Portable X-ray Fluorescence Research Articles

Combined in situ XRF–LIBS analyses as a novel method to determine the provenance of central Mediterranean obsidians

This work presents a new calibration method for determining the provenance of obsidian artefacts based on the combined use of XRF and laser-induced breakdown spectroscopy (LIBS). At first, obsidian samples collected from the main Mediterranean sources were characterized using portable XRF and LIBS systems. After data treatment, elemental information was used to carry out principal component analysis (PCA) for each technique. Rb, Sr, Zr, Y and Fe elements, detected by using XRF, were found to be the key parameters enabling obsidians discrimination. Likewise, LIBS data helped differentiating the analysed patterns by the intensity of their main elemental components (Ca, Al, Mg and K). After selecting the key parameters detected by each technique, a new data matrix combining XRF and LIBS data was finally built. According to PCA results, the discrimination of Mediterranean sources based on combined XRF–LIBS data ensured a higher reliability over mono-analytical models, by increasing the Euclidean distance between sources projections over three-dimensional principal components plots. Knowing that the representativeness of elemental data could be compromised by the presence of superficial degradation products or deposition patinas, a shot-to-shot comparison of in-depth LIBS analyses is finally proposed as a method to disclose whether the spot under analysis was superficially contaminated or altered. Thus, the proposed strategy based on the combined use of portable XRF and LIBS spectrometers could be particularly useful for the in situ analysis of obsidian artefacts that underwent superficial alteration or could be covered by patina products.Graphical abstract

Using pXRF and Vis-NIR for characterizing diagnostic horizons of fine-textured podzolic soils in subtropical forests

Proximal soil sensing is a promising tool to quantify soil properties through spectral data and machine learning algorithms for application in pedological investigations. However, the relationship between pedological characteristics and sensor signals is difficult to be elucidated with machine learning models. This study aimed to establish direct linkages between pedological features and data from proximal sensors, namely portable X-ray fluorescence spectrometry (pXRF) and visible and near-infrared spectroscopy (Vis-NIR). Ten podzolic soil profiles, including seven Spodosols, two Ultisols, and one Inceptisol, were described and sampled from Central Taiwan. Principal component analysis (PCA) and k-means clustering method revealed that the major variances of the pXRF were affected by the amounts of spodic materials and organic carbon derived from plant debris. For Vis-NIR, a remarkable absorption of Fe-oxides was observed in the B horizons, and the major variations of Vis-NIR spectra extracted by PCA represented the influence of metal-complexed organic carbon and clay. The principal components (PC) of pXRF and Vis-NIR can be used to separate soil horizons, especially the E horizons were clearly separated as indicated by its high user’s and producer’s accuracies. However, the B and C horizons were poorly separated by the PCs and k-means clustering method. Moreover, the PCs can be used directly to predict the nanocrystalline Fe and Al and the optical density of the oxalate extract. Ten soil profiles were classified based on the predicted values, and nine out of ten soil profiles were in agreement with their classification using chemical extractions. The proposed pXRF and Vis-NIR approaches predicted the chemical criteria of diagnostic horizons and facilitated fast determination of Spodosols.

In-Field Obsidian XRF Analysis of Sites in the Lion Mountain Area and Gallinas Mountains of West-Central New Mexico

ABSTRACT The Gallinas Mountains of west-central New Mexico were home to agriculturalists between ca. a.d. 850 and 1450. Ongoing research of the Lion Mountain Archaeology Project (LMAP) has allowed for in-field analysis of surface obsidian artifacts via portable handheld energy dispersive X-ray fluorescence spectrometry (ED-XRF). Influenced by principles of preservation archaeology and the archaeological repository curation crisis, the LMAP has sought to design and conduct field research to gather the most data with the least amount of impact to sites. Non-destructive in-field analysis via portable handheld ED-XRF subscribes to these goals while also providing answers to significant questions about human behavior. Results show that variable patterns of obsidian source utilization and procurement strategies existed both through time and between contemporaneous populations. These results are indicative of a shifting system of exchange and social interaction between residents of the region and surrounding areas during the Ancestral Pueblo occupation of the area.

