Wavelength Dispersive X-ray Fluorescence Spectrometry Research Articles

Evaluation of Physico-Chemical Characteristics of Cement Superplasticizer Based on Polymelamine Sulphonate.

Cementitious materials are used to construct an engineered barrier in repositories for radioactive waste. The cement matrix may contain a variety of organic compounds, some of which are polymeric admixtures used as plasticizers. Superplasticizers (SPs) are highly effective organic cement additives for reducing water amount, increasing workability, homogeneity, plasticity and the non-segregation of mortars and grouts, improving mechanical properties and resistance to destructive environments. SPs in cement could have an impact on the long-term safety of the disposals of radioactive waste. These organic agents can leach from the cementitious matrix into groundwater and may affect the migration behaviour of radionuclides. The detailed chemical composition and other characteristics of the cement (CEM I 42.5 R, Sweden) used for the leaching experiments were evaluated. It contained mainly CaO (52.51 ± 1.37, %), and the surface area of the cement particles was 13.2 ± 1.3 m2/g. An insignificant increase in pH (from 12.6 ± 0.1 to 12.8 ± 0.1) was observed for the leachates over 10 days. A commercially available cement superplasticizer based on polymelamine sulphonate (PMS) Peramin SMF10 (Peramin AB, Sweden) was chosen for the research. The product's chemical composition was analysed using wavelength-dispersive X-ray fluorescence (WD-XRF) spectroscopy, while other physico-chemical properties of the PMS superplasticizer were assessed by Raman spectroscopy and thermo-gravimetric analysis. In aqueous solutions and powders of PMS, the same most intensive features were observed at 774 cm-1 (ring out-of-plane deformation), 977 cm-1 (C-N-C bending, SO stretching) and 1055 cm-1 (C-N=C bending) in the Raman spectra. At up to 270 °C, the polymer was thermally stable. Raman and UV/Vis spectroscopies were used to assess the rate of the alkaline degradation of PMS superplasticizer in different aqueous solutions. No changes were observed in the hydrolytic solutions with any of the above analytical methods over a period of 3 years. The results obtained revealed a good thermal and chemical stability (in highly alkaline media, pH = 9.9-12.9) of the PMS polymer.

A new approach for sample preparation to determine the multi-element composition of cobalt-rich crust samples by wavelength dispersive X-ray fluorescence spectrometry

A new approach for sample preparation to determine the multi-element composition of cobalt-rich crust samples by wavelength dispersive X-ray fluorescence spectrometry

A review of laboratory, commercially available, and facility based wavelength dispersive X-ray fluorescence spectrometers

Wavelength dispersive X-ray fluorescence (WD-XRF) spectroscopy is a widely used instrumental spectroscopy method for a variety of samples.

Elemental analysis and quantification method development & validation of stigmasterol in Malaxis acuminata-A vanishing orchid

Orchids are highly valued for their therapeutic properties. Malaxis acuminata (vernacular name: Jeevak), is a vanishing orchid that has mystical healing potential. Wavelength dispersive X-ray fluorescence (WD-XRF) spectroscopy was employed to conduct elemental analysis of this orchid plant. Elements Potassium (K), Calcium (Ca), Phosphorus (P), Magnesium (Mg), Silicon (Si), Sulphur (S), Chlorine (Cl), Aluminium (Al), Iron (Fe), Ruthenium (Ru), Manganese (Mn), Zinc (Zn), Rubidium (Rb), Titanium (Ti), Copper (Cu), Strontium (Sr), and Nickel (Ni) are documented quantitatively and qualitatively. These elements are pivotal in shaping the plant's medicinal potential. Likewise, a multitude of organic molecules within the plant exhibit therapeutic potential. Stigmasterol is one such molecule, esteemed for its remarkable properties and a spectrum of health benefits. The present investigation additionally encompassed the establishment and validation of a methodology for the precise quantification of stigmasterol within the petroleum ether extract, utilizing high-performance thin-layer chromatography (HPTLC). The bioactive compound was isolated through the utilization of a specific mobile phase of toluene: ethyl acetate: methanol (8:1.5:0.5, v/v/v), and an optimal wavelength of 580 nanometers was ascertained. Validation of this method was conducted by the guidelines established by the International Council for Harmonisation (ICH). The calibration range for the stigmasterol was established to span from 400 to 3600 micrograms per spot (μg/spot). The Rf (retention factor) value for the separation of stigmasterol was determined to be 0.56 ± 0.04. The limit of detection (LOD) and limit of quantification (LOQ) were established at 15.954 nanograms per spot (ng/spot) and 48.344 ng/spot, respectively. Linearity (r2 0.999), accuracy (98.14– 99.21 %), and RSD of precision (1.953–2.984). specificity and robustness were evaluated by ICH guidelines. The stigmasterol content was 634.6 ± 3.28 μg/ml, which demonstrates promising results. This method exhibits substantial applicability in pharmaceuticals, nutraceuticals, food, and health-related sectors.

