X-ray Fluorescence Technique Research Articles

Uranium removal from aqueous solution using macauba endocarp-derived biochar: Effect of physical activation.

The main aim of this study was to evaluate options for addressing two pressing challenges related to environmental quality and circular economy stemming from wastage or underutilization of abundant biomass residue resources and contamination of water by industrial effluents. In this study we focused on residues (endocarp) from Macaúba palm (Acrocomia aculeata) used for oil production, its conversion to activated biochar, and its potential use in uranium (U) removal from aqueous solutions. Batch adsorption experiments showed a much higher uranyl ions (U(VI)) removal efficiency of activated biochar compared to untreated biochar. As a result of activation, an increase in removal efficiency from 80.5% (untreated biochar) to 99.2% (after activation) was observed for a 5mgL-1 initial U(VI) concentration solution adjusted to pH 3 using a 10gL-1 adsorbent dosage. The BET surface area increased from 0.83 to 643m2g-1 with activation. Surface topography of the activated biochar showed a very characteristic morphology with high porosity. Activation significantly affected chemical surface of the biochar. FTIR analysis indicated that U(VI) was removed by physisorption from the aqueous solution. The adsorbed U(VI) was detected by micro X-ray fluorescence technique. Adsorption isotherms were employed to represent the results of the U adsorption onto the activated biochar. An estimation of the best fit was performed by calculating different deviation equations, also called error functions. The Redlich-Peterson isotherm model was the most appropriate for fitting the experimental data, suggesting heterogeneity of adsorption sites with different affinities for uranium setting up as a hybrid adsorption. These results demonstrated that physical activation significantly increases the adsorption capacity of macauba endocarp-derived biochar for uranium in aqueous solutions, and therefore open up a potential new application for this type of waste-derived biochar.

Radiological and physical properties of tissue equivalent mammography phantom: Characterization and analysis methods

This article provides methods to fabricate and characterize tissue equivalent properties of mammography phantom. The characterized properties are elemental composition, effective atomic number, electron density, attenuation coefficient and CT number. Polyvinyl alcohol (PVAL), ethanol solution and graphite powder were used to develop samples of breast phantoms. First, the microstructure and elemental composition of the phantom materials were acquired from the field emission scanning electron microscopy (FESEM). FESEM micrography was a good analytical technique to indicate void spaces within the phantom. Next, the effective atomic number and electron density were calculated from the percentage of elemental composition based on the energy dispersive X-ray analysis (EDXA). Mayneord's formula and the Phy-X/ZeXTRa software were used to evaluate the effective atomic number. The calculations show that the effective atomic number ranged from 7.137 to 7.264 and 6.75–7.05 for Mayneord and Phy-X/ZeXTRa approach respectively. The electron density ranged from 3.191–3.209 × 1023/g. These values were found to be in good agreement with water and breast tissue by ICRP and AAPM standards. Then, the mass attenuation coefficients of the PVAL were calculated based on the transmission of low photons by using X-ray fluorescent (XRF) technique at 16.61–25.26 keV. The mass attenuation coefficient values were found to be close to water and breast tissue when results were compared to XCOM values. Finally, CT images were acquired to measure CT numbers, which were found to be near to CT number of breast tissues, −21.40 to 24.13 HU. Based on the ICRP, AAPM, BIRADS and XCOM standards, the study successfully showed methods to fabricate and characterized mammography phantoms.

Synchrotron based X-ray fluorescence for trace elemental analysis of industrial sludge

This research article presents the application of the synchrotron-based X-ray fluorescence (XRF) technique for the resolution of trace elemental accumulation in industrial sludge/waste. The X-ray fluorescence using synchrotron radiation presents an expeditious exposition of a wide scale of elements (Sodium to Uranium) together with an ingenuous sample preparation procedure. The present X-ray fluorescence studies carried out for the paper and toothpaste industry sludge at synchrotron source (Beam Line -16), Indus-2, Raja Ramanna Centre for Advanced Technology, Indore, India. The XRF results show very low traces of heavy metals present in paper and toothpaste industry sludge and therefore recommend for safe and efficient reuse.

X-ray Fluorescence Techniques in Determining the Habitat Preferences of Species-Ulva pilifera (Ulvales, Chlorophyta) from Montenegro Case Study.

