Trace Metal Chemical Fractionation in Airborne Particulate Matter from a Tropical Urban Area in Brazil

This study aims to employ a modified BCR method for metal chemical fractionation in total suspended particulate (TSP) and inhalable particulate matter (PM ₁₀ ) samples. The chemical fractionation of Cd, Cu, Fe, Mn, Ni, Ti and V in airborne particulate matter (APM) samples from a tropical urban area in the city of Aracaju, Sergipe, Northeastern Brazil was performed, adapting a sequential extraction method encompassing six fractions characterized by a gradual increase in the solvent strength, as follows: (1) water-soluble fraction; (2) ion exchange fraction; (3) carbonate-bound fraction; (4) metal oxide-bound fraction; (5) organic metal complex or sulfide-bound fraction; and (6) residual fraction. Iron and Ti concentrations were the most abundant among organic metal complex and sulfides and silicate fractions for both TSP and PM ₁₀ . Cadmium concentrations, in general, were higher in the organic metal complex and sulfides, silicate, and oxide fractions, while Cu was most detected in the organic metal complex and sulfides, oxide, and silicate fractions. Nickel, Mn and V were not determined in either of the samples. A multivariate data analyses indicated three groups, associating Cu and Cd to similar sources, i.e ., vehicular traffic and fossil fuel burning. This is the first time this sequential method was applied to investigate metal mobility and metal distribution in APM, assessing beyond the bioavailability, solubility, and geochemical transport trace metals.