Range Of Element Concentrations Research Articles

Combinatorial Study of Phase Composition, Microstructure and Mechanical Behavior of Co-Cr-Fe-Ni Nanocrystalline Film Processed by Multiple-Beam-Sputtering Physical Vapor Deposition.

A combinatorial Co-Cr-Fe-Ni compositional complex alloy (CCA) thin film disk with a thickness of 1 µm and a diameter of 10 cm was processed by multiple-beam-sputtering physical vapor deposition (PVD) using four pure metal sources. The chemical composition of the four constituent elements varied between 4 and 64 at.% in the film, depending on the distance from the four PVD sources. The crystal structure, the crystallite size, the density of lattice defects (e.g., dislocations and twin faults) and the crystallographic texture were studied as a function of the chemical composition. It was found that in a wide range of elemental concentrations a face-centered cubic (fcc) structure with {111} crystallographic texture formed during PVD. Considering the equilibrium phase diagrams, it can be concluded that mostly the phase composition of the PVD layer is far from the equilibrium. Body-centered cubic (bcc) and hexagonal-close packed (hcp) structures formed only in the parts of the film close to Co-Fe and Co-Cr sources, respectively. A nanocrystalline microstructure with the grain size of 10–20 nm was developed in the whole layer, irrespective of the chemical composition. Transmission electron microscopy indicated a columnar growth of the film during PVD. The density of as-grown dislocations and twin faults was very high, as obtained by synchrotron X-ray diffraction peak profile analysis. The nanohardness and the elastic modulus were determined by indentation for the different chemical compositions on the combinatorial PVD film. This study is the continuation of a former research published recently in Nagy et al., Materials 14 (2021) 3357. In the previous work, only the fcc part of the sample was investigated. In the present paper, the study was extended to the bcc, hcp and multiphase regions.

Microstructure, Hardness, and Elastic Modulus of a Multibeam-Sputtered Nanocrystalline Co-Cr-Fe-Ni Compositional Complex Alloy Film

A nanocrystalline Co-Cr-Ni-Fe compositional complex alloy (CCA) film with a thickness of about 1 micron was produced by a multiple-beam-sputtering physical vapor deposition (PVD) technique. The main advantage of this novel method is that it does not require alloy targets, but rather uses commercially pure metal sources. Another benefit of the application of this technique is that it produces compositional gradient samples on a disk surface with a wide range of elemental concentrations, enabling combinatorial analysis of CCA films. In this study, the variation of the phase composition, the microstructure (crystallite size and defect density), and the mechanical performance (hardness and elastic modulus) as a function of the chemical composition was studied in a combinatorial Co-Cr-Ni-Fe thin film sample that was produced on a surface of a disk with a diameter of about 10 cm. The spatial variation of the crystallite size and the density of lattice defects (e.g., dislocations and twin faults) were investigated by X-ray diffraction line profile analysis performed on the patterns taken by synchrotron radiation. The hardness and the elastic modulus were measured by the nanoindentation technique. It was found that a single-phase face-centered cubic (fcc) structure was formed for a wide range of chemical compositions. The microstructure was nanocrystalline with a crystallite size of 10–27 nm and contained a high lattice defect density. The hardness and the elastic modulus values measured for very different compositions were in the ranges of 8.4–11.8 and 182–239 GPa, respectively.

Expansion of the Element Content Range through the Use of Self-Absorption Lines

As a rule, the width of a spectral line in atomic emission spectral analysis with arc sources is much smaller than the hardware function of the spectral device. Thus, the spectral line contour is determined by the hardware function of the device and can be approximated, e.g., by the Voigt function. However, when reference samples with a wide range of element concentrations are analyzed, there is a frequent problem of self-absorption that causes one to change the analytical line, which is not always possible. It is proposed to modify the Voigt function by adding a factor that describes self-absorption, by analogy with the Bouguer–Lambert law. The possibility of using the proposed function is evaluated during the analysis of reference samples of rocks, ores, and sandstones in a Grand-Potok spectral system with a MAES analyzer and BLPP-2000 photodetector arrays. The use of the proposed approximating function has provided an increase in the working range of the calibration curves of Cu 327.3954 nm, Cu 324.7532 nm, Pb 287.3311 nm, Ni 305.0818 nm, and Mo 313.2594 nm by 1–3 orders of magnitude.

