External dose assessment from the measured radioactivity in soil samples collected from the Islamabad capital territory, Pakistan

A national survey of natural radionuclides in soils and terrestrial radiation exposure in Iran

In the past, some efforts have been made for measuring natural radioactivity and evaluating public exposure to natural radiation in certain areas of Iran especially in well-known High Level Natural Radiation Areas (HLNRA) in Ramsar and Mahallat. However, the information on radionuclide concentrations, and, consequently, terrestrial radiation exposure for many other areas are not available. There was therefore a need for a systematic and nation-wide survey. For this purpose, 979 soil samples from 31 provinces were collected. The activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were measured by HPGe detector. The average activity concentrations for Iran were found to be 457.7 Bq/kg for ⁴⁰K, 24.3 Bq/kg for ²²⁶Ra and 25.8 Bq/kg for ²³²Th. Results were compared with previous regional or provincial surveys. The population-weighted average outdoor and indoor annual effective dose due to external exposure to terrestrial sources of radiation are 0.06 mSv and 0.33 mSv, respectively. It was shown that there is a significant correlation between the activity concentrations of ²³²Th and ⁴⁰K in soil. In addition, the results of chi square tests show normal and lognormal distributions cannot be considered for the frequency distributions of activity concentration of ²³²Th and ²²⁶ Ra while ⁴⁰K has a normal distribution.

Study of natural radioactivity and estimation of radiation dose in the environment of Tumkur, Karnataka, India

The activity concentration of (226)Ra, (232)Th and (40)K was measured for soil samples collected from 34 locations of Tumkur District, Karnataka, India, using HPGe detector. The activity concentration of (226)Ra, (232)Th and (40)K varied from 9.6 to 71.6, 12.3 to 333.3 and 194.3 to 1527.7 Bq kg(-1) with an average value of 33.15, 123.01 and 877.76 Bq kg(-1), respectively. The absorbed and annual effective outdoor doses were found to be highest at Ponnasamudra with 258.98 nGy h(-1) and 317.62 μSv and lowest at Sira with 36.42 nGy h(-1) and 44.67 μSv, respectively. The external hazard index ranged from 0.21 to 1.58 with an average of 0.75. It was significant in 11 locations as it exceeded unity.

Radiological hazards due to naturally occurring radionuclides in the selected building materials used for the construction of dwellings in four districts of the Punjab Province, Pakistan

This paper presents the finding of a study undertaken to determine the naturally occurring radionuclides present in commonly used building materials for dwellings and workplaces in four districts of the Punjab Province, Pakistan. The concentrations of (226)Ra, (232)Th and (40)K were measured by using gamma-ray spectroscopy. A total of 80 samples of building materials were collected from various manufacturers and suppliers of the studied area. The specific activities of (226)Ra, (232)Th and (40)K were measured in building samples, and results ranged from minimum values of 9 ± 1, 9 ± 2 and 27 ± 8 Bq kg(-1) to maximum values of 106 ± 5, 133 ± 5 and 914 ± 21 Bq kg(-1) with mean values of 42 ± 3, 48 ± 3 and 376 ± 16 Bq kg(-1), respectively. From the measured activity concentrations, equivalent radium (Ra(eq)), terrestrial absorbed dose rate, annual effective dose as well as external and internal hazard indices were calculated and found to range from 52 ± 7 to 274 ± 15 Bq kg(-1), 23 ± 3 to 130 6 nGy h(-1), 0.15 ± 0.02 to 0.80 ± 0.03 mSv, 0.14 ± 0.02 to 0.75 ± 0.04 and 0.2 ± 0.02 to 0.98 ± 0.05, respectively. These results were comparable to the results of similar studies undertaken locally and in other countries. The samples considered were safe for use in construction of dwellings in the study area and do not pose any significant source of radiation hazard.

Natural and artificial radionuclide measurements and radioactivity assessment of soil samples in eastern Sichuan province (China)

The activity concentrations of natural and artificial radionuclides were measured in the eastern region of Sichuan province (China). One hundred and ninety-three soil samples from this region were collected and analysed by high-purity germanium gamma spectrometry. The measured results show that the average radioactivity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in the soil samples are 26, 49, 440 and 6 Bq kg(-1), respectively. The calculated average radium equivalent activity is 130 Bq kg(-1), which is less than the recommended limit of 370 Bq kg(-1). The absorbed dose rate and annual effective dose are 60 nGy h(-1) and 74 µSv, respectively. This is the first time the absorbed dose rate in the east region of Sichuan has been mapped. Overall, the environmental radiation background is greater in the southern part of the area studied than in the northern.

Radiological impacts of natural radioactivity from soil in Montenegro

Soil samples from Montenegro were analysed by the HPGe detector with 40 % of relative efficiency, for radioactivity due to (226)Ra, (232)Th and (40)K. The average activity concentrations have been found to be 39.9, 43.5 and 437.6 Bq kg(-1), respectively, i.e. in accordance with those in the other South European countries. In order to evaluate the health hazard, radium equivalent activity, absorbed dose rate, annual effective dose rate, external hazard index, annual gonadal dose equivalent and excess lifetime cancer risk (CR) have been calculated. The excess lifetime CR (× 10(-3)) had a range from 0.12 to 0.79, with an arithmetic mean of 0.27, which is in accordance with the global average. Mean gonadal dose equivalent was higher than the world average, and one location was found with the radium equivalent activity >370 Bq kg(-1), i.e. with the external hazard index higher than unity, which means the radiation hazard is not negligible.

Measurement of natural radioactivity in sand samples collected along the bank of rivers Indus and Kabul in northern Pakistan

Radioactivity is a part of the natural environment. The presence of natural radioactivity in sand and other building materials results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radionuclides, namely (232)Th, (226)Ra and (40)K in sand, bricks and cement which are commonly used as building materials in Pakistan. In this context, sand samples were collected from 18 different locations covering an area of ∼1000 km(2) along the banks of river Indus (Ghazi to Jabba) and river Kabul (Nowshera to Kund) in the northern part of Pakistan, whereas bricks and cement samples were collected from local suppliers of the studied area. In order to measure the specific activities in these samples, a P-type coaxial high-purity germanium-based gamma-ray spectrometer was used. In sand samples, the average specific activities of (226)Ra, (232)Th, and (40)K were found to be 30.5±11.4, 53.2±19.5 and 531±49 Bq kg(-1), whereas in brick samples, specific activities of 30±14, 41±21 and 525±183 Bq kg(-1) were observed, respectively. In cement samples, measured specific activity values were 21±5, 14±3 and 231±30 Bq kg(-1), respectively. Radium equivalent activities were calculated and found to be 143.8±38.6, 124±49.8 and 56.69±7 Bq kg(-1) for sand, brick and cement samples, respectively. The annual mean effective dose for the studied sand samples was found to be 0.40 mSv. External and internal hazard indices were less than unity for all the studied samples. The present results have been compared with those reported in the literature.