Indian Journal of Pure & Applied Physics Vol. 50, April 2012, pp. 224-230

Natural radioactivity levels and associated radiation hazards in river sediments from to El-Minia, Upper

A El-Taher1,2 & Adel G E Abbady3  1Physics Department, Faculty of science, Al-Azhar University, (Assuit branch), Egypt 2Physics Department, Faculty of Science, Qassium University, Buraydah, 51452, Saudi Arabia 3Physics Department, South Valley University, Faculty of Science, , Egypt E-mail: [email protected] Received 9 September 2011; revised 17 November 2011; accepted 3 January 2012

The natural radionuclides 226Ra, 232Th and 40K contents in the Nile river sediments at various locations in Upper Egypt from Aswan to El-Minia have been investigated using gamma spectrometric analysis. Determination and measurement of radionuclide concentration are of great importance for assessment of external radiation dose received by man. The range and mean values of 226Ra, 232Th and 40K activity concentrations are 13-42 (29), 10-67 (45) and 74-139 (123) Bq kg−1, respectively. These results are found to be in agreement with those reported data for Egyptian soil as 17 (5–64), 18 (2–96) and 320 (29–650) Bq/kg dry weight (UNSCEAR, 2000). The mean radium equivalent (Raeq) and dose rates are 100.21± − − 10.01 Bq kg 1, 44.88±6.69 n Gy h 1, respectively. The measured activity concentrations differ widely as their presence in the Nile river depends on the pertinent environmental situation such as the presence of dams, barrages and sediments type. The other factors controlling the distribution of the detected natural radioisotopes have been discussed. Keywords: Natural radioactivity, Nile river sediments, Radiation hazards, Upper Egypt

1 Introduction The Nile river, which passes through several In Egypt, the Nile River water is the main source of climatic zones and various geologic settings, must water, providing nearly 95% of water requirements. have attracted the attention of scientists long ago. The Nile is the longest river in the world and is the Construction of the Aswan High Dam in 1961 and creator of the fertile land of Egypt, and it has increased human activities in the Nile valley have sustained its existence and supported man early drastically changed the chemistry and mineralogy of civilization. As a result of the growth of the industrial the river flux. A few studies have focused on the river activities it has subjected to the continuous discharge water chemistry3-6, suspended mater7 and sediment of different types of waste water without adequate composition8,9. A complementary data on the treatment. So, a remarkable increase in pollution concentrations of natural radionuclides and the especially heavy metals has been recorded in the radiation hazard parameters in the River Nile aquatic environment of the Nile. sediments from Aswan to El-Mina have been River sediments may be regarded as at least, a provided in order to: temporary sink of many materials which pass through Establish a reference level activity concentrations the various aquatic chemical and biological cycles of primordial and long lived hazardous radionuclides. operating on the earth’s surface. Thus, sediments From such data any further increase in these levels become an environmental host for many of the waste from any reasons could be evaluated. Identify areas products discharged by society. The effects of these which may be radiologically hazardous from the man-made emissions, in some situations, can be public. sufficiently strong to affect highly the composition of the deposited sediments. Once a substance has been 1.1 Study Area and Sampling incorporated into a sediment, its ultimate fate depends Sediment samples have been collected from 30 on a number of very complex factors. An element sites on the coastal area from Aswan to El-Minia, may considered to be locked permanently into a Upper Egypt. River sediments was taken at 5 to 10 m sediment component or it may later be released and distance from the river side at a water depth of about take part in various biogeochemical reactions1,2. 1-2 m, each sample of about 1 kg was placed in EL-TAHER & ABBADY: NATURAL RADIOACTIVITY LEVELS AND ASSOCIATED RADIATION HAZARDS 225

