Average Activity Concentrations Of 40K Research Articles

Distribution of 40K, 238U and 232Th and associated radiological risks in river sand sediments across Enugu East, Nigeria

The distributions of 40K, 238U and 232Th in sand sediments of rivers in Enugu east, Southeastern, Nigeria have been studied and measured using NaI(TI) gamma-ray spectrometry detector. The average activity concentrations of 40K, 238U and 232Th across the studied locations were found to range from 13.18 (at Emene river) to 109.64 Bqkg–1 (at Trans-Ekulu river), 8.52 (at Abakpa river) to 15.45 Bqkg–1 (Eke express river) and 10.67 (at Emene river) to 16.94 Bqkg–1(at Abakpa river), respectively. The overall averages were found to be 60.55, 12.07 and 13.02 Bqkg–1 for 40K, 238U and 232Th, respectively. The activity concentrations of the radionuclides in sediments of the study areas were found to be lower than their world average of 400, 35, and 30 Bqkg–1, respectively. Radium equivalent activity, external hazard index, internal hazard index, absorbed dose rate, total Annual effective dose, excess lifetime cancer risk and gamma representative index were calculated. The purpose was to assess the radiological suitability of the use of the sediments as building material. The overall average values of the radiological indices were 35.35 Bqkg–1, 0.10, 0.13, 15.96 nGyh–1, 0.10 mSvy–1, 0.34 × 10–3 and 0.25, respectively, which are lower than their respective recommended worldwide limits. The results of the study have shown that the radiation hazard associated with the use of these sediments is insignificant and therefore can be used for building construction purposes without restriction.

Heavy metals and natural radioactivity concentration in sediments of the Mediterranean Sea coast

Heavy metal assessment and natural radioactivity determination in sediments of North Cyprus (Mediterranean coast) were carried out using different analysis methods. The average activity concentrations (range) of 226Ra, 232Th, and 40K were found to be 20.1 (30.6–9.2) Bq kg−1dry weight, 18.4 (26.9–12.4) Bq kg−1dw, and 467.3 (619.9–147.6) Bq kg−1dw, respectively. The average activity concentrations of 226Ra and 232Th in the sediment samples were less than the acceptable limits, whereas the average activity concentration of 40K in the sediment samples was higher than the worldwide average concentration. With regard to the studied heavy metals, the corresponding decreasing average concentration orders were found to be Mn > Zn > Cr > Ni > Cu > Pb. The heavy metal concentration values that were determined for sediment samples were compared with the values obtained in other studies. According to contamination indexes, the results (except for Cu in S-9) indicated no significant contaminated area.

Radiological risk assessment of naturally occurring radioactive materials (NORMS) from selected quarry sites in Edo State, South-south, Nigeria

This study was carried out to evaluate activity concentrations of naturally occurring radioactive materials (NORMs) to assess the distribution of 226Ra, 232Th, and 40K in selected quarries in Edo State, South-south, Nigeria and to appraise the radiological hazard they may pose to the general public when used as building material. Twenty five (25) quarry samples were collected from five (5) selected quarries in the study area and their activity concentrations were measured using gamma-ray spectroscopy technique. The radiological hazard parameters: radium equivalent activity, absorbed gamma dose rate, internal and external hazard indices and annual effective dose were also determined. The average activity concentrations of 226Ra and 232Th from all the quarries are observed to be higher than internationally recommended value. The average activity concentrations of 40K from two quarries were found to be below the internationally recommended value while it is higher in the remaining three quarries. The results also revealed that a couple of the calculated radiological hazard parameters are higher than permissible limit, hence, such quarry products may pose a radiological risks to the exposed population when used as building construction material. Correlation matrix for the activity concentrations of the NORMs and all the radiological variables is presented to determine the correlation between the variables in various samples.

Radioactivity Levels of Some Natural Stones in Burdur, Turkey

Radionuclides such as uranium, thorium and potassium have existed in the environment since the world's existence. It is important to know the distribution of these radionuclides in terms of human health and environmental protection. For this reason, the measurements of these natural radionuclides were made for the 6 stone samples extracted in the province of Burdur. To measure the natural activity concentrations of potassium-40, radium-226 and thorium-232 radionuclides, a gamma spectrometry method was used with a NaI (T1) detector which is a multichannel analytical detector in the gamma spectrometer laboratory of Suleyman Demirel University. The average activity concentrations of 40K, 226Ra and 232Th were 290.53 Bq/kg, 35.49 Bq/kg and 42.88 Bq/kg, respectively. To evaluate the radiological hazard of natural radioactivity to humans and the environment, radium equivalent activity, absorbed dose ratio, annual effective dose ratio, internal and external hazard indices were calculated. These calculated values were found to be suitable with the standard limit values.