Methodologies for the Characterization and Identification of Natural Atacamite as a Pigment in Andean Colonial Painting

Painting materials used in Spanish American Colonial art comprised pigments and binders from European origin as well as those that were already known in pre-Hispanic times. In recent years, we have identified for the first time the mineral atacamite, a basic copper chloride (Cu2Cl(OH)3), in Andean Colonial art pieces (Viceroyalty of Peru, 16th–18th centuries). This work proposes a methodology based on a multitechnical approach to identify and establish the origin (natural or synthetic) of the atacamite pigment in Andean cultural heritage objects. Optical microscopy (OM), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), portable X-ray fluorescence spectroscopy (pXRF), attenuated total reflection infrared spectroscopy (FTIR-ATR), micro-Raman spectroscopy, and wide-angle X-ray scattering (WAXS) were applied to analyse green pigments from the altarpiece of the Church of Ancoraimes, atacamite mineral samples from Chile, and atacamite obtained as a secondary product from traditional recipes used to produce verdigris, a copper acetate. Viride salsum by Teófilo Presbítero (SXII) and the Spanish translation by Andrés de Laguna (1566) of “De Materia Médica” from Dioscorides are both texts that include recipes involving the use of metallic copper as a starting material. These studies will contribute to the history of Spanish American Colonial art and to the knowledge on technological capacities and skills in the Andean region during this period.

Testing the suitability of portable X-Ray Fluorescence (pXRF) analysis of dried herbarium specimens to detect Ni hyperaccumulators in South Africa

Metal hyperaccumulators accumulate particular metals or metalloids in their leaves to concentrations hundreds or thousands of times greater than is normal for most plants. Globally, Ni is the most often hyperaccumulated metal, with 532 hyperaccumulator species documented to date. Hyperaccumulators have attracted much attention as potential candidates for green technologies, including phytoremediation and agromining. In South Africa, six serpentinite-associated plants in the genera Berkheya and Senecio hyperaccumulate Ni (to > 0.1% of leaf tissue dry weight). It is surprising that only six of about 70 Berkheya and 290 Senecio species native to South Africa hyperaccumulate Ni, given about ∼10–20% of taxa from each genus occur on serpentinite. While it is costly and time consuming to field collect and chemically analyze leaves of all species in these genera, a novel method (portable X-Ray Fluorescence or pXRF analysis of herbarium specimens) allows for rapid (100 s of specimens/day) and non-destructive measurement of Ni in dry herbarium specimens. We tested the accuracy of this approach on known Ni hyperaccumulators vouchered at two South African herbaria (C.E. Moss Herbarium (J) of the University of the Witwatersrand and A.P. Goossens Herbarium (PUC) from North-West University). While the absolute concentrations of Ni determined by ICP-MS and pXRF were not always directly in agreement, we had 100% success in confirming those that were known to hyperaccumulate Ni with those that did not. We propose pXRF as a cheap, effective, and efficient approach to rapidly screen herbarium specimens across South Africa to discover additional metal hyperaccumulators for much-needed remediation purposes.

O75 (not presented) Evaluation of a portable X-ray fluorescence device for a sustainable mineral nutrition in dairy herds

O75 (not presented) Evaluation of a portable X-ray fluorescence device for a sustainable mineral nutrition in dairy herds

Multi-analytical techniques for characterization of ancient Egyptian pottery objects from Cairo University excavations at Saqqara

Archaeological pottery shows various forms of deterioration and degradation. This research aims to determine the chemical composition and diagnose the damage manifestations of three pottery vessels from the archaeological site of Saqqara. The AutoCAD, digital microscope, X-ray diffraction, polarized microscope, portable X-ray fluorescence, and scanning electron microscopy are utilized to understand the preservation status of pottery vessels. According to the investigation’s findings, the chosen vessels had cracks, accumulated dirt, missing parts, peeling of the slip layer, and black deposits. The X-ray diffraction analysis showed that Albite, Anorthite, Wollastonite, Quartz, Calcite, and Hematite are the primary constituents of the vessels. However, the polarized microscope showed the plagioclase feldspar, indicating that the Nile clay is the source of the raw clay and that the temperature rose above 800 °C. Portable X-ray fluorescence and scanning electron microscopy revealed different concentrations of Si, Fe, and Ca, which are the main pottery components. In addition to the presence of high concentrations of chloride salts. There is no doubt that this will help to preserve the archaeological pottery in future studies.