plastic packets and transported to the laboratory. The average concentrations of the 214Pb (351.9keV) and sediments are mainly derived from the basic volcanic 214Bi (609.3 and 1764.5 keV) decay products 14. rocks, whereas the pre-Nile sediments were derived from acidic and metamorphic rocks and the pre- 3 Results and Discussion existing sedimentary rocks. After removing stones The disintegration of 226Ra and 232Th in the crust of and other non-sample materials, it was kept in a earth is the main source of exposure to ionizing stainless steel tray for 3-5 days in open air for drying. radiation15. The activity concentrations of the They were dried again in an oven at about 105°C to radionuclides have been measured in a selected ensure that moisture is completely removed, The sediment samples from different locations along Nile samples were crushed, homogenized and sieved River from Aswan to El-Minia as presented in through a 200 mesh, which is the optimum size Table 1. enriched in heavy minerals. Weighted samples were In Aswan Governrate, the activity concentration of 3 placed in polyethylene beaker of 350-cm . The 226Ra ranged from 18.61±3.05 Bq kg−1 in beakers were completely sealed for 4 weeks to reach to 42.44±4.68 Bq kg−1 in El Sibayia with the mean secular equilibrium where the rate of decay of the value of 30.21 Bq kg−1 while 232Th ranged from daughters becomes equal to that of the parent. It was −1 222 220 30.06±1.51 Bq kg in Kom Ombo to 66.89±3.35 Bq assumed that Rn and Rn could not escape from −1 10−12 kg in 2 after iron alloy factory with the mean the sealed containers after closure . This step is value of 56.50 Bq kg−1 and for 40K ranged from necessary to ensure that radon gas confined within the − 91.53±4.58 Bq kg 1in Aswan Dam to 126.49±6.33 volume and the daughters will also remain in the near Kema fertilizer factory with the the mean value sample. −1 of 113.51 Bq kg . 2 Methodology In Qena Governrate, the activity concentration of − Activity measurements were performed by gamma 226Ra ranged from 24.11±3.36 Bq kg 1 in Nag ray spectrometer, employing a scintillation detector Hamady to 41.57±4.68 Bq kg−1 in City near 3″×3″. It is hermetically sealed assembly, which El-Sibayia with the mean value of 29.34 Bq kg−1 includes a NaI (Tl) crystal, coupled to PC-MCA while 232Th ranged from 30.15±1.52 Bq kg−1 in Esna Canberra Accuspes. To reduce gamma ray city to 60.88±3.05 Bq kg−1 in 2 near industrial background, a cylindrical lead shield (100 mm thick) area which include paper, suger cain factories with the with a fixed bottom and movable cover shielded the mean value of 42.69 Bq kg−1 and for 40K ranged from detector. The lead shield contained an inner 103.41±5.17 Bq kg−1 in Nag Hamady to 128.55±6.43 concentric cylinder of copper (0.3 mm thick) to in Qus 1 between suger cain and paper factories with absorb X-rays generated in the lead. In order to the mean value of 117.90 Bq kg−1. determine the background distribution in the In Governrate, the activity concentration of environment around the detector, an empty sealed 226 −1 beaker was counted in the same manner and geometry Ra ranged from 19.94±3.54 Bq kg in Sohag city to 34.38±4.52 Bq kg−1 in Gerga with the mean value as the samples. The measurement time of activity or −1 232 background was 12 h. The background spectra were of 24.80 Bq kg while Th ranged from 10.15± −1 −1 used to correct the net peak area of gamma rays of 0.56 Bq kg in Sohag city 60.77±3.04 Bq kg in −1 measured isotopes. A dedicated software program Gerga with the mean value of 31.86 Bq kg and − (Genie, 2000) from Canberra has carried out the for 40K ranged from 106.88±5. Bq kg 1 in to online analysis of each measured "-ray spectrum13. 139.48 ± 15.23 in with the mean value of 124.31 Bq kg−1. 2.1 Data collection Calculations of count rates for each detected photo In Assuit Governrate, the activity concentration of 226Ra ranged from 27.06±3.80 Bq kg−1 in Abu Teeg to peak and radiological concentrations (activity per −1 mass unit or specific activity) of detected 34.38±4.52 Bq kg in Mangbad near Assuit fertilizer −1 radionuclides depend on the establishment of secular factory with the mean value of 30.88 Bq kg while 232 −1 equilibrium in the samples. The concentration of 232Th Th ranged from 44.47±2.23 Bq kg in Assuit city − was determined from the average concentrations of 60.77±3.04 Bq kg 1 in Mangbad near Assuit fertilizer − 212Pb (238.6 keV) and 228Ac (911.1keV) in the factory with the mean value of 31.86 Bq kg 1 and for samples, and that of 226Ra was determined from the 40K ranged from 111 ±5.55 Bq kg−1 in Mangbad to 226 INDIAN J PURE & APPL PHYS, VOL 50, APRIL 2012

