Significance of HOx and peroxides production due to alkene ozonolysis during fall and winter: A modeling study

In an attempt to identify new mechanisms for the generation of oxidants dur ing fall and winter, we carried out a modeling investigation in which ozono lysis reactions of alkenes that were primarily anthropogenic in origin were considered. Our results indicate that the ozonolysis reactions of these mo lecules can be the major sources of HOx, H2O2, and organic peroxides during the night and therefore especially during dark seasons. These O-3-initiate d oxidation reactions produce more peroxy radicals than those initiated by HO or NO3. This increase in RO2 also results in an increase in HO, HO2, and H2O2. The direct HO formation pathways by ozonolysis of alkenes can form m ore HO radicals than that from the reaction of O(D-1) + H2O during the dark seasons, This additional source of HO can augment significantly atmospheri c oxidation. H2O2 formation by ozonolysis also appears to be the most impor tant dark season tropospheric sources of this oxidant. Our modeling results suggest that the existence of pollutant hydrocarbons and trace amount of b iogenically produced terpenes can also lead to important production of HOx, H2O2, and organic peroxides, Substantially enhanced gasphase production of H2O2 and organic peroxides due to ozonolysis reactions can cause significa nt liquid-phase oxidation of S(IV) to S(VI), and hence the role of ozonolys is reactions can be important for the sulfur conversion studies.