Complementarity of analytical tools in biomonitoring studies

International audienc

The inclusion of atmospheric particles into the bark suber of ash trees

International audienc

Identification de la localisation et de la nature chimique des particules minérales chez des patients porteurs de pathologie infiltrative par analyse minéralogique (AM) des biopsies tissulaires en paraffine en utilisant la microscopie électronique à balayage (MEB)

International audienc

Atmospheric element deposit on tree barks : the opposite effects of rain and transpiration

International audienc

The inclusion of atmospheric particles into the bark suber of ash trees

International audienc

Atmospheric inorganic contaminants and their distribution inside stem tissues of Fraxinus excelsior L

International audienceThe elements present on and in 4-year-old stem of Fraxinus excelsior L. were analysed and estimated quantitatively. The superficial deposit on the bark is a complex mixture mainly composed of organic matter, mineral nutrients, clay and anthropogenic elements coming from the atmosphere. The elements present inside the stem tissues represent a total amount which is generally much higher than the superficial deposit. The distribution of elements such as Ca, K, Fe, Mn, Zn, Cu and Pb was shown by PIXE analysis in stem transversal cuttings, showing the presence of solid multimineral particles only inside the suber. A new strategy of mechanical tissues isolation on fresh stems was carried out in order to obtain high amounts of each tissue allowing an accurate ICP-MS analysis and estimation of > 20 elements in each tissue. A concentration decreasing gradient was measured for each element from suber to wood and pith in good agreement with the PIXE results. In the dividing cells of the vascular cambium, elements concentrations were very high since the cell wall weight was minimal. When expressing the amounts of each element per bark area unit, the whole bark content was only twice the wood + pith content for the studied elements. All these results suggest that, in Fraxinus stems, the root uptake and xylem transport of elements are generally not intense enough to hide the atmospheric flux of mineral contaminants. (C) 2007 Published by Elsevier Ltd

The anthropogenic atmospheric elements fraction: A new interpretation of elemental deposits on tree barks

International audienceThe superficial deposit on the bark surface of several trees (mainly Fraxinus excelsior L) was sampled in the experimental station of the university campus in Grenoble (France). Its composition was studied by scanning electron microscopy-energy dispersive X-ray emission (SEM-EDX) and, after digestion, by inductively coupled plasma-mass spectrometry (ICP-MS). The deposit was composed of 81.3% +/- 7.4 organic matter, 9.4% +/- 4.9 of geogenic minerals issued from the atmosphere (atmospheric geogenic fraction: AGF) and 9.3% +/- 2.7 of a mixture of elements which was called anthropogenic atmospheric elements fraction (AAEF). The SEM-EDX analysis showed the presence of particles of geogenic compounds such as different types of silicates, phosphates, carbonates, sulphates, oxides and also particles of metals such as iron or of alloys of Fe-Zn, Fe-Ni, Ni-Cr and Ca sulphates or phosphates. Typical spheres of "fly ashes" composed of pure iron or Al-silicates were detected. Using the SEM-EDX analysis of the deposit and the average local soil composition, an empiric formula for the AGF (without polluting elements) was chosen, which presented a clear analogy with the global formula of the upper continental crust. In the same way, a formula for the pure organic matter fraction was chosen. Withdrawing the elements corresponding to these two fractions allows a tentative estimation of the content of the AAEF which was supposed to better represent the elemental anthropogenic contamination issued from the atmosphere. In the station, most of Sb, Cd, Sn, Pb, Cu, V and Zn were found in the AAEF. This AAEF composition was compared to that of the deposit in a highway tunnel where Pb and Cu were at a very high level. The meaning and the limits of the AAEF concept were critically discussed. (C) 2008 Elsevier Ltd. All rights reserved