2005～2006年秋冬季西宁大气中黑碳气溶胶的浓度变化特征

Change Features of Black Carbon Concentration in Atmosphere in Xining from Autumn of 2005 to Winter of 2006

结合气象观测资料,对2005年9月—2006年2月在西宁获得的黑碳气溶胶(BC)观测资料进行了分析。结果表明,该地区秋冬季大气黑碳气溶胶浓度变化比较剧烈,日平均浓度为4.211μg/m3,其变化范围为1.04~9.65μg/m3;由于局地人为活动和大气垂直对流扩散等的影响,BC浓度的日变化具有明显的双峰值特征,即BC高浓度出现在上午9:00~11:00和傍晚19:00~21:00两个时段,低浓度出现在凌晨0:00~5:00和下午14:00~17:00;与附近(90 km处)瓦里关全球大气本底站的黑碳气溶胶浓度相比,偏高约17倍,但与国外一些城市和我国已监测的几个城市相比还是较低;由小时平均浓度最大出现频数统计分析得出该地区大气黑碳气溶胶本底浓度约为2.300μg/m3。

The meteorological data and concentration values of Black Carbon(BC) aerosol were analysed in Xining from Sep.2005 to Feb.2006.The results show that the concentration variations of BC in this area is greater during autumn and winter,and daily average concentration is 4.211 μg/m3 with the range 1.04~9.65 μg/m3.In addition,the daily variation of BC concentration is characterized by a pronounced double-peak patterns,and with the highest concentration during 9:00~11:00 and 19:00~21:00 and lowest during 0:00~5:00 and 14:00~17:00,which is attributed to human activity and atmospheric vertical convection diffusion.The BC concentration in this area is 17 times larger than the value observed at Waliguan Global Atmospheric Baseline Observatory(90 km from Xining).But it is still lower compared with some cities at home and abroad.The base BC concentration of this study area is about 2.300 μg/m3 based on the maximum frequency of hourly mean concentration.