[摘要] Its location in the Mediterranean region and its physical characteristicsrender Mt. Cimone (44°11′ N, 10°42′ E), the highest peak of theItalian northern Apennines (2165 m asl), particularly suitable to study thetransport of air masses from the north African desert area to Europe. Duringthese northward transports 12 dust events were registered in measurements ofthe aerosol concentration at the station during the period June–December2000, allowing the study of the impact of mineral dust transports on freetropospheric ozone concentrations, which were also measured at Mt. Cimone.Three-dimensional backward trajectories were used to determine the air massorigin, while TOMS Aerosol Index data for the Mt. Cimone area were used toconfirm the presence of absorbing aerosol over the measurement site.
A trajectory statistical analysis allowed identifying the main source areasof ozone and aerosols. The analysis of these back trajectories showed thatcentral Europe and north and central Italy are the major pollution sourceareas for ozone and fine aerosol, whereas the north African desert regionswere the most important source areas for coarse aerosol and low ozoneconcentrations. During dust events, the Mt. Cimone mean volume concentrationfor coarse particles was 6.18 µm3/cm3 compared to 0.63 µm3/cm3in dust-free conditions, while the ozone concentrationswere 4% to 21% lower than the monthly mean background values. Ourobservations show that surface ozone concentrations were lower than thebackground values in air masses coming from north Africa, and when these airmasses were also rich in coarse particles, the lowest ozone values wereregistered. Moreover, preliminary results on the possible impact of the dust events onPM10 and ozone values measured in Italian urban and rural areas showed that duringthe greater number of the considered dust events, significant PM10 increases and ozonedecreases have occurred in the Po valley.