X-ray Fluorescence Analysis of Waste Sm-Co Magnets: A Rational Approach

Determination of the chemical composition of waste Sm-Co magnets is required for their efficient recycling. The non-stereotypical composition of said magnets makes an analysis extremely challenging. X-ray fluorescence spectrometry is a promising analytical tool for this task. It offers high accuracy and simplicity of sample preparation as it does not require sample dissolution. However, a serious limitation of X-ray fluorescence analysis is the spectral interference of matrix elements and impurities. In this work, a two-stage technique has been developed for the determination of the main components (Sm, Co) and impurities (Fe, Cu, Zr, Hf, Ti, Ni, Mn, Cr) in samples of spent samarium–cobalt magnets using wavelength dispersive X-ray fluorescence spectrometry. In order to overcome the main limitation of the chosen method and to maximize its capabilities of qualitative and quantitative analysis, we propose an approach to the selection of analytical lines and experimental conditions, as well as a preparation method for the calibration standards. The obtained results have been shown to have a good correlation with ICP-OES. The limits of detection are in the range of 0.001–0.02 wt%, and the limits of quantification are 0.003–0.08 wt%.

In vitro techniques for evaluating smear layer removal by root canal irrigants: a literature review.

Introduction: The purpose of this review is to address the most commonly used techniques for evaluating smear layer removal ability or chelating capacity of root canal irrigants, including Energy Dispersive X-Ray Spectroscopy (EDS or EDX), Atomic Absorption Flame Spectrometry (AASF), wavelength dispersive X-ray fluorescence spectrometry (WDXRF), inductive coupled plasma emission spectroscopy (ICP-AES), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR).
 Methods: An electronic literature search was conducted in the Pub Med / MEDLINE database of indexed journals from 1992 to 2020. The search terms included chelating, chelation, calcium chelation, smear layer, smear layer removal, and demineralizing effect. 
 Results: All the techniques were classified in terms of their results, both quantitatively and qualitatively. Even though smear layer removal and chelating capacity are not the same parameters, most of the studies included both techniques to correlate their results. SEM is the most commonly used technique for evaluating smear layer removal using various root canal irrigants. Ethylenediaminetetraacetic acid (EDTA) (17%) was the most widely studied root canal irrigant. 
 Conclusion: Different techniques can be used to evaluate smear layer removal and chelating capacity of root canal irrigants. All of these methods have their corresponding advantages and disadvantages. This study aimed to provide researchers with a background for the selection of technique(s) to study the irrigant´s capacity for calcium chelation, which is applicable to smear layer removal

GEMAS: Chemical weathering of silicate parent materials revealed by agricultural soil of Europe

The chemical composition of soil represents to a large extent the primary mineralogy and geochemistry of the source bedrock, the effects of pre- and post-depositional weathering and element mobility, either by leaching or mineral sorting with the addition of secondary products such as clays. Agricultural soil in Europe (0–20 cm, 33 countries, 5.6 million km2) was sampled during the continental-scale soil mapping project (GEochemical Mapping of Agricultural and grazing land Soil - GEMAS). Total element concentrations were determined by wavelength dispersive X-ray fluorescence spectrometry. Bulk content of major elements (SiO2, TiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, P2O5) in soil has been used to calculate weathering indices such as chemical index of alteration (CIA), reductive and oxidative mafic indices of alteration (MIA), the change in mass balance (τ calculation relative to immobile Nb) for soil derived from silicate bedrocks (granite, gneiss and schist) at the European continental-scale, which are useful tools for evaluating chemical weathering trends.The greatest variation of CIA values is exhibited by soil derived from granite, followed by soil derived from schist. The CIA results show clearly that Ca and Na are removed from agricultural soil (0–20 cm) during soil development. Geographical distribution of weathering indices shows that weak chemical weathering of agricultural soil samples, sourced from gneissic and granitic bedrock, occurs in the Fennoscandian Shield; intermediate chemical weathering in granite, schist and gneiss occurring in the Iberian Peninsula and France, and intense chemical weathering in schist sourced agricultural soil occurring in areas with intense rainfall and moderate temperature (Wales, England, Ireland and western Iberia). In addition, values of CIA and MIA, higher than those for standard rock compositions, suggest more active enrichment/depletion processes during soil formation and subsequent soil weathering/maturation.The range of the elemental mass transfer coefficient τ is wide for agricultural soil derived from gneiss and granite, and narrow for agricultural soil sourced from schist parent rocks. The weathering behaviour of chemical elements, assessed by using the τ mass transport model, suggests an order of susceptibility of K ≈ Na > Al > Fe > Ca > Mg > Ti.Weathering indices and gain-loss mass transfer coefficients, tested on agricultural soil samples, provide an insight to the weathering processes affecting the silicate parent rocks and their impact on soil development at the European scale. This can have further implications for evaluation of soil nutritional conditions and mitigating of soil erosion and deprivation.

