2009年北京市春季大气颗粒PM_(2.5)和黑碳浓度变化特征

为了评价奥运会后车辆限行、施工减少等措施对北京市大气环境质量的影响,利用黑碳仪和颗粒物在线观测仪,于2009年4月26日—5月16日对北京市大气悬浮颗粒PM2.5质量浓度,2009年4月21日—5月21日对黑碳浓度实行连续观测,采用SPSS11.5和EXCEl2003对数据进行统计分析,获PM2.5和黑碳的日均值、小时均值和观测时段内小时均值的连续变化资料。结果表明:观测时段内PM2.5浓度日均值为(9.3±0.2)μg/m3,低于北京市以往同期记录,达到美国EPA的PM2.5推荐标准。黑碳浓度的日均值为(2319±18)ng/m3,低于我国其他城市和北京市历史记录。说明北京市实行的污染源控制手段收到了明显效果。PM2.5浓度呈现周变化趋势,日变化表现两个峰值。黑碳浓度日变化为一峰一谷,未出现以往研究的两个峰值,推测可能受晚间车辆和烹饪活动的影响,晚间峰值被次日升高趋势遮盖。

Concentration Variance of Suspended Particles PM2.5 and Black Carbon in 2009's Spring of Beijing

Aimed to evaluate the effect of vehicle restrictions and construction reduction on air quality in Beijing after the Olympic Games,taking advantage of online black carbon(BC) equipment and particulate monitor,PM2.5 concentration value was continuously monitored from April 26 to May 16 and BC from April 21 to May 21,2009 in Beijing.Observed time series of PM2.5 and BC concentrations were analyzed using software of SPSS11.5 and EXCEl 2003 to get their daily average,hour-average and continuous hour variance.The results showed that daily average value of PM2.5 concentration in the observation period was (9.3±0.2) μg/m3,it was lower than historical records but reaches the suggested PM2.5 standards of USEPA.Daily averaged BC concentration was (2 319±18) ng/m3,respectively,and lower than those in other Chinese cities or in Beijing before.It was implied that control of pollution emission brought an obvious effect on air quality melioration.PM2.5 concentration showed weekly changes and two apexes per day.The pattern of one apex and one bottom was seen for BC,which was different from previous studies showing two apexes.The reason might be that frequent night vehicle and cooking leading to continuous BC increase,covered by next morning apex.Further investigations including longer monitoring and more components analysis should be put on the judgment of Beijing air quality in near future.