Iron Speciation in Different Saharan Dust Advections and Effect of the Procedural Blank on the Results From X-ray Absorption Spectroscopy and Selective Leaching Experiments
Chiara Petroselli,
Beatrice Moroni,
Stefano Crocchianti,
Roberta Selvaggi,
Francesco Soggia,
Marco Grotti,
Francesco d’Acapito,
David Cappelletti
Affiliations
Chiara Petroselli
Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton SO17 1BJ, UK
Beatrice Moroni
Dipartimento di Chimica, Biologia e Biotecnologie, Universitá degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy <email>[email protected]</email> (B.M.)
Stefano Crocchianti
Dipartimento di Chimica, Biologia e Biotecnologie, Universitá degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy <email>[email protected]</email> (B.M.)
Roberta Selvaggi
Dipartimento di Chimica, Biologia e Biotecnologie, Universitá degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy <email>[email protected]</email> (B.M.)
Francesco Soggia
Dipartimento di Chimica e Chimica Industriale, Universitá degli Studi di Genova, via Dodecaneso 31, 16146 Genova, Italy
Marco Grotti
Dipartimento di Chimica e Chimica Industriale, Universitá degli Studi di Genova, via Dodecaneso 31, 16146 Genova, Italy
Francesco d’Acapito
CNR-IOM-OGG c/o ESRF LISA CRG, 71 Avenue des Martyrs, F-38043 Grenoble, France
David Cappelletti
Dipartimento di Chimica, Biologia e Biotecnologie, Universitá degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy <email>[email protected]</email> (B.M.)
In this work, we applied X-ray Absorption Spectroscopy (XAS) and selective leaching experiments for investigating iron speciation in different dust advections collected on different unwashed quartz fiber filters. XAS analysis evidenced a predominance of Fe(III) in 6-fold coordination for Saharan dust and a trend towards Fe(II) and 4-fold coordination in the order: Saharan dust, mixed Saharan, and non-Saharan aerosol samples. The role of the sampling substrate was evaluated explicitly, including in the analysis a set of blank filters. We were able to pinpoint the possible contribution to the overall XAS spectrum of the residual Fe on quartz as the concentration decrease towards the blank value. In particular, the filter substrate showed a negligible effect on the structural trend mentioned above. Furthermore, selective leaching experiments evidenced a predominance of the residual fraction on Fe speciation and indicated the lowest Fe concentrations for which the blank contribution is μ g for the first three steps of the procedure (releasing the acid-labile, reducible and oxidizable phases, respectively) and 10 μ g for the last step (dissolving the insoluble residuals).
