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.

     

Assessment of radon concentration and external gamma radiation level in the environs of Narwapahar uranium mine,India and its radiological significance

In the environs of uranium mining, milling and processing facilities and in the uranium mineralized terrain, a little higher ambient radon concentration and gamma radiation level may be expected in comparison with natural background. The present study gives a brief account of atmospheric radon concentration, gamma absorbed dose rate and radiation dose received by the members of public in the vicinity of Narwapahar uranium mine. The ambient radon concentration in the air in the study area was found to vary from 5 to 107 Bq m⁻³ with geometric mean of 24 Bq m⁻³ and geometric standard deviation of 1.74 Bq m⁻³. The measured gamma absorbed dose rate in air at 1 m above the ground ranged from 87 to 220 nGy h⁻¹ with an overall arithmetic mean of 128 ± 18.5 nGy h⁻¹. The mean annual effective dose received by the members of public from inhalation of radon and its progeny and external gamma exposure was estimated to be 0.32 mSv year⁻¹, which is comparable to other reported values elsewhere.     

Studies on radon concentration in drinking water around Hemavathi river basin,Karnataka State,India

Concentrations of radon in drinking water collected from 32 locations of Hemavathi river basin, Karnataka, India have been measured by emanometry method. The radon concentration in water ranged from 2.7 ± 0.1 to 138.5 ± 1.5 Bq l⁻¹ with a geometrical mean of 25.3 ± 1.1 Bq l⁻¹. The study revealed that about 82.35% of drinking water samples contained radon concentration more than 11.1 Bq l⁻¹, the limit is fixed by Environmental Protection Agency. Among the different parameters measured, concentration of radon showed weak correlation with chloride and no correlation with alkalinity, pH, nitrate, sulphate, fluoride and total dissolved substance.

     

Measurement of radon concentration and assessment of associated cancer risk in some fertilizer warehouses in the Punjab province of Pakistan

Radon concentration was measured by using ³⁹CR track etched detectors in five fertilizer warehouses in the Punjab province of Pakistan. The average concentration of radon was determined to be 20–88 Bq m⁻³. Annual effective dose (AED) and excess lifetime cancer risk (ELCR) have also been assessed using the models of UNSCEAR and ICRP. The corresponding annual dose and ELCR to the workers of warehouses have been estimated to be 0.30–1.02 mSv year⁻¹ and 0.44–1.02%, respectively.

     

Exposure to underground radon in and around Kolkata Municipal Corporation area: an exhaustive study

Air radon survey was carried out at different underground locations at Kolkata using radon monitor. Average radon concentration for basements was found to be 22.70 ± 1.12 Bq/m³ with maximum 59.00 ± 7.18 Bq/m³ and minimum 8.50 ± 3.14 Bq/m³. Average level for sub-ways was 23.05 ± 2.59 Bq/m³ fluctuating between maximum 39.00 ± 1.24 Bq/m³ and minimum 13.50 ± 1.78 Bq/m³. In comparison, open air background at basement entrance was 19.44 ± 1.06 Bq/m³ and subway entrance was 18.58 ± 1.14 Bq/m³. Annual effective dose was calculated to assess probable health risk. Radon concentration level and annual effective dose were found well below safe levels recommended by International Agencies WHO and UNSCEAR.

     

Investigations on the presence and distribution of radon in the Cacica salt mine,Romania

An important parameter for evaluating the possibilities of use of enclosed spaces (mines, caves, spas, etc.) for therapeutic purposes is the concentration of radon in different conditions of ventilation. The aim of this paper is to present the results of continuous radon gas measurement that were performed for ten days, at 20 min time intervals in different locations from Cacica salt mine (Romania) using a portable radon monitor. The average radon concentration was found to be between 96.5 ± 4.76 Bq/m³ and 20.5 ± 1.30 Bq/m³. These values are suitable for therapeutic applications and are useful for future experiments regarding the development of the radon therapy and speleotherapy in this salt mine.     