NATURAL RADIOACTIVITY ASSESSMENT AND THE ASSOCIATED RADIOLOGICAL HAZARDS FOR BEACH SAND, BALTIM AREA, EGYPT.

Natural radioactivity of 238U, 232Th series and 40K of black sand samples collected along El-Fanar and El-Nargess Beaches in Baltim area, north of the Nile Delta in Kafr El-Sheikh Governorate, were measured using a gamma-ray spectrometer with a high purity germanium (HPGe) detector. Results showed that the average activity concentrations of 238U and 232Th in El-Fanar Beach was significantly higher (73.22±5.1 and 70.8 ± 4.9 Bq kg-1) than El-Nargess Beach (31.91±2.2 and 25.95 ±1.8 Bq kg-1) respectively. The average activity concentrations of 40K in El-Fanar Beach was lower (67.47±4.7 Bq kg-1) than that in El-Nargess Beach (80.75±5.6 Bq kg-1). The hazard indices due to these radionuclides have been calculated. The obtained results from this study indicate that the average activity concentrations of 238U, 232Th and40K at El-Nargess Beach are within world median ranges while average activities of 238U and232Th in El-Fanar Beach are higher than the world mean (33and45) Bq kg-1 respectively. This study aimed to establish a baseline map of radioactivity background levels in the aforementioned region to assess any change in the radiological background levels due to any artificial effects attributed to any radiation activities.

Uptake and Distribution of Natural Radionuclides in Cassava Crops from Nigerian Government Farms

Radioactivity distribution and transfer factor (TF) in plants are crucial parameters used to assess radioactive contamination in the environment, impact of soil radioactivity on agricultural crops and its risks to humans. The root crop cassava (Manihot esculenta) provides about 50 percent of the calories consumed in Nigeria. Gamma - ray spectroscopy was used to measure activity concentrations of 226Ra, 232Th and 40K in cassava root and soil. The average activity concentration of 40K, 226Ra and 232Th in cassava was 565.31± 13.17, 21.89±5.94 and 817.28±2.52 Bqkg-1 respectively. The mean activity concentration 40K, 226Ra and 232Th in soil range from 92.07±35.08 to 689.28±14.35 Bqkg-1with a mean value of 413.64±21.22 Bqkg-1, 5.37 ± 8.90 to 64.93 ± 7.23 Bqkg-1 with a mean value of 54.43 ± 3.22 and BDL to 928.15 ± 2.36 Bqkg-1 with a mean value of 561.67 ± 2.21 Bqkg-1. The transfer values for 226Ra, 232Th and 40K were in the range of 0 to 1.81, 0 to 3.41 and 0.68 to 4.5 respectively. The high value of transfer factor for 40k may be due to its importance in plant growth, fertilization and adaptability of plant to environmental pressures. It may have also been enhanced by the application of NPK fertilizers in those farms. Thorium showed the highest mean transfer factor which may be due to its higher accumulation in soil and higher uptake by plants (Figure 3). The average transfer factors of 226Ra (0.99) < 40K (1.55) < 232Th (1.66) show that although activity concentration of the natural radioisotopes in the area under study are high, the rate at which they are transferred to cassava are still moderate. The average values of radium equivalent activity (Raeq), absorbed dose rate (D), annual effective dose rate (AEDE), internal hazard index and excess life cancer risk (ELCR) are 1009.27 Bqk-1, 346.50 nGyh-1, 1.51 mSvy-1, 2.78 and 3.92 x 10-3 for respectively. These values were higher than their corresponding permissible values of 370Bqk-1, 55nGyh-1, 1.0 mSvy-1, 1.0 and 0.29 x 10-3 respectively. The mean values of Hex and Hin are greater than unity and may, therefore, constitute a significant radiological health risk. The mean annual gonad dose estimated value of 2943.90 mSvy-1 was above the world acceptable value of 300 mSvy-1 and the annual effective dose in all the samples except in few locations as shown in Figure 2, exceeded the safe value of 1.0 mSvy-1. The use of soil from these farms and the crops may constitute a threat to the bone marrow and general health conditions of the inhabitants.