Determining the Provenance of Traded Wildlife in the Philippines.

The illegal wildlife trade is a significant threat to global biodiversity, often targeting already threatened species. In combating the trade, it is critical to know the provenance of the traded animal or part to facilitate targeted conservation actions, such as education and enforcement. Here, we present and compare two methods, portable X-ray fluorescence (pXRF) and stable isotope analysis (SIA), to determine both the geographic and source provenance (captive or wild) of traded animals and their parts. Using three critically endangered, frequently illegally traded Philippine species, the Palawan forest turtle (Siebenrockiella leytensis), the Philippine cockatoo (Cacatua haematuropygia), and the Philippine pangolin (Manis culionensisis), we demonstrate that using these methods, we can more accurately assign provenance using pXRF data (x¯ = 83%) than SIA data (x¯ = 47%). Our results indicate that these methods provide a valuable forensic tool that can be used in combating the illegal wildlife trade.

In Situ Study of the Painting “Hiroshima I” (1958) by Werner Tübke (1929–2004)

This article presents the results of technical studies of the oil painting by the artist of German origin Werner Tübke “Hiroshima I” (1958). The creative heritage of this author has not been studied enough and represents scattered data on the technology of painting and artistic techniques. The aim of this work was to determine the art materials and painting technology described in his diaries, using the example of his only painting represented in Russia: “Hiroshima I”. For this purpose, an in situ approach was implemented using some simple museum instrumentations—UV-induced visible luminescence, infrared reflectography (IRR), radiography, portable X-ray fluorescence (XRF), Fourier transform Infrared spectroscopy (FT-IR), and polarizing microscopy using microprobes. As a result, the pigment composition of the painting layers could be determined, the painting technology refined, and a previously unknown hidden portrait of Werner Tübke’s father revealed.

Revisiting the Côte d’Ivoire tektite strewn field

The tektites of the Côte d’Ivoire strewn field, called “ivorites”, come from the Bosumtwi meteorite impact crater formed 1.07 Ma ago in Ghana. Unlike other tektite strewn fields in the world, this tektite strewn field has remained under-explored after the pioneering works of A. Lacroix in the 1930s who reported the first tektites on the African continent, followed by a few explorers in the 1960s. To date, the geochemical properties of only slightly more than 20 ivorites have been measured, while there are potentially thousands to be discovered by analogy with other strewn fields. Based on these earlier works, the ivorites strewn field is considered to form an ellipse of about 1500 km2 around the town of Ouellé and Daoukro, setting apart three isolated finds. We conducted six exploratory missions in Côte d’Ivoire between 2019 and 2023 and report 174 new finds. These discoveries are mostly within the known limits of the strewn field, but several discoveries outside these limits extend the strewn field to an area of 4100 km2. The furthest discovery considered to be part of the strewn field is more than 45 km south of its previous limits. These new ivorites present various shapes (teardrops, dumbbells, spheres, ellipsoids) with masses ranging from 1 to 96 g. A geochemical analysis of 172 of these ivorites was performed using a portable X-ray fluorescence spectrometer. In addition, 87 ivorites (unknown locations), made available by the SODEMI museum (Côte d’Ivoire's governmental mining development company in Abidjan) were also analyzed. Their geochemical composition is clearly distinct from that of tektites from other strewn fields. However, these analyses reveal a more variable chemical composition than the apparent homogeneity previously inferred from a small number of specimens. The magnetic susceptibility of these tektites, measured with the SM150 device, is homogeneous and the small variations are essentially related to the iron content. The measured density of ivorites is comparable to the pore-free densities estimated from their chemical composition, implying that the abundant vesicles commonly observed at the surface, associated with bubbles and degassing of the silicate melt, are not present in the interior.

