Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu,India)

The activity concentrations and absorbed gamma dose of primordial radionuclides ²³⁸U, ²³²Th and ⁴⁰K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg^?1 for ²³⁸U, 66 Bq kg^?1 for ²³²Th and 340.3 Bq kg^?1 for ⁴⁰K as compared to mean values for rock samples (²³⁸U—8.0 Bq kg^?1; ²³²Th—65.1 Bq kg^?1; ⁴⁰K—199.1 Bq kg^?1). The mean absorbed gamma dose rate for soil (61.4 nGy h^?1) marginally exceeded the prescribed limit of 55 nGy h^?1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h^?1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg^?1) than in rock (20.0 Bq kg^?1). However, these values were lower than the limit (370 Bq kg^?1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district.     

Assessment of indoor radiation dose received by the residents of natural high background radiation areas of coastal villages of Kanyakumari district,Tamil Nadu,India

Radiation exposure and effective dose received through two routes of exposure, viz. external and internal, via inhalation, by residents of 10 villages belonging to Natural High Background Radiation Areas (NHBRA) of coastal regions of Kanyakumari District and Tamil Nadu in India were studied. While the indoor gamma radiation levels were monitored using Thermo Luminescent Dosimeters (TLDs), the indoor radon and thoron gas concentrations were measured using twin chamber dosimeters employing Solid State Nuclear Track Detectors (SSNTDs, LR-115-II). The average total annual effective dose was estimated and found to be varying from 2.59 to 8.76 mSv.     

Natural radioactivity in soil samples of Yelagiri Hills,Tamil Nadu,India and the associated radiation hazards

The natural radioactivity of soils at Yelagiri hills has been studied in this paper. The radioactivities of 25 samples have been measured with a NaI(Tl) detector. The radioactivity concentrations of ²³⁸U, ²³²Th and ⁴⁰K ranged from ≤2.17 to 53.23, 13.54 to 89.89 and from 625.09 to 2207.3 Bq kg^?1, respectively. The measured activity concentrations for these radionuclides were compared with world average activity of soil. The average activity concentration of ²³²Th in the present study is 1.19 times higher than world median value while the activity of ²³⁸U and ⁴⁰K is found to be lower. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity Ra_eq, the absorbed dose rate D_R, the annual effective dose rate and the external hazard index (H_ex) have been calculated and compared with the internationally approved values. The study provides background radioactivity concentrations in Yelagiri hills.     

Activity concentration of polonium-210 and lead-210 in tobacco products and annual committed effective dose to tobacco users in Tiruchirappalli District (Tamil Nadu,India)

The present study has carried out with an objective of determining the activity concentrations of two radionuclides namely polonium-210 (²¹⁰Po) and lead-210 (²¹⁰Pb) in smoke tobacco products (cigarette, bidi and cigar) and smokeless tobacco products (chewing tobacco and snuff) consumed in Tiruchirappalli District, Tamil Nadu (India) and their annual committed effective dose to tobacco consumers. The concentration of ²¹⁰Po was always higher than that of ²¹⁰Pb in all the analyzed tobacco products. It also revealed that 79% of Annual committed effective dose comes from ²¹⁰Po and about 21% from ²¹⁰Pb. Maximum concentration (13.2 mBq g^?1) of ²¹⁰Po recorded in cigarette and lowest concentration was observed in snuff (6.4 mBq g^?1). The highest mean committed effective dose of ²¹⁰Po and ²¹⁰Pb in various tobacco products were found in cigarette followed by bidi, cigar, chewing tobacco and snuff. The study revealed that the tobacco products available in Tiruchirappalli District contain a relatively lower concentration of radionuclides when compared to other regional studies. Since this kind of study in India is fragmentary, the present study has generated a base data for the first time for entire Tiruchirappalli District.

