Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 28 This work is licensed under a Creative Commons Attribution 4.0 International License. Radiological Risk Assessment and Radioactivity Concentration in sediment of Tigris River of the Medical City/Bab Al Muadham Athraa Naji Jameel athraanaje@uomustansiriyah.edu.iq Department of Physics, College of Education, Mustansiriyah University, Baghdad, Iraq Abstract The concentrations of natural radionuclides in sediment samples from various locations along the stream of the Tigris riverbank in the Medical city in Bab Al- Muadham, Baghdad, had been examined using NaI(Tl) detector. The mean concentrations of specific activity for 238U, 232Th, 40K and 137Cs for sediments of the river was 13.5±4.6, 35.2±3.1, 272.2±21.4 and 1.5±0.35 Bq/kg respectively. The findings revealed that the concentration values of natural radionuclides and cesium were below permitted limits. The radiological hazard was compared with a global average (Radium equivalent, absorbed dose rate, radiation hazard index and annual effective dose equivalent) finding it was less than reported by UNSCEAR . The radium equivalent activity was 102.22 Bq/kg and the maximum absorbed dose rate was 88.1 nGy/h. At the same time, the mean annual effective dose equivalent was 420.1 µSv/y. The highest risk index was 0.39 and is much less than 1, except for the lifetime cancer risk were valuing between 164.2×10−3 to 1620×10 −3. This is a higher value than the global average. Keywords: Sediments, Tigris River, radiological hazards, gamma-ray spectrometry, Bab Al Muadham. 1. Introduction Since the middle of the twentieth century, radiological pollution has been one of the most critical worldwide environmental issues that have occupied the attention of world governments[1]. Serious trends are represented in the great diversity and the emergence of some industrial complex, which is often accompanied by serious pollution that leads to the degradation of the ocean Biodynamic and erratic global environment . Furthermore, as the use of sources and isotopes of radiation expands in various aspects of human existence, for peaceful or military goals, the risk of radioactive contamination rises[2- 4]. Sediments had an active role in hydrous radioecology; Soil and rocks are the key supply of radiation exposure to the population and additionally a way of radionuclide migration into Ibn Al Haitham Journal for Pure and Applied Science Journal homepage: http://jih.uobaghdad.edu.iq/index.php/j/index Doi: 10.30526/35.1.2796 Article history: Received ,7, November, 2021, Accepted 19, December, 2021, Published in January 2022. https://creativecommons.org/licenses/by/4.0/ mailto:athraanaje@uomustansiriyah.edu.iq Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 29 the surroundings [5,6]. Sediments are a significant source of radiation exposure to aquatic biota, and it acts as a medium of migration for the transfer of radionuclides within the aquatic environment. The sediment deposited at the lowest of rivers most often encompasses sand and gravel of various grain sizes, terribly valuable for building constructions [7,8]. Sediment can have a total body effect due to external radiation originating directly from primordial radionuclides contained in sediment, or it can have an interior effect due to radon inhalation [9]. 