The paper presents four new sites where bright green Ulva thalli were found inhabiting freshwater (a river, a ditch, the Milet Canal) and marine (on the rocky shore of the Adriatic Sea) habitats in Montenegro. The aims of this study were to determine, for the first time, whether specimens of Ulva pilifera collected in Montenegro are phylogenetically and morphologically the same species as the one occurring in Europe. Using total reflection X-ray fluorescence (TXRF) and wavelength dispersive X-ray fluorescence (WDXRF) techniques it assessed the elemental composition of their thalli and its influence to colonise new habitats. Elements: Al, As, Ba, Br, Ca, Cl, Cr, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, S, Si, Sr, Ti, V, and Zn were determined. The highest elemental concentrations were found for Ca = 16.3% (using WDXRF) and for Sr = 292 ppm (using TXRF) in the Ulva thalli. Ulva pilifera analysed from Montenegro, based on classical morphological methods and molecular techniques, are closely related to the same species from inland and coastal waters throughout Europe. The analysis of trace elements showed that the metal content in Ulva thalli is correlated with the trace elements in water and sediments. Ulva pilifera fits numerous features that make it one of the bioindicators of marine pollution, thanks to its worldwide distribution and capacity to accumulate trace elements.

Assessing arsenic in human toenail clippings using portable X-ray fluorescence

Arsenic is a toxic metalloid which has been associated with a wide range of health effects in humans including skin abnormalities and an elevated risk of skin, bladder, kidney, and lung cancer, diabetes, and cardiovascular disease. The measurement of arsenic concentration in nail clippings is often used in population studies as an indicator of arsenic exposure. Portable X-ray fluorescence (XRF) is an emerging technique for measuring arsenic in nail clippings. In the current study, single toenail clippings from 60 Atlantic Canadian participants were assessed for arsenic using a new portable XRF approach. A mono-energetic portable XRF system using doubly curved crystal optics was used to measure each clipping for a total of 900 s. Energy spectra from each clipping were analyzed for arsenic characteristic X-rays to provide a normalized arsenic signal. The same clippings were then analyzed for arsenic concentration using a “gold standard” method of inductively coupled plasma mass spectrometry (ICP-MS). Nail clipping arsenic concentrations measured by ICP-MS ranged from 0.030 μg/g to 2.57 μg/g, with a median result of 0.14 μg/g. Portable XRF results for arsenic were compared against ICP-MS arsenic concentrations, with a linear equation of best fit determined between the two variables. A correlation coefficient of r = 0.77 was found from the 59 nail clippings returning an ICP-MS arsenic concentration above the limit of quantitation. When the comparison was limited to the 20 clippings having an XRF normalized signal at least twice as large as the associated uncertainty of measurement, the correlation coefficient was r = 0.89. With the selection of an arsenic concentration of 0.1 μg/g as a cut-off value between “exposed” and “non-exposed” individuals, the XRF method provided a test sensitivity of 76% and a specificity of 81%. The corresponding positive predictive value was 88% and the negative predictive value was 65%. The portable XRF technique used in this study shows promise as a means of assessing arsenic concentration in toenail clippings.

Application of waste treatment sludge from water treatment in brick production

The aim of the study is to investigate the potential use of water treatment sludge in brick properties as building material. The sludge was collected from water treatment plant and the percentages used in the mixes were 3%, 5%, 7%, 10% 15%, 20%, 40%, and 60% by weight of sand in brick. The specimen without sludge was prepared for comparison. The testing involved chemical analysis of sludges using energy dispersive X-ray fluorescence (ED-XRF) technique. Testing of compressive strength was done for hardened state properties. The samples were cured at 7 and 28 days, and the average of three samples of brick samples was measured. The results revealed that the waste sludges had higher components of Zn, Cu, Pb, and As, which was trace element concentrations in the dry sludge samples. Comparisons in terms of strength were made from the control and brick containing sludge specimens. It was observed that sludge in brick performed better when mixed with 5% as partial replacement of sand. However, the more the addition of percentages of sludge in brick, the lesser the strength observed. It can be concluded that waste treatment sludge as a result from the process of water treatment can be utilized as partial replacement of sand in brick production.

