ATMOSPHERIC BULK DEPOSITION OF CARCINOGENIC PAHS IN A RURAL AREA IN SOUTHERN ITALY

The bulk depositions of seven carcinogenic PAHs were investigated by collecting two monthly samples at seven sites. Deposition rates of individual PAHs ranged 2-89 ng/m(2)/d (BaP, 2-7 ng/m(2)/d), in agreement with the few available rates previously measured at background European sites. On six days, air samples were also collected at three sites and resulted in mean particle-bound BaP ranging 0.01-0.04 ng/m(3). The ratios between the concentrations of each PAH and BaP in the deposition samples were significantly higher than those in the air samples. To investigate if an on-sampler BaP degradation during a 1-month sampling period could generate a measurable artefact, a test was carried out by two co-located samplers collecting, respectively, one continuous 5-week sample and five weekly samples. No difference in PAH profiles was found among the samples collected by the two samplers. The occurrence of PAH profiles different from those commonly found in air may affect the validity of the BaP-marker approach in risk assessment for deposition samples.