| Carbonyl compounds are ubiquitous species in the atmosphere,participating in the atmospheric chemistry in the troposphere and having an important effect on free radicals and human health.Central China is the heart of China's agriculture and industry with developed economy and convenient land and water transportation.As the rapidly developed urbanization and industrialization in the central region,the environmental pollution has appeared and can't be ignored.But the studies about carbonyl compounds are limited in central areas.Three typical areas were recognized as urban(ZY),suburban(JX)and background(JS)sites in this study.Based on the air collected samples,the spatial and temporal distribution characteristics of carbonyl compounds were analyzed.Source of formaldehyde was identified by using the multiple linear regression model at ZY and JX sites.The effect of air masses transport to JS site was also investigated by using the HYSPLIT model.The study can provide scientific data and research basis on the control of atmospheric carbonyl compounds in Central China.The average concentrations of total carbonyl compounds were decreasing in the order of ZY(21.98±8.60?g/m3)>JX(17.42±8.34?g/m3)>JS(13.50±6.60?g/m3).Formaldehyde,acetaldehyde and acetone were the three most abundant species in the atmosphere.For the seasonal variation,there were similar trends at ZY,JX and JS.The concentration of formaldehyde was high in summer and low in winter,while the concentrations of acetaldehyde and acetone had an opposite trend.For the diurnal variation,formaldehyde had a distinct characteristic in summer,and the concentration was high during 9:00-11:00 while it decreased during 12:00-14:00.Acetaldehyde and acetone had a distinct characteristic in winter at ZY and JX,and high concentrations were observed during 9:00-11:00 and 19:00-21:00 while low values appeared during12:00-16:00.Ratios and correlation analysis were used to investigate the potential sources of carbonyl compounds.High values of C1/C2 and C2/C3 with a strong correlation between carbonyl compounds with O3 suggested that the photochemical reactions of natural volatile organic compounds(VOCs)are an important source for carbonyl compounds in summer.In winter,low values of C1/C2 and C2/C3 were observed for all sampling sites.At ZY and JX,the strong correlation between formaldehyde and CO indicated that formaldehyde might come from the vehicular exhaust in winter.In addition,strong correlation between formaldehyde,acetaldehyde and NO2,CO at JS implied the effect of air masses transport.Multiple linear regression model was used to identify the relative source contributions of HCHO in summer and winter at ZY and JX.The result showed the high contributions of 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).HYSPLIT model was used to analyze the effects of air masses transport on the concentrations of carbonyl compounds at JS.In winter,air masses from southwest was the source of formaldehyde and acetaldehyde,while air masses from southeast would increase the concentration of acetone.In summer,air masses from southeast originated from the continent had a higher concentration of carbonyl compounds.As for spring and autumn,air masses from different directions had equal effects on the carbonyl compounds at JS. |
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