Characteristics of atmospheric carbonyls pollution in winter around petrochemical enterprises over North China

Carbonyl compounds cause adverse effect on human health and play important roles in the atmospheric chemical reactions in the troposphere. However, their characteristics and complicated environmental impacts were poorly understood around petrochemical enterprises over North China. In this study, we found that acetone (2.8 +/- 1.39 ppbv), acetaldehyde (2.74 +/- 1.45 ppbv) and formaldehyde (2.73 +/- 1.48 ppbv) were the three most abundant carbonyls, accounting for about 85% of the total concentration of the 15 carbonyls measured in the petrochemical industrial area of Jinan during the winter. The dominant sources of atmospheric carbonyls were vehicle exhaust, petrochemical processes and residential combustion as inferred by the good correlation between carbonyls and primary pollutants such as CO and NOx and the diagnostic ratios of formaldehyde to acetaldehyde (C-1/C-2, 1.00 +/- 0.11). In addition, backward trajectories suggest that air mass transport also contributes to carbonyl compounds. Furthermore, carbonyls showed strong positive correlation with PM2.5, probably due to the promoting effect of carbonyl compounds on atmospheric oxidation capacity (AOC), which in turn makes PM2.5 concentration increase. On the other hand, PM2.5 photochemical aging causes an increase in secondary carbonyls concentration. Overall, the present study indicates considerable impacts of carbonyls on PM2.5 pollution in petrochemical enterprises area and suggests the urgent need for intensive study on the related processes.