A. Chandrasekaran

Measurement of natural radioactivity in building materials of Namakkal, Tamil Nadu, India using gamma-ray spectrometry

The natural level of radioactivity in building materials is one of the major causes of external exposure to γ-rays. The primordial radionuclides in building materials are one of the sources of radiation hazard in dwellings made of these materials. By the determination of the radioactivity level in building materials, the indoor radiological hazard to human health can be assessed. This is an important precautionary measure whenever the dose rate is found to be above the recommended limits. The aim of this work was to measure the specific activity concentration of (226)Ra, (232)Th and (40)K in commonly used building materials from Namakkal, Tamil Nadu, India, using gamma-ray spectrometer. The radiation hazard due to the total natural radioactivity in the studied building materials was estimated by different approaches. The concentrations of the natural radionuclides and the radium equivalent activity in studied samples were compared with the corresponding results of different countries. From the analysis, it is found that these materials may be safely used as construction materials and do not pose significant radiation hazards.

Multivariate statistical analysis of radiological data of building materials used in Tiruvannamalai, Tamilnadu, India

Using γ spectrometry, the concentration of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K has been measured in soil, sand, cement, clay and bricks, which are used as building materials in Tiruvannamalai, Tamilnadu, India. The radium equivalent activity (Raeq), the criterion formula (CF), indoor gamma absorbed dose rate (DR), annual effective dose (HR), activity utilization index (AUI), alpha index (Iα), gamma index (Iγ), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the building materials. From the analysis, it is found that these materials used for the construction of dwellings are safe for the inhabitants. The radiological data were processed using multivariate statistical methods to determine the similarities and correlation among the various samples. The frequency distributions for all radionuclides were analyzed. The data set consisted of 15 measured variables. The Pearson correlation coefficient reveals that the (226)Ra distribution in building materials is controlled by the variation of the (40)K concentration. Principal component analysis (PCA) yields a two-component representation of the acquired data from the building materials in Tiruvannamalai, wherein 94.9% of the total variance is explained. The resulting dendrogram of hierarchical cluster analysis (HCA) classified the 30 building materials into four major groups using 15 variables.

Spatial distribution and lifetime cancer risk due to gamma radioactivity in Yelagiri Hills, Tamilnadu, India

Abstract The spatial distribution of natural radioactivity due to uranium, thorium and potassium was investigated in soils from the undisturbed areas in Yelagiri Hills, Tamilnadu, India by Isodose map. The radiological hazards due to natural radionuclides content such as representative level index (RLI), activity utilization index (AUI), excess lifetime cancer risk (ELCR) and internal radiation hazards (Hin) of the soil samples in this area were calculated. The calculated radiological hazard parameters are compared with different countries of the world. The calculated range of ELCR is 0.326 × 10−3 to 1.067 × 10−3 with an average of 0.700 × 10−3 for soils. This average value of ELCR is more twice than the world average (0.290 × 10−3). A correlation analysis was made between measured dose rate and individual radionuclides, in order to delineate the contribution of the respective nuclides toward the dose rate. The U/Th concentration ratio in surface soil samples ranged from 0.05 to 1.72 with an average of 0.43 which is more higher (80%) than the world average of 0.26. The application of cluster analysis (CA) and principal component analysis (PCA), coupled with Pearson correlation coefficient analysis, were utilized to analyze the data, identify and clarify between the radiological parameters to know the existing relations. The CA and PCA results showed that the former method yielded three distinctive groups of the soil variables whereas the latter one yielded the number of variables into two factors with 94.47% variance explanation.

Measurement of natural radioactivity and evaluation of radiation hazards in coastal sediments of east coast of Tamilnadu using statistical approach

Abstract The concentrations of natural radionuclides in the sediments from Thazhankuda (Cuddalore) to Kodiyakkarai of east coast of Tamilnadu have been measured using gamma-ray spectrometry. Using the activity concentrations of these radionuclides, radiological hazard indices were evaluated in order to determine the effects of the sediments. The calculated average value of uranium, thorium and potassium are 3.8, 26.23 and 328.68 Bq kg−1, respectively. The radium equivalent activity (Raeq), absorbed dose rate, annual effective dose rate, activity utilization index, internal and external radiation hazard indices were calculated to study the hazardous nature. These values obtained from the coastal sediments were less than the recommended safe and criterion limits given by UNSCEAR. Results of the study could serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area. The statistical methods were applied to study the relationship between all the calculated natural radionuclides.

Assessment of Heavy Metal Contamination in Marine Sediments of East Coast of Tamil Nadu Affected by Different Pollution Sources

The aim of this study was to determine the concentration of heavy metals in the sediments of Periyakalapet to Parangipettai coast, east coast of Tamil Nadu, by using energy-dispersive X-ray fluorescence (EDXRF) technique. The average heavy metal concentrations in the sediment samples were found in the order Al>Fe>Ca>Ti>K>Mg>Mn>Ba>V>Cr>Zn>La>Ni>Pb>Co>Cd>Cu. The average heavy metal concentrations were below the world crustal average. The degree of contamination by heavy metals was evaluated using pollution indices. The results of pollution indices revealed that titanium (Ti) and cadmium (Cd) were significantly enriched in sediments. Pearson correlation analysis was performed among heavy metal concentrations to know the existing relationship between them. Multivariate statistical technique was employed to identify the heavy metal pollution sources.

