Radiological and pollution risk assessments of terrestrial radionuclides and heavy metals in a mineralized zone of the siwalik region (India).

The present study reveals the distribution of terrestrial radionuclides (226Ra, 232Th and 40K) and heavy metals (Cr, Ni, Cu, Zn, Pb, Co) from soil samples of Una, Hamirpur and Kangra districts of Himachal Pradesh (India). The 226Ra, 232Th, 40K activity concentration in the studied region has been varied from 8 to 3593 Bq kg-1; 21-370 Bq kg-116; 62-7130 Bq kg-1 respectively. High disequilibrium factor (238U/226Ra) depicts that uranium constantly migrates from clay oxidizing zone and getting precipitated with enrichment towards south. An attempt has been made to correlate the distribution of these radionuclides and heavy metals with geology and rock type formation of Siwalik region. The concentration of Pb, Zn and Co was found higher than Indian average background value. Multiple radiological and pollution indices have been estimated for proper risk analysis in the studied region. The annual effective dose in studied region is lower than the recommended limit of 1.0 mSv a-1. The obtained geo-accumulation index and enrichment factor indicated that the sites located in the Hamirpur and Kangra regions were moderately contaminated with Pb and Co. The Nemerow pollution index and contamination security index suggested that almost 45% sites were slightly to moderately polluted. The non-carcinogenic and carcinogenic risks for both children and adults were within acceptable limits.

Quantification of an alpha flux based radiological dose from seasonal exposure to 222Rn, 220Rn and their different EEC species.

This study summarizes the seasonal experimental data on the activity concentrations of indoor 222Rn (Radon), 220Rn (Thoron) and their progeny in Mansa and Muktsar districts of Punjab (India) using LR-115 solid state nuclear track detector based time integrated pin-hole cup dosimeters and deposition based progeny sensors for the assessment of radiological dose. The indoor 222Rn concentration was observed higher in the rainy and winter seasons while 220Rn concentration was observed higher in the winter season. However, Equilibrium Equivalent Concentrations (EECs) of 222Rn and 220Rn exhibited distinct seasonal behaviour unlike their parent nuclides. The average equilibrium factors for 222Rn (FRn) and 220Rn (FTn) were found 0.47 ± 0.1 and 0.05 ± 0.01, respectively. The annual arithmetic means of unattached fractions of 222Rn ([Formula: see text]) and 220Rn ([Formula: see text]) were found to be 0.09 ± 0.02 and 0.10 ± 0.02, respectively. The attachment rate (XRn) and attachment rate coefficients (ß) of 222Rn progeny were also calculated to understand the proper behaviour of progeny species in the region. A new alpha flux based technique has been proposed and used for the assessment of absorbed dose rate and annual effective dose rate for radiation protection purpose.

Structural, photoluminescence and dielectric investigations of phosphatic shale.

In the current study, the structural and spectroscopic properties of phosphatic shale samples obtained from the Atomic Minerals Directorate for Exploration and Research were probed for potential use as a phosphor material. X-ray diffraction and Raman and Fourier transform infrared spectroscopy revealed that the beneficiated phosphatic shale samples were primarily monophasic consisting of fluorapatite [Ca5 (PO4 )3 F, (FAP)] with minor traces of haematite (α-Fe2 O3 ) and calcite (CaCO3 ). Energy dispersive X-ray fluorescence revealed the presence of U, Eu, Dy and Tb in the FAP matrix substituted at Ca(I) and Ca(II) sites of FAP. A reduced optical direct band gap of 4.46 eV was calculated from the Tauc plot. Photoluminescence spectral studies revealed multicolour emissions (red, yellow, green and blue) on ultraviolet light excitation that were attributed to luminescence spectra from rare earth ions Eu3+ , Tb3+ , U4+ and U6+ in the FAP matrix. The overall emissions for the rare earth and actinide-doped FAP were obtained in the cool white region and the corresponding Commission Internationale de l'Eclairage chromaticity coordinates were calculated to be (0.274, 0.317). The corresponding colour correlated temperature obtained was 9342 K. Furthermore, phosphatic shale had a high room temperature dielectric constant of 11 at a frequency of 1 kHz that demonstrated its suitability for use in biological sensors. The study showed that natural phosphatic shale could be a potential material for optical, biological and dielectric applications.