Chemical characteristics of atmospheric carbonyl compounds and source identification of formaldehyde in Wuhan, Central China

The chemical characteristics of carbonyl compounds were investigated concurrently at urban (ZY) and suburban (JX) sites in Wuhan in 2017. Thirteen carbonyl compounds were quantified, with average total mixing ratios of 11.29 ± 3.85 ppbv at ZY and 8.72 ± 3.75 ppbv at JX. Formaldehyde (HCHO), acetaldehyde (CH3CHO) and acetone (CH3COCH3) were the three most abundant atmospheric carbonyl compounds, accounting for >85% of the total carbonyl compound mixing ratio at both sites. HCHO exhibited highest concentrations during summer and lowest concentrations during winter at ZY and JX. In contrast, CH3CHO and CH3COCH3 showed an opposite seasonal trend, suggesting that HCHO may be mainly generated by photochemical reactions in summer, while CH3CHO and CH3COCH3 might be originate from primary emissions in winter. Diurnal variations were assessed, with HCHO exhibiting peak values at midnight in all seasons, with levels associated with diesel-fuel vehicle emissions. High ratios of C1/C2 and C2/C3 were observed in summer at ZY and JX, suggesting biogenic sources significantly contribute to carbonyl compound formation. Furthermore, linear regression analysis showed a high HCHO contribution from primary sources in winter (73.5% at ZY, 58.6% at JX) and secondary sources in summer (67.2% at ZY, 47.4% at JX). The results of this study will help formulate effective emission control strategies for carbonyl pollution in Wuhan.