Influence of the building material and ventilation rate on the concentration of radon, thoron and their progenies in dwelling rooms using SSNTD and Monte Carlo simulation

A new Monte Carlo computer code was developed for determining the detection efficiencies of the CR-39 and LR-115 II solid state nuclear track detectors (SSNTD) for a-particles emitted by radon (²²²Rn) and thoron (²²⁰Rn) series inside the atmosphere of dwelling rooms. Alpha-activities due to radon, thoron and their decay products, were evaluated for the determination of the detection efficiencies of the SSNTD utilized for the emitted a-particles by measuring the corresponding track densities. The influence of the ventilation rate and building material on the concentration of radon, thoron and their progenies was investigated. Equilibrium factors between radon and its progeny and between thoron and its daughters have been evaluated in the air of the rooms.     

Chitosan impregnated Ca-alginate: a new hybrid material for removal of uranium from potable water

Novel sorbent, chitosan impregnated calcium alginate (Cal-Alg-Chi) bead was developed to sorb uranium from potable water without compromising water quality parameters. The uptake study in batch mode, showed more than 98% sorption of uranium in the concentration range of 0.1–50 µg mL⁻¹. Cal-Alg-Chi beads, reduced the concentration of uranium below 15 ng mL⁻¹ from 100 to 450 ng mL⁻¹ in groundwater collected from effected regions in India. Sorption isotherm followed Langmuir model and maximum sorption capacity was evaluated as 36.04 mg g⁻¹. The sorption was endothermic with ΔG ⁰ value of −9.76 kJ mol⁻¹ and kinetics followed pseudo-second order rate law.

     

Thermal stability and lifetime of [AMIM]Cl-PFSA composite membranes

1-Allyl-3-methylimidazolium chloride [AMIM]Cl hybrid perfluorosulfonic acid (PFSA) composite electrolyte membrane was prepared and characterized by TG and FTIR technique. The conductivity was measured using AC impedance method. The results showed that when raised from 20 to 90 °C, the conductivity of composite membrane was increased from 4.50 × 10⁻⁶ to 1.34 × 10⁻⁵ S cm⁻¹, before and after the modification of triethylamine, the thermal stability of composite membrane was not changed, but the TEA-PFSA with [AMIM]Cl reactivity was a little difference. However, the heat resistance of composite membrane was significantly enhanced compared with that of PFSA membrane, the peak temperature of composite membrane almost disappeared in first stage, and offset to the high-temperature zone. When heated at 350 °C, the decomposition rate of PFSA, 10%[AMIM]Cl-PFSA and 10%[AMIM]Cl-TEA-PFSA membrane was 13.71, 3.67 and 1.26%, respectively. If the decomposition process follows isothermal first-order reaction and the conversion rate α is 10%, the activation energy E _α of the composite membrane is 97.4 kJ mol⁻¹. Besides, the isothermal lifetime of composite membrane was also measured.

     

Preparation and application of alginate-Ca/attapulgite clay core/shell particle for the removal of uranium from aqueous solution

The radioactivity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in 42 samples from different types of cements produced in Turkey were measured using gamma-ray spectrometer. The determined values were 18–143 Bq kg⁻¹ (²²⁶Ra), 5–66 Bq kg⁻¹ (²³²Th) and 142–540 Bq kg⁻¹ (⁴⁰K). Additionally, the calculated radiological hazard parameters such as absorbed dose rate, annual effective dose, radium equivalent activity, the external hazard, activity and alpha indices were found to be in the range of 38–158 nGy h⁻¹, 188–776 µSv year⁻¹, 41–182 Bq kg⁻¹, 0.11–0.49, 0.15–0.65 and 0.09–0.71, respectively. Finally, the results were statistically evaluated and compared with the reported data in other countries and the international standard values given by European Commission and UNSCEAR.

     

Radiological characterization of commercially available “radon spa sources”

Nowadays, artificial “radon spa sources” for home baths are commercially available. Although these sources could give a potential radiation exposure to the users, few studies have been reported on their radiological measurements. In the present study, five types of radon spa sources were collected and their radiological characterization was investigated. The followings were estimated for these samples: (1) radon emanation coefficients (dry and water-saturated conditions), (2) surface γ-ray dose rate, (3) surface count rates for α- and β-rays, (4) activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K, and (5) concentrations of radon and thoron generated from the sources located in an air flow system. The activity concentrations were very high (except for one sample (named “sample B”), although radon emanation coefficient was low compared with soil. This leads to high concentrations of radon/thoron generated from the sample. The maximum surface γ-ray dose rate was observed for sample A (2.7 μGy h⁻¹). If people stay very close to the sample for a long time, the exposure might be significant.     