Major element analysis of geological samples with wavelength Dispersive X-ray Fluorescence (WDXRF) spectrometry using glass disks and pressed powder pellets

Major element analysis of geological samples with wavelength Dispersive X-ray Fluorescence (WDXRF) spectrometry using glass disks and pressed powder pellets

Non-destructive techniques for the determination of magnetic particle and element contents in grapevine leaves and soil as an eco-sustainable tool for environmental pollution assessment in the agricultural areas.

The concentration of magnetic particulate matter (PM) on the leaf surface (an indicator of current pollution) and topsoil (an indicator of magnetic PMs which have geogenic natural signal or historical pollution origin) was assessed in agricultural areas (conventional and organic vineyards). The main aim of this study was to explore whether magnetic parameters such as saturation isothermal remanent magnetization (SIRM) and mass-specific magnetic susceptibility (χ) can be a proxy for magnetic particulate matter (PM) pollution and associated potentially toxic elements (PTEs) in agricultural areas. Besides, wavelength dispersive X-ray fluorescence spectroscopy (WD-XRF) was investigated as a screening method for total PTE content in soil and leaf samples. Both magnetic parameters (SIRM and χ) pinpoint soil pollution, while SIRM was more suitable for evaluating magnetic PM accumulated on leaves. The values of both magnetic parameters were significantly (p < 0.01) correlated within the same type of sample (soil-soil or leaf-leaf), but not between different matrixes (soil-leaf). Differences between magnetic particles' grain sizes among vegetation seasons in vineyards were obtained by observing the SIRM/χ ratio. WD-XRF was revealed to be an appropriate screening method for soil and leaf total element contents in agricultural ambient. For a more precise application of WD-XRF leaf measurements, specific calibration using a similar matrix to plant material is required. In parallel, measurements of SIRM, χ, and element content (by WD-XRF) can be recommended as user-friendly, fast, and eco-sustainable techniques for determining magnetic PM and PTE pollution hotspots in agricultural ambient.

Mining waste acting as a precursor of environmental stress in sediments

Abstract Waste generated by mineral extraction is globally associated with environmental disturbances due to its deleterious effect on water resources. However, research focused on the influence of mine tailings resulting from the extraction of semi-precious stones on fluvial systems is still incipient in the environmental literature. From this perspective, this study quantified the average concentrations of major oxides present in the fine fractions of the sediment samples from the Várzea river, in the State of Rio Grande do Sul, southern Brazil, using wavelength dispersive X-ray fluorescence spectrometry. This region is acknowledged as the largest rock amethyst mining area in the world. Additionally, geochemical indices were established to characterize potential sources of production, maturity, degree of weathering, and sediment pollution. To evaluate the influence of mine tailings on the Várzea river sediments, the contents of Al2O3, Fe2O3, MnO, P2O5, CaO, SiO2, K2O, CuO, ZnO, and TiO2 major oxides present in sediment samples were determined and compared to the local background values; the values varied significantly (p &lt; 0.05), classifying them as polluted and medium polluted. Also, the sediment samples with evident characteristics of extreme chemical weathering consist mainly of clay minerals and mafic igneous rocks, and similarities were found between sediment samples and tailings from the mineral extraction zone. The Principal Component Analysis and the cluster analysis also suggest the existence of three distinct mineral oxide groups, differentiating the zones leaving and upstream the mining zone from the other sampling points.

