Application of magnetic nanoparticles for the extraction of radium-226 from water samples

Bare (unmodified) and crown ether (CE)-modified Fe₃O₄ magnetic nanoparticles (MNPs) were investigated for the rapid extraction of ²²⁶Ra from water samples. It involved synthesizing the MNPs, introducing them into the sample solutions, ultrasonicating and agitating the suspension, magnetically separating the nanoparticles from solution, and measuring the ²²⁶Ra content in the supernatant. Experimental parameters such as salt choice, salt concentration and pH were optimized to achieve maximum extraction of ²²⁶Ra onto the MNPs. ²²⁶Ra content was determined using a Hidex 300SL liquid scintillation counter with α/β separation capability, or a gamma spectrometric detection system. The bare Fe₃O₄ nanoparticles showed significant pH dependence for the extraction of ²²⁶Ra from an aqueous solution over a pH range of 2–10. They gave an extraction of 95 ± 1 and 98 ± 1 % at pH 9 in 0.1 M NaCl and 0.1 M NaClO₄, respectively, whereas an extraction of 8–24 % was obtained, over the pH ranges from 2 to 5. The CE-modified MNPs yielded extraction efficiencies as high as 99 ± 1 % in the presence of 0.01 M picric acid at pH 4. This study demonstrates that the surface functionalization of Fe₃O₄ MNPs with suitable ligand modification can offer a selective mode of extraction for ²²⁶Ra in the presence of its daughter progenies.     

Effects of low-molecular-weight organic ligands and phosphate on DNA adsorption by soil colloids and minerals

Adsorption of DNA on montmorillonite, kaolinite, goethite and soil clays from an Alfisol in the presence of citrate, tartrate and phosphate was studied. A marked decrease in DNA adsorption was observed on montmorillonite and kaolinite with increasing anion concentrations from 0 to 5 mM. However, the amount of DNA adsorbed by montmorillonite and kaolinite was enhanced when ligand concentration was higher than 5 mM. In the system of soil colloids and goethite, with the increase of anion concentrations, a steady decrease was found and the ability of ligands in depressing DNA adsorption followed the sequence: phosphate > citrate > tartrate. Compared to H2O2-treated clays (inorganic clays), a sharp decrease in DNA adsorption was observed on goethite and organo-mineral complexes (organic clays) with increasing ligand concentrations. The results suggest that the influence of anions on DNA adsorption varies with the type and concentration of anion as well as the surface properties of soil components. Introduction of DNA into the system before the addition of ligands had the greatest amount of DNA adsorption on soil colloids and goethite. Organic and inorganic ligands promoted DNA adsorption on montmorillonite and kaolinite when ligands were introduced into the system before the addition of DNA. The results obtained in this study have important implications for the understanding of the persistence and fate of DNA in soil environments especially rhizosphere soil where various organic and inorganic ligands are active.     

Radioecology around a closed uranium mine

The uranium mine and mill at ?irovski vrh, Slovenia, operated from 1982 to 1990. After processing, the uranium mill tailings were deposited onto the Bor?t waste pile lying close to the mine. Radioecological studies focused on assessing the mobility and bioavailability of deposited radionuclides were initiated some five years ago. The mobility of ²³⁸U, ²³⁴U, ²³⁰Th and ²²⁶Ra in soil was studied by applying sequential extraction protocols. The highest activity concentrations were found at the bottom of the waste pile. Uranium isotopes were the most mobile, followed by ²²⁶Ra whose mobility appeared to be suppressed by high sulphate concentrations and ²³⁰Th. The wetland plants grown in soils contaminated with seepage waters from the tailings contained higher levels of ²³⁸U, ²²⁶Ra and ²³⁰Th compared to plants from a control site. The activity concentration of ²²⁶Ra was the highest in all studied plant species. The radiological risk to wildlife around the mine area as assessed by the ERICA Tool was negligible. Activity concentrations in bovine milk from the area of ?irovski vrh were comparable to the reference location, except for uranium where the content was higher. The combined annual effective dose for adults consuming milk from the ?irovski vrh area is 13.0 ± 1.7 μSv a^?1.     

