The concentrations of the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in 15 different water samples from Elba protective area, south-eastern desert of Egypt, have been determined using NaI(Tl) detector. Gamma ray spectrometric analysis was performed and the concentrations obtained for each of the radionuclides expressed in Bq l⁻¹ ranging from 1.6 to 11.1 for ²²⁶Ra, 0.21 to 0.97 for ²³²Th and 9.1 to 23 for ⁴⁰K. A reasonable correlation was found between ²²⁶Ra, ²³²Th concentrations and pH, although no general trend was observed with conductivity and total dissolved solids. The mean effective doses of 0.56 mSv y⁻¹ for ²²⁶Ra, 0.065 mSv y⁻¹ for ²³²Th and 0.04 mSv y⁻¹ for ⁴⁰K were estimated for the ingestion of these waters by adults.

Levels of ^226,228Ra, ²³²Th, ²¹⁰Pb, ²¹⁰Po and ⁴⁰K in sediments from four monitoring areas, El Hamraween and Ras El Behar (Red Sea, Egypt) and LL3A and JML (Baltic Sea, Finland), have been investigated using alpha and gamma spectrometry. The average activity concentrations were 238±4 Bq kg⁻¹ (²²⁶Ra), 215±11 Bq kg⁻¹ (²¹⁰Pb) and 311±18 Bq kg⁻¹ (²¹⁰Po) for El Hamraween area. In Ras El Behar area, the corresponding values were 16±0.4, 18±1 and 20±5 Bq kg⁻¹, respectively. The activity concentrations for ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po (uranium series) in El Hamraween bottom sediment are much high compared with those in Ras El Behar area, which indicates the enhanced levels due to the activities of phosphate mining and shipment operations in El Hamraween area. Excluding the influence of phosphate mining activities, it can be concluded that the levels of radioactivity in Baltic Sea sediments are higher than those in Red Sea sediments.

External exposures of population to ionising radiation due to naturally occurring radionuclides in sixty-three granite samples from three different locations in south eastern desert of Egypt were considered in this article. Average outdoor gamma dose rates in air were 190, 290 and 330 nGy h⁻¹ for Elba, Qash Amir and Hamra Dome granites, respectively. The corresponding doses in indoor air are 270, 400 and 470 nGy h⁻¹, respectively. These average values give rise to annual effective dose (outdoor, indoor and in total) 0.24, 1.4 and 1.6 mSv for Elba granite. For Qash Amir and Hamra Dome granites the corresponding values were 0.35, 2 and 2.3 mSv and 0.41, 2.3 and 2.7 mSv, respectively.

AlphaGUARD radon gas analyzer and NaI (Tl) spectrometer were used to measure the concentration levels of ²²²Rn and, ²²⁶Ra, ²³²Th, and ⁴⁰K respectively in 109 groundwater samples collected from four different districts in Qena governorate, Egypt. The average values of the activity concentration were 3.57 ± 0.08, 0.54 ± 0.03, 0.40 ± 0.03, and 5.10 ± 0.44 Bql⁻¹ for ²²²Rn, ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively. The average values of ²²²Rn, ²²⁶Ra, and ²³²Th are lower than, 100, 1, and 1 Bql⁻¹, respectively, the WHO recommended permissible levels for drinking water. For radiation exposure assessment, the annual effective doses due to ingestion of ²²⁶Ra and ²³²Th and inhalation of ²²²Rn for adults were determined and compared with the reference limits. The annual effective doses due to ingestion 139.21–201.34 µSvy⁻¹ are higher than the public annual dose limit 100 µSvy⁻¹ recommended by WHO. These indicate that the ingestion of groundwater from the study areas might pose radiological health hazards.