Spatial and Temporal Variations of Ambient Carbonyl Compounds in Beijing and Its Surrounding Areas
北京及周边地区大气羰基化合物的时空分布特征初探

Concentrations of 23 carbonyl compounds were measured by DNPH/HPLC method at 38 sites within Beijing and its surrounding areas on June 24, July 22, August 22, September 14 in 2010 and January 13, 2011.The average mixing ratios of total carbonyl compounds in Beijing were (16.38±6.03) ×10-9 and (8.50±5.27) ×10-9 in summer and winter; and the average mixing ratios in surrounding cites were (13.19±5.71) ×10-9 and (13.05±2.44) ×10-9 in summer and winter, respectively. The most abundant carbonyl compound was formaldehyde, followed by acetaldehyde and acetone, the sum of these 3 species accounted for 78% to 91% of the total mixing ratio of carbonyl compounds. The average mixing ratio in summer was significant higher than that in winter, and higher in morning (09:00-12:00) hours than in afternoon (13:00-16:00). The spatial distributions for carbonyl compounds showed that:in summer, high mixing ratios were typically found in city center; while in winter, a building-up trend was found from northwest to southeast, driving by the prevailing northwest wind. In summer, vehicular exhaust had important contributions to ambient carbonyls, and combined with the adverse weather conditions and the strong photochemical production, resulted in carbonyls pollutions; in winter, directly emissions were the main sources of carbonyls, such as vehicular exhaust and coal burning.