Evaluation of 20 Elements in Soils and Sediments by ED-XRF of Monochromatic Excitation

There is an urgent need for the accurate analysis of heavy metal contamination in the field of ecology and environmental sciences, especially in the case of trace heavy metals, such as cadmium. Using doubly curved crystals (DCC) to achieve the monochromatic X-ray excitation of the sample to be measured and a silicon drift detector (SDD) to collect the fluorescence of the sample elements, combined with an algorithm analysis of the fundamental parameters (FP), the monochromatic energy-dispersive X-ray fluorescence (MED-XRF) system significantly improved the detection limits of the target elements. The detection limits, precision, and accuracy of the MED-XRF acquisition for 20 elements, including cadmium, lead, and arsenic, were evaluated and compared with the Determination of Inorganic Elements in Soil and Sediment Wavelength-Dispersive X-ray Fluorescence Spectrometry report and tested on the actual samples. The test results showed that the detection limit of the inorganic elements in soil and sediment determined by MED-XRF was mostly better than the industry standard, especially the detection limit of Cd, which was 0.04 mg/kg. The accuracy and correctness fully met the requirements for daily laboratory testing and, as a quality control tool, the actual sample testing and laboratory ICP-MS results were consistent. The research conducted in this project constituted a useful attempt to expand and improve the analytical methods for inorganic elements in soil and sediment, showing that MED-XRF is superior to conventional ED-XRF and WD-XRF and is the current new method of analysis for a low content of Cd in soil. MED-XRF offers a very important contribution to research on soil census, conservation, the rational use of agricultural land, and soil restoration and improvement, and provides strong support for field testing.

Application and Validation of Analytical Software (SQX) for Semi-Quantitative Determination of the Main Chemical Composition of Solid, Bulk and Powder Fuel Samples by Wavelength Dispersive X-ray Fluorescence Technique

Determination of the content of chemical elements occurring in waste in large, small and trace amounts was performed using two instrumental analysis techniques: ICP-OES—Inductively Coupled Plasma Optical Emission Spectrometry and WDXRF—Wavelength Dispersive X-ray Fluorescence Spectrometry. Since such analyses are expensive and time-consuming, the objective of the work presented in this paper was the development of a quick and inexpensive method for preliminary, scanning-based identification of the chemical composition of tested samples (solid, bulk or powder) using standardless, semi-quantitative analysis. An optimized method of preparing samples for X-ray measurements by pressing into a durable tablet, universal for all materials tested, was developed. Moreover, limits of quantification were determined, and the uncertainty of the results obtained was estimated by comparing them with the results acquired with the use of the accredited calibration method, employing standards and certified reference materials.

Optimization of Parameters of the New Turner-Fairbank Alkali-Silica Reactivity Susceptibility Test (T-Fast)

Abstract Prevention is an effective strategy to avoid damage caused by the alkali-silica reaction (ASR) in concrete structures. The effectiveness of this strategy heavily depends on the use of reliable accelerated tests to determine if an aggregate used in the concrete has the potential to cause ASR. Recently, a new provisional standard test, AASHTO TP 144-21, Determining the Potential Alkali–Silica Reactivity of Coarse Aggregates (TFHRC-TFAST), has been approved by the American Association of State Highway and Transportation Officials. The test accurately predicted the ASR-induced expansion of aggregates used in more than 50 different mortar and concrete samples, including concrete blocks in outdoor testing facilities and concrete in the field. This manuscript presents the results of the collaborative study among three laboratories conducted as part of an overall effort to standardize the new AASHTO TP 144-21. The objectives of the study were to evaluate the suitability of wavelength dispersive x-ray fluorescence (WDXRF) spectroscopy as the main analytical technique, determine the optimal particle size and effect of moisture on calcium oxide (CaO), and evaluate sample preparation on the results. A total of 18 aggregates were evaluated under the TP 144-21 using 4 different CaO samples and 2 sample preparation protocols. The results indicated that the alkali-silica reactivity of the aggregates can be accurately determined by using WDXRF. Upon exposure to the atmosphere, CaO reacts rapidly with moisture to produce calcium hydroxide [Ca(OH)2]. The particle size distribution and amount of Ca(OH)2 in the CaO influenced the ASR classification of marginal (moderately and slow reactive) and nonreactive aggregates. The researchers obtained optimal results using a reagent grade powder CaO with an average particle size of 4.6 μm and less than 5 % of Ca(OH)2. These conclusions were important to validate and optimize the TP 144-21 protocol before launching a wider interlaboratory study.

