摘要
Street dust is one of the most important carriers of heavy metals(HMs)originating from natural and anthropogenic sources.The main purpose of the work was to identify which of Fe-bearing phases bind HMs in street dust.Magnetic parameters of the Fe-bearing components,mainly magnetically strong iron oxides,are used to assess the level of HM pollution.Chemical sequential extraction combined with magnetic methods(magnetic susceptibility,magnetization,remanent magnetization)allowed determining the metal-bearing fractions and identifying the iron forms that aremostly associated with traffic-related HMs.The use of Mossbauer spectrometry(MS)supplemented bymagnetic methods(thermomagnetic curves and psarameters of hysteresis loops)enabled precise identification and characterization of iron-containing minerals.The classification of HMs into five chemical fractions differing in mobility and bioaccessibility revealed that iron is most abundant(over 95%)in the residual fraction followed by the reducible fraction.HMs were present in reducible fraction in the following order:Pb>Zn>Mn>Cr>Ni>Fe>Cu,while they bound to the residual fraction in the following order:Fe>Ni>Cr>Mn>Pb>Cu>Zn.The signature of the anthropogenic origin of street dust is the presence of strongly nonstoichiometric and defected grains of magnetite and their porous surface.Magnetite also occurs as an admixture with maghemite,and with a significant proportion of hematite.A distinctive feature of street dust is the presence of metallic iron and iron carbides.Magnetic methods are efficient in the screening test to determine the level ofHMpollution,while MS helps to identify the iron-bearing minerals through the detection of iron.
基金
supported in part by the statutory grant 3179/25/P-DBUPB/2015/063
research work No. 3522/182/P realized in University of Technology and Humanities in Radom
statutory activities No. 3841/E-41/S/2022 of the Ministry of Science and Higher Education of Poland
