Operational speciation of Cd, Cr, Cu, Mn, Ni, Pb, V and Zn in dust samples from schools in Caracas, Venezuela.

Abstract

A sequential extraction approach has been applied to analyze Cd, Cr, Cu, Mn, Ni, Pb, V y Zn in dust samples from different schools chosen according with their location in areas with different concentrations of Total Suspended Particles (TSP). The aim of this work is to provide information about the chemical species or forms of metal content. Hence, information about the origin, mode of occurrence, mobilization and transport of metals could be obtained. Total metal concentration was further determined by analyzing the samples after sample acid digestion procedure. The results compare very well with those obtained by the sequential extraction method. The metals are associated with various chemical forms as distinguished by sequential chemical extraction. The carbonate and Fe-Mn oxide phases dominate for Pb, Zn and Cu whereas for Ni the organic phase is most important. Vanadium, manganese, chromium, cadmium and a proportion of lead remain in the residual material.