Natural radioactivity measurements in the granite rock of quarry sites,Johor, Malaysia

This study was conducted to determine the concentration of natural radionuclides in the granite rocks of selected quarry sites in Johor state, Malaysia and their possible radiological effects. The activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K in the areas of study indicated varying values of ²³⁸U, ²³²Th and ⁴⁰K. The highest values of ²³⁸U and ²³²Th concentrations (67±1 and 85±2 Bq kg^?1, respectively) were observed at Kamad Quarry (IJM), whereas the highest value of ⁴⁰K concentration (722±18 Bq kg^?1) was detected in Kim Seng Quarry, while the values of activity concentration are lower in Hanson Quarry Products (Kulai) (25±0.5 for ²³⁸U, 24±0.5 for ²³²Th and 429±11 for ⁴⁰K). Overall, ⁴⁰K has the highest concentration in the granite rocks of the quarry sites, followed by ²³²Th and the least for ²³⁸U. The radium equivalent activity concentration was found in the range between 94 and 239 Bq kg^?1, the absorbed dose rate was found to be in the range between 47 and 112 nGy h^?1, and effective dose ranged from 58 to 137 μSv h^?1. Moreover, the internal and external hazard index values were given in results lower than unity.     

Natural radioactivity in cultivated land in the vicinity of a phosphate fertilizer plant in Nigeria

Natural radioactivity in soil and vegetable samples in cultivated land in the vicinity of an active phosphate fertilizer plant in Kaduna, Nigeria was carried out to assess the potential radiological impact of the plant on its immediate environment. The activity counting was carried out using sodium iodide gamma spectrometry. The annual committed effective dose for two vegetables in the farmlands due to uranium (²³⁸U) and thorium (²³²Th) was assessed. The mean activity concentration of radionuclides in the soil samples ranges from 20.5±7.3 to 31.6±4.1 Bq kg^?1 for ²²⁶Ra, 19.6±1.6 to 53.2±3.7 Bq kg^?1 for ²³²Th and 203.9±6.3 to 253.6±9.5 Bq kg^?1 for ⁴⁰K. The annual intake of ²³⁸U and ²³²Th from consumption of okra were 1.9 Bq kg^?1 and 5.22 Bq kg^?1 and for tomatoes 2.66 Bq kg^?1 and 5.1 Bq kg^?1 respectively. The committed effective doses from consumption of okra and tomatoes were 0.1 μSv y^?1 and 0.12 μSv y^?1 respectively.     

Effect of the natural radioactivity concentrations and 226Ra/238U disequilibrium on cancer diseases in Penang,Malaysia

Natural radioactivity measurements and assessment of radiological hazards in soil and sand samples obtained from Penang, Malaysia were carried out using the Exploranium GR-135 Plus “Identifier” Radioisotope Identification Device and high-resolution High Purity Germanium (HPGe) detector system. The activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 184±11, 396±22, 165±14, and 835±28 Bq kg^?1 respectively, and the external gamma dose rate is 315±44 nGy h^?1 for soil samples. For sand samples, the activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were 31±8, 62±16, 36±6, and 369±17 Bq kg^?1, respectively, and the external gamma dose rate is 66±12 nGy h^?1. To assess the radiological hazard of radioactivity present in the samples, the radium equivalent activity, annual effective dose, annual gonadal dose equivalent, external hazard, and internal indices were calculated.The Ra_eq values of soil samples were higher than the limit of 370 Bq kg^?1, which is equivalent to a gamma dose of 1.5 mSv yr^?1, whereas the Ra_eq for sand samples was lower than 370 Bq kg^?1. The calculated concentrations by HPGe spectroscopy were compared with the measured concentrations detected by a GR-135 spectrometer. The calculated and measured gamma dose rates had an ideal correlation coefficient R of 0.72. The gamma dose rates in Penang increased with the average annual age-standardized rates (ASR) for all cancers between 1994 and 2010. The effects of the pH value of soil and sand samples on natural radionuclides concentrations were investigated. The high concentration of ²²⁶Ra/²³⁸U ratio disequilibrium (²²⁶Ra/²³⁸U of 1.76–2.33) was observed in the sampling sites. Moreover, a portable continuous radon monitor (SNC, model 1029, Sun Nuclear Corporation) was used to measure the radon concentration of the soil surface. The radon concentrations were found to vary from 7 to 50 Bq m^?3. A positive correlation was observed between the radon and radium concentrations in samples measured by the SNC continuous radon monitor and HPGe detector.     

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.     