Trace element distribution in human cortical bone microstructure: the potential for unravelling diet and social status in archaeological bones

Variation in the trace element chemistry of cortical bone microstructure is delineated for interred and non-interred human femora. This was done to investigate the range of element concentrations that might occur within single bones, specifically the original laminar bone and later osteons, and its potential for investigating chemical life histories. To do so, femora were chosen from individuals who experienced quite different ways of life over the past two millennia. The distributions of Sr, Ba, Cu, and Pb, mostly in partial (early) and complete (late) osteons, in cross-sections of proximal femora were characterized through Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Absolute calibrations of these data were obtained using solution Inductively Coupled Plasma Mass Spectrometry on adjacent dissolved bulk samples. Chemical life histories were approximated by classifying bone microstructure into four categories: laminar bone and 1st, 2nd, and 3rd generation osteons. This four-part sequence, on average, charts the temporal dimension of an individual’s life. Consistent with recent studies of medieval bones, Sr and Ba are thought to be mainly responsive to diet, presumably related to the consumption of mostly locally produced food, while Cu and Pb do the same for heavy metal exposure often attributable to social status or occupation. No systematic differences in these elements were found between interred and non-interred individuals. The effect of diagenesis on interpretations of life histories based on archaeological bone, therefore, are minimized by plotting element concentrations across cortical bone cross-sections.

A Microscale Analysis of Hydrothermal Epidote: Implications for the Use of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Mineral Chemistry in Complex Alteration Environments

Abstract High-resolution, quantitative imaging of epidote from the Ann Mason fault block, Yerington district, Nevada, using scanning electron microscopy (SEM), X-ray fluorescence (XRF), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has revealed at least two types of epidote (type 1 and type 2), each with different major and trace element chemistry. Type 1 epidote is coarser grained, typically greater than 50 μm in diameter, and forms euhedral crystals that display twins and sector zones enriched in Fe, Sr, and Mn. Type 2 epidote is finer grained, typically less than 30 μm in diameter, irregularly zoned with respect to Fe and Al, and forms polycrystalline aggregates that include void space. Two sources of intragranular compositional variability are defined in this study—one related to different generations of epidote only visible on the microscale, and the other related to crystallographic features such as sector zones and twins. Intragranular compositional variations within Yerington epidotes highlight the potential importance of detailed sample characterization in complex alteration environments prior to undertaking mineral chemistry studies in the context of resource exploration. Based on statistical analysis of LA-ICP-MS spot data from one sample, the optimal number of spot analyses to adequately represent the range in element concentrations within zoned or twinned crystals is determined to be at least 40.

Processing and characterization of a multibeam sputtered nanocrystalline CoCrFeNi high-entropy alloy film

Physical vapor deposition (PVD) is a well-known route for manufacturing hard coatings. In recent years, PVD has also been applied to create high-entropy alloy (HEA) thin films. HEAs are multicomponent alloys with nearly equal atomic fractions. To achieve the desired composition, typically alloy targets are used in the deposition process. The present work demonstrates that HEA thin films can also be processed using a multiple beam sputtering system in PVD, which does not require preliminary manufacturing of HEA targets, but rather uses commercially pure metal targets. The effectivity of this technique was demonstrated on a nanocrystalline CoCrNiFe HEA film with a thickness of about 1 μm. A part of the compositional gradient sample exhibited equal elemental fractions. The microstructure and the hardness of this part of the PVD film were studied in detail, and the results were compared with those obtained on a bulk nanocrystalline sample having the same chemical composition, but was prepared by the high pressure torsion (HPT) technique. The crystallite size and the texture were characterized by X-ray diffraction, while the hardness was measured by nanoindentation. The PVD film exhibited an exceptionally high hardness of 9.8 ± 0.3 GPa, a value that was notably higher than that determined for the HPT sample (7.3 ± 0.3 GPa). This study also demonstrated the capability of this new multiple beam sputtering technique for the production of compositional gradient samples with a wide range of elemental concentrations, enabling combinatorial analysis of multiple elements high-entropy alloy.

