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Minia University (2016)

Assessment of Natural Radioactivity Level in the Environment

Farghaly, Lamiaa Yehia.

Titre : Assessment of Natural Radioactivity Level in the Environment

Auteur : Farghaly, Lamiaa Yehia.

Etablissement de soutenance : Minia University

Grade : Master of Science (MS) 2016

Résumé
The knowledge of natural radioactivity content of the various radionuclides in the soil play an important role in the health physics because of the population exposure to the radiation. The exposure depends on the activity concentration of the naturally occurring radionuclides (226Ra,232Th, and 40K) which distributed in the soil. The study is devoted to assess the specific activity and to examine the radiation hazard indices of naturally occurring radionuclides 226Ra, 232Th, and 40K in soil samples ( farm, reclaimed, and under reclamation ) as well as Eastern desert from El-Minya governorate at different locations in El-Minya governorate which covered area from Deir Mawas (38° 37′ 34″ N ; 30° 98′ 03″ E) to Maghagha (38° 28′ 39″ N ; 30° 83′ 32″ E) about 139 km, and includes 9 regions : Deir Mawas (17 samples), Mallawy (17 samples), Abu-Qurqas (25 samples), Minya (15 samples), Samallot (16 samples), Matay (16 samples), Bani Mazar (16 samples), Maghagha (15 samples), and the Eastern desert (30 samples). Measurements were carried out by γ-spectrometric method using 3״ x 3״ NaI(Tl) with 8192 multichannel analyzer(MCA). About 131 soil samples were collected, and stored in tight sealed containers for 4 weeks to reach seculer equilibrium. 226Ra and 232Th activities determined via their γ-emitting daughters (214Pb, and 214Bi for 226Ra and 212Pb, 228Ac, and 208Tl for 232Th) under the assumption of radiation equilibrium, while 40K is a direct γ-ray emitter, also the radiological indices of soil samples were determined through the calculation of radium equivalent Raeq, absorbed dose rate D, representative gamma index Iγr, the external and internal hazars Hex,Hin, the annual effective dose equivalent AEDE, and Excess Lifetime Cancer Risk ELCR. The results show that the activity concentrations for farm soil samples ranged from 12.43±0.62 Bq.kg-1 in Deir Mawas to 30.15±1.51 Bq.kg-1 in Samallot with an average 20.58±1.04 Bq.kg-1 for 226Ra, while ranged from 7.27±0.35 Bq.kg-1 in in Abo Qurqas to 25.74±1.28 Bq.kg-1 in El-Minya with an average 14.37±0.75 Bq.kg-1 for 232Th, And ranged from 149.24±7.45 Bq.kg-1 in Deir Mawas to 270.94±13.59 Bq.kg-1 in Maghagha with average 270.94±13.59 Bq.kg-1 for 40K. The activity concentrations for reclaimed soil ranged from 9.39±0.46 Bq.kg-1 in Abo Qurqas to 20.78±1.04 Bq.kg-1 in Mattay with an average 13.92±0.71 Bq.kg-1 for 226Ra, while ranged from 7.37±0.37 Bq.kg-1 in Bani Mazar to 16.79±0.86 Bq.kg-1 in Mattay with an average 11.91±0.63 Bq.kg-1 for 232Th, and ranged from 124.68±6.23 Bq.kg-1 in Bani Mazar to 359.32±17.96 Bq.kg-1 in Mattay with average 193.55±9.67 Bq.kg-1 for 40K. The activity concentrations for under reclamation soil samples ranged from 5.32±0.27 Bq.kg-1 in Maghagha to 17.23±0.85 Bq.kg-1 in Mattay with an average 11.93±0.59 Bq.kg-1 for 226Ra, while ranged from 5.84±0.29 Bq.kg-1 in Abo Qurqas to 16.42±0.83 Bq.kg-1 in Mattay with an average 9.64±0.48 Bq.kg-1 for 232Th, and ranged from 116.54±5.82 Bq.kg-1 in Abo Qurqas to 250.38±12.52 Bq.kg-1 in Samallot with average 159.28±9.57 Bq.kg-1 for 40K. The activity concentrations of sandy soil ranged from 26.09±1.34 Bq.kg-1 to 37.47±1.97 Bq.kg-1 with an average 30.3±1.56 Bq.kg-1 for 226Ra, while ranged from 8.16±0.41Bq.kg-1 to 9.18±0.46 Bq.kg-1 with an average 8.52±0.44 Bq.kg-1 for 232Th, and ranged from 123.94±6.18 Bq.kg-1 to 148.03±7.39 Bq.kg-1 with average 136.93±6.83 Bq.kg-1 for 40K. The average dose rates and other calculated hazard indices were lower than the average national and world recommended values, therefore, did not pose health risks to the population of the area.

Présentation étendue (EULC)

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