Vertical distribution of carbonaceous material in urban atmosphere

The carbonaceous Particulate Matter in downtown Rome accounts for 30-40 % of the PM10 at ground level and is formed by 60-70% of Elemental Carbon and 30-40% of Organic Carbon. The total carbon contribution decreases remarkably at 20 m height, especially due to elemental carbon of primary origin. At ground level, elemental carbon and organic carbon are well correlated, due to their common origin: the motor vehicle emission. At ground level, the ratio EC/OC is always up 1, while in the altitude, where the primary biogenic contribution due to plants is higher, it becomes opposite. Polycyclic Aromatic Hydrocarbons, n-Alkane and n-Alkanoic acids have been identified among the constituents of the OC fraction, sulphates, nitrate and ammonia within the hydrosoluble inorganic fraction, and heavy metals (Cd, Cr, Fe, Ni, Pb, V, Zn) within the non-hydrosoluble inorganic fraction. The PM10 temporal trends have been interpreted using the measurements of natural radioactivity (radon and its short-lived decay products) as tracer of the dynamic properties of the atmospheric boundary layer, and have been correlated with primary gaseous pollutants and the variable Ox, which indicates the occurrence of radical oxidative processes in the atmosphere.