Expansion of the analyte concentration range using self-absorption lines

The width of a spectral line in atomic emission spectral analysis with arc radiation sources is, as a rule, much smaller than the hardware function of the spectral device. Thus, the spectral line shape is determined by the hardware function of the spectral device and can be approximated, for example, by the Voigt function. However, when analyzing standard samples with a wide range of element concentrations, the problem of self-absorption often occurs, due to which the analytical line has to be changed, which is not always possible. We propose to modify the Voigt function by adding a factor that describes self-absorption, by analogy with the Bouguer-Lambert law. The possibility of using the proposed function was evaluated in analysis of standard samples of rocks, ores and sandstones on a Grand-Potok spectral system with a MAÉS analyzer and BLPP-2000 linear photodetector arrays. The use of proposed approximating function is shown to provide an increase in the working range of the calibration curves of Cu 327.3954 nm, Cu 324.7532 nm, Pb 287.3311 nm, Ni 305.0818 nm, and Mo 313.2594 nm by 1 – 3 orders of magnitude.

Interface optical phonons and its ternary mixed effects in ZnS/CdxZn1-xS quantum dots

Taking into account cadmium element concentrations, the interface optical (IO) phonons, electron-phonon couplings in ZnS/CdxZn1-xS quantum dots are investigated theoretically within the framework of macroscopical dielectric continuum model (MDCM) and modified random-element isodisplacement model (MREIM). The numerical results indicate that the cadmium element concentrations have important effects on the properties of IO phonons and electron-phonon interactions in a single ZnS/CdxZn1-xS quantum dot. The dependences between IO phonon frequencies and cadmium element concentrations are linearly decreases in high frequency range (HF-range), and are non-linearly decreases in low frequency range (LF-range). The numerical results also suggest that the dependent relations between the absolute value of electron-phonon coupling strengths and cadmium element concentration are linear relationship in high frequency range (HF-range), and are non-linear relationship in low frequency range (LF-range), especially in higher cadmium element concentration range.

Determining the Source of Fugitive Dust in Lattimer, Pennsylvania

Fugitive dust samples collected from residential properties in the village of Lattimer, Pennsylvania were analyzed for total concentrations of major and minor elements Si, Al, Ti, Fe, Mg, Na, K, C, and S using energy dispersive x-ray spectrometry. Observed under high magnification, the individual dust particles are irregular-shaped with angular edges and range in size from 20 to 150 microns. Rock samples of gray to black organic-rich mudstone, shale, and siltstone units interbedded with thin layers of anthracite coal were collected next to a rock quarry operation that is suspected as a possible source of the fugitive dust. Major and minor element concentrations in the rock samples are compared to major and minor element concentrations in 150 individual dust particles. The fugitive dust and rock samples that were analyzed have Si concentrations that vary from 0.08 to 43.34 wt.% and C concentrations that vary from 3.36 to 95.68 wt.%. All of the major and minor element concentrations in the rock samples lie within the representative range of element concentrations in the individual dust particles. The Si and C concentrations in the fugitive dust suggest that the particles originated from a carbon-rich silicate rock source. Five of the fugitive dust particles analyzed had C concentrations in excess of 60 wt.% and can be considered coal dust. Results suggest that the chemical composition of the fugitive dust particles is consistent with the chemical composition of the rocks that are actively extracted and crushed at the rock quarry site located adjacent to the village of Lattimer, Pennsylvania.

Potential Health Risk of Herbal Distillates and Decoctions Consumption in Shiraz, Iran.

Concentration of 26 elements in 16 different herbal distillates and 5 herbal decoctions, were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The elemental content of five raw herbal materials used for making decoctions and seven distilled and boiled residues were also evaluated by inductively coupled plasma optical emission spectrometry (ICP-OES). The results indicated that herbal products display a wide range of elemental concentrations. Compared with world health regulations, the concentrations of the elements in herbal distillates and decoctions did not exceed the recommended limits. The analysis of herbal extracts did not show a significant transfer of toxic elements during decoction preparation. Comparison of elemental content among fresh herbal material and herbal distillate and decoction of the same herb showed that, besides the elemental abundance of herbal organs, the ionic potential of elements also play an important role in elemental content of herbal products. Based on the results of the research, it seems that most health benefits attributed to herbal products (especially herbal distillates) are more related to their organic compounds rather than elemental composition. Calculated hazard quotient (HQ) and hazard index (HI) were used to evaluate the noncarcinogenic health risk from individual and combined metals via daily consumption of 100 ml of herbal distillates and 250 ml of herbal decoctions. Both HQs and HI through consumption of herbal distillates and herbal decoctions (except Valerian) were below 1. Apparently, daily consumption of herbal distillates and decoctions at the indicated doses poses no significant health risk to a normal adult.