Thickness measurement of low-Z films fabricated on thick substrate using EDXRF technique

The present work reports a method for thickness measurements of low-Z films deposited on a thick substrate using energy dispersive X-ray fluorescence (EDXRF) technique. For this, ZnO and single-wall carbon nanotubes (SWCNTs) films (thickness ~ 1–100 mm) were fabricated on thick Si substrates using a sol-gel spin coating technique. The fabricated films were characterized using X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. The thicknesses of fabricated films were determined from the measured attenuation of Si-Kαβ characteristics X-rays emitted from the thick Si substrate in coated materials. The thick substrate was excited by Mn Kα (5.895 keV) and Kβ (6.492 keV) X-rays obtained from annular 55Fe radioactive source in reflection mode geometrical setup. The emitted characteristics X-rays were detected by a low energy Ge (LEGe) detector coupled with PC based multichannel analyzer. The obtained results show good agreement with the values obtained from well-established X-ray fluorescence (XRF) and atomic force microscopy (AFM) measurements. The experimental results recommend the use of reported methodology for thickness measurement of low-Z materials deposited on a thick substrate for material characterization in future.

Grazing incidence-x-ray fluorescence for a dimensional and compositional characterization of well-ordered 2D and 3D nanostructures

The increasing importance of well-controlled ordered nanostructures on surfaces represents a challenge for existing metrology techniques. To develop such nanostructures and monitor complex processing constraints fabrication, both a dimensional reconstruction of nanostructures and a characterization (ideally a quantitative characterization) of their composition is required. In this work, we present a soft x-ray fluorescence-based methodology that allows both of these requirements to be addressed at the same time. By applying the grazing-incidence x-ray fluorescence technique and thus utilizing the x-ray standing wave field effect, nanostructures can be investigated with a high sensitivity with respect to their dimensional and compositional characteristics. By varying the incident angles of the exciting radiation, element-sensitive fluorescence radiation is emitted from different regions inside the nanoobjects. By applying an adequate modeling scheme, these datasets can be used to determine the nanostructure characteristics. We demonstrate these capabilities by performing an element-sensitive reconstruction of a lamellar grating made of Si3N4, where GIXRF data for the O-Kα and N-Kα fluorescence emission allows a thin oxide layer to be reconstructed on the surface of the grating structure. In addition, we employ the technique also to three dimensional nanostructures and derive both dimensional and compositional parameters in a quantitative manner.

Relationship of levels of trace elements in saliva and dental caries in preschool children using total reflection X-ray fluorescence technique (TXRF)⋆

BackgroundConsidering that studies on the relationship between dental caries and trace elements present contradictory and inconclusive results, the purpose of this study was to determine the levels of salivary trace elements in saliva samples of preschool children and investigate their relationship with dental caries. MethodsIn total, 120 samples of unstimulated saliva were collected from children aged 36–72 months, of both sexes, who participate in the preventative educational program in oral health at the State University of Londrina, Brazil. The children were divided into two groups, caries (n = 60) and non-caries (n = 60). Levels of Al, Cu, Fe, Mn, and Zn were analyzed by total reflection X-ray fluorescence (TXRF). Descriptive statistics, the Student’s t-test, Mann-Whitney U test, and Pearson’s Chi-squared test were performed (P < 0.05). ResultsThe concentrations of Mn and Fe were significantly higher in the caries group (Mn =0.015 mg/L [0.007−0.020]; Fe =0.080 mg/L [0.031−0.239] than the non-caries group (Mn =0.010 mg/L [0.001 – 0.017]; Fe =0.044 mg/L [0.023 – 0.107]). ConclusionThe results suggest a relationship between trace elements and dental caries, indicating possible involvement of these elements in the metabolism of microorganisms involved in the carious process. In addition, the use of TXRF presented satisfactory results, with a simple and fast methodology for the detection of the studied elements.

MICRO X-RAY FLUORESCENCE IMAGING COUPLED WITH CHEMOMETRICS TO DETECT AND CLASSIFY ASBESTOS FIBERS IN DEMOLITION WASTE

Asbestos was largely used in the past by several countries all over the world. From 1900 to 1990 asbestos-containing materials (ACMs) were produced in large amounts and mainly utilized for the production of insulation, flame retardant materials, as well as to improve the mechanical and the chemical characteristics of construction materials. Its extensive use has therefore led to the presence of fibers in existing buildings and within the construction and demolition waste. A fast, reliable and accurate recognition of ACMs represents an important target to be reached. In this paper the use of micro X-ray fluorescence (micro-XRF) technique coupled with a statistical multivariate approach was applied and discussed with reference to ACMs characterization. Different elemental maps of the ACMs were preliminary acquired in order to evaluate distribution and composition of asbestos fibers, then samples energy spectra where collected and processed using chemometric methods to perform an automatic classification of the different typologies of asbestos fibers. Spectral data were analyzed using PLS-Toolbox™ (Eigenvector Research, Inc.) running into Matlab® (The Mathworks, Inc.) environment. An automatic classification model was then built and applied. Results showed that asbestos fibers were correctly identified and classified according to their chemical composition. The proposed approach, based on micro-XRF analysis combined with an automatic classification of the elemental maps, is not only effective and non-destructive, it is fast and it does not require the presence of a trained operator. The application of the developed methodology can help to correctly characterize and manage demolition waste where ACMs are present.