− Table 1 — Activity concentrations of 226Ra, 232Th and 40K in (Bqkg 1) for Nile river sediment samples

Sample Location Governrate Ra-226 Th-232 K-40 number

1 Aswan Dam Aswan 32.1±1.75 59.09±2.96 91.53±4.58 2 Aswan city 28.19±3.71 66.69±3.34 119.74±5.99 3 Kema 25.53±3.09 59.45±2.98 126.49±6.33 4 Kom Ombo 18.61±3.05 50.86±2.34 115.62±5.78 5 Edfu 1 31.70±3.50 62.50±3.13 110.32±5.52 6 Edfu 2 32.91±3.54 66.89±3.35 118.36±5.92 7 El Sibayia 42.44±4.68 30.06±1.51 112.55±5.63 Average 30.21 56.50 113.51 8 Esna city Qena 41.57±4.68 30.15±1.52 112.89±5.65 9 Esna Dam 28.02±4.11 45.17±2.26 116.18±5.81 10 city 39.32±5.45 30.82±1.55 115.38±5.77 11 Qus 1 30.09±4.15 43.16±2.17 128.55±6.43 12 Qus 2 36.06±3.67 60.88±3.05 127.91±6.40 13 Qena 26.91±4.05 47.56±2.38 121.02±6.05 14 Nag Hamady 24.11±3.36 41.11±2.25 103.41±5.17 Average 29.34 42.69 117.90 15 El Balyana Sohag 13.14±1.38 28.26±1.58 136.47±6.82 16 Gerga 34.38±4.52 60.77±3.04 111.00±5.55 17 Sohag 19.94±3.54 10.15±0.56 127.75±6.39 18 El Maragha 28.63±2.20 20.53±1.81 139.48±15.23 19 Tahta 27.95±4.35 39.60±1.99 106.88±5.34 Average 24.80 31.86 124.31 20 Adu Teag Assuit 27.06±3.80 46.82±2.35 115.11±5.67 21 Assuit 32.07±3.58 44.47±2.23 112.66±5.63 22 Mangabad 34.38±4.52 60.77±3.04 111.00±5.55 23 Manfalout 30.04±3.32 57.46±2.89 119.63±5.98 Average 30.88 52.42 114.60 24 Der Maws El-Minia 30.35±4.67 51.54±2.59 126.46±6.32 25 Malawi 29.27±2.65 46.68±2.34 115.11±5.75 26 El Minia 31.50±3.50 46.86±2.35 134.76±6.73 27 Samalout 31.29±3.06 39.58±1.99 95.02±4.75 28 Bani Mazar 30.82±3.88 34.46±1.73 74.59±3.72 29 Matai 29.33±3.14 36.23±1.83 106.76±5.33 30 Maghagha 31.05±3.22 38.42±1.93 105.36±5.26 Average 30.54 41.96 108.29

119.63±5.98 in Manfalout with the mean value of concentration of 226 Ra and 232Th in Aswan and Qena 114.60 Bq kg−1. is higher than other governments while the activity 40 In El-Minia Governrate, the activity concentration concentration of K in Sohag government is higher 226 −1 than in other governments. The significant of Ra ranged from 29.33±3.14 Bq kg in Matai to 226 30.35±4.76 Bq kg−1 in Der Mawas with the mean observation is that higher concentrations of Ra in − sediment samples from Aswan and Qena value of 30.54 Bq kg 1 while 232Th ranged from − governments. It is evident that the higher 34.46±1.73 Bq kg 1 in Bani Mazar to 51.54±2.59 Bq concentration of radionuclides is due to the disposal kg−1 in Der Mawas with the mean value of 41.96 Bq −1 40 −1 of industrial wastes from the phosphate mining. The kg and for K ranged from 74.59±3.72 Bq kg in observed maximum value of 226Ra is 42.44±4.68 Bq −1 Bani Mazar to 126.46±6.32 Bq kg in Der Mawas kg−1 and the mean activity is 29±5.3 Bq kg−1. The −1 with the mean value of 108.29 Bq kg . river area near the phosphate miming is contaminated Figure 1 shows a comparison between the natural by phosphate raw materials. Some phosphate ore and radioactivity levels in Nile River sediments from five other phosphate materials are also discharged into the governments in Upper Egypt from Aswan to river and to the riverside during unloading of El-Minia. From Fig. 1, one can see that the activity materials from ship and transportation to the factory EL-TAHER & ABBADY: NATURAL RADIOACTIVITY LEVELS AND ASSOCIATED RADIATION HAZARDS 227