Removal of 226Ra from aqueous media and its thermodynamics and kinetics

The composite adsorbent prepared by mixing of polyacrylonitrile and clinoptilolite was used for investigating the adsorption behaviour of ²²⁶Ra in column system. The effective parameters like initial activity concentration, pH of the solution, contact time and temperature for adsorption behaviour of ²²⁶Ra were studied. Adsorption efficiency of ²²⁶Ra on composite adsorbent from aqueous solution was determined to 98.73 ± 0.59 % at pH 5.0 and 30 °C in a short time. The isotherm models were studied to evaluated adsorption characteristics of ²²⁶Ra onto composite adsorbent. The thermodynamic parameters were showing that the processes for ²²⁶Ra were exothermic. Adsorption kinetics of the radium is also studied.

     

Assessment of 226Ra and 228Ra activity concentration in west coast of India

An investigation on the distribution of ²²⁶Ra and ²²⁸Ra activity concentration in coastal surface sea water from Okha in Gujarat to Ratnagiri in Maharashtra state along the west coast of India was carried out. In-situ pre-concentration technique was used to measure radium isotopes by passing 1,000 L of seawater through MnO₂ impregnated polypropylene filter cartridges at all the locations. ²²⁶Ra was estimated using gamma ray peak of its daughter radionuclides ²¹⁴Bi and ²¹⁴Pb. ²²⁸Ra was estimated from its daughter ²²⁸Ac. In the coastal waters, ²²⁶Ra and ²²⁸Ra activity concentration were observed to be in the range of 1.5–2.9 and 2.5–8.6 Bq m^?3 with a mean of 2.2 and 4.9 Bq m^?3 respectively. The activity of ²²⁸Ra was observed to be more than ²²⁶Ra in all the locations. The variation in spatial distribution of the radium isotopes activity concentration and its ratio with respect to location is discussed in the paper. The radioactive database obtained represents reference values for coastal environment of India.     

Studies on radionuclides around Hemavathi river basin of Karnataka,India

The activity concentration and total annual effective dose of the terrestrial naturally occurring radionuclides (²³²Th, ²²⁶Ra and ⁴⁰K) were measured in soil and rock samples collected from various locations of Hemavathi river basin in Karnataka, using HPGe detector. The results revealed that activity concentration of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil had geometrical mean values of 16.7 ± 0.6, 33.9 ± 1.2 and 359.9 ± 9.2 Bq kg^?1, respectively. In rock samples activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K had geometrical mean values of 20.2 ± 0.7, 18.0 ± 0.9 and 276 ± 9.6 Bq kg^?1, respectively. The external Hazard index and indoor hazard index were found to be within safety limits prescribed by European commission 1999 report.     

Cloud Point Phenomenon in Amphiphilic Drug Promethazine Hydrochloride+Electrolyte Systems

Herein we report clouding phenomenon occurring in amphiphilic drug promethazine hydrochloride (PMT) in the presence of electrolytes. The CP of 50 mM drug solution, prepared in 10 mM sodium phosphate buffer, was found to decrease with increasing pH due to deprotonation of drug molecules at high pH. Addition of inorganic salts (KF, KCl and KBr) to drug solutions at fixed pH (6.7) and drug concentration (50 mM) caused an increase in CP. The results have been discussed on the desorption/adsorption of counterions to the headgroups. Cations also increased the CP by affecting the water structure with their effectiveness being in the order: Li⁺<Na⁺<K⁺<NH₄ ⁺. In the presence of NaCl, increase in drug concentration increased the CP while increase in pH showed an opposite trend.     

Using the 186-keV peak for 226Ra activity concentration determination in Hungarian coal-slag samples by gamma-ray spectroscopy

The uranium isotopic abundance and the ²³⁸U–²²⁶Ra secular equilibrium were determined in nine Hungarian coal slag samples. The ²²⁶Ra activity concentration was measured based on the radon decay products and also the ²²⁶Ra peak at 186 keV. Secular equilibrium existed in eight samples, whereas one sample showed a slight disequilibrium. The direct and fast measurement using only the 186 keV peak was validated which can be used after measuring the uranium isotopic ratio and verifying the ²³⁸U–²²⁶Ra secular equilibrium. This method can be used to measure the ²²⁶Ra content of high number of samples from the same geochemical background.     