Fluvial Morphology as a Driver of Lead and Zinc Geochemical Dispersion at a Catchment Scale

Metal-mining exploitation has caused ecosystem degradation worldwide. Legacy wastes are often concentrated around former mines where monitoring and research works are mostly focused. Geochemical and physical weathering can affect metal-enriched sediment locations and their capacity to release metals at a catchment scale. This study investigated how fluvial geomorphology and soil geochemistry drive zinc and lead dispersion along the Nant Cwmnewyddion (Wales, UK). Sediments from different locations were sampled for geochemical and mineralogical investigations (portable X-ray fluorescence, scanning electron microscope, X-ray diffraction, and electron microprobe analysis). The suspended sediment fluxes in the streamwater were estimated at different streamflows to quantify the metal dispersion. Topographical and slope analysis allowed us to link sediment erosion with the exposure of primary sulphide minerals in the headwater. Zinc and lead entered the streamwater as aqueous phases or as suspended sediments. Secondary sources were localised in depositional stream areas due to topographical obstruction and a decrease in stream gradient. Sediment zinc and lead concentrations were lower in depositional areas and associated with Fe-oxide or phyllosilicates. Streamwater zinc and lead fluxes highlighted their mobility under high-flow conditions. This multi-disciplinary approach stressed the impact of the headwater mining work on the downstream catchment and provided a low-cost strategy to target sediment sampling via geomorphological observations.

Lead exposure of mainland Australia's top avian predator

Lead (Pb) toxicity, through ingestion of lead ammunition in carcasses, is a threat to scavenging birds worldwide, but has received little attention in Australia. We analyzed lead exposure in the wedge-tailed eagle (Aquila audax), the largest raptor species found in mainland Australia and a facultative scavenger. Eagle carcasses were collected opportunistically throughout south-eastern mainland Australia between 1996 and 2022. Lead concentrations were measured in bone samples from 62 animals via portable X-ray fluorescence (XRF). Lead was detected (concentration >1 ppm) in 84% (n = 52) of the bone samples. The mean lead concentration of birds in which lead was detected was 9.10 ppm (±SE 1.66). Bone lead concentrations were elevated (10–20 ppm) in 12.9% of samples, and severe (>20 ppm) in 4.8% of samples. These proportions are moderately higher than equivalent data for the same species from the island of Tasmania, and are comparable to data from threatened eagle species from other continents. Lead exposure at these levels is likely to have negative impacts on wedge-tailed eagles at the level of the individual and perhaps at a population level. Our results suggest that studies of lead exposure in other Australian avian scavenger species are warranted.

Simultaneous combined XRF-XRD analysis of geological sample: New methodological approach for on-site analysis on New-Caledonian Ni-rich harzburgite

There is a growing interest in on-site, real-time analytical solutions for mining and environmental projects to characterize large areas and/or volumes of raw materials that are sometimes highly heterogeneous in terms of elemental distribution and mineralogy. Several fast and cost-effective methods are used for rapid on-site screening and real-time chemical and mineralogical characterization, such as portable X-ray fluorescence (pXRF) and X-ray diffraction (pXRD). However, these methods are not always applicable due to limitations in the detection and quantification of light elements (Mg, Al, Si) for pXRF or complex or minor minerals for pXRD, whose results need to be supported by laboratory analysis.This study presents a new methodological approach for in situ rapid chemical and mineralogical characterization of samples, based on the use of a transportable instrument (called ID2B) that allows, in a single acquisition step, a combined XRD-XRF analysis to identify and quantify the chemical elements and their associated minerals. The HI0 harzburgite sample from New Caledonia used to evaluate the data was analyzed in the laboratory (SEM-EDS, EPMA, XRF and XRD) and with the ID2B instrument to highlight the potential of our new methodology. In order to demonstrate the interest of using the ID2B combined XRF-XRD analysis approach directly in the field, where sample preparation is not always easy to implement, this comparison was made on the same sample (HI0), prepared in two different ways, either as a powderized (optimal preparation) or as-sawn (unprepared) sample. After automated processing of the combined XRF-XRD datasets acquired with the ID2B instrument, the chemical elements and mineralogical phases identified on both the powder and as-sawn samples are identical to the laboratory analyses.The chemical proportions calculated from the combined XRF-XRD data sets are also close to the laboratory XRF analysis with relative errors <5 % for Al, Mg and Si and even closer for Ca, Cr, Mn, Ni and Fe. The variability in the calculated chemical proportions is attributed to the sample heterogeneity highlighted by the mineral proportions that vary slightly between the laboratory XRD and XRD ID2B analyses of the powder, and more pronounced for the as-sawn XRD ID2B analysis. These observations show that the combined XRF-XRD approach performed on powder and as-sawn samples provides accurate chemical and mineralogical results to those obtained in the laboratory. The deployment of this new methodological approach directly on the field can provide valuable chemical and mineralogical analyses.

