Investigation of the mineralogical composition and spatial distribution pf Pb and Sb species in corroded bullets by Sr-micro XRF and XRD

FERNANDA MERA; MARCELO RUBIO; A. GERMANIER; VICTOR MARTÍN GALVÁN JOSA; CARLOS PEREZ

Carlos Paz

Congreso; XIV Latin American Seminar of Analysis by X-Ray Techniques; 2014

FaMAF-UNC

Lead, antimony and others toxic metals from pellets alloy are disperse in the soil of the shooting fields. As long as the corroding bullets are present in soil, secondary Pb and Sb phases in the weathering crusts appears being an important source of bioavailable Pb and Sb.We investigated the mineralogical composition and spatial distribution of Pb and Sb species in corroded ammunitions to understand how metallic Pb and Sb reacts in the soil, influencing the bioavailability, the risk of contamination in soil and the potential toxic effects on the environment We performed XRF quantification of elements in soils and X-ray diffraction analysis (XRD) to characterize the mineral phases present in crust powder removed from corroded Pb bullets. Powder XRD patterns of crust material showed encrustation of relevant Pb and Sb phases like: Hydrocerussite (Pb3(CO3)2(OH)2), Litharge (PbO-tetragonal), Hydroxypyromorphite (Pb5(PO4)3(OH)), Gebhardite (Pb8OCl6(As2O5)2, Sb metallic, Stibnite (Sb2S3), Tripuhyite (FeSbO4) and Potassium Sodium Antimony Oxide (KO13Sb5). We considered essential to investigate the spatial distribution of Pb and Sb species in corroded ammunitions using SR μXRF and correlate these spectra with mineral phases on bullets and crust. The experiment was carried out in the XRF station at LNLS. The samples measured were corroded bullets cemented by epoxy resin and flat polished, crust dust and entire ammunitions. Thanks to the high sensitivity of the SR beam and the feasibility to perform micro mapping, it was possible to observe that bullets cores are conformed of few metallic Sb grains dispersed into a metallic Pb matrix, rather than a Pb-Sb alloy. It was determined the relationship between Sb and Fe in the corrosion process of the bullets observing that Sb was correlated to Fe-compounds in bullet crust material. It was also performed μXRF quantification of elements in crust samples. The 2014 research proposals approved by LNLS as SXS 16953 and XAFS1 ? 16907 will aim to add SXS synchrotron technique for environmental studies concerning speciation of toxic elements in soil and the study of spatial distribution of elements (essential and toxics) in plant tissues grown in contaminated soils to develop phytotechnologies for soil remediation.