Soil Organic Carbon Stabilization: Influence of Tillage on Mineralogical and Chemical Parameters

The interaction of organic carbon (OC) with clay minerals and amorphous iron and aluminum oxides, especially in the finest soil fractions (&lt;20 μm), represents a good method for its stabilization, and different tillage practices can improve or reduce the persistence of OC in soils. This study investigates the effects of conventional (CT) and no (NT) tillage and soil depth (0–30, 30–60, and 60–90 cm) on the soil organic carbon (SOC) in four soil size fractions and its interactions with clay minerals and amorphous oxides. To identify the mineralogical composition of the four soil size fractions isolated from each soil, the X-ray powder diffraction (XRPD) technique was used with near infrared (NIR) spectroscopy, while the X-ray fluorescence (XRF) technique was used to determine the chemical composition of soil fractions. The higher OC content found in the finest soil fraction is related to its higher content of clay minerals and amorphous oxides. The SOC content is similar among CT and NT treatments as well as the mineralogical composition and the amount of amorphous oxides, suggesting that more than ten years of different tillage did not influence those parameters.

Determination of trace elements in cabbage (Brassica oleracea L.var.acephale) and its grown soil at the Black sea region in Turkey

Purpose The most consumed urban crops having many benefits for human health in the northeast Black Sea black cabbage (Brassica oleracea L.var.acephale) leaf and theirs own grown soils were collected from Black Sea cities and towns; Rize, Trabzon, Giresun, Ordu ve Samsun of Turkey from totally 55 stations to determine the element levels in percent of the black cabbage. It is purposed that to obtain the data for each city in terms of element distribution. This study is a very comprehensive work covering almost the entire eastern Black Sea region for elemental measurements in black cabbage and its soil and comparing them between provinces and districts. Method The samples were analyzed by using Energy Dispersive X-Ray Fluorescence (EDXRF) technique that is a nondestructive method by giving reliable results. The obtained data were evaluated by using the ordinary cricking method and some statistical methods (Mann-Whitney- U Test, Oneway-ANOVA, Pearson and Spearman-Brown correlation test) to determine the correlations between soils, the black cabbage and both compared the element levels between the sampling points. The statistical analysis in soil and black cabbage samples were carried out for 19 and 11 elements, respectively. Results Mg (Magnesium), K (Potassium), Ca (Calcium), Al (Aluminum), Si (Silica), P (Phosphor), S (Sulphur), Ti (Titanium), Fe (Iron), Sr (Strontium), V (Vanadium), Cr (Chromium), Mn (Manganese) for the black cabbage sample and Na (Sodium), Mg, Al, Si, P, S, K, Ca, Ti, Fe, Cu (Copper), Zn (Zinc), Sr, V, Cr, Mn, As (Arsenic), Rb (Rubidium) and Pb (Lead) for soil samples were determined. The determining elements for soils and the black cabbage samples were compared between the working provinces. Conclusions The obtained data showed that the element distribution is similar and not showed a statistical difference for both between each station and cities. Besides, the trace elements in soils are not much affected the black cabbage however Al was found in the cabbage even it is less.

Fabrication of thin Nb target for lifetime measurements of short lived excited nuclear states

The quality of target foils often plays an important role in the success of nuclear physics experiments. Specially, in an experiment intended to measure the level lifetimes of short lived excited nuclear states with Doppler shift attenuation method (DSAM), an isotopically enriched thin target on appropriately thick backing foil of high-Z material is preferentially required. In the present work, a thin (thickness ≈ 0.9 mg/cm2) mono-isotopic Nb target on thick (thickness ≈ 9.2 mg/cm2) lead backing has been prepared using rolling technique at the Inter University Accelerator Center (IUAC), New Delhi. To meet the important criteria of sufficient thickness and proper sticking of two foils without any air gap in-between, some novel methods like heating of stainless steel (SS) pack before rolling, frequent change of rolling pack, use of alcohol during rolling, unidirectional rolling under low pressure specially for rolling lead foil and the composite target, were adopted. The quality check of prepared target foil was done with the energy dispersive X-ray fluorescence (EDXRF) technique. The prepared target has been successfully used in a recent DSAM lifetime measurement experiment at IUAC, New Delhi.

