Ho K F, Lee S C, Guo H, Tsai W Y
Department of Civil and Structural Engineering, Research Center for Urban Environmental Technology and Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
Sci Total Environ. 2004 Apr 25;322(1-3):155-66. doi: 10.1016/j.scitotenv.2003.10.004.
Ambient VOCs samples were collected at three locations (PolyU campus (PU), Kwun Tong (KT), Hok Tsui (HT)) in Hong Kong during the periods of November 2000-February 2001 and June 2001-August 2001. Also the concentrations of VOCs in Cross Harbor tunnel in Hong Kong were obtained in order to determine the vehicular sources of VOCs. Toluene was the most abundant VOC detected in Hong Kong. At the PU station, which is close to a main road, the concentrations of most VOCs were higher in summer than in winter. However, at the background location HT, the concentrations of all VOCs except tetrachloroethene were higher in winter than in summer. Regional physical dispersion/transportation and mixing depth may be the reasons for higher VOC concentrations in winter at HT. The BTEX (benzene:toluene:ethylbenzene:xylene) ratios of PU and KT during winter period were (1.9:10.1:1.0:1.8) and (1.9:10.4:1.0:1.5), and (0.9:8.3:1.0:2.2) and (0.8:29.6:1.0:1.8) for summer season, respectively. The xylene/ethylbenzene (X/E) ratio was used to assess the relative age of the air parcels in this study. The concentrations of VOCs in the atmosphere in Hong Kong were mainly affected by direct emissions from vehicles, evaporation of fuels, photochemical reactions and few industrial emissions. The BTEX ratio in the tunnel was 2:10.4:1:3.2. The BTEX ratios at PU and KT during the winter period were similar to that in tunnel (except for xylenes). The X/E ratio in the tunnel was higher than that in the ambient air. This indicated that the freshly emitted xylenes in the tunnel decayed at different rates from OH-oxidation in the atmosphere. Good BTEX correlations (r>0.8) were found at PU and KT in winter (**P<0.01). Vehicular exhaust was the dominant source at PU and KT stations, and less evaporation of fuel or additive occurred at low temperature in winter. Diurnal variations of mean BTEX concentrations at the roadside monitoring station (PU) showed two peaks associated with traffic density and vehicle type.
2000年11月至2001年2月以及2001年6月至8月期间，在香港的三个地点（香港理工大学校园（PU）、观塘（KT）、鹤咀（HT））采集了环境挥发性有机化合物（VOCs）样本。此外，还获取了香港海底隧道内VOCs的浓度，以确定VOCs的车辆来源。甲苯是在香港检测到的含量最高的VOC。在靠近主干道的PU站点，夏季大多数VOC的浓度高于冬季。然而，在背景站点HT，除四氯乙烯外，所有VOC的浓度冬季均高于夏季。区域物理扩散/传输和混合深度可能是HT冬季VOC浓度较高的原因。冬季期间PU和KT的苯系物（苯：甲苯：乙苯：二甲苯）比例分别为（1.9:10.1:1.0:1.8）和（1.9:10.4:1.0:1.5），夏季分别为（0.9:8.3:1.0:2.2）和（0.8:29.6:1.0:1.8）。本研究中使用二甲苯/乙苯（X/E）比例来评估气团的相对年龄。香港大气中VOC的浓度主要受车辆直接排放、燃料蒸发、光化学反应以及少量工业排放的影响。隧道内的苯系物比例为2:10.4:1:3.2。冬季期间PU和KT的苯系物比例与隧道内的相似（除二甲苯外）。隧道内的X/E比例高于环境空气中的。这表明隧道内新排放的二甲苯在大气中因羟基氧化而以不同速率衰减。冬季在PU和KT发现了良好的苯系物相关性（r>0.8）（**P<0.01）。在PU和KT站点车辆尾气是主要来源，冬季低温时燃料或添加剂的蒸发较少发生。路边监测站（PU）苯系物平均浓度的日变化显示出与交通密度和车辆类型相关的两个峰值。
