title: Foliar or root exposures to smelter particles: consequences for lead compartmentalization and speciation in plant leaves.
abstract: In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO4, chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO3. In rye-grass, the changes in Pb speciation were even more egregious: Pb-cell wall and Pb-organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to better assess the health risks involved.
authors: Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l'Agrobiopole, 31326 Castanet-Tolosan, France; CNRS, EcoLab, 31326 Castanet-Tolosan, France; Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue E. Belin, F-31400 Toulouse, France.
authors: Eva
authors: E
authors: Schreck
authors: LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d'Ascq Cedex, France.
authors: Vincent
authors: V
authors: Dappe
authors: ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble, France.
authors: Géraldine
authors: G
authors: Sarret
authors: LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d'Ascq Cedex, France.
authors: Sophie
authors: S
authors: Sobanska
authors: Department of Chemistry, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin, Poland.
authors: Dorota
authors: D
authors: Nowak
authors: Department of Chemistry, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin, Poland.
authors: Jakub
authors: J
authors: Nowak
authors: Department of Chemistry, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin, Poland.
authors: Elżbieta Anna
authors: EA
authors: Stefaniak
authors: ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble, France.
authors: Valérie
authors: V
authors: Magnin
authors: CEA-INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
authors: Vincent
authors: V
authors: Ranieri
authors: Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l'Agrobiopole, 31326 Castanet-Tolosan, France; CNRS, EcoLab, 31326 Castanet-Tolosan, France. Electronic address: camille.dumat@ensat.fr.
authors: Camille
authors: C
authors: Dumat
mesh_terms: D004784:Environmental Monitoring; D007854:Lead / Q000032:analysis*; D018545:Lactuca / Q000737:chemistry; D008129:Lolium / Q000737:chemistry; D008669:Metallurgy; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D012989:Soil Pollutants; D007854:Lead
keywords: Lactuca sativa L.; Lolium perenne L.; Microscopy and spectroscopy techniques; Pathway of uptake; Pb; Speciation and compartmentalization