Wang Xin, Shen Zhenxing, Cao Junji, Zhang Leiming, Liu Li, Li Jianjun, Liu Suixin, Sun Yufan
Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, China.
J Environ Monit. 2012 Jan;14(1):116-26. doi: 10.1039/c1em10541h. Epub 2011 Nov 9.
Surface ozone concentrations in Xi'an, China were monitored from March 23, 2008 to January 12, 2009 using the Model ML/EC9810 ozone analyzer. The daily average O(3) ranged from <1 ppb to 64.2 ppbv with an annual average of 16.0 ppbv. The seasonal average of O(3) in summer (32.5 ppbv) was more than 10 times higher than that in winter (3.0 ppbv). A significant positive correlation was found between ozone concentration and ambient temperature, indicating that the intensity of solar radiation was one of the several major factors controlling surface ozone production. Using the NOAA HYSPLIT 4 trajectory model, the three longest O(3) pollution episodes were found to be associated with the high biogenic volatile organic carbon (BVOC) emissions from the vegetation of Qinling Mountains. No significant weekday and weekend difference in O(3) levels was detected due to the non-significant change in NO(x) emissions. O(3) depletion by NO emission directly emitted from vehicles, low oxygenated VOC concentrations, and low-level solar radiation caused by high aerosol loading all contributed to the low levels of O(3) found in Xi'an compared to other cities and rural areas.
2008年3月23日至2009年1月12日期间，利用ML/EC9810型臭氧分析仪对中国西安的地表臭氧浓度进行了监测。每日平均O₃浓度范围为<1 ppb至64.2 ppbv，年平均浓度为16.0 ppbv。夏季O₃的季节平均浓度（32.5 ppbv）比冬季（3.0 ppbv）高出10倍以上。臭氧浓度与环境温度之间存在显著的正相关关系，这表明太阳辐射强度是控制地表臭氧生成的几个主要因素之一。利用美国国家海洋和大气管理局（NOAA）的HYSPLIT 4轨迹模型，发现三次最长的O₃污染事件与秦岭植被中高生物源挥发性有机碳（BVOC）排放有关。由于NOₓ排放没有显著变化，未检测到O₃水平在工作日和周末有显著差异。与其他城市和农村地区相比，车辆直接排放的NO导致的O₃消耗、低氧化态挥发性有机化合物浓度以及高气溶胶负荷导致的低水平太阳辐射，都是造成西安O₃水平较低的原因。