Radioactivity level of soil around Baqiao coal-fired power plant in China

Natural radioactivity level of soil around Baqiao coal-fired power plant in China was determined using gamma ray spectrometry. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied soil samples range from 27.6 to 48.8, 44.4 to 61.4 and 640.2 to 992.2 Bq kg^?1 with an average of 36.1, 51.1 and 733.9 Bq kg^?1, respectively, which are slightly higher than the average values of Shaanxi soil. The radium equivalent activity, the air absorbed dose rate and the annual effective dose rate were calculated and compared with the internationally reported or reference values. The radium equivalent activities of the studied samples are below the internationally accepted values. The air absorbed dose rate and the annual effective dose rate received by the local residents due to the natural radionuclides in soil are slightly higher than the mean value of Xi'an and worldwide.     

Natural radioactivity and radiological hazards of building materials in Xianyang,China

Common building materials collected from Xianyang, China were analyzed for the natural radioactivity of ²²⁶Ra, ²³²Th and ⁴⁰K using γ-ray spectroscopy. The average activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied building materials ranges from 13.4 to 69.9, 13.1–99.1 and 124.7–915.1 Bq kg^?1, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and with the worldwide average activity of soil. To assess the radiation hazard of the natural radioactivity in all samples to the people, the radium equivalent activity, external hazard index, internal hazard index, indoor absorbed dose rate and total annual effective dose were estimated. The radium equivalent activities of the studied samples are below the internationally accepted values. The external hazard index and internal hazard index of all analyzed building materials are less than unity. The mean values of indoor absorbed dose rate for all building materials except for lime are higher than the world population-weighted average of 84 nGy h^?1 and the total annual effective dose values of building materials are lower than 1 mSv y^?1 except for some cyan brick samples. The study shows the measured building materials do not pose significant source of radiation hazard and are safe for use in the construction of dwellings.     

Radon exhalation and natural radiation exposure in low ventilated rooms

In the first part of this paper, the influence of radon (²²²Rn) exhalation rate from walls and air exchange upon its concentration in room air was considered using a simple mathematical room model. The exhalation rates have been determined in ten low ventilated rooms of ten villas in Jeddah city (Western Province) of Saudi Arabia. An electroprecipitation method has been applied for the determination of the ²²²Rn gas concentration in these rooms. The mean ²²²Rn gas concentration was found to be 46.80±8.80 Bq m^?3. The mean ²²²Rn exhalation rate was estimated to be 20.11±6.90 Bq m^?2 h^?1. The mean inhalation dose due to the exposure to ²²²Rn gas was calculated to be 1.18±2.30 mSv y^?1.The second part of this paper deals with a study of natural radionuclide contents of samples collected from the building materials of these rooms under investigations in part one. Analyses were performed in Marinelli beakers with a gamma spectroscopy system to quantify radioactivity concentrations. The collected samples revealed the presence of the uranium–radium (²²⁶Ra) and thorium (²³²Th) radioisotopes as well as ⁴⁰K. The mean activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K was determined to be 48.30±5.08, 43.90±5.63 and 223.90±7.55 Bq kg^?1, respectively. These activities amount to a radium equivalent (Ra_eq) of 125.96±15.90 Bq kg^?1 and to a mean value of external hazard index (H_ex) of 0.34±0.04.     

Heavy elements concentrations,physiochemical characteristics and natural radionuclides levels along the Saudi coastline of the Gulf of Aqaba

This paper represents the first work on the concentrations of heavy elements, physiochemical characteristics and activity levels of the naturally occurring radionuclides in the Saudi Arabian coastline of the Gulf of Aqaba. Concentrations of 19 heavy elements were measured, namely: Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn. The radioactivity levels of ²³⁸U, ²³²Th and ⁴⁰K were estimated to be: 17 ± 1.7, 22.5 ± 3.7 and 649.6 ± 64.2 Bq kg^?1, respectively. The measurements were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). In addition, physiochemical characteristics of 19 sediment samples (i.e., saturation percentage, pH, electrical conductivity, organic matter, cation exchange capacity and content of clay, silt and sand) have been determined. Indications for high correlation between most heavy elements are found. The correlation between heavy elements and the radionuclides ²³⁸U, ²³²Th and ⁴⁰K was generally significant.     

