| Popis: |
Ambient levels of six carbonyls, formaldehyde (⩽70 ppb), acetaldehyde (⩽56 ppb), propanal, (⩽37 ppb), n-butanal (⩽8 ppb), 2-butanone (⩽15 ppb) and benzaldehyde (⩽2 ppb) have been measured in samples collected at several locations in the Los Angeles area. Reasonable agreement for formaldehyde, but significant discrepancies for other carbonyls, were found when comparing carbonyl/CO ratios measured at a near-source location to those derived from emission inventories, e.g., total carbonyl emission rate of ∼ 30 tons/day from measured ratios vs. ∼ 70–80 tons/day from inventory data. Comparison of carbonyl/CO ratios at the smog receptor and near-source locations indicates that photochemical production of carbonyls, up to 500 tons/day during smog episodes, dominates over direct emissions in controlling carbonyl levels in Los Angeles air. |