Degradation of diazinon contaminated waters by ionizing radiation

Study of degradation of diazinon pesticide by ⁶⁰Co gamma irradiation in a single aqueous solution was conducted on a laboratory scale and the effect of ionizing radiation on the removal efficiency of diazinon residues was investigated. Distilled water solutions at three different concentrations of targeted compound (i.e. 0.329, 1.643 and 3.286 μmol dm⁻³) were irradiated over the range 0.1–6 kGy. The initial concentration of contaminant and irradiation doses play a significant role in the rate of destruction; this was evident from the calculated decay constants of diazinon residue. Gamma radiolysis showed that the absorbed doses from 1.5 to 5.6 kGy at a dose rate of 4.79 kGy h⁻¹ achieved 90% destruction for diazinon with initial concentrations over the range 0.329–3.286 μmol dm⁻³. The radiolytic degradation by-products and their mass balances were qualitative determined with good confidence by using GC/quadrupole mass spectrometry (GC/MS) with EI⁺ or CI in positive and negative ionization mode and diazinon degradation pathways were proposed. Additionally, the final products of irradiation were identified by ion chromatography (IC) to be acetic and formic acid.     

Distribution of activity concentration and dose rates in selected coastal areas on western and eastern Black Sea

Radioactivity measurements were performed, at the east (Georgia) and west (Romania) part of the Black Sea, for natural radionuclides and ¹³⁷Cs in collected water and sediment samples using lab-based and in situ gamma-ray spectrometry. The activity concentrations of ¹³⁷Cs at Georgian area in the sediment and seawater ranged between 20 to 50 Bq kg⁻¹ and 8 to 25 Bq m⁻³, respectively while at the Romanian area the activity concentration ranged from 10 to 30 Bq kg⁻¹ and 3 to 15 Bq m⁻³, respectively. The activity concentration values of ⁷Be at the Georgian area reached values up to (30 ± 4) Bq kg⁻¹. The induced dose rates to marine organisms in both areas estimated by the ERICA assessment tool were much lower than the screening value of 10 μGy h⁻¹.

     

Investigation of Sr uptake by birnessite-type sorbents from seawater

Sorption of micro- and microamounts of Sr from seawater has been studied using granulated Na-birnessite. Distribution coefficients of ⁹⁰Sr in the natural seawater are 0.8–1.2?×?10³ ml g^?1, in the model seawater they are 1.6–1.8?×?10³ ml g^?1. Application of Na-birnessite was shown to be prospective in sorption–desorption–regeneration regime. In dynamic sorption conditions, over 150 bed volumes of seawater can be purified till 5% breakthrough occurs at feed rate 10 BV h^?1. Na-birnessite can be used for ⁹⁰Sr radionuclide removal from liquid radioactive wastes containing seawater.

     

Background radiation study in Coimbatore city,Tamilnadu

The activity concentration and absorbed gamma dose rates due to primordial radionuclides (²³⁸U, ²³²Th and ⁴⁰K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations of ²³²Th, ²³⁸U and ⁴⁰K in the soil samples have been found to be 31.4 Bq·kg⁻¹, 12.8 Bq·kg⁻¹ and 698.0 Bq·kg⁻¹, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h⁻¹. Grab sampling technique has been used to determine the indoor radon (²²²Rn) and thoron (²²⁰Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to 10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon and thoron progeny has been found to be 0.14 mSv·y⁻¹.     

Radon and thoron progeny levels in air samples at Udagamandalam region of Nilgiris in India

Measurement of concentration of radon and thoron daughter products in various indoor environment covering four seasons of a year in Udagamandalam Taluk of Nilgiris biosphere has been carried out using a high volume air sampler to asses the inhalation dose to the population which delivers higher dose than the radon and thoron gas alone. The potential alpha-energy concentrations of the radon and thoron progeny ranged from 0.97 to 12.72 mWL and from 1.63 to 15.83 mWL with a geometric mean of 6.02 and 7.89 mWL, respectively, taking all seasons into account. These measurements have yielded a wealth of data on the variation among the indoor radon and thoron progeny in various places during different seasons. The radon and thoron progeny levels are higher in winter seasons and are less in summer season with autumn and spring data lie in between winter and summer. Using the dose conversion factor for indoor exposures given in UNSCEAR 93 report the internal equivalent dose to the inhalation of radon progeny is evaluated to be 1357 mSv^.y^–1 and the corresponding annual effective dose equivalent value has been found to be 2.13 mSv^.y^–1. It can be observed that the mean value of radon is higher than the Indian average. Also it is found the radon and thoron progeny levels are higher in the case of houses built with rock and granite and in tiled type houses of nearly 100 years old. The levels are less in the case of houses built with brick and cement. The observed results for different types of houses and seasons are discussed in this paper.     

