Assessment of natural radionuclide distribution in shore sediment samples collected from the North Dune beach, Henties Bay, Namibia

Abstract

The activity concentrations of 238 U, 232 Th and 40 K were determined using gamma spectrometry (HPGe detector) and their radiological hazards are presented in this study for shore sediment samples from the North Dune beach of Henties Bay, Namibia. The activity concentrations were found to range from 25.32 ± 1.24 Bq.kg À1 to 232.33 ± 0.62 Bq.kg À1 with an average value of 175.59 ± 0.92 Bq.kg À1 for 238 U, BDL to 77.99 ± 45 Bq.kg À1 with an average value of 40.17 ± 27 Bq.kg À1 for 232 Th and 222.39 ± 8 Bq.kg À1 to 482.16 ± 10 Bq.kg-1 with an average value of 349.66 ± 8 Bq.kg À1 for 40 K. In order to assess the radiological hazard of the shore sediment samples, the radiological hazard indices such as absorbed dose rates (ADR), radium equivalent (R eq) annual effective dose equivalent (AEDE), the hazard indices (H ex and H in), and the excess lifetime cancer risk (ELCR) were calculated. The values obtained in the present study were compared with world acceptable limits and it was found that the average values of radium equivalent (Req) and external hazard index (Hex) were below the world allowable limits. However, the average values of absorbed dose rates (ADR), annual effective dose equivalent (AEDE) (outdoor and indoor), internal hazard index (H in) and excess lifetime cancer risk (ELCR) exceeded the world acceptable limits.

Determination of specific activity of²³⁸U, ²³²Th and ⁴⁰K and radiological hazard assessment of Tuomo River Sediments in Burutu, Delta State, Nigeria

“…Only one sample (S1) was found to have Hin value greater than the permissible limit. The average value of Hex and Hin in the present study is lower when compared respectively to values of 1.87 and 2.9 in Malaysia (Almayahi et al, 2012) and 0.70 and 1.18 in Henties Bay, Namibia (Onjefu et al, 2017), but higher than values of 0.56 and 0.67 in Oguta lake, Nigeria (Isinkaye and Emelue, 2015) and 0.228 and 0.233 in east coastal of Tamilnadu, India (Ravisankar et al, 2014).Generally, the mean values are less than the permissible limits of 1, indicating that the radiation hazard in the sediment is insignificant and can thus be used as building materials without restriction. In order to further assess the radiological risk of external exposure to radiation arising from naturally radionuclides 238 U, 232 Th and 40 K, the absorbed dose rate (DR) was determined.…”

“…Samples collection and preparation: Five sediment samples of about 1.0 kg were collected at different locations from Tuomo river in Burutu local government area of Delta State, Nigeria into a polyethene bag and labeled accordingly to avoid mix up. The sampling points were carefully chosen to represent areas where human populations are involved in various activities (Onjefu et al, 2017). The samples were transported to the laboratory and air dried at Determination of Specific Activity of 238 U, 232 Th and 40 K…..728 room temperature for five days.…”

“…In order to further assess the radiological risk of external exposure to radiation arising from naturally radionuclides 238 U, 232 Th and 40 K, the absorbed dose rate (DR) was determined. The absorbed dose rate (in nGyh −1 ) in air at 1 m above the ground surface was evaluated by applying conversion factor of 0.462, 0.604 and 0.0417 for 238 U, 232 Th and 40 K respectively (Beretka and Mathew, 1985;UNSCEAR, 2000;Onjefu et al, 2017). The outdoor annual effective dose equivalent (AEDE) associated with the DR was also estimated using a dose conversion factor of 0.7 SvGy −1 and an occupancy factor of 0.2 as recommended by UNSCEAR (2000).…”

Assessment of heavy metals pollution in sediment at the Omaruru River basin in Erongo region, Namibia

“…Sources of water contamination in Namibia include point sources and non-point sources, which in general, can be summarised as urban/rural domestic effluent, industrial generated effluent, sediment from mining sites and agricultural activities as well as waste from wildlife farm and tourist resorts [9]. There exists high potential for the contamination of water bodies in the Erongo region due to many anthropogenic activities [10].…”

Apply X-Ray Fluorescence and γ-Ray Spectroscopy to Analyze Igneous and Sedimentary Environmental Samples of Al-Atawilah (Al-Baha), Saudi Arabia

“…3) All crushed sieved rock samples were filled into Marinelli beakers, weighed and hermetically sealed for more than one month, in order to achieve the secular equilibrium between Ra-226 and Th-232 and their progenies (Onjefu et al, 2017;Chowdhury et al, 2020).…”