Determination of Radionuclides in Borehole Water in the Adenta Municipality of Greater Accra Region

This study was carried out in the Greater Accra Region of Ghana mainly in the Adenta Municipality to determine the baseline radioactivity levels of naturally occurring radioactive material of water in boreholes using gamma spectrometry. According to WHO, the recommended limit of total committed annual ef-fective dose should be 100 uSv/yr for radioactive materials such as 40K, 226Ra and 232Th, which will be the subject of interest in the borehole water in the Adenta Municipality. Their average total committed annual effective dose due to intake was estimated to be 33.86 μSv/yr, respectively, which is far below the WHO recommended value. The average activity concentrations of 40K, 226Ra and 232Th in the fifth teen boreholes were measured as follows, 8.76 Bq/L ± to 1.28 Bq/L for 40K, 0.82 Bq/L ± to 0.15 Bq/L for 226Ra and 0.69 Bq/L ± to 0.11 Bq/L for 232Th respectively. Two of the boreholes exceeded the WHO recom-mended values for total committed annual effective dose. These are BW2 and BW7 with recording values of 138.41 and 131.21 respectively. The results from this study will serve as baseline data for further research in the Adenta Munic-ipality.

Presence of radionuclides and toxic elements in feedstuffs and food of animal origin

Introduction. The aim of this study was to determine the content of radionuclides and toxic elements in samples feedstuffs and food of animal origin collected between 2007- 2017 from two suburban areas of Belgrade, the municipalities of Palilula and Surcin, both areas with intensive agricultural production. Materials and Methods. Radionuclides (40K and 137Cs) and toxic elements (As, Cd, Cu, Ni, Pb and Zn) were determined in samples of corn, hay, meat, milk and eggs, by gamma ray spectrometry and inductively coupled plasma spectrometry (ICP-OES, Spectro Genesis). Results and Conclusions. The obtained results showed that natural 40K was present in all investigated samples. The average activity concentration of 40K was 94 Bq/kg in corn, 117 Bq/kg, 108 Bq/kg and 95 Bq/kg in beef, pork and chicken meat, respectively, as well as 61 Bq/kg in cow?s milk and 48 Bq/kg in eggs. Anthropogenic radionuclide 137Cs was not detected. The trend for toxic element levels according to the average concentrations found in the studied feed samples (corn and hay) was as follows: Zn>Cu>Pb>As>Ni>Cd. Arsenic was detected in animal feed in both Belgrade municipalities, with the average concentration being 1.08 mg/kg (0.5-1.37 mg/kg), and in corn, the As content was higher than in hay samples. In food of animal origin, only Zn and Cu were detected. It is concluded that the presence of radionuclides and toxic elements in feedstuffs and foods of animal origin does not pose a health risk for either humans or animals.

Environmental radioactivity of soils and sediments: Egyptian sector of the Nile valley

ABSTRACTThe activity concentrations of natural 40K, 232Th, and 238U in 89 soil and 84 sediment samples collected over the entire Egyptian Nile River basin including the Nile delta are reported based on the results of epithermal neutron activation analysis. The average activity concentrations of 40K, 232Th, and 238U equal to 15.3 ± 6.6, 15.6 ± 11.1 and 220 ± 31 Bq/kg, respectively, are significantly lower than those reported for the Upper Continental Crust, World Average Sediments as well as World Average Soils, suggesting the presence of a considerable portion of mafic material, most probably originating from the Ethiopian High Plateau. Their average activity concentrations are statistically the same in soil and sediments, indicating that the Nile sediments and soil material are of the same origin. The main goal of this study was not only to estimate the radiological hazards but also to show the influence of sedimentary material transportable by the Blue Nile from the Ethiopian High Plateau. The different hazard indices like the radium equivalent, gamma index, external hazard as well as the internal hazard show a low radiological exposure either on direct contact or if local mud bricks are used in the construction of dwellings.

Background Radiation Measurement and the Assessment of Radiological Impacts due to Natural Radioactivity Around Itakpe Iron-Ore Mines

Mining activity and metal extraction processes have been identified as one of the major pathways through which natural radionuclides are accumulated in the terrestrial environment. Exposure to excessive radiation from natural radionuclides can cause deleterious health hazards to man. In this study therefore, the activity concentrations of primordial radionuclides (40K, 238U and 232Th) were measured in rock, soil, tailings and water samples collected from abandoned iron ore mines in order to estimate the radiological impacts associated with the previous mining and metal extraction activities within the environment of abandoned Itakpe iron-ore mines. Gamma spectrometry utilizing a well calibrated NaI(Tl) detector was employed for the measurements. Results show that the average activity concentrations of 40K, 238U and 232Th are 1084 ± 581, 11.0 ± 7.7 and 5.0 ± 1.8 Bq kg−1 respectively for rock samples and 415.6 ± 197.5, 12.8 ± 5.7 and 8.8 ± 5.8 Bq kg−1, respectively for soil samples. The activity concentrations of the three radionuclides are much lower in water samples compared to rocks and soil. Radiological hazard indices calculated from the activity concentrations show that the mining activities have little or no negative impacts on the environment as the radiological risk indices obtained are all lower than their permissible limits.

