Formaldehyde(HCHO)and glyoxal(CHOCHO)are important oxidization intermediates of most volatile organic compounds(VOCs),but their vertical evolution in urban areas is not well understood.Vertical profiles of HCHO,CHOCHO,and nitrogen dioxide(NO2)were re-trieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)observations in Hefei,China.HCHO and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO2,which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher altitudes.Monthly means of HCHO concentrations were higher in summer,while enhanced amounts of NO2 were mainly observed in winter.CHO-CHO exhibited a hump-like seasonal variation,with higher monthly-averaged values not only occurred in warm months(July-August)but also in cold months(November-December).Peak values mainly occurred during noon for HCHO but emerged in the morning for CHO-CHO and NO2,suggesting that HCHO is stronger link to photochemistry than CHOCHO.We further use the glyoxal to formaldehyde ratio(GFR)to investigate the VOC sources at differ-ent altitudes.The lowest GFR value is almost found in the altitude from 0.2 to 0.4 km,and then rises rapidly as the altitude increases.The GFR results indicate that the largest con-tributor of the precursor VOC is biogenic VOCs at lower altitudes,while at higher altitudes is anthropogenic VOCs.Our findings provide a lot more insight into VOC sources at vertical direction,but more verification is recommended to be done in the future.

Qianqian Hong;Cheng Liu;Qihou Hu;Yanli Zhang;Chengzhi Xing;Jinping Ou;Weei Tan;Haoran Liu;Xiaoqing Huang;Zhenfeng Wu

School of Environment and Civil Engineering,Jiangnan University,Wuxi 214122,China;Center for Excellence in Regional Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,China;Key Lab of Environmental Optics&Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;Department of Precision Machinery and Precision Instrumentation,University of Science and Technology of China,Hefei 230026,China;Anhui Province Key Laboratory of Polar Environment and Global Change,University of Science and Technology of China,Hefei 230026,China;Guangdong Key Laboratory of Environmental Protection and Resources Utilization,State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality,Guangzhou 510632,China;Institute of Physical Science and Information Technology,Anhui University,Hefei 230601,China

环境科学学报（英文版）

[1]Qianqian Hong;Cheng Liu;Qihou Hu;Yanli Zhang;Chengzhi Xing;Jinping Ou;Weei Tan;Haoran Liu;Xiaoqing Huang;Zhenfeng Wu-.Vertical distribution and temporal evolution of formaldehyde and glyoxal derived from MAX-DOAS observations:The indicative role of VOC sources)[J].环境科学学报（英文版）,2022(12):92-104

CHOCHO,trieved

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