2. Materials and methods 2.1 Sample Collection and Preparation Fourteen sediment samples have been collected from diverse places alongside the river bank. Sample collection was at a depth of four cm alongside the Tigris river around Medical City in Bab Al-Muadham were examined to estimate the natural radioactivity level. Then, the samples were place after collection in Plastic bags. The samples had been oven-dried at a temperature of 120 oC for four hours, then the grinding and sieving process. All sediment samples had been weighed and sealed in Marinelli containers. The samples had been sealed hermetically and stored for about four weeks to reach secular equilibrium. 2.2 Radioactivity measurement Samples have measurement with gamma spectrometry method the use of 3×3 inch NaI(Tl) detector, Alpha Spectra Inc., Made in USA. The detector has a relative performance of 90% and a power of 28.74 KeV at a 60Co gamma ray energy of 1332 KeV. A specialized computer program can control this analyzer (bMCA). The Analyzer with multiple channels. It studies and analyses the gamma spectrum of gamma rays. It has a red light indicator for intermittent gamma-rays to the detector,and it is connected to a computer via USB cable to send the signal to the bMCA program. The consists of radionuclides and includes all of 241Am (59.5KeV), 60Co (1173.24 and 1332.50 KeV), (137Cs 661.66 KeV). To measure the radiological background, the activity of 238U was given through the Gamma line of its product decay 214Bi (1764.5 KeV). The activity of 232Th was provided by the product of 208Tl (583.19 and 2614.5 KeV). The concentrations of 40K and 137Cs were determined by calculating their gamma Energy lines, 1460.8 KeV and 661.61 KeV, respectively. 3. Calculations 3.1. Specific activity The levels of radioactivity for radium, thorium, and potassium are calculated according to the equation [10]: 𝑨(𝒕) = 𝑵 𝜺(𝑬𝜸)×𝑰(𝑬𝜸)×𝒎 ×𝒕 (1) Where N: Net counts, ε(Eγ) is the detector efficiency I(Eγ): the abundance of energy, t: Time for data collection, m is the mass of samples. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 30 3.2 Radium equivalent activity The specific activity concentration level of components which includes 286Ra, 232Th, and 40K use of the equation [11]. Raeq = ARa + 1.43 × ATh + 0.077 × AK (2) 3.3. Absorbed dose rate The following equations are used to calculate the indoor and outdoor absorbed dose rates [12,13]. ) 3( KA+ 0.0417 Th+ 0.621A Ra(nGy/h) = 0.462A 𝑜𝑢𝑡D ) 4( ℎ𝑇𝐴 1.1+ 𝐾𝐴 + 0.081 Ra𝐴 ) = 0.92ℎ/𝑛𝐺𝑦(inD Where Ra, 𝐴𝑇ℎ and 𝐴𝐾 are the activity concentrations in (𝐵𝑞/𝑘𝑔) of uranium, thorium and potassium respectively. 3.4. Annual effective dose equivalent The annual effective dose equivalent rate is calculated, which considering the conversion coefficient from the absorbed dose inside the air (0.7 Sv/Gy) and the outdoor occupancy factor (0.2). Therefore, the annual effective dose equivalent rates in mSv/y are calculated via the following formulation [14]: 𝐴𝐸𝐷𝐸𝑜𝑢𝑡= 𝐷𝑜𝑢t (𝑛𝐺𝑦/ℎ) × 0.7(𝑆𝑣/𝐺𝑦) × 8760(ℎ/𝑦) × 0.20 × 10 −3 (5) 𝐴𝐸𝐷𝐸in= 𝐷in(𝑛𝐺𝑦/ℎ) × 0.7(𝑆𝑣/𝐺𝑦) × 8760(ℎ/𝑦) × 0.80 × 10 −3 (6) 3.5 Hazard index The outside and inner hazard index is used for the assessment of outside exposure to gamma radiation. The equations can be used to compute the outdoor and the indoor hazard index [15,16]: Hex = AU 370 Bq/kg + ATh 259 Bq/kg + AK 4810 Bq/kg (7) Hin = AU 185 Bq/kg + ATh 259 Bq/kg + AK 4810 Bq/kg (8) 3.6. Extra Lifetime cancer risk (ELCR) Radionuclides may be envisioned in terms of extra lifetime cancers danger. It calculates the use of the equation [17,18]. )9( 𝑅𝐹× 𝐷𝐿× 𝑜𝑢𝑡𝐴𝐸𝐷𝐸= 𝑜𝑢𝑡𝐸𝐿𝐶𝑅 𝐸𝐿𝐶𝑅𝑖𝑛 = 𝐴𝐸𝐷𝐸𝑖𝑛 × 𝐷𝐿 × 𝑅𝐹 (10) Where AEDE is the annual effective dose equivalent, DL isthe duration of life (70yrs),and RF is the risk factor (0.05 Sv-1). For stochastic effects, ICRP 60 uses of 0.05/Sv . Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 31 4. Results and Discussion Table (1) shows specific activity concentrations of the samples collected from the sediment of the Tigris river region, the activity concentration of 238U range from 9.7 to 18.5 Bq/kg with a mean value 13.5±4.6 Bq/kg and from 24.33 to 54.00 Bq/kg for 232Th with mean value 35.2±3.1 Bq/kg. The concentration for 40K range from 173.44 to 370.7 with a mean value 272.2±21.4Bq/kg and 0.066 to 1.99 Bq/kg with a mean value of 1.5±0.35 Bq/kg for 137Cs as shown in Figure 1. The variation of values in The radionuclide activity concentration and radioactivity coefficients in sediments are determined by particle size, pH, and waste from hospitals and industrial dumped in rivers. Regarding the activity concentration of natural radionuclides and 137Cs for the sediment of Tigris river samples were Within the permissible limits as reported by UNSCEAR, 2010. Table 1. Specific activity concentrations of 238U, 232Th, 40K and 137Cs in samples sediment of Tigris river. Codes Specific activity concentration (Bq/kg) 40K 228U 232Th 137Cs 226Ra 214Pb 214Bi S1 298.87 9.8 4.960 6.55 42.50 1.179 S2 173.44 9.7 3.20 3.1 24.33 0.13 S3 212.76 14.457 5.071 7.52 43.33 0.066 S4 218.92 14.33 4.007 7.71 25.79 0.23 S5 233.64 8.45 5.996 3.81 30.98 1.80 S6 207.45 14.67 3.409 4.39 33.00 1.04 S7 278.37 16.30 6.123 7.62 44.79 1.894 S8 215.37 16.8 6.44 4.34 38.04 1.00 S9 370. 7 18.5 12.44 14.1 54.00 1.99 S10 245.5 10.98 5.33 3.51 46.00 1.33 S11 298.38 12.00 4.55 6.68 43.68 1.008 S12 120.64 9.77 4.44 3.4 35.18 1.00 S13 220.33 14.6 9.54 5.1 2 28.0 1.00 S14 345 12.5 12.5 3.71 25 1.44 Average 272.2± 21.4 13.5± 4.6 17.6± 4.7 6.21± 0.81 35.2± 3.1 1.5± 0.35 Limit UNSCEAR,[19] 400 33 45 2 [20] Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 32 Figure 1. Specific activity concertation in sample sediment of Tigris river. Tables 2 and 3 shows the calculated results of radiation hazard indices (radium equivalent activity, absorbed dose rate, annual effective dose equivalent, hazard index, and Lifetime cancer risk) for all samples. All of the radiation risk indices have values below the allowed limits. The computed values for radium equivalent activities are shown in Figure 2, where. It turns out that values ranged 48.778 Bq/kg in sample 12 to 102.22 Bq/kg in sample 9 with a mean value 79.01± 2.24 Bq/kg in Tigris river sediment samples. The values obtained of the outside, absorbed dose rate in the sampled sediment of Tigris river various from 22.653 nGy/h to 54.12 nGy/h. While, inside absorbed dose rate ranged from 47.749 nGy/h to 88.1 nGy/h, The highest absorbed dose rate outside and inside the body became recorded in sample 9. While the lowest values are in sample 4 as shown in Figure 3. The results of annual effective dose in the sediment samples. The highest concentration within the annual effective dose outside and inside the body is 420.1to 55.3 μSv/y that is sample 9. The lowest the annual effective dose outside and inside the body was 272.783 to 41.234 μSv/y of sample 2 as shown in Figure 4. