Vol.:(0123456789) 1 3 Journal of Radioanalytical and Nuclear Chemistry https://doi.org/10.1007/s10967-021-07886-7 Natural radioactivity in soils of Elephant hills, Tamilnadu, India B. Jananee 1  · A. Rajalakshmi 1  · V. Thangam 1  · K. Manikanda Bharath 2  · V. Sathish 1 Received: 27 March 2021 / Accepted: 30 June 2021 © Akadémiai Kiadó, Budapest, Hungary 2021 Abstract The aim of the present work is to determine the activity concentrations of natural radionuclides and the associated radiation hazards in soils of Elephant hills, Tamil Nadu, India using gamma-ray spectrometry. The average activity concentrations of 238 U, 232 Th and 40 K are 52, 48, and 840 Bq kg −1 respectively. The average dose rate of 89 nGy h −1 is nearly 1.5 times higher than the outdoor world average, but the average annual efective dose equivalent (AEDE) is less than the recommended limit of unity. Pearson correlation analysis indicates that 40 K does not contribute to radioactivity in these soils. Keywords Elephant hill soils · Natural radioactivity · Gamma ray spectrometry · Pearson correlation analysis Introduction Radiation and natural environment both possess a remark- able bond that natural ionising radiation is ubiquitous. A vast majority of natural radioactivity on Earth and its related doses result from the natural radionuclides such as 238 U, 232 Th and 40 K which are well known gamma ray emitters [1–4]. Exposure to these gamma radiations may cause cell modification that can usually be repaired. However, an imperfect repair will eventually lead to hereditary disorders or cancer associated with organs such as lung, breast or thy- roid [5]. High doses impacting the body in a short duration of time could be harmful depending on the person’s resist- ance, diet habits, physical and mental health [6]. Hence, it is essential to ascertain the radioactive concentration living beings are exposed to. The natural radionuclides are wide spread in the Earth’s environment and is found in various geological formations such as soils, sediments, rocks and water [7–9]. Of these, soil plays a major role in building construction and agriculture activities. A striking feature of soil is that it acts as a migration web for the continuous transfer of radio- nuclides into human biological systems [10]. Radioactivity in soil is primarily dependent on the geology of the rocks that form the soil [7–10]. Besides geology, regional geologi- cal events, latitude and altitude of site, industrial wastes, use of pesticides and fertilizers, mineral processing, water treat- ment and use of fossil fuels, and natural occurrences like seismic events and forest fres can modify the distribution of radionuclides in soil [11]. Thereby, the natural radioactivity can vary considerably between soil types [11]. Hence, the determination of natural radioactivity in soils is an essential precautionary step for assessing long term exposure to living beings [12, 13]. An increasing number of literature studies indicate that, the Southern Western Ghats bordering Kerala and Tamil Nadu are one of the Naturally High Background Radiation Areas (NHBRA’s) due to signifcant quantities of monazite deposition [14–16]. Monazite comprises of thorium oxide (7–10%), uranium oxide (less than 0.5%), and the remain- ing of rare earth oxides thus contributing to higher natural radioactivity [17]. In the present study, Elephant hills which is popularly known as Anaimalai in Tamil Nadu, India was selected for radioactivity studies since it is located in the border between the southern Western Ghats of Kerala and Tamil Nadu in India [18]. From the assessed literature sur- vey, there have been no radioactivity studies reported in the study area till date. Therefore the main objectives of the present work are (i) establishing a comprehensive baseline data of the activity concentrations of the radionuclides in Elephant hill soils (ii) analysing the impact of radionuclides to the population by determining the associated radiological parameters (iii) assessing the correlation between the natural * A. Rajalakshmi rajalakshmia@ssn.edu.in 1 Department of Physics, Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam, Tamilnadu 603110, India 2 Institute for Ocean Management, Anna University, Chennai 600025, India