Background Atmospheric Levels Of BTEX In A Medium-sized City And Surrounding Area In Southern Italy

Abstract

Background atmospheric levels of BTEX in the suburb of Caserta (41° 04’ N, 14° 20’ E), a Southern Italian city with about 75,000 inhabitants and a low level of industrialization, were measured during weekdays in 2005. The average annual concentrations (µg m-3) were 8.7 benzene, 26.0 toluene, 6.5 ethylbenzene, 14.4 (m+p)-xylene and 12.5 o-xylene, with higher values during summer. The average daily concentrations of the different BTEX hydrocarbons were strongly correlated (average correlation coefficients = 0.93). The (m+p)- xylene/ethylbenzene concentration ratio was relatively low (2.2) and did not show statistically significant seasonal variations. In Naples, a densely populated city on the coast, 25 km from Caserta, the ratio was significantly higher (3.3). Intermediate ratios were recorded in sampling sites located between the two cities. The results suggest that BTEX tend to stagnate in Caserta area, producing relatively high levels with low X/E value, or, alternatively, that they are in greater part produced elsewhere, very likely in Naples, and are transported towards Caserta. To discriminate between these two hypotheses analysis of the patters of local winds is in progress.