Quantification of radon/thoron exhalation rates of soil samples collected from district Faridabad of Southern Haryana, I
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Quantification of radon/thoron exhalation rates of soil samples collected from district Faridabad of Southern Haryana, India Bhupender Singh1,2 · Krishan Kant1 · Maneesha Garg2 · B. K. Sahoo3 Received: 24 February 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract This paper describes radon mass exhalation rate ( Jm ) and thoron surface exhalation rate ( Js ) of 46 soil samples of district Faridabad, Southern Haryana, India. Scintillation detector based SMART RnDuo (AQTEK System, India) coupled with exhalation chamber was used. Outdoor gamma exposure rate was measured by GM counter based survey meter. Jm of one −2 h−1 for Jm sample and Js of 95% samples were found higher than world average values of 57 mBq k g−1 h−1 and 3600 Bq m and Js respectively reported by UNSCEAR 2000. No significant correlation was observed between radon/thoron exhalation rates with outdoor gamma exposure rate. Keywords Radon/thoron · Gamma · Mass/surface exhalation · Alpha scintillometry
Introduction Exposure from radon isotopes and their progeny received significant recognition by world community because of their dangerous health effects [1]. Natural radioactivity depends primarily on geological and geographical conditions of the region [2, 3]. Radon is a naturally occurring radioactive gas and is produced continuously in rocks and soils grain due to radioactive decay of 226Ra, originating from the primordial radionuclide—238U present in the rock and soil. There are two fundamental processes by which Radon migrates from rocks and soil grains to environment. The first stage is emanation from the material grain and the second is exhalation from the matrix through different transport processes [4–6]. Emanation is the process by which radon atom escape from the solid mineral grains to the air-filled pores. Exhalation is the process of transport of radon gas from air-filled pores to the atmosphere. Radon transport in soil pore is mainly governed by (1) diffusion brought out by concentration gradient * Maneesha Garg [email protected] 1
Department of Physics, Aggarwal College Ballabgarh, Faridabad, Haryana 121004, India
2
Department of Physics, J.C. Bose University of Science and Technology, YMCA, Faridabad, Haryana 121006, India
3
Radiological Physics and Advisory Division, Bhabha Atomic Research Center, Mumbai 400085, India
and (2) advection brought out by pressure driven flow of soil gas [5, 7]. Radon being eight times heavier than air travels near to ground and can deposit its progeny in form of solid radioactive fallout on soil surface, vegetation and water. Radon can migrate due to Brownian motion if it finds way to diffuse. The permeability, medium porosity, pressure difference, moisture and temperature have large impact on concentration of radon in soil [8, 9]. Along with natural radioactivity, anthropogenic activities like industrial wastes and extensive use of phosphate fertilizers are also responsible for soil radioactivity. Based on the experimental observations and studies involving the models for ra
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