Natural radioactivity in different commercial ceramic samples used in Yemeni buildings

In this work we calculated the radioactivity concentrations of the natural radioactive nuclides ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K for 10 commercial samples collected from 10 different companies which are used in the construction of Yemeni buildings. Gamma ray spectroscopy was used to analyze the samples and the concentrations of radioisotopes were determined using a hyper-pure germanium (HPGe) detector in Bq/kg dry-weight. The average concentrations of ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K were found to be 131.4, 83.55, 131.88 and 400.7 Bq/kg respectively. Different hazard indices were also determined. The results showed that the average radium equivalent activity (Ra_eq), the absorbed dose rate (D_r), the annual effective dose equivalent (AEDE), the external hazard index (H_ex) and representation level index (I_γ) were: 307.52 Bq/kg, 139.31 nGy/h, 1.40 mSv/yr, 0.83 and 2.15 respectively. The mean value of (Ra_eq) obtained in this study is in good agreement with that of the international value while the mean values of the other indices are found to be higher than the international reference values. The measured activity concentrations for these radionuclide were compared with the reported data obtained from similar materials used in other countries.     

Radon concentration in hot springs of the touristic city of Sarein and methods to reduce radon in water

The aim of this research was to measure the efficiency of various simple methods to decrease the concentration of radon in hot springs of the touristic city of Sarein (a touristic city in northwest Iran). With the aid of “RAD7” radon detector, concentrations in water varied from 212 Bq m^?3 to 3890 Bq m^?3. Using 250 mL vials half-filled with water samples, our research showed that when the temperature of the water increased from 17 °C to 27 °C, the radon concentration decreased from 3230 Bq m^?3 to 745 Bq m^?3. The mixing of the sample at a speed of 500 rpm for 12 min led to a radon reduction of about 70%. Aerating the water sample with 0.2 L min^?1 of ambient air resulted in a 90% decrease in radon concentration in 6 min. Strong exponential correlations (>95%) were reported, which verified that the effectiveness of these methods in reducing dissolved gas in the waters used would be high.     

Temperature and sodium chloride effects on the solubility of anthracene in water

The solubility of anthracene was measured in pure water and in sodium chloride aqueous solution (salt concentration, m/mol · kg^?1 = 0.1006, 0.5056, and 0.6082) at temperatures between (278 and 333) K. Solubility of anthracene in pure water agrees fairly well with values reported in earlier similar studies. Solubility of anthracene in sodium chloride aqueous solutions ranged from (6 · 10^?8 to 143 · 10^?8) mol · kg^?1. Sodium chloride had a salting-out effect on the solubility of anthracene. The salting-out coefficients did not vary significantly with temperature over the range studied. The average salting-out coefficient for anthracene was 0.256 kg · mol^?1.The standard molar Gibbs free energies, Δ_trG°, enthalpies, Δ_trH°, and entropies, Δ_trS°, for the transfer of anthracene from pure water to sodium chloride aqueous solutions were also estimated. Most of the estimated Δ_trG° values were positive [(20 to 1230) J · mol^?1]. The analysis of the thermodynamic parameters shows that the transfer of anthracene from pure water to sodium chloride aqueous solution is thermodynamically unfavorable, and that this unfavorable condition is caused by a decrease in entropy.     

The solubility measurements of sodium dicarboxylate salts; sodium oxalate,malonate, succinate,glutarate, and adipate in water from T = (279.15 to 358.15) K

The solubility measurements of sodium dicarboxylate salts; sodium oxalate, malonate, succinate, glutarate, and adipate in water at temperatures from (278.15 to 358.15 K) were determined. The molar enthalpies of solution at T = 298.15 K were derived: Δ_solH_m (m = 2.11 mol · kg^?1) = 13.86 kJ · mol^?1 for sodium oxalate; Δ_solH_m (m = 3.99 mol · kg^?1) = 14.83 kJ · mol^?1 for sodium malonate; Δ_solH_m (m = 2.45 mol · kg^?1) = 14.83 kJ · mol^?1 for sodium succinate; Δ_solH_m (m = 4.53 mol · kg^?1) = 16.55 kJ · mol^?1 for sodium glutarate, and Δ_solH_m (m = 3.52 mol · kg^?1) = 15.70 kJ · mol^?1 for sodium adipate. The solubility value exhibits a prominent odd–even effect with respect to terms with odd number of sodium dicarboxylate carbon numbers showing much higher solubility. This odd–even effect may have implications for the relative abundance of these compounds in industrial applications and also in the atmospheric aerosols.     

