Biomonitoring of airborne metals in urban environments: new tracers of vehicle emission, in place of lead

摘要

Samples of Quercus ilex leaves and of the inhalable fraction of atmospheric particulate (PMlo) were collected along a busy road and in a park in Florence (Italy). Quantitative comparisons and correlations of element concentrations in PMlo collected by air samplers at two sites showed that Ba, Cu, Fe, Mn, Pb and Zn were the main metal pollutants emitted by vehicles in Florence. Very similar results were obtained by the analysis of Q. ilex leaves which were found to accumulate airborne metals as a function of the exposure time (i.e. their age). One-year-old leaves showed the highest rate of metal accumulation. Our results show that the pro- gressive phasing-out of leaded petrol in Italy has resulted in a decrease of about 20 per year in the Pb concentrations in PM_10. Both PM_10 and Q. ilex analysis singled out Ba and Zn as valid tracers of automotive traffic instead of Pb.