Fluxes and concentrations of volatile organic compounds above central London, UK
Fluxes and concentrations of volatile organic compounds above central London, UK
复制标题
DOI：
10.5194/acp-10-627-2010
复制
发表时间：
2010-01-01
影响因子：
6.3
通讯作者：
Hewitt, C. N.
中科院分区：
文献类型：
--
作者：
Langford, B.;Nemitz, E.;Hewitt, C. N.
2006年10月，在伦敦市中心的一座高楼上测量了8种挥发性有机化合物(VOC)的浓度和通量，这是CityFlux对ReparteI活动的贡献的一部分。采用连续流动分离涡旋协方差技术，并结合质子转移反应质谱仪进行分析。含氧化合物(甲醇、乙醛和丙酮)的日平均VOC混合比为1-19 ppb，芳香族化合物(苯、甲苯和C-2-苯)的VOC混合比为0.2-1.3 ppb。典型的VOC通量范围为0.1-1.0 mg m(-2)h(-1)。大多数被测化合物的VOC通量与交通密度之间存在非线性关系。据估计，交通活动约占芳香化合物通量的70%，而与交通无关的来源对甲醇和异戊二烯的通量更重要。测得的排放通量与英国国家大气排放清单中芳香族挥发性有机化合物和一氧化碳的估计值相当。相比之下，含氧化合物的通量大约是库存估计的三倍。对于异戊二烯和乙腈，这一差异要大许多倍。在超过25摄氏度的温度下，据估计，在伦敦市中心观察到的异戊二烯有一半以上是生物来源的。
Concentrations and fluxes of eight volatile organic compounds (VOCs) were measured during October 2006 from a high telecom tower above central London, as part of the CityFlux contribution to the REPARTEE I campaign. A continuous flow disjunct eddy covariance technique with analysis by proton transfer reaction mass spectrometry was used. Daily averaged VOC mixing ratios were within the range 1-19 ppb for the oxygenated compounds (methanol, acetaldehyde and acetone) and 0.2-1.3 ppb for the aromatics (benzene, toluene and C-2-benzenes). Typical VOC fluxes were in the range 0.1-1.0 mg m(-2) h(-1). There was a non-linear relationship between VOC fluxes and traffic density for most of the measured compounds. Traffic activity was estimated to account for approximately 70% of the aromatic compound fluxes, whereas non-traffic related sources were found to be more important for methanol and isoprene fluxes. The measured fluxes were comparable to the estimates of the UK national atmospheric emission inventory for the aromatic VOCs and CO. In contrast, fluxes of the oxygenated compounds were about three times larger than inventory estimates. For isoprene and acetonitrile this difference was many times larger. At temperatures over 25 degrees C it is estimated that more than half the isoprene observed in central London is of biogenic origin.