The use of FPXRF in the determinations of selected trace elements in historic mining soils in the Holy Cross Mts., south-central Poland

In this study, concentrations of As, Cu, Mn, Pb, and Zn were determined in 231 samples of mine soils and spoils by field portable X-ray fluorescence (FPXRF), and by inductively coupled plasma-mass spectrometry (ICP-MS) as a comparison method. The use of both spectrometric methods allows for comparison of the total and aqua regia -extractable contents of elements. The study areas encompassed three historic metal-ore mining sites and one abandoned mine tailings site in the Holy Cross Mountains, in south-central Poland. Sample collection in these areas, which are characterized by various bedrock mineralogy and lithology and different anthropogenic impacts, enabled us to test the FPXRF performance for a wide range of element concentrations. The results of FPXRF and ICP-MS determinations were found to be significantly correlated with the highest r 2 (coefficient of determination) value of 0.987–0.991 for Pb, irrespective of the soil mineralogy, bedrock lithology or concentration levels of this element. Overall, the FPXRF showed excellent performance in determining selected trace elements in contaminated soils.

Volcanism on the flanks of the East Pacific Rise: Quantitative constraints on mantle heterogeneity and melting processes

We present major and trace element and Sr, Nd and triple-spike Pb isotope data for 17 fresh volcanic glasses from Seamount 6, a 10-km diameter seamount located 140km east of the East Pacific Rise at 12°45′N. Geological and geochronological evidence show that magma compositions evolved from tholeiitic basalts to alkalic basalts and basaltic trachyandesites during the 1–2Ma active lifetime of the seamount. Major and trace element compositions in Seamount 6 lavas vary systematically with isotope ratios; the youngest lavas with the highest incompatible trace element concentrations have the highest La/Yb, Nb/Zr, K2O/TiO2, 87Sr/86Sr, 206Pb/204Pb and the lowest 143Nd/144Nd, MgO and CaO. The range in element concentrations, incompatible element ratios, and isotope compositions in Seamount 6 lavas exceeds that observed in lavas erupted at the adjacent ridge axis, and is comparable to the range in lava compositions reported from all near-ridge seamounts studied to date. The observed range in lava compositions is consistent with mixing between enriched and depleted melts at shallow levels in the crust. The inferred difference in composition between these mixing endmembers cannot be explained by variable degrees of melting of a single source composition, and requires that the upper mantle is extremely heterogeneous on the scale of the melting region beneath a single seamount.We can show that the range in composition of EPR seamount lavas cannot be generated by melting of variably heterogeneous mantle in which enriched and depleted materials contribute equally to melting (source mixing). Instead, the trace element and isotope compositions of seamount lavas can be reproduced by melting models in which more enriched, fertile mantle lithologies are preferentially melted during mantle upwelling. At progressively lower degrees of melting, erupted lavas are thus more enriched in incompatible trace elements, have higher La/Yb, K/Ti, 87Sr/86Sr ratios and lower 143Nd/144Nd. If this is a common process, then mantle-derived magmas are unlikely to inherit the average incompatible trace element and isotope composition of their mantle source, which is likely to be significantly more depleted, nor will they display the full range of compositions present in the mantle melting region. These results have implications for the way in which oceanic basalts can be used to infer the composition of the upper mantle.

Analysis of Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in seawater using the Nobias-chelate PA1 resin and magnetic sector inductively coupled plasma mass spectrometry (ICP-MS)

A method was developed using the chelating resin Nobias-chelate PA1 in an off-line pre-concentration manifold with magnetic sector inductively coupled plasma mass spectrometry (ICP-MS) detection for analysis of Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb. This multi-element method allows for the simultaneous extraction of eight samples in a closed column manifold. Standard additions to seawater demonstrated quantitative recovery and eliminated the need to use isotope dilution to account for non-quantitative recoveries of the metals on the resin. UV-oxidation of seawater samples before extraction was necessary to provide accurate total dissolved concentrations of Co and Cu. Samples (40mL) were loaded onto the chelating resin column at a pH of 6.2±0.3 after pH adjustment with a basic ammonium acetate (NH4Ac) solution. The columns were rinsed after sample loading with a weak (0.05M) NH4Ac solution to remove the bulk of the major ions in seawater. The trace metals were eluted with 3 to 4mL of 1N Q-HNO3 and analyzed on a magnetic sector ICP-MS. This multi-element method is ideal for high sample throughput and quantification over a broad range of element concentrations with low blanks and detection limits. We report results here from the SAFe and GEOTRACES reference samples as well as the U.S. GEOTRACES Atlantic and Pacific Baseline profiles.

