敦煌地区春冬季黑碳气溶胶观测研究

Observation on black carbon aerosol in spring and winter in Dunhuang area

利用2012年4月和12月敦煌的黑碳气溶胶(Black Carbon,简称BC)小时平均质量浓度、散射系数、能见度和地面观测资料,对BC质量浓度的变化,以及风速、风向对BC质量浓度的影响以和BC的吸收消光特性进行了分析。结果表明:BC质量浓度冬季大于春季,其中4月和12月BC质量浓度平均值分别为2.56μg/m^3和3.93μg/m^3。风速在(0~3)m/s区间时,BC质量浓度随风速的增加而迅速降低;风速在(3~6)m/s区间时,浓度与风速关系不大;风速大于6m/s时,浓度随着风速的增加而波动变大。4月和12月人类活动所排放的BC质量浓度是排放前的3.44倍和3.74倍。4月和12月偏东风和西风的风速大,对应在此风向上的BC质量浓度较低,南风和北风风速小,对应的BC质量浓度较高。汽车排放与燃煤是敦煌地区主要的BC污染源。4月和12月BC吸收消光分别占大气总消光系数的7.25%和8.54%,BC吸收消光分别占大气总吸收消光系数的19.82%和27.58%,能见度与BC质量浓度呈典型的负相关。

Based on the hourly averaged data of black carbon aerosol（ BC） mass concentration,scattering coefficient and visibility in April and December 2012 of Dunhuang,the variation of BC mass concentration and the absorption coefficient characteristics of BC were analyzed. Results showed that BC mass concentration in winter was much larger than spring. In April and December,the averages of BC were 2. 56μg/m^3 and 3. 93μg/m^3,respectively. The time of maximum concentration coincided with the time of human activities. When the wind velocity was in the range of（ 0 ～ 3） m/s,the concentration of BC decreased rapidly with the increase of wind speed,the concentration was not related to wind speed in the range of（ 3 ～ 6） m/s,and when the wind speed was greater than 6 m/s,the concentration fluctuated with the increase of wind speed. The concentration of black carbon aerosol emitted by human activities was 3. 44 times higher than that before in April,and 3. 74 times in December.The easterly winds and the westerly winds were the highest in April and December,corresponding to the lowest concentration of BC in this wind direction. South wind and north wind speed were low,corresponded with the high concentration of BC. Vehicle emissions and coal might be the main source of BC pollution in Dunhuang.The extinction of BC in April accounted for 19. 82% of the total absorption extinction coefficient,and the December was for 27. 58%.