Characteristics of atmospheric carbonyls during haze days in Beijing, China

Characteristics of atmospheric carbonyls during haze days in Beijing were studied in August 2006. Formaldehyde (35.65 ± 14.74 μg/m3), acetaldehyde (15.65 ± 12.37 μg/m3) and acetone (8.83 ± 5.23 μg/m3) are three most abundant carbonyls, accounting for ~ 75% of total carbonyls. Their levels and O3 clearly peaked in the afternoon (especially for formaldehyde), implying photochemical formation. The observed C1/C2 (2.69 ± 0.78) and C2/C3 (6.29 ± 2.87) ratios indicated the important influence of anthropogenic source on carbonyls, and the higher C1/C2 (2.69) ratio in haze days also implied photochemical formation of carbonyls. Correlation coefficient (R2) among formaldehyde, acetaldehyde, acetone and total carbonyls were 0.66–0.95 together with C1/C2 ratio analysis and diurnal variations of carbonyls and O3, indicating ambient carbonyls in haze days of Beijing are mainly dominated by photochemical formation.