奥运期间北京SO_2、NO_2、O_3以及PM_(10)污染水平及变化特征分析

Investigation of Variation Characteristics and Levels of SO_2,NO_2,O_3 and PM_(10) in Beijing During 2008 Olympic Games

结合遥感所、云岗镇、燕山石化及首都机场4个站点2008年6月至9月期间SO_2、NO_2、O_3以及PM_(10)的监测结果,对北京奥运期间主要污染物浓度水平和变化特征进行分析。PM_(10)为北京市的主要污染物,各时段市区站点PM_(10)均明显高于市郊站点,城郊差异从7月1日至7月19日以及7月20日至8月24日时段的50%减少至8月8日至8月24日以及9月6日至9月17日时段的25%左右。城郊各阶段PM_(10)日变化的差异主要表现在凌晨至11:00前后的时段。一次污染物SO_和NO_2均达到国家大气环境质量二级标准,随着减排措施的实施,降幅均超过14%。从日变化曲线来看,各站点NO_2基本呈双峰型特征,SO_2在燕山石化和云岗镇站点表现出双峰态。O_3作为光化学烟雾的指示剂,各站点O_3呈现出白天高、夜晚低的日变化特征。云岗镇和燕山石化的O_3日变化表现出明显的双峰型。4个站点O_3在实施减排措施的初始阶段呈现出升高的趋势,7月20日后的统计数据表明后期O_3浓度持续下降,平均日变化最大值和最小值的比值减小。各个污染物浓度在8月8日至8月24日时段下降最为显著。相比于7月1日至7月19日减排措施实施的起始阶段,各站点在7月20日至8月24日奥运期间SO_2、NO_2、O_3和PM_(10)降低幅度分别为14%～33%,15%～61%,2.5%～14%和10%～12%。

The concentrations and the variation characteristics of the main pollutants including SO2, NO2, O3 and PM10 during Beijing Olympic Games were investigated based on data collected during the period from June 20th to September 22nd, 2008, at four locations in Beijing： Institute of Remote Sensing Applications, Yungang Town, Yanshan Petrochemical and Capital Airport. PM10 is reported to be the major pollutant. The analysis shows a significant higher level of PMlo in urban site than in rural. A ratio difference of 50% for PM10 between rural and＇ urban site in the first period （from July 1st to 19th and from July 20th to August 24th） was observed, which decreased to about 25% during the second period （from August 8th to 24th and from September 6th to 17th）. The difference on diurnal variation of PM10 mainly appeared during 01：00-11：00. The concentrations of primary pollutant SOs and NO2 were below the Grade-II standards. With the implementation of mitigation measures, a decrease of the above two pollutants exceeded 14%. The results also showed that diurnal variation of NO2 had a very clear cycle with two peaks in most stations, but only the case for SO2 in Yanshan Petrochemical and Yungang Town stations. As the indicator of photochemical smog O3 exhibited an obvious diurnal variation with high levels during daytime and low levels in nighttime. Two peaks of O3 diurnal variation during daytime were observed in Yanshan Petrochemical and Yungang Town stations. Based on the statistical data the levels of O3 increased at the early stage of reduction of pollutant emissions （before July 20th） and then continuous declined. The ratios of the maximum to minimum for O3 showed a downward trend after June by analyzing the different diurnal patterns. Each pollutant of the above revealed a remarkable drop during the period from August 8th to 24th, 2008. Comparing the statistical data obtained from July 1st to 19th, with those obtained from July 20th to August 24th in 2008, SO2, NO2, O3 and PM10 decreases by 14%-33%, 15%-61%, 2.5%-14% and 10%-12% respectively. Key words： SO2; NO2; PO3; PM10; photochemical pollution; air quality