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S. Orecchio et al. / Environmental Research 107 (2008) 371–379 375

Fig. 3. Recoveries of the selected compound extracted by Soxlhet.

Fig. 4. Concentration of single PAH (micrograms/kg d.w.) measured three times in the sample no. 2.

Simonich and Hites (1995) studied the PAHs partitioning main PAHs in diesel exhaust particles are 3- and 4-ring
between the vegetation and atmosphere during the growing compounds, primarily fluoranthene, phenanthrene and pyrene
season and under natural conditions. They found the partitioning (Howsam and Jones, 1998).
process to be dependent primarily on the atmospheric gas-phase The analytical method used in this work is more convenient
PAH concentration and the temperature. Their models showed than that which we used in some previous researches (Culotta
that about 44% of PAHs emitted into the atmosphere from any et al, 2002, 2005) because it reduces both the analysis steps and
source were removed by vegetation. They further hypothesized the working time. Under the experimental conditions used here,
that most of the PAHs absorbed by vegetation at the end of the the average recovery is 88% (Fig. 3). The reproducibility is also
growing season are incorporated into the soil and permanently satisfactory, as the relative standard deviation was less than 12%.
removed from the atmosphere. As an example, in Fig. 4 the results of the three analysis of sample
The composition of PAH emissions vary with the combustion no. 2 are reported.
source. For example, emissions from residential wood combustion The detection limits for all the compounds under investigat-
contain more acenaphthylene than other PAHs, whereas auto ion are reported in Table 5.In Table 6, we report the concentrat-
emissions contain more benzo[g,h,i]perylene and pyrene. The ion of each individual PAH in the barks collected. The total