Unsupervised learning for identifying silicified and dolomitized zones in pre-salt using portable XRF data

The discovery of significant oil reserves in the pre-salt region along the eastern coast of Brazil marks a significant milestone in hydrocarbon exploration and production, triggering extensive discussions on the origin and composition of non-marine carbonate rocks. Dolomitization and silicification have been identified as major processes responsible for substantial syn/post-depositional alterations in pre-salt reservoir rocks. In this study, we assess the feasibility of employing machine learning techniques to identify highly dolomitized and/or silicified intervals. A 25-m-thick rock succession from a drill core in the Tupi oil field, Santos Basin, was selected for analysis. Chemical element measurements were collected at approximately 10 cm intervals using an Olympus Vanta M Series model portable XRF analyzer. Subsequently, the acquired dataset underwent preprocessing and processing steps, including: (i) standardization of the database, (ii) data cleaning and imputation, (iii) basic statistical analysis, (iv) data transformation, and (v) outlier removal. Due to the considerable number of variables, the dataset was reduced to three principal components (PCs) using principal component analysis (PCA). Unsupervised learning was performed using the k-Means clustering algorithm, which employs Euclidean distance to determine the similarity between objects. Pearson's correlation analysis was also conducted to support the chemical interpretation of the clusters by comparing them with macroscopic and microscopic geological information. To ensure the optimal representativeness of the data, five clusters (C1, C2, C3, C4, and C5) were defined. Clusters C1, C2, and C3 exhibited increasing values on PC1, while C4 and C5 were characterized by higher values on PC2 and PC3, respectively. Based on significant correlations identified by Pearson's analysis, we can conclude that there is a progressive increase in Si content represented by C1, C2, and C3, accompanied by a relative decrease in all other chemical elements measured by the portable XRF. C1 not only emerged as the most frequently occurring cluster but also displayed the most common chemical composition in the studied interval, with Ca > Si. C2 and C3 corresponded to more intensely silicified levels. C4 exhibited a stronger affinity to Ca and Mg, suggesting intensified dolomitization. C5 stood out due to its relationship with Ba, an element associated with barite, a mineral that may result from the percolation of hydrothermal fluids depending on the associated paragenesis.

New chemical and mineralogical data on mosaics from the South aisle wall of Monreale Cathedral (Italy)

Due to the surprising lack of knowledge concerning raw materials and production technology employed to make mosaics after the twelfth century, an archaeometric investigation was carried out on the materials constituting the mosaic decoration of the South aisle wall of Monreale Cathedral (Italy), taking advantage of a conservation intervention. In this work, fallen coloured or gilded glass tesserae to be repositioned were studied by means of a combination of a molecular technique (Raman spectroscopy) and an elemental one (portable X-ray Fluorescence, pXRF); also, efflorescences affecting the general conservation state and samples of the respective bedding mortar were analysed with the former technique and with X-ray diffraction (XRD). The raw materials used and, consequently, the different compositions characterizing gilded vs. coloured glass tesserae were highlighted with the vibrational spectroscopy; chromophores and trace elements were detected by pXRF. This complementary approach allowed to disclose clues about glass-manufacturing technique and raw materials. The nature of the salts was also ascertained through Raman spectroscopy and XRD, for the benefit of the conservation procedure, and connected to the mortars’ composition.