Sulfonated poly(ether ether ketone)/manganese dioxide composite for the removal of low level radionuclide ions from aqueous solution

Various composite adsorbents based on sulfonated poly(ether ether ketone)/manganese dioxide were prepared for the removal of stable and radioactive ions from contaminated aqueous solution. Batch adsorption experiments revealed superior adsorption capacities of the composite using very low initial concentration of studied elements. Starting with 1000 µg L⁻¹ contaminated solution, the maximum equilibrium metal uptake capacity reached 2.0 mg g⁻¹ for Pb²⁺, 1.9 mg g⁻¹ for Cd²⁺, Cu²⁺ and Zn²⁺, and 3.7 mg g⁻¹ for Co²⁺. In addition, the distribution coefficient reached 11,600 mL g⁻¹ for ¹³⁷Cs and 70,000 mL g⁻¹ for ²¹⁰Pb.

     

Radon concentration in drinking water sources of the Main Campus of the University of Peshawar and surrounding areas, Khyber Pakhtunkhwa, Pakistan

Radon and its progenies in indoor environment have been identified as the main sources of radiation dose to the people from natural radioactive sources. Presence of radon in drinking water causes radiation related health hazards both through inhalation and ingestion. In this study 36 drinking water samples from taps, boreholes and deep tube wells within the Main Campus of the University of Peshawar and adjoining area were analyzed with RAD7 electronic device for radon content determination. These water samples have a mean, maximum and minimum radon value of 8.8 ± 0.8, 18.2 ± 1.0, and 1.6 ± 0.3 Bq L⁻¹, respectively. Eleven drinking water samples analyzed have radon levels in excess of the EPA recommended maximum contaminant level (MCL) of 11.1 Bq L⁻¹. These include 89% from tube wells, 8% from tap water, and 50% from shallow boreholes. Radon levels of about 31% of the total samples used by the inhabitants of the study area are higher than the EPA advised level of 11.1 Bq L⁻¹. The annual effective dose from radon in water due to its ingestion and inhalation per individual has also been estimated. The mean radon concentration and mean annual effective dose due to radon in water of this study have been compared with the mean radon concentration and mean annual effective dose of earlier investigators due to radon in water from different localities of India and Pakistan. The mean annual effective doses of all the samples are lower than the reference level of 0.1 mSv a⁻¹ for drinking water of WHO and EU Council. It has been concluded that drinking water of the study area is generally safe as far as radon related health hazards are concerned with the exception of a few isolated cases. It has been found that radon levels within the region have a positive correlation with depth of the water sources.     

Thermostable ultrafiltration and nanofiltration membranes from sulfonated poly(phthalazinone ether sulfone ketone)

Modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid was carried out in order to prepare thermally stable polymers as membrane materials having increased hydrophilicity and potentially improved fouling-resistance. The sulfonated poly(phthalazinone ether sulfone ketone)s (SPPESK) were fabricated into ultrafiltration (UF) and nanofiltration (NF) asymmetric membranes. The effects of SPPESK concentration and the type and concentration of additives in the casting solution on membrane permeation flux and rejection were evaluated by using an orthogonal array experimental design in the separation of polyethyleneglycol (PEG12000 and PEG2000) and Clayton Yellow (CY, MW 695). One UF membrane formulation type had a 98% rejection rate for PEG12000 and a high pure water flux of 867 kg m⁻² h⁻¹. All the NF membranes made in the present study had rejections of ≥96%, and one had a high water flux of 160 kg m⁻² h⁻¹. Several of the NF membrane formulation types had ∼90% rejection for CY. When the membranes were operated at higher temperatures (80°C), the rejection rates declined slightly and pure water flux was increased more than two-fold. Rejection and flux values returned to previous values when the membranes were operated at room temperature again. Mono- and divalent salt rejections and fluxes were studied on an additional NF membrane set.