Gamma radioactivity measurements in Nile River sediment samples

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1. (Bq kg −1 ) (Bq kg −1 ) (Bq kg −1 ) Greece 6 5 497 Papaefthymiou et al. (2007) Egypt 6 4 45 El Mamoney and Khater (2004) Algeria 5–31.7 9–607.4 Benamar et al. (1997) Iran 26 395 Abdi et al. (2008) Spain 41–2939 12–63
2. Lozano et al. (2002) Turkey 15–116 17–87 51–1605
3. Kurnaz et al. (2007) Evaluation of radiological hazard effects Absorbed dose rate Calculating the absorbed dose rate is the first major step for evaluating the health risk. With regard to biological effects, the radiological and clinical effects are directly related to the absorbed dose rate (Ramasamy et al., 2011). The measured activity concentrations of 226 Ra, 232 Th, and 40 K are converted into doses by applying the conversion factors 0.462, 0.604, and 0.0417 for uranium, thorium, and potassium, respectively (UNSCEAR, 2000). These factors are used to calculate the total dose rate (D) (nGy h −1 ) using the following equation: D = 0.462C Ra + 0.604C T h + 0.0417C K (nGy h −1 ), where C Ra, C T h, and C K are the activity concentrations (Bq kg −1 ) of 226 Ra, 232 Th, and 40 K in the river sediments, respectively. The calculated values for the samples are presented in Table 3. The average absorbed dose rate for the sediment samples in Maghagha, Beni-Mazar, Samalott, Abu-Qurqas, and Mallawi was lower than the world average value (57 nGy h −1 ) (UNSCEAR, 2000). The average absorbed dose rate for sediment samples in Mattay, Minia, and Deir Mawas was higher than the world average value (57 nGy h −1 ) (UNSCEAR, 2000). Table 2 reports that the highest average value of the dose rate was found in Mattay. The annual effective dose equivalent Annual estimated average effective dose equivalent (AEDE) received by an individual was calculated using a conversion factor of 0.7 Sv Gy −1, which was used to convert the absorbed rate to the human effective dose equivalent with an outdoor occupancy of 20% and 80% for indoors (UNSCEAR, 1993). The annual effective dose is determined using the following equations: AEDE (outdoor) ( µ Sv year −1 ) = absorbed dose (nGy h −1 ) × 8760 h × 0.7 Sv Gy −1 × 0.2 × 10 −3, AEDE (indoor) ( µ Sv year −1 ) = absorbed dose (nGy h −1 ) × 8760 h × 0.7 Sv Gy −1 × 0.8 × 10 −3 In Table 3 we can observe the calculated minimum and maximum values of the AEDE for the investigated locations. The average indoor AEDE values for the sediment samples were lower than the world average values at 450 µ Sv year −1 ( ¨ Org¨ un et al., 2007). The average outdoor AEDE values for the sediment samples