Interactions between chlorinated and biogenic compounds.

BEMA (Biogenic Emissions in the Mediterranean Area) researches are mainly f ocused on biogenic compound impact on tropospheric chemistry (especially oz one formation). Three sites have been studied: Castelporziano (Italy), Montpellier (France) and Burriana (Spain). Biogenic and Anthropic VOCs were detected demonstrat ing that it is quite difficult to find purely biogenic sites. Moreover, upc oming atmospheric air masses loaded with chlorinated VOCs could fly over su ch forests emitting many terpene compounds. So, the interactions between BVOCs and AVOCs have been simulated in a smog chamber in presence of OH radicals. It has been pointed out that when chlor inated compounds were present, the beta-pinene degradation seemed to be enh anced. Thus, after one hour reaction, with ethene trichloro, the degradated beta-pinene quantity was about twice higher than without any chlorinated c ompound. Moreover, in the presence of ethene trichloro and ethane 1,1,1-tri chloro, the beta-pinene rate constant with OH radicals increased as followi ng constant were determined: k(OH [with chlorinated VoCs]) = 95+/-6 cm(3).molecules(-1).s(-1) k(OH) ([without chlorinated VOCs]) = 78+/-8 cm(3).molecules(-1).s(-1).