Interaction of radium with freshwater sediments and their mineral components

Radiotracer method has been used for investigation of the adsorption and desorption of traces of radium on kaolinite and montmorillonite under conditions similar to those prevailing in waste and surface waters. It has been found that adsorption depends on the pH and ionic strength of the solution, and the character of these dependences is different for kaolinite and montmorillonite. Sulfates at concentration 60 mg·l^–1 have negligible effect on the adsorption. Montmorillonite represents better adsorbent for radium than kaolinite, but both minerals may significantly affect the form and migration of radium in surface waters, if present as (major) components of freshwater sediments. Radium can be quantitatively desorbed by 1M HCl from kaolinite but not from montmorillonite. The desorption by 0.1M NaCl is generally lower and depends on the pH during the preliminary adsorption. Mechanisms of radium adsorption on both minerals and the character of the adsorption sites are discussed.     

Assessment of natural uranium and 226Ra concentration in ground water around the uranium mine at Narwapahar, Jharkhand, India and its radiological significance

A brief study on dissolved radionuclides in aquatic environment, especially in ground water, constitutes the key aspect for assessment and control of natural exposure. In the present study the distribution of natural uranium and ²²⁶Ra concentration were measured in ground water samples collected within a 10 km radius around the Narwapahar uranium mine in the Singhbhum thrust belt of Jharkhand, India in 2007–2008. The natural uranium content in the ground water samples in this region was found to vary from 0.1 to 3.75 μg L^?1 with an average of 0.87 ± 0.73 μg L^?1 and ²²⁶Ra concentration was found to vary from 5.2 to 38.1 mBq L^?1 with an average of 13.73 ± 7.34 mBq L^?1. The mean annual ingestion dose due to intake of natural uranium and ²²⁶Ra through drinking water pathway to male and female adults population was estimated to be 6.55 and 4.78 μSv y^?1, respectively, which constitutes merely a small fraction of the reference dose level of 100 μSv y^?1 as recommended by WHO.     

Radiological measurement of phosphate rock and phosphogypsum from fertilizer industries in India

Phosphate deposits are generally characterized by high levels of natural radionuclide concentrations. Natural radionuclides from the uranium and thorium series were measured, using high-resolution gamma-spectrometry in phosphate rock and phosphogypsum samples from the phosphate fertilizer industry in India. Equilibrium was found to be disrupted during the chemical processing of phosphate rock with 83 % of the ²²⁶Ra and only 5 % of ²³⁸U fractionating to phosphogypsum. Activity concentrations of ²³⁸U and ²²⁶Ra in phosphogypsum produced from various fertilizer industries of India showed levels < 1,000 Bq kg^?1 and pose no restriction for use in building/construction material.     

Assessment of ingestion dose due to radioactivity in selected food matrices and water near Vizag,India

Activity concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs were measured in milk, egg, fruit and fish samples collected around a proposed site for setting up nuclear facilities, near Vishakhapatanam. The activity concentrations of the radionuclides ranged from 0.002 to 10.6, 0.002 to 2.8, 0.1 to 7.2, 3 to 110.8, 0.03 to 3 mBq g^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs considering analysed food matrices. Natural uranium was measured in drinking water samples and the values were below 15 ppb. The average ingestion dose was 2.07 ± 2.01, 2.81 ± 4.38, 7.66 ± 8.24, 1.28 ± 0.84 and 0.04 ± 0.05 μSv year^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs in milk, egg, fruit, fish and water. The ingestion dose received was the highest for milk, due to its high ingestion rate. It was observed that ²²⁶Ra is the largest contributor of measured radionuclides in this study for the different food matrices analysed due to its high dose conversion factor. The study was carried out as a part of baseline data generation for this region with which future changes in the radiological scenario can be compared.     

