P. Shahul Hameed

A study on the impact of phosphate fertilizers on the radioactivity profile of cultivated soils in Srirangam (Tamil Nadu, India)

Abstract Phosphate fertilizers are enriched with 238U during its production from phosphate rocks. Since, application of phosphate fertilizers in modern agriculture is ever on the increase, the present study investigated the impact of phosphate fertilizers on the radioactivity profile of cultivated (fertilized) soils as against virgin soils. Thirty soil samples each from cultivated fields and virgin fields were collected from Srirangam taluk and analyzed for the activity concentrations of 238U, 232Th and 40K employing gamma ray spectrometry. Similar analysis was also undertaken in commonly used phosphate fertilizers. Among the phosphate fertilizers analyzed single super phosphate (396.3Bq/kg) and triple super phosphate (284.2Bq/kg) registered higher level of 238U. The mean activity level of 238U in cultivated soil (8.4Bq/kg) was 25% higher than that of virgin soil (6.8Bq/kg), while the mean 232Th and 40K activities in cultivated soil (98.4Bq/kg & 436Bq/kg) were elevated by 12.4% and 4% respectively as compared to virgin soil (87.5Bq/kg & 419Bq/kg). The mean radium equivalent (Raeq) value for virgin and cultivated soil samples was found to be 164.5Bq/kg and 181.7Bq/kg respectively. It is evident that the application of phosphate fertilizers elevated 238U level of the soil. However, the mean Raeq value for soil samples is well below the permissible limit of 370Bq/kg and hence cultivated soils do not pose any radiological risk.

Radioactivity in Building Materials and Assessment of Risk of Human Exposure in the Tiruchirappalli District of Tamil Nadu, India

AbstractThis study aims to generate a database on the radioactivity content of the building materials mined and used in Tiruchirappalli District employing a high-resolution NaI(Tl) detector. Ninety-two different types of building materials were collected from the local construction suppliers. The results indicated that Ra226, Th232, and K40 concentrations in the building materials of the study area were found to vary from below detection limit (BDL) to 367.2  Bq/kg, BDL to 190.3  Bq/kg, and BDL to 1,227  Bq/kg, respectively, with arithmetic mean values of 45.5  Bq/kg, 73.5  Bq/kg, and 302.6  Bq/kg. Other radiation hazard indices, like radium-equivalent activity, absorbed dose rate, external and internal hazard indices, indoor and outdoor effective doses, and radioactivity level index, were also calculated. Building materials such as phosphogypsum, granite tiles, and fly ash show a higher level of radium-equivalent activity (>370  Bq/kg) and Iγ activity (>1). Hence, the use of phosphogypsum, granite tiles,...

Radon exhalation rate from the building materials of Tiruchirappalli district (Tamil Nadu State, India)

Tiruchirappalli district has enriched resources of building materials such as stone, granite, sand, brick, cement, etc., which are also supplied to the neighboring districts. Since radon is considered as one of the causative factors for human lung diseases, the measurement of the radon level in these building materials is imperative for the assessment. The samples of building materials were collected from their original sources spread over Tiruchirappalli district. The sealed can technique with solid state nuclear track detector (SSNTD) was employed for the measurement of radon exhalation. The activity concentrations of radon in sedimentary rocks analyzed ranged from 13.2 Bq/m 3 to 218.0 Bq/m 3 with the geometric mean activity of 46.3 Bq/m 3 . However, radon concentrations in igneous rocks are distinctly higher than those of sedimentary rocks and ranged from 95.6 Bq/m 3 to 1140 Bq/m 3 with the geometric mean activity concentration of 392.6 Bq/m 3 . The radon exhalation from sand, brick, and cement were found to be non-uniform (sand: 119.8-656 Bq/m 3 , brick: 31-558 Bq/m 3 , cement: 172-300 Bq/m 3 ). The activity concentration of radon in these building materials follow a descending order: Granite > sand > cement > brick > sand stone. The mass and surface exhalation (E M and E A ) rates also follow the same order. The study concludes that since the radon exhalation from the building materials was less than the International Commission on Radiological Protection limit of 1500 Bq/m 3 , they do not pose any radiological risk.

Environmental radioactivity evaluation in the coastal stretch of Bay of Bengal from Pondycherry to Velanganni (South East coast of India)

