Vol.:(0123456789) 1 3 Environmental Earth Sciences (2019) 78:35 https://doi.org/10.1007/s12665-018-8029-7 ORIGINAL ARTICLE Measurements of radon ( 222 Rn) and thoron ( 220 Rn) exhalations and their decay product concentrations at Indian Stations in Antarctica Rama Prajith 1  · R. P. Rout 1  · D. Kumbhar 1  · Rosaline Mishra 1  · B. K. Sahoo 1  · B. K. Sapra 1 Received: 29 May 2018 / Accepted: 20 December 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract During the 33rd summer expedition to the two Indian Stations at Antarctica, Bharati and Maitri, radon and thoron progeny concentrations in indoors and outdoors were measured along with radon ( 222 Rn)/thoron ( 220 Rn) exhalation rate measure- ments of soil samples, radionuclide content and 222 Rn emanation coefcient. This investigation was based on the reports of the higher gamma radiation levels reported around these stations. The results will give an estimate of the radioactivity level as well as the total dose received by personnel carrying out long-term measurements at these stations. Radon and thoron progeny concentrations were measured using direct radon and thoron progeny sensors (DRPS and DTPS). The soil radionuclide content was measured using HPGe gamma spectrometry while radon/thoron exhalation rates were measured using the accumulation method by scintillation radon/thoron monitor. In contrast to a higher radiation feld and radioactiv- ity content, studies showed the radon/thoron exhalation rates and progeny concentration to be similar to that measured in normal background areas of other parts of the world. This could be attributed to the ice deposits and the larger atmospheric dispersion, and also to the soil nature which is mainly loamy sands with low clay content contributing to a lower emanation. The results are discussed. Keywords Antarctica · Radionuclide content · 222 Rn/ 220 Rn exhalation rate · EETC · EERC · Accumulation method · DTPS/ DRPS Introduction Antarctica has ice coverage of 98% and possible larger deposits of Uranium and Thorium in sedimentary basins that existed prior to the breakup of Gondwana. Uranium minerals or anomalous levels of radioactivity have been reported in several locations in Antarctica, particularly in Enderby Land, the Adelie Coast and the Trans-Antarctic Mountains of Victoria Land in East Antarctica (Congress 1989). Radon ( 222 Rn) and its isotope thoron ( 220 Rn) are naturally occurring radioactive gases, continuously being generated in rocks and soil containing primordial radionu- clides uranium and thorium, respectively. The process by which radon and thoron escapes from the rock/soil matrix and reaches to the atmosphere is called exhalation (Nazarof and Nero 1988). 222 Rn exhalation from a matrix is mainly governed by coefcient of radon emanation from soil grain to the porous volume and then difusion rate in pore space of the matrix (Sahoo and Mayya 2010). 222 Rn emanation coef- fcient is generally higher for fne soil grain and lesser for coarse grain. 222 Rn difusion in the pore space depends upon the porosity and moisture content in the soil matrix. For example, clay loam soils are characterised by its high sorp- tivity or low infltration capacity (Dutt et al. 2012; Verma et al. 2015; Maheshwar et al. 2015; Szajdak and Karabanov 2010), and hence may hold more water content in the pores, enabling trapping of more 222 Rn atoms within the matrix and thereby difusing lesser 222 Rn atoms to the atmosphere. Jonas et al. (2016) had carried out thoron exhalation of the samples and observed that it increased as a function of the Th-232 content and the emanation factor as well. Further, no correlation was found between the Th-232 content and the emanation factor. The results clearly proved that the emana- tion factor is of great importance with regard to exhalation * Rama Prajith rama@barc.gov.in 1 Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, 400094 Mumbai, India