Natural radioactivity measurements and evaluation of radiological hazards in sediment of Oguta Lake, South East Nigeria

Evaluation of radiological hazards in the sediments of Ogun river, South-Western Nigeria

The activity concentration of naturally occurring radionuclides ⁴⁰K, ²²⁶Ra and ²³²Th have been measured in different brands of fertiliser samples sold to farmers in retail markets in six commercial cities in southwestern Nigeria. Gamma ray spectroscopy was employed in the measurements of these radionuclides. The results of measurements showed that the average activity concentration of ⁴⁰K in the nitrogen, phosphorus and potassium fertilisers across the cities varied from 3972.0 ± 416.9 to 5089.3 ± 111.3 Bq kg⁻¹, 9.9 ± 7.3 to 450.6 ± 14.3 Bq kg⁻¹ for ²²⁶Ra, while for ²³²Th it varied from less than lower limit of detection to 15.1 ± 2.8 Bq kg⁻¹. The activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th in single super phosphate (SSP) fertilisers and phosphate rocks were also determined. However, high activity concentrations of ²²⁶Ra were obtained in the SSP fertiliser and phosphate rocks and in particular, two brands of fertilisers from ITL/TAK and F & C companies. The values of the activity concentration of the radionuclides in the brands of fertilisers used in Nigeria are within the range of values reported in several other countries except ⁴⁰K.

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Activity concentrations of 226Ra, 232Th and 40K in brands of fertilisers used in Nigeria

The activity concentrations of naturally occurring radioactive materials such as (226)Ra, (238)U, (232)Th, (40)K and (137)Cs were measured for 44 plant samples collected from different locations in the northwestern region of the West Bank, Palestine, using high-resolution gamma ray spectroscopy. The activity concentrations of radionuclides in the investigated plant samples ranged from 7.5 to 157.6 Bq kg(-1) for (226)Ra, 7.5 to 66.1 Bq kg(-1) for (238)U, 1.8 to 48.5 Bq kg(-1) for (232)Th, 14.3 to 1622 Bq kg(-1) for (40)K and <0.1 to 4.7 Bq kg(-1) for (137)Cs. The average values of these activities were 48.3, 26.5, 10.1, 288.0 and 2.2 Bq kg(-1), for (226)Ra, (238)U, (232)Th, (40)K and (137)Cs, respectively. The study presents the total gamma radiation dose rate assessed from natural radionuclides,(137)Cs and cosmic radiation, the dose rate of each radionuclide and the effective dose for all the samples. The radiological health implication to the population that may result from these doses is found to be low, except in few cases. The measurements have been taken as representing a baseline database of values of these radionuclides in the plants in the area.

Radioactivity levels in plant samples in Tulkarem district, Palestine and its impact on human health.

Assessment of the natural radioactivity levels in Kirkuk oil field

Radioactivity measurements have been carried out using gamma-ray spectroscopy to determine the radionuclide concentrations in soil samples in the premises of the Warri Refining and Petrochemical Company located in the Niger Delta region of Nigeria and also in communities around it. The radionuclide contents of the crude oil and petroleum additives were also similarly determined. Results indicate that on the premises used by the company, the ranges of activity concentrations of 40K, 226Ra and 228Th in the soil samples were 261.3–932.3 Bq kg−1,<4.2–23.0 Bq kg−1 and<5.1–10.2 Bq kg−1, respectively. For the 13 villages studied, activity concentrations ranged from <17.2–766.3 Bq kg−1,<4.2–104.7 Bq kg−1 and<5.1–13.7 Bq kg−1, respectively, for 40K, 226Ra and 228Th. The lowest radionuclide concentrations were found in the crude oil relative to the petroleum additives. The highest outdoor effective dose rate obtained in the study was 47.5 µSv y−1 for the villages and 35.2 µSv y−1 within the company premises. These values are less than the world average outdoor value of 70 µSv y−1 given by UNSCEAR. Overall, it can be concluded that the long duration of refining activities does not seem to have affected radionuclide concentrations in the environment. Measurements also showed that the observed radiation dose rates did not vary significantly from the previously determined Warri City outdoor gamma radiation dose rates, for which the probability of occurrence of any health effects of radiation was judged low. The measurements, therefore, are interpreted to represent baseline radiometric data for future reference and research in the area.

https://iopscience.iop.org/article/10.1088/0952-4746/28/3/006/pdf

N N Jibiri

Papers

Soil radionuclide concentrations and radiological assessment in and around a refining and petrochemical company in Warri, Niger Delta, Nigeria.