Using Mn based on lightweight expanded clay aggregate (LECA) as an original catalyst for the removal of NO2 pollutant in aqueous environment

The NO2 gas is one of the by- products of incineration processes that is the main source of the atmospheric pollutants, So the removal of NO2 is essential for reducing the environmental contamination. In this study, the oxidation of NO2 and producing nitric acid by Mn based on LECA, (Mn/LECA), as a novel nanocatalyst was investigated in aqueous solution. The progress of the treatment reaction in a Semi-batch reactor (SBR) was monitored by conductometry. The Mn/LECA was prepared and characterized by Fourier Transform Infra-Red (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Energy-Dispersive X-ray spectroscopy (EDX) techniques. The Box−Behnken design (BBD) was employed to optimize the operational variables, including the amounts of nanocatalyst, temperature, the concentration of NO2, and the time of reaction in NO2 oxidation. The graphical response surfaces were applied to obtain the optimal circumstances. The Analysis of variance (ANOVA) presented a great value of determination coefficient (R2 = 0.9945, Radj2=0.9881 and Rpred2=0.969) and acceptable prediction second-order regression model. The highest efficacy in the oxidation of NO2 was 94.3%, at a primary temperature of 30 °C, amounts of Mn/LECA at 9 g/L, time of reaction at 60 min, and concentration of NO2 at 3 mg/L. The reusability and durability of the catalyst were good, and the oxidation efficiency of NO2 was 91 and 89.6% after 120 and 180 min, in second and third cycles, respectively.

Radioactivity and Radiation Hazard Indices Assessment for Phosphate Rock Samples from Al-Jalamid, Turaif, Umm Wu’al, and As-Sanam, Saudi Arabia

In this study, the activity concentration of 235U, 40K, 238U, 226Ra, and 232Th in phosphate rock found in the Kingdom of Saudi Arabia has been measured by gamma-ray spectrometry. Phosphate is extracted from the northern region in Saudi Arabia and widely used in agriculture as fertilizers as well as in the chemical industry. The average activity concentration of 235U, 238U, 226Ra, 232Th, and 40K has been measured as (10.34 ± 1.49 Bq kg−1, 260.99 ± 19.68 Bq kg−1, 242.33 ± 2.74 Bq kg−1, 3.42 ± 0.94 Bq kg−1, and 47.50 ± 3.03 Bq kg−1) for Al-Jalamid phosphate rock ores, respectively; (46.10 ± 2.61 Bq kg−1, 1028.31 ± 36.88 Bq kg−1, 989.98 ± 6.41 Bq kg−1, 13.75 ± 1.68 Bq kg−1, and 51.93 ± 3.82 Bq kg−1) for Turaif phosphate rock ores, respectively; (63.60 ± 3.33 Bq kg−1, 1353.25 ± 41.58 Bq kg−1, 1304.29 ± 7.70 Bq kg−1, 13.45 ± 1.64 Bq kg−1, and 40.26 ± 3.67 Bq kg−1) for Umm Wu’al phosphate rock ores, respectively; and (13.83 ± 1.59 Bq kg−1, 318.72 ± 21.78 Bq kg−1, 350.50 ± 3.14 Bq kg−1, 5.01 ± 1.13 Bq kg−1, and 42.15 ± 3.02 Bq kg−1) for As-Sanam phosphate mines, respectively. The radiological parameters (gamma index, absorbed dose, outdoor and indoor annual effective dose, and total excess lifetime cancer risk (ELCR)) have also been calculated to assess the health hazards. The radiation indices, effective dose, and ELCR have been found high in all samples corresponding to International Commission on Radiological Protection (ICRP) safety limits, which reflects a radiological health risk for workers and population. The X-ray diffraction (XRD) analysis confirms the concentration of dominant elements like fluorapatite (Ca5(PO4)3F), dolomite (CaMg (CO3)2), and minor traces of quartz (SiO2) and calcite (CaCO3). The elemental concentration of CaO, Al2O3, P2O5, SiO2, MgO Al2O3, and Fe2O3 has been measured by X-ray fluorescence (XRF) technique.