Evaluation of the Activity of Gamma-Emitting Natural Radionuclides in Seafood and Estimation of the Annual Effective Dose for Different Age Groups in KSA.

Twenty-six brands of canned tuna and sardines imported from several countries in Southeast Asia to consume in the KSA. All samples were prepared and analyzed by using a High Pure Germanium Detector of 40% efficiency. Natural radionuclides 40K, 238U (226Ra) and 232Th(228Ra) series were observed with a varying range in all analyzed samples. The values found to be 192.3 ± 14.6, 1.5 ± 0.8 and 1.0 ± 0.6 Bq kg-1 for canned tuna and 219.8 ± 15.8, 0.37 ± 0.3 and 1.2 ± 0.3 Bq kg-1 for canned sardines, respectively. Cesium-137 was not detected at any sample. The comparison between the average activity concentrations of 40K, 238U(226Ra) and 232Th(228Ra) in both canned tuna and sardines was performed and discussed. The dose assessment due to consume/ingestion of seafood was calculated and observed that the calculated committed effective dose is within the global internal dose (290 μSv/y).

Estimation of annual effective dose from ingestion of 40K and 137Cs in foods frequently consumed in Korea

The activity concentrations of natural (40K) and anthropogenic (137Cs) radionuclides were measured in the 30 most commonly consumed foods in Korea. The average activity-concentrations of 40K and 137Cs were 67 Bq kg−1 and 46 mBq kg−1 fresh weight of food, respectively. The total annual intakes of 40K and 137Cs by humans were 14915 and 3.64 Bq year−1, respectively. The calculated mean annual effective doses from ingestion of the investigated foodstuffs were 92 µSv for 40K and 0.047 µSv for 137Cs. Our results can provide useful background information on radiation protection in Korea, and in other countries as well.

Distribution and environmental impacts of heavy metals and radioactivity in sediment and seawater samples of the Marmara Sea

In this study, the natural and anthropogenic radioactivity levels in the sediment samples collected from the Marmara Sea in Turkey were determined. The average activity concentrations (range) of 226Ra, 238U, 232Th, 40K and 137Cs were found to be 23.8 (13.8–34.2) Bq kg−1, 18.8 (6.4–25.9) Bq kg−1, 23.02 (6.3–31.1) Bq kg−1, 558.6 (378.8–693.6) Bq kg−1 and 9.14 (4.8–16.3) Bq kg−1, respectively. Our results showed that the average activity concentrations of 226Ra, 238U and 232Th in the sediment samples were within the acceptable limits; whereas the average activity concentration of 40K in the sediment samples was higher than the worldwide average concentration. The average radium equivalent activity, the average absorbed dose rate and the average external hazard index were calculated as 100.01 Bq kg−1, 48.32 nGy h−1 and 0.27, respectively. The average gross alpha and beta activity in the seawater samples were found to be 0.042 Bq L−1 and 13.402 Bq L−1, respectively. The gross alpha and beta activity concentrations increased with water depth in the same stations. The average heavy metal concentrations (range) in the sediment samples were 114.6 (21.6–201.7) μg g−1 for Cr, 568.2 (190.8–1625.1) μg g−1 for Mn, 39.3 (4.9–83.4) μg g−1 for Cu, 85.5 (11.0–171.8) μg g−1 for Zn, 32.9 (9.1–73.1) μg g−1 for Pb and 49.1 (6.8–103.0) μg g−1 for Ni. S5 station was heavily polluted by Cr, Cu, Ni and Pb. The results showed that heavy metal enrichment in sediments of the Marmara Sea was widespread.