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 33 Table 2. Radium equivalent activity, Absorbed dose rate and Annual effective dose equivalent of samples from Tigris river. Code Raeq (Bq\kg) D(nGy/h) ADED(μSv/y) inside Outside inside Outside S1 89.161 76.403 41.32 373.747 50.543 S2 59.993 47.749 31.145 272.783 41.234 S3 87.984 73.765 40.085 361.862 49.16 S4 59.796 50.789 22.653 258 37.782 S5 72.117 62.042 33.357 304.353 40.909 S6 69.663 59.083 32.001 289.838 40.246 S7 95.521 80.058 30.376 295.904 53.253 S8 77.919 65.52 35.577 321.415 43.632 S9 102.22 88.1 54.12 420.1 55.3 S10 87.34 73.576 39.978 360.934 49.029 S11 86.071 79.783 39.109 352.139 47.963 S12 48.778 53.8 29.5 290.97 39.479 S13 76.2 60.2 34.11 315.5 42.1 S14 71.568 63.958 33.945 313.752 41.63 Average 79.01 ±2.24 66.34 ±1.96 36.158 ±0.98 329.25 ±7.98 44.44 1.16± Limit[19] 370 84 290 [21] Figure 2. Radium equivalent activity in samples sediment of Tigris river. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 34 Figure 3. Absorbed dose rate in samples sediment of Tigris river. Figure 4. Annual effective dose equivalent in samples sediment of Tigris river. Table 3 and Figures 5, 6 explain the hazard index and Extra lifetime cancer risk in Sediment samples. The highest external hazard index value was 0.33 Bq/kg in sample 9, but the highest value was 0.39 Bq/kg in internal. In contrast, the lowest value sample 4. The highest value and the lifetime risk of cancer in the body, is found in the sample 1 but the highest outside value in sample 7 in the Sediment samples of the Tigris river. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 35 Table 3. Annual gonadal dose equivalent, Hazard index, and Extra Lifetime cancer risk in Sediment of Tigris river. Codes Hazard index(Bq/kg ) ELCR(mSv/y) Hout Hin Inside Outside S1 0.24 0.25 1370.115 177.901 S2 0.178 0.231 912.241 109.319 S3 0.238 0.264 1266.517 172.06 S4 0.134 0.177 970.5 116.237 S5 0.157 0.221 1065.236 143.182 S6 0.188 0.226 1014.433 137.361 S7 0.23 0.299 1385.664 186.386 S8 0.21 0.232 1145.9 152.712 S9 0.33 0.39 1620 164.2 S10 0.236 0.255 1263.2 171.602 S11 0.232 0.235 1232.48 185.871 S12 0.213 0.20 924.89 126.677 S13 0.173 0.33 1134.1 134.2 S14 0.193 0.218 1098.13 145.705 Average 0.257± 0.040 0.265± 0.019 1181.41± 29.19 153.138± 5.2 Limit[22] 1 1.16 ×10−3 0.29 × 10−3 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 53 (1)2022 36 Figure 5. Hazard index in Sediment of Tigris river. Figure 6. Extra Life Time cancer risk in Sediment of Tigris river. 5. Conclusion Radioactivity in sediment samples from various locations along the stream the Tigris riverbank stream in the Medical city in Bab Al- Muadham in Iraq, was using the NaI(Tl) gamma-ray spectrum detector measured. The mean activity concenspecific activity concentration of 40K,238U and 232Th is within the world average. The radium-equivalent equivalent, annual effective dose rate, absorbed rate and risk indices are all estimated under the permissible limits. Still, the values lifetime cancer risk (ECLR) is above the worldwide average according to UNSCEAR. The results obtained show that there may be no health implication for the general populace, but prolonged exposure could lead to radiation related health hazard. Therefore, the government should monitor the release of environmental pollutants and industrial activities along the river. Acknowledgments The author would like to thank Mustansiriyah university (www.uomustansiriyah.edu.iq) in Baghdad –Iraq for its support in the present work. References 1.Fathi, R. A.; Matti, L. Y.; Al-Salih, H. 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