Rare Earth Elements' particles in road dust : A mineralogical perspective for source identification
Navarro Ciurana, Didac (Universitat Autònoma de Barcelona. Departament de Geologia)
Corbella i Cordomí, Mercè (Universitat Autònoma de Barcelona. Departament de Geologia)
Farré-de-Pablo, Júlia (Universitat de Barcelona. Departament de Mineralogia)
Corral, Isaac (Universitat Autònoma de Barcelona. Departament de Geologia)
Buixadera, Elisabeth (Universitat Autònoma de Barcelona. Departament de Geologia)
Morera-Valverde, Robert (Universitat Autònoma de Barcelona. Departament de Geologia)
Proenza, Joaquín A. (Universitat de Barcelona. Departament de Mineralogia)

Fecha:	2023
Resumen:	Roadside dust contains many mineral grains and, among them, some of REEs (Rare Earth Elements) which have an uncertain origin. This paper characterizes and illustrates for the first time the occurrence of such REEs' particles from four locations near Barcelona (Spain), by means of mineralogical studies, with the aim of identifying their source and understanding their accumulation. The observed REEs' particles contain Ce and low amounts of La and Nd and are spheroidal, rounded, elongated, or angularly shaped (<5 μm), often forming nanoparticles' aggregates. The identical chemical composition and morphology of the REEs' particles (CeO2), independently from the sampling location and its geological background, points to a sole non-natural anthropogenic origin. Moreover, the absence of U and Th in the studied CeO2 grains is an additional robust indicator of their anthropogenic source, as the naturally formed CeO2 (the mineral cerianite) is characterized by containing those radioactive elements. Therefore, the identified grains consist of ceria particles, the non-natural cerium oxide. Ceria must originate in autocatalytic converters, where it is broadly used in solid solution with ZrO2 (zirconia) in the form of CeZrOx. The roadside dust ceria particles do not contain Zr, but zirconia crystals are also found in the dust, with no Ce traces. This might indicate that they were released as separated neo-formed ceria and zirconia phases, which is consistent with a metastable CeZrOx segregation at the autocatalyzer under vehicles' engine operating conditions. The small size, and thus inhalable, ceria particles emitted by vehicles are a significant environmental health hazard, revealing the need for further assessment of CeO2 concentrations generated by automobiles in urban areas worldwide.
Ayudas:	Agencia Estatal de Investigación PID2019-109018RB-I00 Agència de Gestió d'Ajuts Universitaris i de Recerca 2022/SGR-00308
Nota:	Altres ajuts: acords transformatius de la UAB
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Anthropogenic inhalable particles ; Autocatalyst ; Ceria nano-particles ; REE mineralogy ; Vehicle emissions
Publicado en:	Atmospheric Environment, Vol. 309 (September 2023) , art. 119927, ISSN 1873-2844

DOI: 10.1016/j.atmosenv.2023.119927

13 p, 14.2 MB

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