Metals associated with airborne particulate matter in road dust and tree bark collected in a megacity (Buenos Aires, Argentina)

Multielemental profiles in bark suber of green ash trees and road dust collected in three representative areas of Buenos Aires, Argentina were assessed as potential air pollution indicators. Ten elements: Al, Ba, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn, were measured by inductively coupled plasma optical emissions spectrometry and their concentrations in the Buenos Aires road dust are reported for the first time. Measured concentrations and enrichment factors were used to characterize the environmental signatures of air pollution sources with impact in the studied areas. The analysis based on enrichment factors provided a common framework for the comparison of our results on tree bark and road dust with PM10 concentrations measured in previous studies. This unified analysis proved to be a valuable tool showing the consistency of our findings. The analysis based on either concentration profiles or enrichment factors showed that bark clearly differentiated sampling areas, resulting to be a better air pollution indicator than road dust. Road dust did not provide a clear differentiation between areas; this might be indicative of a certain degree of spatial mixture on street surfaces.