yard. The activity of 232Th was also found to be and 40K in Egyptian soil are 17 (5-64), 18 (2-96) higher. The observed maximum value is 66.89± and 320 (29-650) Bq/kg dry weight (UNSCEAR, 3.35 Bq kg−1 and the mean activity is 45±6.7 Bq kg−1. 2000), respectively. For comparison, the activity The range and mean values of 226Ra, 232Th and 40K concentrations of 238U, 226Ra, 232Th and 40K for river activity concentration are 13-42 (29), 10-67 (45) and and coastal environmental sediments of different 74-139 (123) Bq kg−1, respectively. These results are countries are presented in Table 2. Table 3 presents found to be in agreement with those reported in the comparison between the average radioactivity UNSCEAR (2000) for Egyptian soil. The average levels and absorbed dose rate in Nile River activities (range) of 226Ra (238U) series, 232Th series sediments from delta and upper Egypt with the reported data16.

3.1 Absorbed dose rate Conversion factors to transform specific activities AK, ARa and ATh of K, Ra and Th, respectively, in absorbed dose rate at 1m above the ground (in nGy h−1 by Bq kg−1) are calculated by Monte Carlo method16 as:

−1 D(nGy h ) = 0.0417AK + 0.462ARa+0.604 ATh … (1)

Fig. 1 — Comparison between the average activities of 226Ra,232Th and 40K in (Bq kg−1) for sediment samples from where ARa, ATh and AK are the specific activities of 226 232 40 −1 different locations in Upper Egypt Ra, Th and K in Bqkg . Table 2 — Comparison of radioactivity of our sediments with other areas of the world

Country Range (Mean) activity in Bq kg−1 References Ra-226 Th-232 K-40

World 10-50 (25) 7-50 (25) 100-700 (370) (16) Danube River, Serbia 31 26 395 (21) Krka River, Croatia ND 1.9-29.4 18-457 (22) Loco Bayon basin 20.6-47.6 24.7-70.5 ND (23) River Tagus, Spain 13-100 (42) 19-145 (63) 48-1176(572) (24) Republic of Irland 10-200 (60) 3- 60 (26) 40-800 (350) (25) Island of Ustica Italy ND 16-147 201-1350 (26) Aegian Region Turkey ND 5-63 (24) 220-3202 (27) Lousiana USA (64) (36) (472) (28) China 18-135 (50) 35-228 (90) 281-711 (524) (29) The Netherlands ND 22-27 290-700 (30) Japan 5-130 5-185 75-1400 (31) Belgium 13-43 9-47 170-610 (32) Oslo Nerway 720-1760 26-50 700-1400 (33) Aplioulia Italy 17-630 16-62 398-649 (34) Aegean sea Greece 24-764 (212) 18-66 (43) 258-2464 (1130) (35) Abano Terme, Italy ND 31-37 (33) 410-475 (443) (36) South Aegean Sea Greece 21-115 (50) 19-152 (60) 429-1676 (881) (37) French Ribers 1 9-62 (38) 16-55 (38) 120-1026 (599) (38) French Ribers 2 6-40 (28) 32-52 (44) 230-1100 (700) (39) Libingston Island Soils Antarctica 6-12 (8.5) 6-18 (10) 149-302 (210) (40) River Tego, Portugal 42-57 54-76 ND (4) River Douro, Portugal 42-51 60-85 ND (41) Lake Nasser 4-48 (21) 8-50 (23) 16-487 (155) (42 Nile Delta and Middle 2-96 (18) 5-64 (17) 26-653 (316) (43) Upper Egypt 13-42 (29) 10-67 (45) 74-139 (123) Present Work ND : not detected

