Measurements of volatile organic compounds in the middle of Central East China during Mount Tai Experiment 2006 (MTX2006): observation of regional background and impact of biomass burning

摘要

The measurement of volatile organic compounds (VOCs) was carried out at thesummit of Mount Tai, located in the center of the Central East China (CEC)region, in June 2006 as part of the Mount Tai Experiment 2006 (MTX2006),which focused on the ozone and aerosol chemistry in the region. Temporalvariations of simple VOCs between 2 June and 28 June revealed thecharacteristics of an aged air mass with minimum local influence. Acomparison of VOCs observed at Mount Tai with other Chinese sites revealedrelatively similar VOC levels to remote sites and, as expected, a lowerlevel compared to more polluted sites. However, relatively high acetyleneand benzene levels at Mount Tai were evidently indicated from comparisonwith normalized VOC profile by ethane suggested for Beijing. Owing to ashift in boundary layer height, we observed considerable differences betweendaytime and nighttime VOC mixing ratios. This suggests that the sitepotentially has a very useful characteristic of being able to measureregional polluted air and the free troposphere regional background airquality. Influence of emissions from biomass burning in the region wasevidently found to be extensive during the first half of the campaign(2–15 June), using fire spot data coupling with backward trajectory analysis.Agricultural residue burning was suggested as the primary source ofemissions elucidated by the slope of the correlation plot between CHCland CO obtained during the first half of the campaign.