Assessment of natural radioactivity is very important from different points of view, especially for assessment of radiation exposure to human. In the present study, natural radionuclide concentrations of ²³⁸U, ²³²Th, and ⁴⁰K were measured by gamma spectrometry using HPGe detector in soil samples collected from Southwest coast of Kanyakumari district, Tamil Nadu. The radiological index parameters due to natural radionuclides such as radium equivalent activity, absorbed dose rate, annual effective dose rate, external hazard index, internal hazard index, and gamma index were calculated for the soil samples. All the calculated radiological index values are higher than world average values and the recommended safety limits. Multivariate statistical techniques such as Pearson correlation, principal component analysis, and cluster analysis were applied to know the relation between radionuclides and radiological parameters and to study the spatial distribution of radionuclides.

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Accurate determination of uranium isotope ratio can act as an efficient fingerprint in the nuclear forensics to identify source and intended use of illicit trafficking of uranium material. In this context, a rapid chemical separation technique to isolate uranium from uranium ore sample was developed using commercial extraction chromatographic resin. Uranium isotope ratio was measured using thermal ionization mass spectrometry (TIMS). Standard reference material (NBS U010) was used for validating the accuracy and precision of isotope ratio measurement by TIMS. The method is successfully applied to a natural ore (uraninite ore) for the determination of naturally occurring uranium isotope ratio.

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Distribution studies of natural radionuclides in soil, statistical analysis of activity concentrations, and transfer factors (TFs) from soil to the vegetables grown in some selected farming communities within the Greater Accra Region in Ghana were carried out. The measurements were carried out through a gamma-ray spectrometry. The mean activity concentrations of ²²⁶Ra, ²²⁸Ra, and ⁴⁰K in the fertilized soils were 20.0 ± 3.9 Bq/kg, 39.0 ± 7.0 Bq/kg, and 143.6 ± 23.3 Bq/kg, respectively. For the nonfertilized soils, mean activity concentrations were found to be 12.07 ± 2.55 Bq/kg for ²²⁶Ra, 27.1 ± 6.3 Bq/kg for ²²⁸Ra, and 87.8 ± 18.5 Bq/kg for ⁴⁰K. These results were compared with reported ranges in the literature from other location in the world. The TF for ²²⁶Ra, ²²⁸Ra, and ⁴⁰K from fertilized soil to vegetables was evaluated. ²²⁶Ra TF values from fertilized soil to vegetables were found to be higher in lettuce in Farm 6. The highest TF for ⁴⁰K and ²²⁸Ra was found in cauliflower in Farm 4. ⁴⁰K TF was higher than those values reported in other studies. The activity concentration in fertilized and unfertilized soil exhibited slightly positively skewed, negatively skewed, leptokurtic, and platykurtic distribution in terms of skewness and kurtosis. The activity concentration of natural radionuclides in fertilized and unfertilized soil is statistically insignificant at 5% level of significance using independent t-test. Pearson's correlation coefficient exhibited a negative correlation between ²²⁶Ra and ²²⁸Ra in fertilized soil and ²²⁶Ra and ²²⁸Ra in vegetables but was statistically insignificant while ⁴⁰K in fertilized soil exhibited a positive correlation with ⁴⁰K in vegetables and was statistically significant at 5% level of significance with a coefficient of determination of 1%, 61%, and 10% for ²²⁶Ra, ⁴⁰K, and ²²⁸Ra, respectively.

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Selected heavy metals (Cr, Co, Ni, Cu, Zn, As, and Pb) in sediments from Periyakalapattu to Parangipettai of east coast of Tamil Nadu were determined to assess the contamination status and potential ecological risk. The pollution indices such as enrichment factor (EF), contamination factor (CF), geoaccumulation index (I_geo), and pollution load index (PLI) were calculated to determine the contamination level and enrichment of metals in sediments. EF analysis suggested that anthropogenic influence on the environment has been significant in case of Cr. The values of CF indicate that the sediments are not contaminated with these heavy metals. I_georesults reveal that the study area is not contaminated with respect to Cr, Co, Ni, Cu, Zn, As, and Pb. This results of I_geoare in good agreement with PLI. Based on the sediment quality guidelines, it is observed that Cr and Ni would be a concern for the ecotoxicological risk in study area.

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The activity concentrations of natural radionuclides in the sediments from Pulicat Lake to Vada Nemmeli of Chennai Coast, Tamil Nadu, have been measured using gamma-ray spectrometry. The average concentration of ²³⁸U, ²³²Th, and ⁴⁰K are 10.14, 35.02, and 425.82 Bq/kg, respectively, in sediments. Using measured activity concentrations of natural radionuclides, the radium equivalent activity (Ra_eq) was calculated to assess radiation hazard associated with the sediments. The calculated Ra_eqvalue of all the locations showed less than the recommended safe limit. The obtained results of the study could serve as an important baseline for radiometric data for future monitoring initiatives in the study area.

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A study on radon concentration in groundwater samples collected from different villages of Sira and Tiptur taluk of Tumkur district has been conducted using emanometry method, and the effective dose to the public was estimated. The geometric mean of the activity concentration of dissolved radon was found to be 39.13 ± 1.99 and 3.78 ± 0.05 Bq/L for Sira and Tiptur taluk, respectively. The total annual effective dose for adult, children, and infants was also estimated and was found to be 0.20, 0.18, and 0.31 mSv/year, respectively, in Sira taluk and 0.019, 0.017, and 0.029 mSv/year in Tiptur taluk, respectively. Water samples were also analyzed for the physicochemical parameters to assess the quality of drinking water and also to understand the influence of these parameters on dissolved radon concentration. Poor correlation was observed between dissolved radon concentration and pH in both taluks.

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Surface soil samples from coastal region of Visakhapatnam were analyzed for uranium series and thorium series radionuclides by high-resolution gamma-ray spectrometry. Isotopic ratios of ²²⁶Ra/²³⁸U and ²²⁴Ra/²³²Th were calculated to investigate the radioactive equilibrium status in the samples. ²²⁶Ra/²³⁸U and ²²⁴Ra/²³²Th ratios were found to vary from 0.80–1.40 to 0.94–1.40 with mean values of 1.05 and 0.99, respectively. Results showed a prevalent radioactive equilibrium for both uranium and thorium series radionuclides in the surface soil of the study area.

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³²P is preferentially eliminated from the body in urine and is estimated by in situ precipitation of ammonium molybdophosphate (AMP) in the urine followed by gross beta counting. The amount of AMP formed depends on the amount of stable phosphorus (P) present in the urine. Hence, the present study was undertaken to estimate daily urinary excretion of P by the spectrophotometry method. P forms a colorless complex (phosphomolybdate) with molybdic acid, which on reduction produces deep-blue-colored complex called molybdenum blue. The intensity of this blue color is directly proportional to the amount of P present in the sample. 24 h urine samples collected from radiation workers were analyzed for stable P, and its range was observed to be between 0.4 and 1.4 g/day. This information was valuable in finalizing volume of the urine sample required for analysis of ³²P in bioassay sample by gross beta counting technique.

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