杭州市道路空气中挥发性有机物及其大气化学反应活性研究

研究了夏季杭州市主要类型道路（隧道、快速道路、主干道和支路）空气中挥发性有机物的污染特征,以及2010年11月—2011年7月间快速道路空气中VOC的季节变化规律.分析结果表明,杭州市道路空气中VOC浓度显著大于风景区内VOC浓度,隧道浓度最高（828.4μg·m-3）,其它道路空气中VOC浓度随着车流量减少而降低.源解析结果发现道路空气中VOC的主要贡献者为机动车排放,但同时也受到溶剂挥发、煤或生物质燃烧的影响,风景区内VOC则受煤或生物质燃料燃烧的影响更大.快速道路空气中VOC浓度和反应活性由机动车排放、植物排放和气象条件共同决定,呈现夏〉秋〉冬〉春的季节变化特征.机动车排放的烯烃和芳香烃是道路空气中主导的活性VOC物种,说明机动车排放是杭州市大气反应活性的最大贡献者.此外,在夏、秋季节,植被排放的异戊二烯显著的增强了道路空气中VOC的反应活性.

Analysis of volatile organic compounds (VOCs) and their atmospheric chemical reactivity in ambient air around urban traffic roads in Hangzhou

Volatile organic compounds(VOCs)in the ambient air were measured around main types of urban traffic roads (tunnel, expressway, trunk road and brach) from October 2010 to July 2011 in Hangzhou, China. The results showed that VOC concentration around the traffic roads was much higher than that in scenic spot, and the concentration decreased with the decrease of vehicle flow rate. Source apportionment results indicated that the VOCs in Hangzhou mainly came from anthropogenic sources, including vehicle emission, solvent evaporation, biomass fuel and coal burning. The VOCs around the traffic roads were mainly influenced by vehicle emissions, while the VOCs in scenic spot were more readily impacted by biomass fuel or coal burning. The concentration and chemical reactivity of VOCs around expressway was the highest in summer and lowest in spring, which was influenced by vehicle emissions, temperature, biogenic VOC and topographic conditions. Alkenes and aromatic compounds from the vehicle emissions contributed more than 80% of the VOCs reactivity in the air around all kinds of the traffic roads, suggesting that the VOCs reactivity in ambient air in Hangzhou was determined mainly by vehicle emissions. In summer and autumn, the emission of isoprene from plants increased the VOCs reactivity in the air around roads remarkably.