Radioactivity of coal and ashes from Figueira coal power plant in Brazil

Summary The Figueira coal-fired power plant (CFPP) is among the Brazilian CFPP which presents higher uranium concentration. Gamma-ray spectrometry was used to determine ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³² Th and ⁴⁰K contents in pulverized coal, furnace bottom ash and fly ash samples. The natural radionuclide concentrations in pulverized coal ranged from 813 to 2609 Bq ^. kg^-1 for U series and from 22 to 40 Bq ^. kg^-1 for ²³² Th. The fly ash fraction gave concentrations ranging from 1442 to 14641 Bq ^. kg^-1, for uranium series. The same enrichment factor was observed for ²³⁸U, ²²⁶Ra and ²³² Th. Only ²¹⁰Pb and stable Pb presented a high enrichment factor for the last stage filter fly ash. The concentration of the uranium series found in the ashes is close to the limit adopted by the Brazilian guideline (CNEN-NN-4.01).²² Therefore, it is advisable to evaluate the environmental impact of the installation.     

Assessment of natural radioactivity in silt samples from Moticher lake near Kakrapar Atomic Power Station,India

The naturally occurring radioisotopes such as ²³⁸U, ²³²Th and ⁴⁰K in the silt samples collected from Moticher lake, Gujarat were evaluated. The activity of ²³⁸U, ²³²Th and ⁴⁰K was found to be 4.4-9.7 Bq kg⁻¹ with a mean 6.4 ± 1.3 Bq kg⁻¹, 10.5–21.2 Bq kg⁻¹ with a mean 15.6 ± 2.5 Bq kg⁻¹ and 102–231 Bq kg⁻¹ with a mean 160 ± 40 Bq kg⁻¹, respectively. The depth profile study could not reveal any significant vertical correlation on radioactivity levels of ²³⁸U, ²³²Th and ⁴⁰K. Radium equivalent activity (Ra_eq), external hazard index (H _ex) and internal hazard index (H _int) were calculated by using the activity of ²³⁸U or ²²⁶Ra, ²³²Th and ⁴⁰K in silt samples. Annual Effective Dose Equivalent (AEDE) level in Moticher silt was found to be 24.8 ± 5.0 μSv year⁻¹, which is much lower than the worldwide average value. The relative contribution to dose due to ²³⁸U and ²³²Th series were found to be 14% and 53%, followed by the contribution of 33% due to ⁴⁰K.     

Double-layer capacitance of waste coffee ground activated carbons in an organic electrolyte

Using ZnCl₂ activation we prepared a series of carbon electrodes from waste coffee grounds to study the effect of mesopores on double-layer capacitance in a tetraethyl ammonium tetrafluoroborate/acetonitrile electrolyte. The activated carbon with the largest mesopore volume achieved an energy density of 34 Wh kg^?1 at low current loads, and significantly retained an energy density of 16.5 Wh kg^?1 and specific capacitance of more than 100 F g^?1 at fast charge–discharge rates (20 A g^?1). The effect of mesopores on capacitance at fast charge–discharge rates is discussed.     

Radiological assessment of natural and fallout radioactivity in the soil of Chamba and Dharamshala areas of Himachal Pradesh,India

This paper presents the results of measurement of natural and fallout radioactivity in soil samples of Chamba and Dharamshala areas in Himachal Pradesh, India. Spatial distribution of ²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K, ¹³⁷Cs was determined using High resolution gamma-ray spectrometry. The mean activity concentration in Chamba region due to ²³⁸U, ²³²Th, ⁴⁰K and ¹³⁷Cs was 32.3, 58.4, 588.3, and 10.9 Bq kg⁻¹, respectively, whereas in Dharamshala it was 35.7, 61.3, 594.9, 10.0 Bq kg⁻¹, respectively. Absorbed gamma dose rate (D) in air was calculated using appropriate dose conversion factors, which was varying from 45 to 103 nGy h⁻¹. To control the radiation exposure due to natural radioactivity in soil, if it is used as building materials, radium equivalent activity (Ra_eq) and activity index were also evaluated. Radium equivalent activity calculated for the soil ranged from 95.5 to 234.2 Bq kg⁻¹ with average of 171.0 Bq kg⁻¹.The calculated Activity concentration index was ranged from 0.34 to 0.85 with an average value of 0.64. The natural and fallout radioactivity in soil of this region is comparable with Indian average and other parts of the world. The percentage contribution of ²³⁸U, ²³²Th and ⁴⁰K and ¹³⁷Cs to the average external gamma dose rate was 22, 46, 32, 2%, respectively. This shows that the dose contribution due to fallout radioactivity is negligible as compared to the natural radioactivity.     

