QUASI-CONTINUOUS MEASUREMENTS OF NONMETHANE HYDROCARBONS (NMHC) IN THE GREATER ATHENS AREA DURING MEDCAPHOT-TRACE

During the comprehensive field campaign MECAPHOT-TRACE (20 August to 2 0 September 1994) quasi-continuous measurements of NMHC in the range o f C-4-C-12 were carried out for the first time in the Greater Athens a rea simultaneously at two sites, by means of on-line gas;chromatograph ic methods. The results show a heavy load of hydrocarbons in ambient a ir, especially during stagnant weather conditions that favour the deve lopment of land-sea-breeze circulations. Overall the urban hydrocarbon mix reflects the emission of traffic. This influence is confirmed thr ough correlation analyses of hydrocarbon ratios, especially aromatic c ompound ratios, and their dependence on both wind direction and wind v elocity at a suburban receptor site. The ethylbenzene/m-xylene-ratio t urned out to be a good indicator for the impact of anthropogenically r elated hydrocarbon chemistry leading to the formation of secondary pol lutants. Episodes will be discussed that elucidate the importance of h ydrocarbons in the course of ozone formation. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.