Towards rapid analysis with XRF sensor for assessing soil fertility attributes: Effects of dwell time reduction

The analysis time used for the diagnosis of soil fertility attributes using portable X-ray fluorescence spectroscopy (XRF) sensors (between 30 and 90 s) is too long for in situ applications. The present study aimed at evaluating the trade-off between dwell time and XRF performance for assessing soil fertility attributes. A total of 102 soil samples acquired in two Brazilian agricultural fields were used, whose spectra were obtained using dwell times of 90, 60, 30, 15, 10, 7, 4, and 2 s to build and validate calibration models for clay, cation exchange capacity, and extractable K and Ca. Results revealed that it is possible to make drastic reductions in the XRF dwell time (from 90 to 2 s), while keeping excellent prediction performance [ratio of performance to interquartile distance (RPIQ) between 3.52 and 8.32] for all the studied attributes. A dwell time of only 2 s performed satisfactorily and is an analysis time suitable for rapid in situ applications. In addition, it was shown that data from spectral databases previously collected that used long dwell times (e.g., 30, 60, 90 s) can be extrapolated to fast applications with shorter dwell times (e.g., 2 and 4 s), once standardization by the detector's live time has been performed. Anyhow, calibrations using a dwell time similar to the one of the validation set tended to show superior results and are therefore recommended. This study addresses the need and provides guidelines for optimizing XRF sensor analysis time for in situ applications in the context of precision agriculture.

Sensor-based field methods for pedology and soil surveys: Protocol suggestions for Brazilian tropical soils

Although limited alternatives have been proposed to describe soils by using proximal sensors under natural conditions, efforts must be made to apply the newest technologies to assist in soil characterization and mapping. Our main objective was: to create a protocol incorporating technology that assists pedologists: (i) to compare soil horizonation by using visible, near, and shortwave infrared (Vis-NIR-SWIR) spectroscopy, mid-infrared spectroscopy (MIR), portable X-ray fluorescence (pXRF) indices, and conventional field observations; (ii) to identify mineralogical and physico-chemical variations between soil horizons by using proximal sensors, with inferences about pedogenic processes; and (iii) to expand punctual information to spatial dimensions with RGB images and terrain attributes. Seven soil profiles located through a toposequence evaluation were analyzed on a farm in the São Paulo State, Brazil. First, when the area consisted of exposed soils, images were obtained by Landsat and an unmanned aerial vehicle (UAV), and a digital surface model (DSM) was then built by stereoscopy, which was subsequently used to calculate thirteen terrain attributes. Each soil profile was evaluated with devices directly in the field (except for the MIR analyses, for which soil samples were brought to the laboratory and dried). Several indices were calculated from the pXRF data during the profile analysis, while principal component analyses (PCA) were performed to reduce the dimensions of the spectral data. Four datasets for each soil profile (VIS-NIR-SWIR, pXRF, MIR, and a combination of all the data) were submitted for k-means clustering analysis and the similarities among the layers were evaluated. Following the profile evaluation, spatialization was performed based on single bands from the RGB image and PCA using terrain attributes. The data were sampled to a punctual view of 370 points, classified, and then interpolated with the spline method. The Vis-NIR-SWIR spectral range, together with soil color, provided better correspondence with conventional field observations. We observed that the combined use of Vis-NIR-SWIR, MIR, and pXRF helped to identify and describe the soil profiles appropriately. Proximal sensors also allowed us to make more robust inferences regarding pedogenesis. We delineated soil information profiles in soil units by using the spatial dimension's terrain attributes and, RGB images from a UAV.