228 INDIAN J PURE & APPL PHYS, VOL 50, APRIL 2012

Table 3—Comparison between the average radioactivity levels and absorbed dose rate in Nile River sediments from delta and upper Egypt with the international UNSCAIR Data

Isotopes Nile Delta (42) Upper Egypt Present work International UNSCAIR Data (16)

U-238 series 2-96 (18) Bqkg1 13-42 (29) Bqkg1 10-50 (25) Bqkg1 Th-232 series 5-64 (17) Bqkg1 10-67 (45) Bqkg1 7-50 (25) Bqkg1 K-40 26- 653 (316) Bqkg1 74-139 (123) Bqkg1 100-700 (370) Bqkg1 Dose rate 7.6-93.2 (31.5) nGy h−1 17-60. (45) nGy h−1 100-200 (55) nGy h−1

3.2 Radium equivalent activity Table 4 — Radium equivalent (Bq kg−1), dose rate (n Gy h−1) and The natural radioactivity of building materials is external hazard indices Hex for Upper Egypt Nile River sediment usually determined from 226Ra, 232Th and 40K Sample Location Governrate Ra eq Dose rate Hex contents. As Ra and its daughter products produce − − number (Bq kg 1) (n Gy h 1) 98.5% of the radiological effects of the U series, the contribution from the 238U has been replaced with the 1 Aswan Dam Aswan 123.04 54.36 0.25 226 2 Aswan city 131.95 58.30 0.28 decay product Ra. Radium equivalent activity is an 3 Kema 119.40 52.98 0.26 index that has been introduced to represent the 4 Kom Ombo 35.07 16.95 0.05 226 232 40 specific activities of Ra, Th and K by a single 5 Edfu 1 128.79 56.99 0.26 quantity, which takes into account the radiation 6 Edfu 2 136.85 60.54 0.28 hazards associated with them. This first index can be 7 El Sibayia 92.31 42.00 0.14 calculated according to Ref. (17) as: 8 Esna city Qena 92.59 42.13 0.14 9 Esna Dam 100.74 45.07 0.20 Raeq = ARa + 1.43ATh + 0.077AK … (2) 10 Luxor city 91.46 41.59 0.14 11 Qus 1 100.81 45.33 0.19 where ARa, ATh and AK are the specific activities of 12 Qus 2 132.07 58.76 0.26 226 232 40 −1 13 Qena 103.40 46.21 0.21 Ra, Th and K in Bqkg , respectively. The Raeq is related to the external "-dose and internal dose due 14 Nag Hamady 37.23 17.93 0.04 to radon and its daughters. 15 El Balyana Sohag 63.10 28.83 0.17 16 Gerga 129.06 57.22 0.26 17 Sohag 43.41 20.67 0.07 3.3 External hazard index 18 El Maragha 83.50 40.82 0.23 The external hazard index is obtained from Raeq 19 Tahta 92.06 41.29 0.18 expression through the supposition that its maximum 20 Adu Teag Assuit 120.84 53.68 0.25 value allowed (equal to unity) corresponds to the 21 Assuit 102.07 45.58 0.20 −1 upper limit of Raeq (370 Bqkg ). This index value 22 Mangabad 103.54 46.37 0.20 must be less than unity in order to keep the radiation 23 Manfalout 129.06 57.22 0.26 hazard insignificant; i.e. the radiation exposure due to 24 Der Maws El-Minia 120.90 54.12 0.23 the radioactivity from construction materials is 25 Malawi 104.27 46.61 0.20 − 26 El Minia 11.95 50.33 0.21 limited to 1.0 mSv y 1. Then, the external hazard 27 Samalout 94.55 42.33 0.17 index can be defined as: 28 Bani Mazar 89.32 40.01 0.15 29 Matai 88.60 39.88 0.16 A AA H =Ra +Th + K ≤ …(3) 30 Maghagha 94.36 42.41 0.17 ex 370 259 4810 The range and the mean radium equavalent Raeq where ARa, ATh and AK are the specific activities of activities and the dose rate values of the Nile River − 226Ra, 232Th and 40K in Bqkg 1, respectively. sediments are higher than the world range. The values Table 4 presents the radium equivalent activity of dose rates are lower than the international −1 16,18,19 −1 (Raeq) in Bq kg , dose rate and external hazard limit (55 n Gy h ). The calculated external indices Hex of the Nile River sediment sample under hazard values for all the samples are found to be investigation. The mean Raeq value for Nile River lower than unity, This indicates that the Nile River − sediments is 100.21 Bq kg 1, the mean dose rates due sediments at the study area can be used safely as to 226Ra, 232Th and 40K radionuclides are 44.88 n building materials. The worldwide average −1 −1 Gy h . The world average for Raeq is 89.25 Bq kg . background dose for a human being is about EL-TAHER & ABBADY: NATURAL RADIOACTIVITY LEVELS AND ASSOCIATED RADIATION HAZARDS 229