Terrestrial gamma exposure in the granodiorite area of Bergama (Pergamon)�CKozak, Turkey

As higher radiation levels are associated with granite and Bergama (Pergamon) has increasingly become a large market for granite use over the last years, an extensive investigation was started in 2009. Samples from the granites and soils underlying this area were collected and analyzed by HPGe gamma spectrometry system. The specific activities of the naturally occurring radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be in the range of 29?C111 Bq kg^?1 for ²²⁶Ra, 35?C87 Bq kg^?1 for ²³²Th and 698?C1100 Bq kg^?1 for ⁴⁰K in granite samples. The ranges of ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations for soils were 32?C82, 42?C88 and 667?C1127 Bq kg^?1, respectively. From these data radiological parameters were calculated and compared with respective data from the UNSCEAR reports.     

Studies on natural and anthropogenic radionuclides in sediment and biota of Mumbai Harbour Bay

Mumbai Harbour Bay (MHB) is a recipient of low level treated effluents from BARC, Trombay and its also a recipient of domestic and industrial wastes from the city of Mumbai and adjoining areas. Sediment samples were collected from various locations of MHB to determine the concentrations of naturally occurring radionuclides like ²²⁶Ra, ²²⁸Ra and ⁴⁰K which varied between 4.0 and 26.0, 5.5 and 19.9, 249.6 and 557.6 Bq kg _(dry) ^?1 respectively and are comparable to the worldwide average concentration. The mean value ratio of ²²⁸Ra/²²⁶Ra in sediment was found to be 1.4, indicating a relatively higher mobility of ²³⁸U compared to ²³²Th. The concentration of anthropogenic radionuclide ¹³⁷Cs in sediment and biota ranged between 3.6 and 54.5 Bq kg _(dry) ^?1 , <0.08 and 0.5 Bq kg _(wet) ^?1 respectively. The ingestion dose to ‘General Public’ due to ¹³⁷Cs intake is 0.02 μSv years^?1 which is negligible compared to the internationally accepted limit of 1,000 μSv years^?1 to ‘members of public’.     

Determining coastal mixing rates of western Taiwan Strait using 224Ra

²²⁴Ra concentrations in the coastal sea water of western Taiwan Strait in winter were measured using Mn-fiber adsorption—successive emanation scintillation method. ²²⁴Ra activities in the seawater of the western Taiwan Strait varied from 0.90 to 16.25 Bq/m³ with an average of 4.60 Bq/m³. The horizontal and vertical distributions of ²²⁴Ra were studied. The distributions of ²²⁴Ra in the surface water decreased gradually with increasing distance offshore. The apparent horizontal and vertical eddy diffusion coefficients estimated from the one dimensional steady state model of ²²⁴Ra were (5.0–55.4) × 10⁶cm²/s and (4.0–51.7) cm²/s, respectively.     

Measurement of 222Rn and 226Ra in municipal supply tap water to evaluate their radiological impacts

ABSTRACT

Radon (²²²Rn) and its parent radionuclide Radium (²²⁶Ra) are classified as carcinogen. Human exposes to radon in water via inhalation and ingestion, although ingestion is the only way for radium to enter the human body. In this research, tap water collected from Bornova distinct was studied to determine the concentration of radon (²²²Rn) and radium (²²⁶Ra) for evaluating their radiological impact. For this reason, the annual effective doses for ingestion and inhalation were estimated. The measurements were performed using a collector chamber method. The mean concentrations of ²²²Rn and ²²⁶Ra were determined as 0.85 and 0.76 Bq/L, respectively. It can be stated that the ²²²Rn and ²²⁶Ra concentrations of tap waters here are lower than the international reference levels. Obtained concentration levels were applied to estimate annual effective dose due to the inhalation and ingestion. The dose values are also found to be lower than the recommended maximum values. On the other hand, it should be considered that consumption of these waters (2 L) and average radon and radium concentrations of water are the significant factors for estimating doses.     

