A.F. Marques

Total reflection X-ray fluorescence and energy-dispersive X-ray fluorescence analysis of runoff water and vegetation from abandoned mining of Pb-Zn ores

The present work reports on the heavy metalcontent: Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb in running waters and vegetation around abandoned mining areas. Two species of mosses (Dicranum sp. and Pleurocarpus sp.) and three different species of wild grass (Bromus sp., Rumex sp. and Pseudoavena sp.) growing on the surrounding areas of old lead-zinc mines (Aran Valley, Pyrenees, NE Spain) have been analyzed. Both water and vegetation were collected in two different sampling places: (a) near the mine gallery water outlets and (b) on the landfill close to the abandoned mineralconcentration factories. For the heavy metalcontent determination, two different techniques were used: total reflection X-ray fluorescence for water analysis and energy-dispersive X-ray fluorescence for vegetation study. Surface waters around mine outlets exhibit anomalous content of Co, Ni, Zn, Cd. Stream waters running on mining landfills exhibit higher Cu, Zn, Cd and Pb than those of the waters at the mine gallery outlets. The results allow us to assess the extent of the environmental impact of the mining activities on the water quality. The intake of these elements by vegetation was related with the sampling place, reflecting the metal water content and the substrate chemistry. Accumulation of metals in mosses is higher than those exhibited in wild grasses. Furthermore, different levels of accumulation were found in different wild grass. Rumex sp. presented the lowest metal concentrations, while Pseudoavena sp. reported the highest metalcontent.

Lead post-mortem intake in human bones of ancient populations by 109Cd-based X-ray fluorescence and EDXRF

In this work we measured the lead concentration in human bones of Middle Age by means of a portable X-ray fluorescence system based on (109)Cd radioactive source. The detection system consists on a Ge hyperpure detector. This system, conceived for in vivo Pb analysis in bone, is portable, non-destructive and is based on lead K lines detection. The analysed bones are part of two collections of bones both from the end of Middle Age and submitted for some years to a lead polluted burial environment. The bones of one collection were buried initially on the soil in a convent, in Lisbon (Portugal) and further on, kept in a lead coffin for around 100 years. The second collection contains bones buried permanently on the soil around an old church on the south of Portugal. This place became a parking car for around 20 years. In this work we studied the distribution of Pb in cortical bone, and trabecular regions from the outside surface to the inner part of the bone and the results are compared with the obtained ones by energy dispersive X-ray fluorescence (EDXRF). The obtained values present a strong contamination of Pb in spongy bones kept in the lead coffin with concentrations ranging from 250 to 350mugPb/g bone mineral, and 4 to 7mugPb/g bone mineral for bones buried in the soil. Good agreement was observed between the results obtained by the two techniques.

Total Reflection X-ray Spectrometry (TXRF) for Trace Elements Assessment in Edible Clams

The present contribution presents a preliminary investigation of the chemical composition with respect to major, minor, trace, and ultratrace elements in several clam species that are frequently used for human consumption in Portuguese markets and worldwide. In order to use a simple and rapid analytical methodology for clam analysis, energy dispersive X-ray fluorescence (EDXRF) spectrometry and total reflection X-ray fluorescence (TXRF) spectrometry were selected as analytical techniques. The analytical capabilities of TXRF spectrometry were evaluated for the determination of minor and trace elements in commercial edible clams. We compared the direct analysis of powdered suspensions (using different sample amounts and dispersant agents) with the analysis of the digested samples for trace element determination. Inductively coupled plasma mass spectrometry analysis of clam digests was also performed to evaluate the analytical possibilities of TXRF spectrometry for trace and ultratrace analysis.

Synchrotron Radiation and Energy Dispersive X‐Ray Fluorescence Applications on Elemental Distribution in Human Hair and Bones

This work is an application of synchrotron microprobe X‐ Ray fluorescence in order to study elemental distribution along human hair samples of contemporary citizens. Furthermore, X‐Ray fluorescence spectrometry is also used to analyse human bones of different historical periods: Neolithic and contemporary subjects. The elemental content in the bones allowed us to conclude about environmental contamination, dietary habits and health status influence in the corresponding citizens. All samples were collected post‐mortem. Quantitative analysis was performed for Mn, Fe, Co, Ni, Cu, Zn, Br, Rb, Sr and Pb. Mn and Fe concentration were much higher in bones from pre‐historic periods. On the contrary, Pb bone concentrations of contemporary subjects are much higher than in pre‐historical ones, reaching 100 μg g‐1, in some cases. Very low concentrations for Co, Ni, Br and Rb were found in all the analysed samples. Cu concentrations, allows to distinguish Chalcolithic bones from the Neolithic ones. The distribution of...