Metals in airborne particulate as polynuclear aromatic hydrocarbons (PAH) source indicators: Preliminary results†

This preliminary report wants to evaluate if relative abundance of certain metals (Pb, V, Ni, Cr) in the particulate may be used as a specific indicator or tracer of the several sources that in an urban area can emit PAHs. This approach may give more accurate information as chemical reactivity of PAHs in the atmosphere makes it difficult to predict possible modifications of their absolute and relative concentrations. This method was used to identify possible origin of atmospheric pollution which occurred at Murta, a little town on the hills, near Genova. The airborne particulate collected in this place was relatively low in Pb and rich in V. Therefore, traffic was excluded as main pollution cause, some industrial process burning oil, being more open to suspicion. V and Ni concentrations showed a good correlation and according to their ratio at least two different types of particulate were present in the atmosphere of Murta. They were probably of different origins depending on anemological conditions difficult to identify owing to the turbulences induced by the hilly nature of the area. No statistically significant correlation between metals and PAHs was found. Since, in any case, all potential sources were at a relative long distance from Murta, a significant decay during the presence in the atmosphere, due to several variables (light intensity, ozone concentration) might be an acceptable explanation. Therefore the analysis of metals seems to be effective for identification of sources emitting PAHs. In the situation studied we concluded that pollutants could derive mainly from an oil refinery, placed in the valley. In some cases, particulate could derive from emissions of two relatively distant factories, a steel plant and a coal‐fired plant.