2.4 mGy/year. This exposure is mostly from cosmic layer and expose the old sediments, which contains radiation and natural isotopes in the Earth. The black sand45. terrestrial radiation varies from place to place, which depends on geological environment, type of living 4 Conclusions accommodation and elevation above the sea level44. Natural radioactivity levels for Nile River sediments in Upper Egypt from Aswan to El-Minia 3.4 Effective factors have been measured using gamma-spectroscopy Many factors could be distinguished to play an system. The results show that the activity effective role in the distribution of the detected concentrations of 226 Ra and 232Th in Aswan and Qena natural radioisotopes along the study area. Firstly, the are higher than other governments while the activity presence of the hydraulic structures on the Nile River of 40K in Sohag government is higher than in other affects the flow and sedimentation rate of the stream. governments. The higher concentrations of 40K distribution has been affected by the locations of radionuclides are due to the disposal of industrial these barrages such as Aswan (from high Dam and wastes for the phosphate fertilizer processing and old Aswan Dam), Isna (from Isna barrage), El-Balyna other heavy industrial locations in the riversides. (from barrage) and Mangabad (from Assuit barrage). The second factor could be the References 1 Chester R & Aston S R, IAEA, Vienna, (1981) 173. sediment types. The measurements confirmed that the 2 Khan Kh, Akhter P, Orfi S D, Malik G M & Tufail M, sandy sediments are characterized by low activity J Radioanal Nucl Chem, 256 (2) (2003) 289. concentrations of the detected radioisotopes relative 3 Kempe S, Geol-Palaont Inst Univ Hamborg, 55 (1983) 401. to the other types. Examples of sandy sediment 4 Kempe S, NATO ASI series C251 Dordrecht: Kluwer Acadmic Publishers (1989)197. stations are Assuit and Malawi. The third factor could 5 Ismail SS & Ramadan A Sci Total Environ, 173/174(1995) be the presence of phosphate as harbouring activities 69. such as El-Sibayia, which showed the relatively 6 Komy Z R & El-Samahy A A, Chem Ecol, 11 (1995) 25. higher 226Ra values. 7 Martins O & Orobst, J L Biogeochemistry of major world The other factor could be the locations of the big rivers, (Wiley, New York), 1991, 127. 8 Elsokkary I H & Muller G, Sci Total Environ, 97/98 (1990) cities. The samples collected from sediments in front 455. of the big cities showed relatively higher activities 9 Ismail, S S, Unfried, E & Grass, F J Radioanal Nucl Chem such as Aswan, Luxor, Qena and El-Minia. This could Lett, 186 (1994) 143. be due to the human activities and its corresponding 10 IAEA Technical report series, (Vienna, Austria), 1989, 295. 11 El-Taher A, Nossair A, Azzam A & Kratz K L, Environ waste. Moreover, the contamination from the drainage protect Engine, 30 (2004) 19. of fertilizers hold radioactive materials, the 12 El-Taher A, Uosif M A M & Orabi, A, Radiat Protect mineralogical of the sites such as the presence of Dosim, 124 (2) (2007) 148. 13 El-Taher A, Radia Prot Dosi, 138 (2) (2010) 158. calcium carbonate and the chemistry of the Nile water 14 El-Taher, A Applied Radiaion & Isotopes, 68 (2010) 511. could be added as another factor controlling the 15 UNSCEAR Report to the general assembly (1988) UN distribution of the radioisotopes under consideration. 16 UNSCAIR Report to the general assembly (2000) UN The transportation of black sand through Nile River 17 Beretka J & Mathew P J Health Phys, 48 (1985) 87. 18 El-Taher A & Makhluf S Indian J Pure & Appl Phys, 48 and the geographical features of the Nile are also (2010) 697. considered as important factors controlling the 19 El-Taher A, Makhluf, S, Nossair A & A SAbdel Halim, Appl distribution of the radioactive isotopes under Radiaion & Isotopes 68 (2010) 169. consideration. Radioactive materials could be 20 El-Gamal A, Nasr S & El-Taher A, Radiat Measur, 42 (2007) 457. transported with the flow of the Nile water from the 21 Bikit I, Slivka J, Veskovi4 M, Varga E, Žiki4-Todorovi4 N, central Africa and Ethiopia such as the black sand, Mr7a D & Forkapi4 S, Radiat Measur, 41 (2006) 477. which is characterized by relatively high radioactivity 22 Cukrov N & Bariši4, D Croatia Chemica Acta, CCACAA, 79 concentrations20. Recently, Lake Nasser and the High (1) (2006) 115. 23 Yeager K M, Santschi P H, Philips J D & Herbert B E, Water Dam have been trapping the majority of these Resources Research, 38 (11) (2002) 1242. sediments. This indicated that the recent sediments in 24 Baeza A, del Rio M, Miro C & Paniagua J M, Radiat Protect Nile River are almost light sediments (not heavy like Dosi, 45(1/4) (1992) 261. black sand). The geographical feature of the stream 25 McAulay I R & Moran D Radiat Protect Dosi, 24 (1/4) (1988) 47. such as Qena and Nag Hammady bend can play 26 Beltia S, Brai M, Hauser S, Puccio P & Rizzo S, Appl Radiat important role to remove the upper light sediments Isot, 48(2) (1997) 287. 230 INDIAN J PURE & APPL PHYS, VOL 50, APRIL 2012

