title: A PIXE and ICP-MS analysis of metallic atmospheric contaminants in tree bark tissues, a basis for biomonitoring uses.
abstract: The qualitative and quantitative metallic content of tree barks of Argania spinosa (L.) Skeels were studied. Argania spinosa is an endemic species in Morocco. This tree is adapted to semi-arid climates and exposed to specific conditions of relative humidity, temperature, wind, and particle transport. Three sites were sampled in Morocco: the large town of Rabat, the harbor of Agadir, and Aït Baha, a countryside location exposed to continuous desert wind. The methodologies included (1) in situ microanalysis with proton-induced X-ray emission (PIXE) and (2) trace element determinations by mass spectrometry with inductively coupled plasma (ICP-MS) associated with extraction procedures. Both methods allowed detection of elements coming from different bark compartments. The profile of airborne contaminants in the barks was typical of the sampling sites. The level of lead in barks sampled in Rabat reached 100 ng cm(-2), or higher, while it varied between 3 and 35 ng cm(-2) in Aït Baha. The in situ study of the microscopic structure of the bark provided the location of major and minor elements at various depths inside the bark. A differential between free deposit on the bark surface and penetrated content was found for the major and trace elements. The free deposit on the bark surface was suspected to be mostly the result of recent contamination. Part of the contaminants spread out on the surface penetrated the superficial suber. This long-term accumulation affected mostly Pb. In deeper levels, airborne elements at low concentrations and elements resulting from root uptake were concurrently present and resulted in a complex situation, as noted for zinc.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France. sophie.ayrault@cea.fr
authors.forename: Sophie
authors.initials: S
authors.lastname: Ayrault
authors.forename: Fatima Ezzahra
authors.initials: FE
authors.lastname: El Alaoui-Faris
authors.forename: Juliette
authors.initials: J
authors.lastname: Asta
authors.forename: Michel
authors.initials: M
authors.lastname: Tissut
authors.forename: Laurent
authors.initials: L
authors.lastname: Daudin
authors.forename: Clarisse
authors.initials: C
authors.lastname: Mariet
authors.forename: Patrick
authors.initials: P
authors.lastname: Ravanel
authors.forename: André
authors.initials: A
authors.lastname: Gaudry
authors.forename: Rajaa
authors.initials: R
authors.lastname: Cherkaoui
mesh_terms: D000393:Air Pollutants / Q000302:isolation & purification*; D002462:Cell Membrane; D004784:Environmental Monitoring; D013058:Mass Spectrometry / Q000379:methods; D008670:Metals / Q000302:isolation & purification*; D009018:Morocco; D024301:Plant Bark / Q000737:chemistry*; D029632:Sapotaceae / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission
chemical_list: D000393:Air Pollutants; D008670:Metals