     

Radiation dose contribution from coal-slags used as structural building material

A significant dose contribution on the population could be derived from coal slags used as isolation material. Extremely high natural activities are measured in the coal slag, derived from the region of the settlement Ajka, Hungary. In some buildings monitored, the elevated -doses were nearly 5–10 times higher than the world average ones. The annual average indoor radon concentrations from the slag exceeded 400 Bq/m³ and in some cases up to 1200 Bq/m³. Due to the elevated exposure and the radon concentrations in the dwellings the annual dose was estimated to 8–24 mSv/y more than 5–10 times of the world average one.     

Measurement of environmental gamma dose levels around Udupi district of coastal Karnataka,India

The outdoor and indoor environmental gamma dose rates in air have been measured in several parts of Udupi district, Karnataka, India using thermoluminescent dosimeters (TLDs). The outdoor annual gamma dose values varies in the range 0.49–1.17 mGy/year with mean 0.75 ± 0.18 mGy/year. Similarly indoor annual gamma dose varies in the range 0.51–1.10 mGy/year with mean 0.74 ± 0.13 mGy/year. The mean values of indoor and outdoor gamma dose rates were 84 and 86 nGy/h respectively with indoor to outdoor dose ratio of 1.02.     

Occurrence of the radionuclides in groundwater of crystalline hard rock regions of central Tamil Nadu,India

A study was conducted to understand the occurrence of the radionuclides in groundwater of crystalline hard rock region. Samples were collected to analyze major cations, anions, U, ²²²Rn and stable isotopes of oxygen, hydrogen. It was inferred that few samples have U and ²²²Rn concentrations higher than the permissible limit of drinking water standard. High degree of weathering of granitic rocks and long contact time of groundwater with the aquifer matrix could be the reason for enhanced U and ²²²Rn levels in groundwater. The association of U with SO₄ also proves that there exists anthropogenic influence in groundwater composition.     

Radon isotope assessment of submarine groundwater discharge (SGD) in Coleroon River Estuary,Tamil Nadu,India

Submarine groundwater discharge is the fresh groundwater discharge to sea that impacts the coastal regions. Radon (²²²Rn) isotope has been used to quantify SGD in coleroon river estuary, India. Continuous ²²²Rn analyses were attempted for 10 days in groundwater and pore water samples at three different locations. ²²²Rn in groundwater ranges between 35.0 and 222.0 Bq m^?3 and in pore water between 14.0 and 150.0 Bq m^?3 irrespective of locations. The radon mass balance estimated total SGD rate ranges between 2.37 and 7.47 m days^?1. The SGD increases with distance from coast, influenced by tides and hydrological features.     

Radon health hazards of some rocks of Iranian origin, frequently used as building stones

Radon exhalation rate from various types of stones, used inside the living buildings, is a major factor for evaluation of the environmental radon level. To verify the significance and lethal impacts of this unknown and obscure source of radiation upon the people around the world, the exhaled radon gas concentrations from the rocks, granodiorite, granite, limestone and aragonite, and the effect of their block sizes on the exhalation rate, have been studied. The block samples, collected from their ores, were transferred to plastic containers in which the CR-39 detectors could properly be placed and air tightened, for concentration measurements. The results show the radon concentration of 7.4 ± 0.8, 6.6 ± 0.6, 0.08 ± 0.02 and 0.09 ± 0.02 kBq m⁻³ for granodiorite, granite, limestone and aragonite, respectively. The corresponding annual dose values in a closed environment are: 186 ± 20, 166 ± 15, 2.5 ± 1 and 2 ± 1 mSv y⁻¹. These absorbed dose values indicate that granodiorite and granite when used inside the buildings could increase the risk of various cancers while aragonite and limestone have much lower risks and are recommended for use inside the buildings. The former ones when used in the closure areas remedial action should be implemented. The results do not show obvious dependence between the rock size of the samples and their radon exhalation rate.     

Comparison of thoron (220Rn) content and gamma radiation level in high background radiation area of Kollam district in Kerala,India

In order to map the thoron prone areas of the coastal region of Kollam district, a well known HBRA of south India, comparative study of radon and thoron exhalation rate was conducted. The in situ measurement of radon and thoron exhalation has been taken. These studies were correlated with the gamma radiation level. The average value of thoron exhalation is found to 5.55 ± 1.35 Bq m⁻² s⁻¹ along the coastal areas and the radon exhalation rate is found to 107.6 ± 32 Bq m⁻² h⁻¹. The value of thoron exhalation was found 12 times greater than the global values in Neendakara and Chavara region and about 6 times greater in the Alappad region.