Assessment of natural radioactivity and radiological hazards in building materials used in the Tiruvannamalai District, Tamilnadu, India, using a statistical approach

Abstract One-hundred-fifty-one samples of six types of building materials were collected from different locations of the Tiruvannamalai District, Tamilnadu, and were analyzed using a gamma ray spectroscopy system. From the results, the highest values observed in the specific activities of 226Ra, 232Th and 40K were 116.1 (soil) 106.67 (sand) and 527.533 (tiles) in Bq kg−1, while the lowest values observed in the specific activities of the same radionuclides were 35.73, 37.75 and 159.83 for cement in Bq kg−1, respectively. The potential radiological hazards were assessed by calculating the radium equivalent activity (Raeq), the indoor absorbed gamma dose rate (DR), the annual effective dose rate (HR), the activity utilization index (I), the alpha index (Iα), the gamma index (Iγ), and the external hazard (Hex) and internal hazard (Hin) indices. The estimated mean value of the absorbed dose rate of 148.35 nGy h−1 is slightly higher than the world average value of 84 nGy h−1, and the annual effective dose in the studied samples is 0.1824 mSv y−1, which is lower than the recommended limit. Multivariate statistical methods are applied to determine the existing relationship between radionuclides and radiological health hazard parameters and to identify the maximum contribution of radionuclide in radioactivity. The values of the hazard indices were below the recommended levels; therefore, it is concluded that the buildings constructed from such materials are safe for the inhabitants. The findings from this research will be useful to assess the radiation hazards of building materials in humans.

Analysis of beach rock samples of Andaman Island, India by spectroscopic techniques

Abstract Beach rock is a peculiar formation when compared to other types of rock formations. One such formation is found in Andaman and Nicobar Island of India. It needs intensive and extensive investigation on its formation. The present work aimed to collect the beach rock samples along the Coast of Andaman Island and subjected to mineral and multi-elemental analysis using spectroscopic techniques. The presence of mineral in beach rock samples is identified by FT-IR spectroscopic technique. The constituents of minerals present in the beach rocks are further confirmed by XRD technique. Elemental concentrations of beach rock samples have been analyzed using non-destructive technique of energy dispersive X-ray fluorescence (EDXRF) spectrometry. The concentrations of Al, Ca, K, Fe, Ti, Si, V, Co, Cu, Ba, Zn, Pb, Cd & Mn are determined. The geochemical behavior of elements in the region is discussed. The spectroscopic techniques reveal the cementing minerals and elemental compositions of beach rocks of Andaman Island, India. Results are discussed and the conclusions are drawn.

Assessment of gamma radiation and associated radiation hazards in coastal sediments of south east coast of Tamilnadu, India with statistical approach

Gamma spectroscopy was performed to determine the concentrations of 226Ra, 232Th and 40K in sediment samples collected from Periyakalapet to Parangaipettai, East coast of Tamilnadu. The activity concentrations were determined by direct counting using a hyper pure germanium (HPGe) detector inter phased with a multi channel analyzer (MCA). The average activity concentrations of the corresponding nuclides were 30.81 Bq kg-1 for 226Ra, 85.67 Bq kg-1 for 232Th and 425.72 Bq kg-1 for 40K. The average activity concentration of 232Th and 40K are slightly higher and 226Ra is lower than world average values. The radiation hazard indices namely Radium Equivalent Activity (Raeq) Absorbed Gamma Dose Rate (DR), Annual Effective Dose Rate (HR), Representative Level Index (RLI), Annual Gonadal Dose Equivalent (AGDE), Internal Hazard Index (Hin) and External Hazard index (Hex) are calculated and compared with the previously reported data. The extracted values are comparable to the recommended values and they all fall within the safety limits. Hence harmful radiation effects are not posed to the public and tourists going to the beaches for recreation or to the fishermen involved in their activities in the area as a result of the natural radioactivity of sediments. Multivariate Statistical analyses were carried out between the parameters obtained from the radioactivity to know the existing relations and to study the spatial distribution of radionuclides.

Statistical assessment to magnetic susceptibility and heavy metal data for characterizing the coastal sediment of East coast of Tamilnadu, India

A rapid urbanization and industrialization enhances the significant heavy metal pollution in the sediments of coastal area and introduced a serious threat to the human health. In the present study, concentration of heavy metals such as Al, Ti, Fe, V, Cr, Mn, Co, Zn, La, Pb, Mg, Ca, Ni, Cd and Ba are determined in sediments along Periyakalapet to Parangaipettai coastal area, Tamilnadu using energy dispersive X-ray fluorescence spectrometer (EDXRF).These metals have more affinity to establish metallic bond with ferrous material leading to enhancement of sediment magnetic susceptibility. Hence, a magnetic susceptibility (χLF, χHF, χFD) measurement was carried for sediments by using MS2B dual frequency susceptibility meter. Multivariate statistical analysis (Pearson correlation, factor and cluster analysis) was carried out between heavy metals and magnetic susceptibility to assess the anthropogenic impact in the sediments. The study revealed that a magnetic susceptibility measurement is an inexpensive, fast, non-destructive and suitable method to identify the heavy metal pollution sources.