As Egypt's largest freshwater reservoir and a critical source of drinking water and fish, Nasser Lake plays a key role in environmental stability and public health. A total of 40 environmental samples-sediment, water, aquatic plants, and fish-were collected from 10 strategically selected sites around the lake. Gamma spectroscopy using sodium iodide activated with thallium [NaI(Tl)] detectors and AlphaGUARD radon monitoring systems was employed to measure radionuclide activity concentrations. Spatial distribution patterns were analyzed using Geographic Information System (GIS) techniques to identify zones of elevated radioactivity. The highest concentrations of Ra, Th and K were recorded in sediment samples near the High Dam, reaching 10.99 ± 0.42 Bq kg, 23.94 ± 1.91 Bq kg, and 277.38 ± 23.86 Bq kg, respectively. A strong positive correlation (Pearson's r = 0.913) was observed between Ra and Rn exhalation rates, confirming that sediment accumulation significantly contributes to local radiological emissions. Bioaccumulation studies showed progressive uptake of radionuclides along the aquatic food chain, with fish exhibiting a bioaccumulation factor (BAF) of 0.74 for Ra. Estimated annual radiation doses from fish consumption reached up to 6.435 microsieverts per year (µSv y), remaining below international reference levels established by the World Health Organization (WHO). However, the combination of localized contamination near the High Dam and high fish consumption in nearby communities may present long-term radiological exposure risks. These findings highlight the importance of continuous monitoring of radioactive contaminants in sediment, water, and aquatic organisms in Nasser Lake. The study also provides a transferable framework for assessing the behavior of technologically enhanced naturally occurring radioactive materials (TENORM) in freshwater environments and supports the goals of the United Nations Sustainable Development Goals (SDGs) for clean water and good health.
本研究调查了埃及纳赛尔湖水生生态系统中天然存在的放射性物质的分布、转移及潜在生态风险，这些物质包括氡 - 222（Rn）、镭 - 226（Ra）、钍 - 232（Th）和钾 - 40（K）。作为埃及最大的淡水水库以及饮用水和鱼类的重要来源，纳赛尔湖在环境稳定和公众健康方面发挥着关键作用。从该湖周围10个经过战略选址的地点共采集了40个环境样本，包括沉积物、水、水生植物和鱼类。使用碘化钠铊激活探测器[NaI(Tl)]的伽马能谱法和AlphaGUARD氡监测系统来测量放射性核素活度浓度。利用地理信息系统（GIS）技术分析空间分布模式，以确定放射性增强区域。大坝附近沉积物样本中记录到的镭、钍和钾的最高浓度分别达到10.99±0.42 Bq/kg、23.94±1.91 Bq/kg和277.38±23.86 Bq/kg。镭和氡析出率之间观察到强正相关（皮尔逊r = 0.913），证实沉积物积累对当地放射性排放有显著贡献。生物累积研究表明，放射性核素沿水生食物链逐渐积累，鱼类对镭的生物累积因子（BAF）为0.74。据估计，每年因食用鱼类产生的辐射剂量高达6.435微希沃特/年（µSv/y），仍低于世界卫生组织（WHO）制定的国际参考水平。然而，大坝附近的局部污染与附近社区较高的鱼类消费量相结合，可能带来长期的放射性暴露风险。这些发现凸显了持续监测纳赛尔湖沉积物、水和水生生物中放射性污染物的重要性。该研究还为评估淡水环境中技术增强型天然存在放射性物质（TENORM）的行为提供了一个可推广的框架，并支持联合国可持续发展目标（SDGs）中关于清洁水和良好健康的目标。
