对2013～2015北京市PM2.5、气体组分及气溶胶谱分布结合气象条件进行系统的分析,结果表明:2013～2015年PM2.5质量浓度显著降低,空气质量呈明显改善;交通源对大气污染的贡献不能忽略,且呈现出逐渐加重的趋势;相对湿度和风速对PM2.5浓度影响的响应相对较快,滞后1h左右对PM2.5浓度的影响最大,而PM2.5的变化对温度的响应相对较慢,一般在改变温度的7～8h后对污染物浓度的影响最大.污染日较清洁日气溶胶的粒径分布均有不同程度地向大粒子一侧拓宽的现象,清洁日时,峰区直径集中在3～5nm,污染天时,峰区直径增大至100～200nm;随降雨量级逐渐增大,气溶胶峰值浓度逐渐向积聚模态方向发展;2015年2月18至2015年2月21日污染事件中,烟花燃放时段烟花对气溶胶数浓度的贡献为26.1％,且伴随新粒子生成.烟花燃放使积聚模态粒子和爱根核模态粒子出现显著的峰值,核模态粒子浓度变化不大.%PM2.5,gas composition,aerosol spectral distribution and meteorological conditions were systematically analyzed during 2013～2015 in Beijing.Results showed that the PM2.5 mass concentration decreased significantly from 2013 to 2015,and the air quality improved significantly.The contribution of traffic sources to air pollution can not be neglected and tended to increase gradually.The influence of humidity and wind speed on PM2.5 concentration was relatively fast and the biggest influence on PM2.5 concentration was about 1h time lag.While the PM2.5 response to temperature changes was relatively slow,generally after time lag 7～8h before the effect reached to the maximum.The particle size distribution of aerosols moved to the larger size in pollution days than cleaning days.On cleaning days,the diameter of the peak area was concentrated at 3～5nm,and increased to 100～200nm on pollution days.With the increasing of precipitation level,the peak concentration of aerosol gradually developed towards to the accumulation mode.During the pollution process,from February 18 to February 21 in 2015,the contribution of fireworks to aerosol concentration was 26.1％ in fireworks time,and accompanied with new particle generation.The discharged of fireworks produced significant peaks in the Accumulation mode and the Aitken mode particles,the Nuclear mode particle concentration changed not much.
展开▼