EVALUATION OF THE NUTRIENT STATUS OF AMERICAN CRANBERRY IN LATVIA DURING 2001–2007

Being a native wetland plant, cranberry culture requires not much nutrients. However balanced and precise mineral nutrition is essential for producing high yield and quality. Surveys were carried out to determine the actual status and trends in mineral nutrition of American cranberries in Latvia during 2001-2007. Together 160 (peat and plant) samples were collected from different cranberry producing sites in Latvia over two periods: 2001-2004 and 2005-2007. Plant tissue analysis and soil testing were used to evaluate cranberry nutrient status (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Mo and B). The results revealed several problems in the system of plant mineral nutrition. Insufficient levels of N, P, S, Fe, Cu, Mo and high concentrations of Mn were found. In general, our results suggest that only about 50% of plant tissue nutrient indices and 25% of soil tests were in the sufficient range. Positive trends in nutrient status of cranberries were found from 2001-2004 to 2005-2007. Indices in optimal range increased for N, P, S, B, Mo and element concentration range became narrower and closer to tissue standards. The lack of increased nutrient concentrations in peat samples indicated that cranberry fertilization practices in Latvia are likely not detrimental to the environment.

Element determination in environmental samples using Z-GFAAS with variable magnetic field

Electrothermal atomic absorption spectrometry methods with Zeeman effect background correction (Z-GFAAS) for determination of As, Sb, Se, Ag, Cd, Pb, Cu, Fe, Zn, Cr, and Ni in water and sludge samples were developed. The measurements using Z-GFAAS and variable magnetic field at the three-field dynamic mode permit the sensitivity adaptation for higher analytical concentrations. Calibration ranges were expanded over two orders of magnitude within one measurement run by the applying three-field dynamic mode of this correction system. There are presented calibration data, furnace programs, modifiers, and microwave digestion programs of the obviously monitored elements in the environmental samples. Very low detection limits (3σ criterion) were obtained. Quality assurance was checked by the suitable CRM. The study brings simultaneous determination of the samples with different element concentration range and different sample matrixes, as an important application information for an analyst working in the area of the eco-analytical research.

Concentrations of major and trace elements in polished rice and paddy soils collected in Aomori, Japan

Rice grain samples and surface paddy soil samples were collected from 20 sites throughout Aomori Prefecture, Japan, and the concentrations of 25 elements in the polished rice and 33 elements in the soils were determined by neutron activation analysis, inductively coupled plasma-mass spectrometer or atomic adsorption spectrometer. The range of essential element concentrations in the polished rice was within one order of magnitude, however, the range for most of the trace elements was more than one order of magnitude. The range of element concentrations, except for I, in the paddy soils was within one order of magnitude. The ±95% confidence intervals of the soil-to-polished rice transfer factors for all elements, except for Pb, were within two orders of magnitude, and the geometric mean values were as follows: Cl, Mo and Zn (0.1–1); K, Cu, Cd, Rb, Mg, Mn, and Ag (0.01–0.1); Ni, As, Ca, Se and I (0.001–0.01); Na, Cs, Sr, Co, Cr, V, Ba, Pb, Fe and Al (<0.001).

Validation of a field filtration technique for characterization of suspended particulate matter from freshwater. Part II. Minor, trace and ultra trace elements

