Aerosol formation studies on aromatic hydrocarbons in the EUPHORE outdoor simulation chamber
Abstract
The present work is an experimental study on the formation of secondary organic aerosol during the photochemical oxidation of aromatic hydrocarbons in an environmental smog chamber under realistic conditions, i.e., low precursor concentrations and natural solar irradiation. A series of newly designed smog chamber irradiations were performed in the EUPHORE chambers (Valencia, Spain) in which concentration levels of precursors were chosen to be near to those measured in urban atmosphere. The objective was to determine the aerosol formation potential of aromatic hydrocarbons under conditions that are prevalent in the urban atmosphere. The obtained experimental results on aerosol yields and organic threshold for aerosol formation have been used to determine the parameters controlling aerosol formation from toluene, benzene, p-xylene and 1,3,5-trimethylbenzene photo-oxidation and to investigate the possible reaction channels responsible for the formation of condensable material. The comparison of the aerosol yields obtained in the present work with previous data indicates that the NOx content in the aromatic system has a strong influence on the aerosol formation during the photochemical oxidation of aromatic hydrocarbons. Nitrogen oxides, and in particular NO, are seen as key species controlling particle formation during the photochemical oxidation of these species; this contrasts with previous work where the aerosol formation capacity was attributed to the presence or the absence of ozone in the system. The results show that there is a competition between OH and NO_3 radicals to form secondary products that act as aerosol precursors, and therefore a dependence of aerosol formation on the NOx content in the system is observed.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....9047W