Investigating counterfeiting of an artwork by XRF, SEM-EDS, FTIR and synchrotron radiation induced MA-XRF at LNLS-BRAZIL

In this work, a painting suspected of counterfeiting was analyzed using the synchrotron-based scanning macro X-ray fluorescence (MA-XRF) technique. The canvas has erasures including a signature erasure; however, some visible numbers indicate that the artwork may be from the 17th century. Through the studies' elemental maps, Cl-K and Ca-K were observed, which allowed us to reconstruct the signature present in the painting. Elemental maps of Ba-K, Ti-K, Fe-K, Zn-K, and Pb-K were also obtained from the painting, which made possible to visualize how the pigments based on these elements were used in the creative composition of the painting. In addition to the signature region, a region of the painting with dimensions of approximately 120mm×120mm was investigated by synchrotron radiation induced MA-XRF, while keeping a high spatial resolution and elemental sensitivity. The measurements were carried out at the D09B micro-XRF beamline of the Brazilian Synchrotron Light Laboratory (LNLS), part of the Brazilian Center of Research in Energy and Materials, in Campinas Brazil. The painting was also investigated by SEM-EDS, and FTIR techniques. Those results, in addition to the supporting elemental maps, allowed additional information to be obtained, such as the binders used on the painting.

Application of TXRF in monitoring trace metals in particulate matter and cloud water

Abstract. Trace metals in ambient particulate matter and cloud are considered key elements of atmospheric processes as they affect air quality, environmental ecosystems, and cloud formation. However, they are often available at trace concentrations in these media such that their analysis requires high-precision and sensitive techniques. In this study, different analytical methods were applied to quantify trace metals in particulate matter (PM) samples collected on quartz and polycarbonate filters as well as cloud water, using the Total reflection X-Ray Fluorescence (TXRF) technique. These methods considered the measurement of filter samples directly without and with chemical pretreatment. Direct measurements involved the analysis of PM samples collected on polycarbonate filters and cloud water samples after they are brought onto TXRF carrier substrates. The chemical treatment method involved the assessment of different acid digestion procedures on PM sampled on quartz filters. The solutions applied were reverse aqua regia, nitric acid, and a combination of nitric acid and hydrogen peroxide. The effect of cold-plasma treatment of samples on polycarbonate filters before TXRF measurements was also investigated. Digestion with the reverse aqua regia solution provided lower blanks and higher recovery in comparison to other tested procedures. The detection limits of the elements ranged from 0.3 to 44 ng cm−2. Ca, K, Zn, and Fe showed the highest detection limits of 44, 35, 6, and 1 ng cm−2, while As and Se had the lowest of 0.3 and 0.8 ng cm−2, respectively. The method showed higher recovery for most trace metals when applied to commercially available reference materials and field samples. TXRF measurements showed good agreement with results obtained from ion chromatography measurements for elements such as Ca and K. Cold-plasma treatment did not significantly lead to an increase in the detected concentration, and the results were element specific. Baking of the quartz filters prior to sampling showed a reduction of more than 20 % of the filter blanks for elements such as V, Sr, Mn, Zn, and Sb. The methods were applied successfully on ambient particulate matter and cloud water samples collected from the Atlas Mohammed V station in Morocco and the Cape Verde Atmospheric Observatory. The obtained concentrations were within the range reported using different techniques from similar remote and background regions elsewhere, especially for elements of anthropogenic origins such as V, Pb, and Zn with concentrations of up to 10, 19, and 28 ng m−3, respectively. Enrichment factor analysis indicated that crustal matter dominated the abundance of most of the elements, while anthropogenic activities also contributed to the abundance of elements such as Sb, Se, and Pb. The results confirm that TXRF is a useful complementary sensitive technique for trace metal analysis of particulate matter in the microgram range as well as in cloud water droplets.