A field filtration method for the concentration and separation of suspended particulate matter (SPM) from freshwater systems and the subsequent determination of minor, trace and ultra trace elements (As, Ba, Be, Cd, Co, Cr, Cs, Cu, Ga, Hf, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Ta, Th, Tl, U, V, W, Zn and Zr) is validated with respect to detection limits, precision and bias. The validation comprises the whole procedure including filtration, sample digestion and instrumental analysis. The method includes two digestion procedures (microwave acid digestion and alkali fusion) in combination with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Total concentrations of these 27 trace and minor elements have been determined in suspended particulate matter (SPM) from lake and river water with low levels of suspended solids (<2 mg L −1 DW), and a wide range of element concentrations. The precision of the method including filtration, digestion and instrumental determination ranges between 8% and 18% RSD for most elements on a dry weight basis. Higher recovery after acid digestion is found for some elements, probably because of volatilization or retention losses in the fusion procedure. Other elements show higher recovery after fusion, which is explained by more efficient decomposition of refractory mineral phases relative to the non-total acid digestion. Non-detectable concentrations of some elements are reported due to small differences between blank filter levels and the amounts of elements present on the filters after sampling. The method limits of detection range between 0.7 ng and 2.65 μg, as estimated from the blank filter samples. These detection limits are 10–550 times higher compared to the corresponding instrumental limits of detection. The accuracy and bias of the overall analytical procedure was assessed from replicate analysis of certified reference materials. A critical evaluation of the instrumental capabilities of the ICP-QMS instrumentation in comparison with a double focusing sector field plasma mass spectrometry technique (ICP-SFMS) is also included. It was found that a modified microwave acid digestion procedure in combination with ICP-SFMS could replace ICP-AES determinations and fusion digestions for most of the investigated elements. Guidelines and limitations for this time- and labour- efficient procedure, offering accurate results for the majority of elements studied are discussed.

Direct Trace and Ultra-Trace Metals Determination in Crude Oil and Fractions by Inductively Coupled Plasma Mass Spectrometry

Abstract A method was developed to analyze direct trace and ultra-trace metal elements in crude oil and its fractions (maltenes-asphaltenes) by ICP-MS after sample dilution in xylene. Efficient introduction of organic compounds requires addition of O2 for complete combustion of the sample, carbon deposit on cones (interface) and extraction lenses was minimized by optimization of argon to oxygen ratio in the plasma. A PFA-100 (100 μl.mn−1) MicroFlow Nebulizer and a Scott “double pass” chilled spray chamber were associated for an optimal introduction of petroleum products. The Q-ICP/MS was equipped with platinum cones to limit drifts caused by cone corrosion during an organic analysis. A standard addition method was realized for the calibration procedure in order to control the matrix effects. Method validation was completed by analyzing three certified reference materials from the National Institute for Standards and Technology (NIST). NIST 1085b, NIST 1084a, and NIST 1634c accuracies were approximately 10 %. Detection limit of ultra trace elements in xylene were at pg.g−1 level. A clean PFA filter system was developed to separate the oil fractions (maltenes and asphaltenes) by precipitation of asphaltenes (heavy fraction) in n-heptane. For optimal detection conditions, the samples were diluted in xylene according to their pre-estimated element concentration range. Total mass balance shows a recovery close to 100 % for Ni, V, Cu, Mo, Ag, Sn, Ba, and Pb. These results show that elements analyzed are highly concentrated in the asphaltenic fraction.

Calibration analysis of bronze samples by nanosecond laser induced breakdown spectroscopy: A theoretical and experimental approach

A theoretical model for nanosecond laser ablation at 1064 nm of quaternary bronze alloys containing Cu, Sn, Zn and Pb was developed. Starting from a known sample composition, the model provides the element concentrations in the laser produced plasma, and therefore the plasma stoichiometry, here studied for different laser energies on the target. For the considered laser excitation, plasma stoichiometry cannot be achieved in the ablation of bronze materials; however, stable element ratios in the plasma occur for a laser fluence above 600 J/cm 2, corresponding to an irradiance of 75 GW/cm 2. The calculated plasma concentrations were then used to simulate calibration plots in the range of element concentrations corresponding to the standards available. Different kinds of internal standardization were theoretically considered and successively applied to the experimental data obtained. Good agreement between experimental results and model predictions was observed, allowing establishing the optimal method for LIBS calibration of bronze alloys. Further validation of the model was attempted by comparing the predicted element concentrations in the plasma with the experimental results obtained by using the Calibration-Free (CF) approach (Corsi et al., Eur.Phys.J. D13, 2001, 373). The results obtained are in excellent agreement between themselves. However, the estimated element concentrations largely differ from those in samples, and the reasons for the discrepancy are discussed.

Radionuclide applications in laboratory studies of environmental surface reactions*1

The advantages of using radionuclides for laboratory studies of environmental processes include the wide range of element concentrations that can be studied, the capability to simultaneously study several isotopes in a single experiment, the direct applicability to the behaviour of radioactive waste or fallout, and the ability to study the mechanisms, reversibility and kinetics of environmental reactions under controlled conditions. These attributes are demonstrated using specific examples drawn from case studies in Australia, including radionuclide fallout onto tropical soils, the association of trace metals with harbour sediments and the behaviour of uranium in natural and contaminated systems.