Radioanalytical assessment of environmental contamination around non-remediated uranium mining legacy site and radium mobility

During the past century extensive uranium mining took place in Portugal for radium and uranium production. One such uranium mine was the Boco Mine, in operation during the 1960s and 70s. Mining waste and open pits were left uncovered since mine closure. During the nineties a quarry for sand extraction was operated in the same site and water from a local stream was extensively used in sand sieving. Downstream the mine area, agriculture soil is used for cattle grazing. Water from the stream, water wells, soil, pasture and sheep meat were now analyzed for radionuclides of uranium natural series. The U-series radionuclide ²²⁶Ra was generally the highest in concentrations especially in soil, pasture, and in internal organs of sheep. ²²⁶Ra concentrations were 1,093 ± 96 Bq/kg (dry weight, dw) in soil, 43 ± 3 Bq/kg (dw) in pasture, and 193 ± 84 mBq/kg (wet weight, ww) in muscle tissue of sheep. Other sheep internal organs displayed much higher ²²⁶Ra concentrations, such as the brain and kidneys with 1,850 ± 613 mBq/kg (ww) and 6,043 ± 6,023 mBq/kg (ww), respectively. Results of analyses of tissue samples from sheep grown in a comparison area were 2 to 16 times lower, depending on the organ. Absorbed radiation doses for internal organs were computed and may exceed 5.2 mGy/y in the case of kidneys, near three times higher than in animals from the reference area, but below the threshold for biological effects. Radionuclide transfer in the terrestrial food chain and radiation exposure of the human population is discussed.     

Distribution of 238U, 226Ra, 232Th and 40K in soil samples around Tarapur,India

The radioactivity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples around Tarapur vary from 11.5 ± 2.6 to 50.3 ± 6.6, 14.9 ± 0.6 to 40.5 ± 1.2, 18.1 ± 0.4 to 75.0 ± 1.5 and 130.1 ± 1.6 to 295.1 ± 2.6 Bq/Kg respectively. The measured activity concentrations for ²³⁸U and ²²⁶Ra were compared and found in good agreement with the Indian as well as world average. The average ²³²Th and ⁴⁰K concentrations in Tarapur were lower than the Indian average value.     

Effect of acid and alkali treatments of a forest waste,Pinus brutia cones,on adsorption efficiency of methyl green

The removal of methyl green (MG) dye from aqueous solutions using acid- or alkali-treated Pinus brutia cones (PBH and PBN) waste was investigated in this work. Adsorption removal of MG was conducted at natural pH, namely, 4.5 ± 0.10 for PBH and near 4.8 ± 0.10 for PBN. The pseudo-second-order model appeared to be the most appropriate to describe the adsorption process of MG on both PBN and PBH with a correlation coefficient R² > 0.999. Among the tested isotherm models, the Langmuir isotherm was found to be the most relevant to describe MG sorption onto modified P. brutia cones with a correlation factor R² > 0.999. The ionic strength (presence of other ions: Cl^?, Na⁺, and SO₄^2?) also influences the adsorption due to the change in the surface properties; it had a negative impact on the adsorption of MG on these two supports. A reduction of 68.5% of the adsorption capacity for an equilibrium dye concentration Ce of 30 mg/L was found for the PBH; while with PBN no significant influence of the ionic strength on adsorption was observed, especially in the presence of NaCl for dye concentrations superior to 120 mg L^?1.     

A preliminary study on 226Ra, 232Th, 40K and 137Cs activity concentrations in vegetables and fruits frequently consumed by inhabitants of Elazığ Region, Turkey

Determining radioactivity levels in foodstuffs is of great importance for the protection of human health. In addition, the literature includes few studies related to this subject in Turkey. In this study, gamma spectroscopic system was used in order to measure ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs activity concentrations in vegetables and fruits produced in Elaz?? Region. The average activity concentrations in vegetables was calculated as 0.64 ± 0.26 Bq kg^?1 for ²²⁶Ra, 0.65 ± 0.14 Bq kg^?1 for ²³²Th, 13.98 ± 1.22 Bq kg^?1 for ⁴⁰K, and 0.54 ± 0.04 Bq kg^?1 for ¹³⁷Cs. The average activity concentrations in fruits were 1.52 ± 0.34, 0.98 ± 0.23, 18.66 ± 1.13 and 0.59 ± 0.16 Bq kg^?1, respectively for ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs. Total committed effective dose value was determined as 20 and 30.55 μSv y^?1, respectively for vegetables and fruits. The findings were compared with previous data reported for Turkey and other regions of the world.