An archaeometric contribution to the interpretation of blue-green glass beads from Iron age Central Italy

Several types of (mostly) blue-green glass beads from Iron-Age archaeological sites in Central Italy were studied using a range of spectroscopic techniques: portable X-Ray Fluorescence spectrometry, Fibre Optics Reflectance Spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometry, micro-Raman spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Complementary information was gathered from each technique and discussed in the frame of the archaeological typology of the objects. The systematic evaluation of the results allowed us to draw some conclusions on the raw materials employed for primary production and to highlight some provenance indicators in the glass. Some of the beads found in the Iron Age (IA) contexts were preliminarily attributed to the Final Bronze Age (FBA) production based on their typology, and the compositional data obtained in this work confirmed that they were low magnesium high potassium (LMHK) glass, typical of FBA in the Italian peninsula. Other beads were assigned to low magnesium glass (LMG) or high magnesium glass (HMG), thus giving further information on the fluxing agents employed in the Early Iron Age (EIA) and beyond. Colour variations among the beads reflected their chemical composition, with different bead typologies coloured in a specific way. In some instances, it was possible to establish different origins for the colouring raw materials. The provenance of the samples was difficult to place, but the chemical evidence suggested a subdivision within the raw glass used to produce the beads: for one set of samples, a local origin of the glass could be hypothesised, whereas several production sites in the Near East were suggested for most of the beads considered in this study. Some preliminary clues for the local working of imported glass were also highlighted for one typological group.

Petrography and Geochemical Signatures of Pegmatites from the Southeastern Part Comoé Basin (South-East Côte d'Ivoire, North Alépé)

The pegmatitic rocks located in the south-east of Côte d'Ivoire between the Comoé basin and the Sefwi belt are the subject of this study. The geology of this region consists of gneisses, granites, microgranites, amphibolites, mylonites and metasediments. All these rocks are generally crosscut by quartz and pegmatite lodes. The petrographic studies allow us to discriminate four groups of pegmatites on the basis of mineralogy: (i) beryl-muscovite bearing pegmatite (Aboisso-Comoé), (ii) albite-tourmaline bearing pegmatite (Aboisso-Comoé), (iii) micas-tourmaline bearing pegmatite (Alosso) and (iv) muscovite-garnet bearing pegmatite (Songan forest). XRD analyzes on 4 samples revealed the presence of lepidolite (lithium ore) in the muscovite-garnet bearing pegmatite (Songan forest) and phengite in beryl-muscovite bearing pegmatite (Aboisso-Comoé). The pegmatite diffractograms of Aboisso-Comoé (beryl-muscovite bearing pegmatite) and Songan forest (muscovite-garnet bearing pegmatite) show almost same signatures and would suggest that those pegmatites come from the same source. Geochemical analyzes by portable XRF carried out on muscovite and feldspar minerals indicate that the samples from Aboisso-Comoé and Songan forest have the characteristics of Lithium-Cesium-Tantale type (LCT) pegmatites. The geochemical diagrams indicated the probable presence of beryl and spodumene type mineralization in the muscovite-garnet bearing pegmatite.

Combining micro- and portable-XRF as a tool for fast identification of virus infections in plants: The case study of ASa-Virus in Fraxinus ornus L.

Plant viruses can affect micro- and macro-nutrients homeostasis in woody plants, with fluctuation in the concentration of some elements at the leaf level due to the pathogen activity and/or the plant physiological response to the infection.Leaves of Fraxinus ornus L. (flowering ash) were sampled for three consecutive years in the city of Hamburg (Germany), from both trees showing the typical symptoms of the ash shoestring associated virus infection (ASaV+) and healthy trees (ASaV-). Such leaves were analyzed by μ-XRF, using both laboratory and synchrotron X-ray sources, and large differences between symptomatic and not symptomatic leaves were observed: ASaV+ samples showed uneven element distribution and regions of the lamina with severe depletions of P, S, and Ca. Differently, K appeared more concentrated. Thus, 139 leaflets sampled from various healthy and infected ash trees over the three-year period were analyzed for K and Ca concentration with a portable XRF instrument. We found that the K:Ca concentration ratio was always significantly higher in ASaV+ samples, and this trend was verified for all the samplings over the tree years. We conclude that the K:Ca ratio parameter has potential in the frame of trendsetting diagnostics and could be used, together with visual symptoms, for a rapid, non-destructive, on-site and cheap indirect ASaV detection.