Background: Since the Madras Atomic Power Station, Kalpakkam and Kudankulam Nuclear Power Plant, Kudankulam are sited in Bay of Bengal coast, radiological study of this coastal environment is imperative to assess the impact of operation of nuclear power plant, if any, on the radioactivity profile of the coast. Materials and Methods: In the present study the environmental radioactivity was evaluated by measuring activity concentrations of primordial radionuclides namely 238 U, 232 Th and 40 K. in the beach sand samples using high purity germanium gamma ray spectrometry. 10 sampling stations were fixed along a 290 km coastal stretch of Bay of Bengal from Pondycherry to Velangannni. Results: The activity concentration of 238 U is always much less than that of 232 Th and 40 K and it ranged from 9 Bq/kg (Pondicherry coast) to 93 Bq/kg (Karaikal coast). However, 232 Th concentration fluctuated from 12 Bq/kg (Pichavaram Mangrove) to 1075 Bq/kg (Karaikal coast). The activity concentration of 40 K varied within a narrow range from 162 Bq/kg to 474 Bq/kg. The distribution of primordial radioactivity was non-uniform along the entire stretch of Bay of Bengal. The elevated levels of 232 Th were recorded in Karaikal coast (S7) (1075 Bq/kg), Tirumullaivasal coast (S4) (215 Bq/kg), and Nagapattinam coast (S9) (146 Bq/kg) and attributed to the presence of thorium-rich monazite as beach placer in coastal sands. Conclusion: The total absorbed gamma dose contributed by the activity of 238 U, 232 Th, and 40 K varied between 29 nGy/h and 308 nGy/h with a GM value of 64.4 nGy/h. Similarly, the annual effective dose recorded for Bay of Bengal ranged from 0.04 mSv/year to 0.38 mSv/year, indicating that the Bay of Bengal, in general, falls under Normal Background Radiation Area.

DISTRIBUTION AND BIOACCUMULATION OF 210Po AND 210Pb IN ABIOTIC AND BIOTIC COMPONENTS OF THE BAY OF BENGAL

&NA; Marine environment is enriched source of heavy minerals associated with radionuclides which are largely responsible for human exposure to radiation. Bay of Bengal is one among the important marine ecosystems in the world because of its high biodiversity. The aim of this work was to generate a comprehensive data on distribution and bioaccumulation of 210Po and 210Pb in marine environment of the Bay of Bengal. For this water and sand samples (10 stations), shellfishes (21 species) and fishes (43 species) were collected and the concentrations of 210Po and 210Pb were measured by radiochemical separation followed by alpha counting method using ZnS(Ag) detector. 210Pb concentration in the marine water (mean: 7.6 ± 3.31 mBq l−1) is always higher than 210Po (mean: 4.1 ± 1.97 mBq l−1). The mean 210Po and 210Pb concentration in sand was 5.2 ± 1.87 and 3.1 ± 1.20 Bq kg−1, respectively; indicating that 210Po concentrations in the sand sample is always higher than that of 210Pb. The concentration of both 210Po and 210Pb depends on grain size of the sand. Surface samples of depth 0‐10 cm recorded maximum 210Po (6.37 Bq kg−1) and 210Pb (4.07 Bq kg−1) concentration. The concentrations of 210Po and 210Pb in biota are following decreasing order: Oyster > Clam > Squid > Crab > Prawn > Fish. The committed effective dose rate calculated for shellfish species maintained a higher range of 81.0‐281.2 &mgr;Sv y−1. However, dose transfer rate from fish species fluctuated from 14.4 to 165.6 &mgr;Sv y−1and this indicated that fish is radiologically safe as compared to shellfish.

Assessment of Radioactivity in Concrete Made with e-Waste Plastic

The paper reports the impact of e-waste plastic [high-impact polystyrene (HIPS)] mixing in concrete on its radioactivity profile. The concrete was prepared with HIPS as a partial replacement for coarse aggregate in varying percentages by volume and radioactivity concentrations of 238U, 232Th, and 40K were measured using gamma-ray spectrometer and radon activity by solid state nuclear track detector (SSNTD) technique. Both gamma radiation and radon activity in standard concrete and concrete with HIPS were well within the permissible limit. However, the gamma-radiation level and radon activity decreased with an increase in HIPS content of the concrete. The study concludes that the concrete with HIPS does not pose any radiation hazard and, hence, is suitable as a construction material.

A Study on Radioactivity Levels in Sedimentary and Igneous Rocks Used as Building Materials in and Around Tiruchirappalli District, Tamil Nadu, India

The paper presents the results of the study on the activity concentrations of primordial radionuclides (238 U, 232 Th and 40 K) in the rock samples collected from eight sedimentary rocks and six igneous rocks which supply stones for construction of buildings in Tiruchirappalli district. In sedimentary rocks, the mean activity concentrations of 238 U, 232 Th and 40 K were found to be 5.4, 12.4, and 372.8 Bq kg−1, respectively. On the other hand, in igneous rocks the mean activity concentrations of 238 U, 232 Th and 40 K were distinctly higher and found to be 15.5, 135 and 859.4 Bq kg−1, respectively. The mean radium equivalent activity (Raeq) recorded in both sedimentary (32.8 Bq kg−1) and igneous rocks (278 Bq kg−1) was well within the limit prescribed for dwellings (370 Bq kg−1) except Narthamalai (S13) (689.3 Bq kg−1). The mean absorbed dose rate from igneous rock (124.5 nGy h −1) exceeded the prescribed limit of 55 nGy h −1. The mean annual effective dose from the sedimentary (0.089 mSv y-1) and igneous rocks (0.63 mSv y−1) did not exceed the prescribed limit (1 mSv y −1) except the igneous rock from Narthamalai (S13) (1.48 mSv y −1). The study concludes that the sedimentary and the igneous rocks analysed were radiologically safe when used as building materials except igneous rock from Narthamalai (S13).