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Visakhapatnam,Andhra Pradesh,India

The present work aims to measure and estimate radioactivity and hazardous radiation indices of the soil. Soil samples were collected from various locations in the Visakhapatnam district in Andhra Pradesh, India. The measurement of specific activity of ²²⁶Ra, ²³²Th, and ⁴⁰K radionuclides is carried out with the help of HP-Ge based gamma spectrometer system. Activity concentration of radionuclides in the samples ²²⁶Ra, ²³²Th and ⁴⁰K ranged from 20 ± 2 to 91 ± 2 Bq.kg^-1, 45 ± 3 to 365 ± 3 Bq.kg^-1, and 400 ± 9 to 607 ± 8 Bq.kg^-1, and the respective mean values are 53.36 Bq.kg^-1, 203.74 Bq.kg^-1 and 479.19 Bq.kg^-1. The measured mean value of the absorbed dose rate is 171.41 nGy.h^-1, which was beyond the worldwide mean outdoor value of 60 nGy.h^-1. Thus, the annual effective dose estimated from the above value is 1.04 mSv.y^-1. The correlation was done among the measured ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations. The estimated radium equivalent dose is 381.60Bq.kg^-1. The estimated health hazard index and annual effective dose rates of dwellers of Visakhapatnam were studied and compared to Indian average values. The study will help to generate the baseline data for assessing hazard indices to the public and geological mapping of natural radiation in India.     

Activity coefficients of CaCl2 in (maltose + water) and (lactose + water) mixtures at 298.15 K

Activity coefficients of CaCl₂ in disaccharide {(maltose, lactose) + water} mixtures at 298.15 K were determined by cell potentials. The molalities of CaCl₂ ranged from about 0.01 mol · kg^?1 to 0.20 mol · kg^?1, the mass fractions of maltose from 0.05 to 0.25, and those of lactose from 0.025 to 0.125. The cell potentials were analyzed by using the Debye–Hückel extended equation and the Pitzer equation. The activity coefficients obtained from the two theoretical models are in good agreement with each other. Gibbs free energy interaction parameters (g_ES) and salting constants (k_S) were also obtained. These were discussed in terms of the stereo-chemistry of saccharide molecules and the structural interaction model.     

Natural radioactivity levels in mineral,therapeutic and spring waters in Tunisia

Radioactivity measurements were carried out in 26 groundwater samples from Tunisia. Activity concentrations of uranium were studied by radiochemical separation procedures followed by alpha spectrometry and that for radium isotopes by gamma-ray spectrometry.The results show that, the concentrations in water samples range from 1.2 to 69 mBq/L.1, 1.3 to 153.4 mBq/L, 2.0 to 1630.0 mBq/L and 2.0 to 1032.0 mBq/L for ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸Ra, respectively. The U and Ra activity concentrations are low and similar to those published for other regions in the world. The natural radioactivity levels in the investigated samples are generally increased from mineral waters through therapeutic to the spring waters.The results show that a correlation between total dissolved solids (TDS) values and the ²²⁶Ra concentrations was found to be high indicating that ²⁶⁶Ra has a high affinity towards the majority of mineral elements dissolved in these waters. High correlation coefficients were also observed between ²²⁶Ra content and chloride ions for Cl^?–Na⁺ water types. This can be explained by the fact that radium forms a complex with chloride and in this form is more soluble.The isotopic ratio of ²³⁴U/²³⁸U and ²²⁶Ra/²³⁴U varies in the range from 0.8 to 2.6 and 0.6 to 360.8, respectively, in all investigated waters, which means that there is no radioactive equilibrium between the two members of the ²³⁸U series. The fractionation of isotopes of a given element may occur because of preferential leaching of one, or by the direct action of recoil during radioactive decay.The annual effective doses due to ingestion of the mineral waters have been estimated to be well below the 0.1 mSv/y reference dose level.     

Apparent molar volumes and apparent molar heat capacities of aqueous tetrahydrofuran,dimethyl sulfoxide, 1,4-dioxane,and 1,2-dimethoxyethane at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

We determined apparent molar volumes V_? at 278.15 ? (T/K) ? 368.15 and apparent molar heat capacities C_p,? at 278.15 ? (T/K) ? 393.15 at p = 0.35 MPa for aqueous solutions of tetrahydrofuran at m from (0.016 to 2.5) mol · kg^?1, dimethyl sulfoxide at m from (0.02 to 3.0) mol · kg^?1, 1,4-dioxane at m from (0.015 to 2.0) mol · kg^?1, and 1,2-dimethoxyethane at m from (0.01 to 2.0) mol · kg^?1. Values of V_? were determined from densities measured with a vibrating-tube densimeter, and values of C_p,? were determined with a twin fixed-cell, differential, temperature-scanning calorimeter. Empirical functions of m and T for each compound were fitted to our V_? and C_p,? results.