27 Kemru M N, Appl Radiat Isot, 48(2) (1997) 295. 37 Florou H & Kriditis P, Radiat Protect Dosi, 5(1/4) (1992) 28 Delune R D, Jones GL & Smith C J, Health Phys, 51 (2) 277. (1986) 239. 38 Lambrechts A, Foulquier L & Garnier-Laplace J, Radiat 29 Ziqiang P, Yin Y & Mingqiang G,Radiat Protect Dosi, Protect Dosi, 45(1/4) (1992). 24(1/4) (1988) 29. 39 Descamps B & Foulquier L, Radiat Protect Dosi, 24(1/4) 30 Koster H W, Keen A, Pennders R M J, Bannink D W & (1988) 143. Winkel J H, Radiat Protect Dosi, 24(1/4) (1988) 63. 40 Baeza A, del Rio M, Miro C, Paniagua J M, Navarro E, 31 Megumi K, Oka T, Doi M, Kinura S, Tsujimoto T, Ishiyama Rodrigues M J & Sanchez F, Appl Radiat Isot, 45 (6) (1994) T & Katsurayama K, Radiat Protect Dosi,24(1/4) (1988) 69. 675. 32 Deworm J P, Slegers W, Gillard J Felmal, J M & Culst J P, 41 Carreira M C U & Sequeira M M, A Radiat Protet Dosi, 24 Radiat Protect Dosi, 24(1/4) (1988) 347. (1/4) (1988) 133. 33 Stranden E & Strand T, Radiat Protect Dosi, 24(1/4) (1988) 42 Ibrahiem N M, Abd El Ghani A H, Shawky S M, Ashraf E M 367. & Farouk M A, Health Phys, 64(6) (1993) 297. 34 Buttaglia A & Bramati L, Radiat Protect Dosi, 24 (1/4) 43 Ibrahiem N M, Shawky S M & Amer H A, Appl Radiat Isot, (1988) 407. 46(5) (1995) 297. 35 Travidon G, Flouro H, Angelopoulos A & Sakelliou L, 44 Singh H N, Shanke r D, Neelakandan V N & Singh V P J Radiat Protect Dosi, 63(1) (1996) 63. Hazardous Mater, 141(2007)267. 36 Doretti L, Ferrar D, Barison G, Gerbasi R & Battiston G, 45 El-Gamal A, Saleh I, Nasr S & Naim M, IAEA-CN-118/31P Radiat Protect Dosi, 45(1/4) (1992) 175. (2006) 290.