HR: 18:05h
AN: B44A-08    [Abstracts]
TI: Stability of Commercial Lead in the Presence of Iron(III)-Sequestering Biogenic Ligands: Implications for Metal Mobility and Bioavailability in Natural Iron-Rich Environments
AU: * Cornejo-Garrido, H
EM: cghgill@yahoo.com.mx
AF: Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AU: * Cornejo-Garrido, H
EM: cghgill@yahoo.com.mx
AF: Instituto de Geografia, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AU: Fernández-Lomelin, P
EM: pilarf@igg.unam.mx
AF: Instituto de Geografia, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AU: Guzman-Mendoza, J
EM: jguzm@ servidor.unam.mx
AF: Instituto de Investigacion en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AU: Sedov, S
EM: sergey@geologia.unam.mx
AF: Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AU: Cervini-Silva, J
EM: jcervini@igg.unam.mx
AF: Instituto de Geografia, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
AB: Mexico is a leader in the production of lead. Exposure of soils contaminated with lead ore waste, ingestion of contaminated waters, or inhalation of suspended particles, among others are examples of common routes of exposure. Solubility often becomes limiting for Pb bioavailability, therein the need to further characterize natural processes that contribute to its mobility in the environment. In oxic environments, such as highly weathered soils or surficial seawater, microorganisms and higher plants produce biogenic ligands such as siderophores to mobilize Fe that otherwise would be unavailable. Siderophores ligands facilitate the dissolution of natural particles that represent a primary reservoir of iron. On the other hand, lead sorbs strongly to minerals, particularly to those bearing high contents of iron. Siderophore ligands have been identified to influence the adsorption behavior of Pb(II) on iron mineral surfaces. Yet, little is known on how siderophore ligands may affect the stability of Pb(0). In this paper we study the stability of Pb(0) in the presence of desferrioxamine (DFO-B), a common siderophore ligand. Batch dissolution experiments of Pb(0) (1 g L-1) in the presence of DFO-B ([DFO-B]0 ƒ¬ 200M) at pH 5 were conducted for 7 days. The adsorption behavior of DFO-B was also characterized. Corresponding experiments in the absence of DFO-B for the purpose of comparison were also conducted. Analyses for soluble Pb were conducted by AA and ICP-AES. Solid characterization was conducted by XRD and SEM-EDX. Analyses for soluble Pb reveal concentrations of up to ca. 40 ppm. White small-sized particles were identified after reaction, regardless of the presence of DFO-B. The suspension chemical composition influenced colloidal stability. In the presence of DFO-B, forming solids showed small aspect ratio ( < 2m), while remained suspended in supernatant solutions. In the absence of DFO-B, solids formed showed varied in size. The were found to remain associated with the Pb(0). Flocculation was observed to occur notingly if in the absence of DFO- B. Intermolecular forces at the mineral-water interface are sought to account for these observatons. As revealed by XRD and SEM-EDX, solid composition is attributed to various lead oxide and hydroxides. The presence of DFO-B influence the solid composition. Thermodynamic considerations lead the authors to suggest that sideophore ligands could act as templates for preferential nucleation of secondary phases, while effectively abating the reaction activation energy of formation.
DE: 0330 Geochemical cycles (1030)
DE: 1705 Biogeosciences
DE: 3612 Reactions and phase equilibria (1012, 8412)
DE: 3947 Surfaces and interfaces
DE: 4840 Microbiology and microbial ecology (0465)
SC: Biogeosciences [B]
MN: 2007 Joint Assembly