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Naturally occurring radionuclides and rare earth elements in weathered Japanese soil samples

Sahoo S., Hosoda M., Prasad G., Takahashi H., Sorimachi A., Ishikawa T., Tokonami S., Uchida S.

Acta Geophysica

2013

Vol. 61, no. 4

876--885

The activity concentrations of 226Ra and 228Ac in weathered Japanese soils from two selected prefectures have been measured using a γ-ray spectroscopy system with high purity germanium detector. The uranium, thorium, and rare earth elements (REEs) concentrations were determined from the same soil samples using inductively coupled plasma mass spectrometry (ICP-MS). For example, granitic rocks contain higher amounts of U, Th, and light REEs compared to other igneous rocks such as basalt and andesites. Therefore, it is necessary to understand the interaction between REEs and nature of soils since soils are complex heterogeneous mixture of organic and inorganic solids, water, and gases. In this paper, we will discuss about distribution pattern of 238U and 232Th along with REEs in soil samples of weathered acid rock (granite) collected from two prefectures of Japan: Hiroshima and Miyagi.

Natural radionuclide analysis in Chattarpur area of southeastern coastal area of Odisha, India

Rautela B., Gusain G., Yadav M., Sahoo S., Tokonami S., Ramola R.C.

Acta Geophysica

2013

Vol. 61, no. 4

1038--1045

The energy released in a spontaneous decay process of natural radionuclides is the main source of the total radiation dose to human beings. Natural radionuclides are widely distributed in soil, rocks, air, and groundwater. In present investigation, the analysis of terrestrial radionuclides such as 226Ra, 232Th, and 40K in soil and sand of Chattarpur area of southeastern coast of Odisha has been carried out using NaI(Tl) gamma ray detector. The higher activity concentrations of naturally occurring radionuclides have been reported from the study area. The gamma radiationdose originating from the terrestrial radionuclides was found to vary from 95 to 1813 nGy/h with an average of 700 nGy/h. This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details.

Radon and thoron parallel measurements in dwellings nearby a closed Hungarian uranium mine

Németh C., Jobbágy V., Kávási N., Somlai J., Kovács T., Tokonami S.

Nukleonika

2010

Vol. 55, No. 4

459-462

Integrated measurements of radon (222Rn) and thoron (220Rn) were executed in a Hungarian village, located in the vicinity of an abandoned uranium mine. The applied passive radon and thoron monitor was the RADUET which is based on a CR-39 track detector. The investigated 35 houses were one storey buildings made of bricks. The rock under the village is a gray-sandstone with an average of 136 and 77 Bqźkg–1 uranium and thorium, respectively. The detectors were mostly placed in the inhabited areas of the houses, such as bedrooms and living-rooms, at a height of 1–1.5 m close to the wall. The measurement periods were between December 2006 and May 2007 and between May 2007 and February 2008. Annual averages of radon concentrations were calculated applying seasonal correction factors to the results of the two measurement periods. The results show that the radon concentrations in the case of considerable part of the investigated dwellings seems to be significantly higher than the Hungarian averages for ground-floor houses (152 Bqźm–3). The thoron concentrations in some cases are also not negligible indicating that radon measurements which are sensitive to thoron can be misleading. Additionally, thoron can also be a contributor of extra dose.