     

Identification of groundwater discharge in Cuddalore coast,Tamil Nadu using radium isotopes

For the optimal exploitation and management of coastal aquifers of Tamil Nadu, it is essential to evaluate the groundwater outflow into the sea also called as submarine groundwater discharge. In this study, radium isotopes (^223,224Ra) were employed to understand the groundwater discharge in coastal areas of Cuddalore district, Tamil Nadu. Sea water samples (100 L) were collected from various locations of Cuddalore coast in October 2011 and passed through Mn-impregnated acrylic fiber columns. These acrylic columns were analyzed for ^223,224Ra activities using radium delayed coincidence counter. The observed higher activities of ^223,224Ra excess (0.02 ± 0.001–3.28 ± 0.16 and 64 ± 3–380 ± 19 mBq/100 L respectively) indicate that groundwater discharge occurs in this coastal region.     

Letter to the Editor: Radon isotope assessment of Submarine Groundwater Discharge (SGD) in Coleroon River Estuary,Tamil Nadu,India

Journal of Radioanalytical and Nuclear Chemistry -     

Spatial distribution of radium in coastal marine waters of Tamil Nadu

An investigation on the distribution of radium activity levels in the entire south eastern coast of Tamil Nadu, India, from Chennai to Kanyakumari was carried out. Insitu preconcentration technique was adopted by passing 1,000?L of seawater through MnO₂ impregnated cartridge filters at all the locations. In the coastal waters, ²²⁶Ra and ²²⁸Ra concentration was observed to be in the range of 1 to 1.81 and 3.1 to 7.5?mBq/L, respectively with an average of 1.52 and 4.53?mBq/L. respectively, while the sediment samples showed ²²⁶Ra activity levels from 8.1 to 129.0?Bq/kg and ²²⁸Ra varied from 14.7 to 430.01?Bq/kg. The Kd values for ²²⁶Ra was observed to be from 5.3E03 to 3.5E05?L/kg and for ²²⁸Ra it was in the range of 2.3E03 to 5.9E04. It was observed that the concentration of ²²⁸Ra was more than ²²⁶Ra in all the locations. The spatial distribution of the activity with respect to location is discussed in the paper. The radioactive database obtained, represents reference values for coastal environment of Tamil Nadu.     

Distribution patterns of gamma radiation dose rate in the high background radiation area of Odisha,India

Journal of Radioanalytical and Nuclear Chemistry - Absorbed dose rates in air for 20 residential areas in Odisha were measured using a vehicle-mounted NaI(Tl) scintillation spectrometer. The...     

Assessment of natural radiation hazards and function of heat production rate in lake sediments of Puliyanthangal Lake surrounding the Ranipet industrial area,Tamil Nadu

Journal of Radioanalytical and Nuclear Chemistry - In this work, 238U, 232Th and 40K activity concentration and the associated radiological implications are determined in the lake sediments at...     

Natural radioactivity and radiation hazards in some building materials used in Isparta,Turkey

The activity concentrations of uranium, thorium and potassium can vary from material to material and it should be measured as the radiation is hazardous for human health. Thus first studies have been planned to obtain radioactivity of building material used in the Isparta region of Turkey. The radioactivity of some building materials used in this region has been measured using a γ-ray spectrometry, which contains a NaI(Tl) detector connected to MCA. The specific activity for ²²⁶Ra, ²³²Th and ⁴⁰K, from the selected building materials, were in the range 17.91–58.88, 6.77–19.49 and 65.72–248.76 Bq/kg, respectively. Absorbed dose rate in air (D), annual effective dose (AED), radium equivalent activities (Ra_eq), and external hazard index (H_ex) associated with the natural radionuclide are calculated to assess the radiation hazard of the natural radioactivity in the building materials. It was found that none of the results exceeds the recommended limit value.