Assessment of selenium spatial distribution using μ-XFR in cowpea (Vigna unguiculata (L.) Walp.) plants: Integration of physiological and biochemical responses

Low concentrations of selenium (Se) are beneficial for plant growth. Foliar Se application at high concentrations is toxic to plants due to the formation of reactive oxygen species (ROS). This study characterized Se toxicity symptoms using X-ray fluorescence (XRF) technique in response to foliar Se application in cowpea plants. Five Se concentrations (0, 10, 25, 50, 100 e 150 g ha−1) were sprayed on leaves as sodium selenate. The visual symptoms of Se toxicity in cowpea leaves were separated into two stages: I) necrotic points with an irregular distribution and internerval chlorosis at the leaf limb border (50–100 g ha−1); II) total chlorosis with the formation of dark brown necrotic lesions (150 g ha−1). Foliar Se application at 50 g ha−1 increased photosynthetic pigments and yield. Ultrastructural analyses showed that Se foliar application above 50 g ha−1 disarranged the upper epidermis of cowpea leaves. Furthermore, Se application above 100 g ha−1 significantly increased the hydrogen peroxide concentration and lipid peroxidation inducing necrotic leaf lesions. Mapping of the elements in leaves using the XRF revealed high Se intensity, specifically in leaf necrotic lesions accompanied by calcium (Ca) as a possible attenuating mechanism of plant stress. The distribution of Se intensities in the seeds was homogeneous, without specific accumulation sites. Phosphorus (P) and sulfur (S) were found primarily located in the embryonic region. Understanding the factors involved in Se accumulation and its interaction with Ca support new preventive measurement technologies to prevent Se toxicity in plants.

Fabrication of 128Te thin target for nuclear levels lifetime measurements

Measuring nuclear level lifetimes of pico-seconds and femto-seconds order is important for understanding typical nuclear shapes. To extract such short lifetimes, specially designed thin targets are needed. A thin isotopically enriched 128Te target of thickness ∼ 1.2 mg/cm2 on the thick backing foil of natural gold of thickness ∼ 9.8 mg/cm2 has been prepared for the Doppler shift attenuation method (DSAM) lifetime measurement. The target was made by vacuum deposition technique using the cryogenic pump based Ultra High Vacuum (UHV) chamber available at the Inter University Accelerator Centre (IUAC), New Delhi. In this activity, a specially designed indigenously developed graphite crucible with 1 mm opening was used to minimize material loss and to improve the deposition efficiency of the material. To get the desired thickness of the target, only 20 mg of isotopically enriched 128Te material was used. The quality check of the prepared foil was done by the Energy Dispersive X-ray fluorescence (EDXRF) technique.

Seasonal Variation, Pollution Indices and Trajectory Modeling of Bio-monitored Airborne Particulate Around Two Smelting Factories in Osun State, Nigeria

This study determined the seasonal variation of the elemental contents of airborne particulates in the exposed lichen and moss samples, estimated the pollution status and established the air mass trajectories of the airborne particulates around two smelting factories in Osun State, Nigeria. The exposed lichen and moss samples were analyzed for elemental contents, employing X-ray fluorescence (XRF) technique. The pollution status was estimated using various indices: pollution load factor (PLF), degree of pollution load factor (DPLF), pollution load index (PLI) and relative accumulation factor, and the trajectories of pollutants were modeled using hybrid single-particle lagrangian integrated trajectory (HYSPLIT 4.0). The average concentrations of Ca and Fe were above 1000 μgg−1 showing their affinity and natural abundance in moss and lichen bio-monitors. Elements such as V, Cr, Co Ni Sr and Rb were below 100 μgg−1 in both seasons for the two sites. The elemental concentrations of moss and lichen samples, for most of the elements, were similar in trend for both sites due to similar production processes. The PLF values of Sc, Cr and Cu, Zn, Ni and Mn and Fe, Rb and Se were > 6, 3 ≤ PLF < 6 and 1 ≤ PLF < 3 for lichen and moss in both seasons and sites. The dry and wet seasonal values of the degree of pollution load factors (DPLF) are 112 and 122 for lichen and 89 and 104 for moss in Ile-Ife site; while, respectively, observed to be 90 and 113 and 93 and 97 for Ikirun site. These values showed very high degree of contamination conditions. The PLI for all the sites and seasons was above 3, indicating a progressive deterioration of the ambient air conditions of the study areas. The RAF values of Sc, Cr, Mn, Co, Ni and Cu were greater than unity, signifying accumulation property and preferential absorption from the deposited airborne particulates on the exposed lichen and moss. The backward trajectories showed arrival of air masses transport from the southwest direction, while forward trajectories showed air masses transport in northeast directions. The trajectory analysis indicates that pollutants contribution were from nearby sources with all season dispersion mostly in the southwestern parts of the smelting factories.