Natural Radionuclides and Hazards in Water and Sediment Samples of Tigris River in Al- Amara city - Maysan - Iraq.

Abstract

The concentrations of the radionuclides namely ²³⁸U, ²³²Th, and ⁴⁰K are measured for water and Sediment Tigris River in AL-Amara city- Missan government- Iraq. Using HPGe detector, based on high-resolution gamma spectrometry system and an energy resolution of (≤1.8 keV) for the 133 MeV gamma transition of ⁶⁰Co. The concentrations of ²³⁸U, ²³²Th and ⁴⁰K  were B.D.L. in all water samples except one sample (Hai Al Hassan Alaskary) which has concentrations of ⁴⁰K(6.818±1.999 Bq/kg). Radium equivalent activity, absorbed gamma dose rate, annual effective dose rate (AED) _in and annual effective doses(AED) _out, hazard indices(H_in) and (H_ex) , and the gamma Index were(0) for all water samples except one sample (Hai Al Hassan Alaskary)  which have (0.524 Bq /kg), ( 0.284 nGy /h), ( 0.0013 mSv/y), ( 0.00034 mSv/y), (0.0014), (0.0014), (0.004) , respectively .The ^238U, ²³²Th, and ⁴⁰K concentrations in the Sediment Tigris River varies from (15.379±1.999 -24.737±1.269)Bq/kg, (9.930±1.033-16.303±1.437) Bq/kg, and (210.628±12.238-415.215±20.750) Bq/kg with over all mean value of (18.220±1.404Bq/kg), (13.792±1.302 Bq/kg), and (317.343±16.997Bq/kg), respectively. The radium equivalent rate (Ra_eq) calculated from concentration of ²³⁸U, ²³²Th, and ⁴⁰K, ranges between(45.798 -72.368) Bq /kg with mean value (63.879 Bq/kg). The absorbed dose Rate(D_γ) for the sediment samples in the study area ranges from (21.886 -35.054) nGy/h with an average value of (29.981nGy/h). The annual effective dose rate (AED)_in range(0.107 -0.171 mSv/y) with an average value of (0.146 mSv/y). The annual effective dose rate (AED)_out range(0.026 -0.042 mSv/y) with an average value of (0.036 mSv/y). The internal hazard index (H_in) range (0.165-0.252) with an average value of (0.217). The external hazard index (H_ex) range (0.123-0.195) with an average value of (0.167). The gamma Index (I_) range (0.342-0.553) with an average value of (0.470). The values of the specific activity of (²³⁸U, ²³²Th, and ⁴⁰K), radium equivalent activity, absorbed dose Rate, indoor and outdoor annual effective dose rates, internal and external hazard indicies, gamma index, all were found to be lower than their corresponding allowed limits.

Keywords: AL-Amara city, sediment, Natural radio activity, Radium-equivalent activities, annual effective dose rate (AED), Gamma Index.