WATER AND SEDIMENT ANALYSIS OF TOURISTIC PLACES IN GUARAPUAVA, PR USING A PORTABLE EDXRF SYSTEM

ABSTRACT The use of the Energy Dispersive X Ray Fluorescence (EDXRF) have increasingly been applied for in situ trace metal analysis in different kinds of samples. Results of a monitoring sampling, in the winter and summer of 2008, respectively, from 6 touristic places in Guarapuava, PR city are presented. The work consisted on the use of a portable EDXRF system constituted by a X-ray tube to excite the samples, a Si-Pin detector, a holder for the excitation-detection system and samples positioning, with the standard data acquisition electronics to register the spectra. The water samples were filtered in membranes for suspended particulate matter retention. After this, APDC precipitation methodology was applied for sample preconcentration with posterior filtering in membranes. So, the dissolved and non dissolved metal fractions were determined separately. Sediment samples were dried at 60 C for 24h and sieved through 60 mesh. Micromatter standards were used for sensitivity determination for membranes samples. For sediments 5 multi-element standards were used and calibration curves were constructed. For water membrane measurements, Fe concentration was quantified from 0.026±0.004 to 5.1±1.0, in mg L -1 . For sediments, considering all the sampling locations, Mn, Cu, Sr, Y and Nb were identified qualitatively, and it was possible to quantify the following range of elements and concentrations, mg Kg and . The performance of the equipment was very good and the results are quite satisfactory for portable equipment

Effect of X-ray tube configuration on measurement of key soil fertility attributes with XRF

The successful use of energy-dispersive X-ray fluorescence (ED-XRF) sensors for soil analysis requires the selection of an optimal procedure of data acquisition and a simple modelling approach. This work aimed at assessing the performance of a portable XRF (XRF) sensor set up with two different X-ray tube configurations (combinations of voltage and current) to predict nine key soil fertility attributes: (clay, organic matter (OM), cation exchange capacity (CEC), pH, base saturation (V), and extractable nutrients (P, K, Ca, and Mg). An XRF, operated at a voltage of 15 kV (and current of 23 mu A) and 35 kV (and current of 7 mu A), was used for analyzing 102 soil samples collected from two agricultural fields in Brazil. Two different XRF data analysis scenarios were used to build the predictive models: (i) 10 emission lines of 15 keV spectra (EL-15), and (ii) 12 emission lines of 35 keV spectra (EL-35). Multiple linear regressions (MLR) were used for model calibration, and the models' prediction performance was evaluated using different figures of merit. The results show that although X-ray tube configuration affected the intensity of the emission lines of the different elements detected, it did not influence the prediction accuracy of the studied key fertility attributes, suggesting that both X-ray tube configurations tested can be used for future analyses. Satisfactory predictions with residual prediction deviation (RPD) >= 1.54 and coefficient of determination (R-2) >= 0.61 were obtained for eight out of the ten studied soil fertility attributes (clay, OM, CEC, V, and extractable K, Ca, and Mg). In addition, simple MLR models with a limited number of emission lines was effective for practical soil analysis of the key soil fertility attributes (except pH and extractable P) using XRF. The simple and transparent methodology suggested also enables future researches that seek to optimize the XRF scanning time in order to speed up the XRF analysis in soil samples

Estudo de cerâmicas do sítio arqueológico Água Limpa (SP) empregando um equipamento portátil de EDXRF

The objective of this paper is to identify the chemical elements present in each fragment and associate it to various factors such as production technology, pigmentation and provenance. Energy Dispersive X-ray Fluorescence (EDXRF) analysis of a representative ensemble of ceramic fragments were performed. The analysis is fast, non-destructive and without sample preparation. Calcium, Ti, Fe, Mn, Zn, Rb and Zr were quantified. It was possible to characterize the ceramic paste composition and the key elements of the raw materials employed for the pigmentation.O objetivo deste artigo é identificar os elementos químicos presentes em fragmentos cerâmicos do sítio Água Limpa, e associá-los a vários fatores como tecnologia de produção, pigmentação e proveniência. Foi realizada uma análise por Fluorescência de Raios X com Dispersão em Energia (EDXRF) de um conjunto significativo de amostras cerâmicas. A análise é rápida, não destrutiva e sem preparação de amostra. Foram quantificados Ca, Ti, Fe, Mn, An, Rb e Zr, possibilitando caracterizar a composição da pasta cerâmica e os elementos chave da pasta empregada nas pigmentações

Laser-induced breakdown spectroscopy (LIBS) for tropical soil fertility analysis

The Laser Induced Breakdown Spectroscopy (LIBS) is a promising technique for soil fertility analysis in a rapid and environmentally friendly way. This application requires the selection of an optimal modelling procedure capable of handling the high spectral resolution of LIBS. This work aimed at comparing different modelling methods of LIBS data for the determination of key fertility attributes in Brazilian tropical soils. A benchtop LIBS system was used for the analysis of 102 soil samples, prepared in the form of pressed pellets. Models for the prediction of clay, organic matter, pH, cation exchange capacity, base saturation, and the extractable nutrients P, K, Ca, and Mg were developed using univariate linear regression (ULR), multiple linear regression (MLR) and partial least squares regression (PLS). The following input data for PLS were used: (i) the full spectra from 200 to 540 nm (38,880 variables), and (ii) variables selected by the interval successive projections algorithm (iSPA). The multivariate models achieved satisfactory predictions [residual prediction deviation (RPD) > 1.40] for eight out of nine fertility attributes. However, the best performances were obtained for the PLS with the variable ranges selected by the iSPA, which achieved satisfactory predictions (RPD ≥ 1.44) for seven out of the nine soil attributes studied. The MLR method obtained lower prediction performance than the iSPA-PLS using only 21 variables. The iSPA-PLS approach allowed a reduction from 3 to 160-fold in the total of variables compared to the full LIBS spectra, making it efficient and accurate modelling method that uses reduced number of variables. Although LIBS technique proved to be efficient for predicting fertility attributes in tropical soils, further research is encouraged in order to reduce the amount of sample preparation conducted in this study