Radioactivity in three species of eastern Mediterranean jellyfish

Activity concentrations of 137Cs, 40K, 210Po, 210Pb, 234U and 238U were determined in umbrella and oral arms of three widely distributed jellyfish species; namely Rhopilema nomadica Galil, 1990, Aurelia aurita Linne, 1758 and Aequorea forskalea Péron & Lesueur, 1810 collected from February 2011 to January 2012 in four sampling locations along the Syrian coast (Eastern Mediterranean Sea). The results have shown significant variations in radionuclides activity concentrations amongst the species. The average activity concentrations of 40K, 210Po, 210Pb, 234U and 238U in the umbrella of R. nomadica species were higher than the average activity concentrations in the umbrella of A. aurita species by about 3.2, 1.4, 1.8, 3.2 and 3.2 folds, and A. forskalea species by about 45.5, 15.4, 19, 7.4 and 7.6 folds, respectively. The average activity concentrations of 40K, 210Po, 210Pb, 234U and 238U in oral arms of R. nomadica species were higher than the average activity concentrations in oral arms of A. aurita species by about 3.8, 1.7, 1.9, 2.8 and 2.9 folds, respectively. 137Cs activity concentrations were below the detection limit in all measured samples. In addition, activity concentrations of 137Cs, 40K, 210Po, 210Pb, 234U and 238U were also determined in 44 surface seawater samples and the activity concentrations ranged between 10.6 and 11.9 Bq l−1 for 40K, 1.1 and 1.4 mBq l−1 for 210Po, 0.5 and 0.7 mBq l−1 for 210Pb, 40.8 and 44.5 mBq l−1 for 234U, and 36.9 and 38.4 mBq l−1 for 238U, while 137Cs activity concentrations were below the detection limit in all measured samples. Moreover, the umbrella and oral arms readily accumulated 40K, 210Po, 210Pb, 234U and 238U above ambient seawater levels in the sequence of 210Po > 210Pb > 4 K > 234U and 238U. Concentration ratio (CR) values were relatively high for 210Po and 210Pb and reached 103 and 102, respectively for the jellyfish R. nomadica species compared to A. aurita and A. forskalea species. Therefore, R. nomadica can be used as biomonitor for these two radionuclides in the Eastern Mediterranean Sea. However, the obtained data can be considered the first reported baseline values for radioactivity in jellyfish.

The radiological situation around the former uranium processing plant MAPE Mydlovary, Czech Republic

The uranium processing plant MAPE Mydlovary in South Bohemia, Czech Republic, was in operation for about 30 years, from 1962 until 1991. Extensive remediation and reclamation work has been done in the area. In the study presented here we measured mass and volume activities of certain radionuclides in soil and water samples from the surroundings and measured gamma equivalent dose rates at the same locations. The average activity concentrations of 40K, 226Ra, and 238U in soil were 307.3 ? 4.4 Bq/kg, 133.4 ? 0.8 Bq/kg, and 113.2 ?3.8 Bq/kg, respectively, whereas in water they were 5.7 ? 0.3 Bq/L, 0.30 ? 0.03 Bq/L, and 1.8 ? 0.16 Bq/L, respectively. The gamma equivalent dose rate at 5 cm and 1 m height above ground was 0.15 ? ? 0.04 ?Sv/h and 0.15 ? 0.03 ?Sv/h, respectively. As shown by comparison with the findings for similar sites elsewhere in the world, as well as with the results of measurements at uncontaminated locations, these values are compatible with regulation limits and there is no reason for concern regarding the radiation protection for workers involved with further remediation and reclamation, or carrying out other activities in the area.

Naturally occurring radioactive materials (NORMs) generated from lignite-fired power plants in Kosovo

The energy production in Kosovo depends primarily on lignite-fired power plants. During coal combustion, huge amounts of fly ash and bottom ash are generated, which may result in enriched natural radionuclides; therefore, these radionuclides need to be investigated to identify the possible processes that may lead to the radiological exposure of workers and the local population. Lignite samples and NORMs of fly ash and bottom ash generated in lignite-fired power plants in Kosovo are analyzed using a gamma-ray spectrometry method for the activity concentration of natural radionuclides. The average activity concentrations of 40K, 226Ra and 232Th in lignite are found to be 36 ± 8 Bq kg−1, 9 ± 1 Bq kg−1 and 9 ± 3 Bq kg−1, respectively. Indications on the occurrence and geochemical behavior of uranium in the lignite matrix are suggested. The activity concentrations of natural radionuclides in fly ash and bottom ash samples are found to be concentrated from 3 to 5 times that of the feeding lignite. The external gamma-ray absorbed dose rate and the activity concentration index are calculated to assess the radiological hazard arising from ash disposal and recycling in the cement industry.