Determination of trace metals by ICP-OES in petroleum cokes using a novel microwave assisted digestion method

Trace metals must be strictly controlled in petroleum coke when it is used as anode, as the function of electrodes depends on their concentration, being detrimental in process operations affecting the purity of the final product.In this research, the determination of Si, Fe, V, Ni, Ca, Na, P, Al, Ti, Mg, K, Zn, Mo, Ba, and Co at trace level in green and calcined petroleum cokes using a new digestion method was performed. The method involved microwave-assisted digestion of the sample using a single-reaction chamber (SRC) followed by ICP-OES measurement. This method aimed for a low sample preparation time and a quantitative extraction of the analytes.After optimization of the digestion process it was found that the best condition to digest green and calcined cokes was mixing 9 g HNO3 and 3 g HCl, heating at a temperature of 260 °C for 55 min, and taking 0.5 g of sample, leading to a recovery higher than 98% for all the elements analyzed. In addition, the developed method allowed the determination of the elements in 1.5 h versus the standard method, which takes about 8 h. The validation of the developed methodology was carried out analyzing certified reference materials and using independent methods, such as, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF).The developed methodology is faster, more accurate and more environmentally friendly than other available methodologies as it does not require the decomposition process involving high temperatures and waste generation is minimized. In addition, low limits of quantification and low uncertainties have been reached enabling this method to be used as a control method.

Tin and Bronze Production at the Outeiro de Baltar Hillfort (NW Iberia)

Findings of Iron Age metallurgical activities related to tin metal and mining are very rare. In the present work, we present a detailed study of the Outeiro de Baltar hillfort, dated to the Late Iron Age/Early Roman period, located in a place where 20th century tin mining work took place. Elemental and microstructural analysis by portable, micro and wavelength dispersive X-ray fluorescence spectrometry (pXRF, micro-XRF and WDXRF) and scanning electron microscopy with energy dispersion spectrometer (SEM-EDS) showed that metallurgical debris found at the archaeological site is related to tin smelting and binary and ternary bronze productions. Analysis of the artefacts of diverse typologies found at the site showed that a variety of metals and alloys were in circulation and use. Samples of tin ores (cassiterite) from the region were analyzed for comparison with an archaeological tin slag from the site. The analytical results point to the production of tin metal using local cassiterite and the production of bronze by directly adding cassiterite into a smelting process. Furthermore, data of remote sensing (airborne Light Detection and Ranging (LiDAR) and historical aerial imagery) and Geographical Information System (GIS) mapping were combined with archival mining documentation and maps to retrieve a landscape context for the site. The study showed that the place of the Outeiro de Baltar hillfort (NW Iberia) was mined periodically over time.

Monochromatic wavelength dispersive X-Ray fluorescence as a tool for monitoring the source of chlorine in the formation of monochloropropane-diol esters during vegetable oil refining

This study presents the applicability of monochromatic wavelength dispersive X-ray fluorescence spectrometry (MWD-XRF) to quantify low range of concentrations, from 0.2 to 10 mg/kg of total chlorine in vegetable oils and bleaching clays effluents. The combination of total chlorine analysis by MWD-XRF and monochloropropanediol fatty acid esters (MCPDE) analysis by LC-MS of vegetable oils at different steps of the refining process allows to identify clays and technical aids used for bleaching as entry points of chlorine, potentially resulting in MCPDE formation during heat treatment of vegetable oils. Efficient washing of clays and technical aids monitored by chlorine measurement in successive effluents by MWD-XRF demonstrates the impact of washing by keeping total 3- MCPD content at low level in bleached vegetable oil. Further investigation on pH of the bleaching clays effluents shows that acidity is a key parameter during the formation of MCPD. • MWD-XRF allows chlorine quantification in vegetable oils. • Chlorine entry points in refining process are identifiable using combined analyses. • Chlorine content and pH of clays effluents are critical for MCPDE formation. • Chlorine monitoring by MWD-XRF can contribute to MCPDE mitigation in refined oil.

TRACING INTERACTION ON SAMOS ISLAND: POTTERY TRADITIONS AND CONNECTIVITY AT KASTRO-TIGANI AND THE HERAION DURING THE AEGEAN LATE–FINAL NEOLITHIC/WESTERN ANATOLIAN MIDDLE–LATE CHALCOLITHIC

