COMPARISON OF H2O2 AND O3 CONTENT IN ATMOSPHERIC SAMPLES IN THE SAN-BERNARDINO MOUNTAINS, SOUTHERN CALIFORNIA

Concentrations of atmospheric H2O2 Were measured in air, rain, cloud a nd dew samples in forested areas of the San Bernardino Mountains, sout hern California, from spring through fall of 1987-1990. O3 measurement s in air were also conducted for comparison. Typical ranges of H2O2 co ncentrations measured were 1-3 ppb in air, 10-90 muM in rain and cloud water, and < 1 muM in dew. The results show that gas-phase H2O2 conce ntrations were slightly higher at nighttime than at daytime or nearly constant throughout a 24-hr period, whereas O3 concentrations were hig hest during the afternoon when polluted air masses from Los Angeles ca rried by daily sea breezes reached the mountain region. Afternoon conc entrations of gaseous H2O2 and O3 in the mountain region were compared with those measured in Los Angeles urban sites to elucidate the regio nal variation of these oxidants. The results show that ambient concent rations of H2O2 and O3 were about 50-100% higher at the mountain sites than at the Los Angeles sites.