Geochemistry and health burden of radionuclides and trace metals in shale samples from the North-Western Niger Delta

Organic sedimentary rock samples were collected from three Oil Wells in the North-Western Niger Delta, Nigeria in order to determine their natural radioactivity and elemental geochemistry, with the aim of determining the concentrations of major radionuclides and their radiological and environmental health implication. The PIXE method of IBA technique and an accurately calibrated Si(Li) detector system was used to measure the elemental concentration of the sediment samples. The radionuclides identified belong to the decay series of naturally occurring radionuclides headed by 238U and 232Th along with the non-decay series radionuclide, 40K. The activity concentrations of the radionuclides and their derived dose were then calculated. The average activity concentrations of 40K were 248 Bq/kg for Well A, 261 Bq/kg for Well B and 273 Bq/kg for Well C. For 232Th the activity concentrations were 1,043 Bq/kg for Well A, 1,400 Bq/kg for Well B, 1,434 Bq/kg for Well C. 238U activity concentrations were 2,210, 3,508 and 250 Bq/kg for the Oil Wells A, B, C, respectively. The equivalent dose ranges from 8.5 ± 1.1 to 24.3 ± 2.1 mSv/year with a mean of 14.5 ± 2.2 mSv/year for Oil Well A, 2.4 ± 0.1–75.0 ± 1.2 mSv/year with a mean of 21.5 ± 1.1 mSv/year for Oil Well B and 3.7 ± 0.2–10.7 ± 0.6 mSv/year with a mean of 9.4 ± 2.5 for Oil Well C. The detected trace metals were majorly V, Ni, Pb, Fe, Cr, Cu, Zn, Co and their concentrations together with those of the radionuclides are compared with the relevant world standard limits. The results obtained were high, and hence, the radioactivity level and trace element content of the sediment samples from the North-Western Niger Delta Oil province could constitute health hazard to occupationally exposed workers, and to the public if not properly disposed. However, despite the careful disposal practice claims by the Oil industries, and given the high concentrations, the sediments could still pose an intrinsic health hazard considering their cumulative effects in the environment.

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

Radioactivity in soil from the city of Kavadarci (Republic of Macedonia) and its environs

The activity concentrations and distribution of natural and anthropogenic radionuclides in soils from the city of Kavadarci, Republic of Macedonia, and its environs were investigated. The purpose of the study, the first of this kind in this region was to evaluate the environmental radioactivity and radiological health hazard, as well as to determine the connection between the concentration of natural radionuclides and the geology of the terrain. A total of 45 surface soil samples were collected from evenly distributed sampling sites. Gross alpha and gross beta activity measurements were made using a gas flow proportional counter, while the activity concentrations of gamma emitting radionuclides were measured using a high purity germanium detector. The average activity concentrations of ⁴⁰K, ²²⁶Ra, ²³²Th and ¹³⁷Cs were found to be 546±118, 38.8±14.6, 43.7±18.4 and 41.5±40 Bq kg⁻¹, respectively. The mean values of gross alpha and gross beta activities were 522±192 and 681±146 Bq kg⁻¹. The mean total absorbed dose rate in air calculated from the concentration of the natural radionuclides was 67.1±20.9 nGy h⁻¹, and the corresponding annual effective dose rate outdoors was 0.082±0.026 mSv y⁻¹. The results of the analysis show strong correlation between the abundance of the natural radionuclides in soils and their geological origin.

Radioactivity levels of staple foodstuffs and dose estimates for most of the Tanzanianpopulation

Levels of natural radioactivity in staple food products (maize and rice) from variouslocalities of Tanzania have been studied. The average activity concentrations of40K,232Th and238U in maizewere 48.79 ± 0.11, 4.08 ± 0.01 and13.23 ± 0.10 Bq kg−1, respectively. In ricethe concentrations of 40K, 232Th and 238U were 24.67 ± 0.03, 3.82 ± 0.02 and5.02 ± 0.02 Bq kg−1,respectively. 137Cs was detected in only one sample collected in Zanzibar. The sample, with activity concentration of5.57 ± 0.01 Bq kg−1, had been imported from Thailand. The relatively high average concentrations of theradionuclides in maize compared to rice may be attributed to the extensive use of phosphatefertilizers in maize production in Tanzania. Total annual committed effective doses due to total232Th and 238U intakes as a result of consumption of staple foodstuffs for infants, children and adults were 0.16, 0.29and 0.36 mSv y−1, respectively, which are lower than the annual dose guideline for the general public.