This paper presents the results from the pilot analytical study of the Aegean Late–Final Neolithic/Anatolian Middle–Late Chalcolithic (c. 5500–3200/3000 BC) pottery from the Kastro-Tigani settlement, located in south-east Samos (east Aegean). In addition to Crete, the region of the insular eastern Aegean has produced the earliest evidence for Neolithic habitation. The archaeological traces at Kastro-Tigani are so far the earliest known on Samos, being partly contemporary with the recently discovered Middle–Late Chalcolithic layers at the Heraion, lying in close proximity to the former site, and at the Agriomernos cave (Megalo Seitani) in the north-west part of the island. The re-evaluation of the ceramic assemblage from Kastro-Tigani has led to the laboratory analysis of 34 samples, using a combination of thin-section petrography and Wavelength Dispersive X-Ray Fluorescence Spectroscopy, in order to determine provenance and establish reference groups for the earliest local production on Samos. This first compositional characterisation of the pottery contributes new data in a relatively under-studied region and provides grounds for comparison with analytical results from the Heraion, with the aim to investigate possible relations between the sites. Hence, the identification of different strategies in pottery production, reflected in the overall distinct fabric and chemical groups, further indicates the practice of several production units and the exploitation of various raw material sources at the Pythagoreion/Chora plain. Isolated examples of possible imported ceramic vessels, as well as exotica (e.g. obsidian, acrolithic and Kilia figurines, ring-shaped features, marble vessels,kratiriskoi) are highlighted as markers of macro-scale interaction in the context of Aegean early maritime connectivity.

Simple Preparation of Photoluminescent and Color-Tunable Polyester Resin Blended with Alkaline-Earth-Activated Aluminate Nanoparticles.

A simple inorganic/organic nanocomposite was used to generate long-lasting phosphorescent pebbles for easy commercial manufacturing of smart products. An organic/inorganic nanocomposite was made from low-molecular-weight unsaturated polyester and rare-earth-activated strontium aluminum oxide nanoparticles doped with europium and dysprosium. The polyester resin was mixed with phosphorescent strontium aluminate oxide nanoparticles and methylethyl ketone peroxide as a cross-linking agent to create a viscous mixture that can be hardened in a few minutes at room temperature. Before adding the hardener catalyst, the phosphorescent strontium aluminate nanoparticles were dispersed throughout the polyester resin in a homogeneous manner to ensure that the pigment did not accumulate. Long-lasting, reversible luminescence was shown by the photoluminescent substrates. The emission was reported at 515 nm upon exciting the pebble at 365 nm. In normal visible light, both blank and luminescent pebbles had a translucent appearance. As a result of UV irradiation, the photoluminescent pebbles produced an intense green color. The three-dimensional CIE Lab (International Commission on Illumination) color coordinates and luminescence spectra were used to investigate the color changing characteristics. Photophysical characteristics, including excitation, emission, and lifetime, were also investigated. Scanning electron microscopy, wavelength-dispersive X-ray fluorescence spectroscopy, and energy-dispersive X-ray analysis were employed to report the surface morphologies and elemental content. Without impairing the pebbles’ original physico-mechanical characteristics, the pebbles showed improved superhydrophobic activity. The current simple colorless long-lasting phosphorescent nanocomposite can be applied to a variety of surfaces, like ceramics, glassware, tiles, and metals.

X-Ray Fluorescence Analysis as a Tool of Monitoring Soil Pollution Around The Central Geological Laboratory

Heavy metal contamination of soil is a major concern from an ecological point of view. This study aims to characterize soil samples from different sites in the Central Geological Laboratory (CGL)’s area and to study heavy metal contamination in the environment. In this work Wavelength dispersive X-ray fluorescence spectrometry has been used to evaluate the heavy metals and some toxic elements pollution in the CGL area.

Mineralogical and Geochemical Characterization of the Sta. Cruz Nickel Laterite Deposit, Zambales, Philippines

In this study, we present mineralogical and geochemical characterization of samples systematically collected from a nickel laterite profile at the Sta. Cruz nickel laterite deposit, Zambales, Philippines. Wavelength-dispersive X-ray fluorescence spectroscopy (WDSXRF), mass-balance element mobility calculations, transmitted and reflected light microscopy, and previously reported results from coupled X-ray diffraction (XRD) and Rietveld refinement analyses reveal that the laterite profile investigated is composed of two main horizons—the limonite and saprolite zones—separated by a thin transitional zone. Based primarily on the mineral assemblage and major element chemistry, the main zones are further subdivided into subzones: upper limonite, lower limonite, transitional zone, upper saprolite, and lower saprolite. Garnierite veins were observed cutting the upper and lower saprolite subzones. Investigation of the structure of goethite within the limonite zone via Rietveld refinement shows that the crystallinity of goethite decreases with increasing Ni content and increasing crystallite size. This suggests that upwards through the limonite zone, as goethite ages, its crystallinity increases, which possibly results in the removal of Ni from its crystal structure and eventual remobilization to the lower laterite zones.