Black carbon (BC) plays a significant role in climate change, which has attracts increasing research interest. Single Particle Soot Photometer (SP2) is used at Wuqing Meteorological Station in Tianjin. SP2 u-tilizes the high optical power available intra-cavity from a Nd: YAG laser as the analytical technique. Light absorbing particles, mainly BC in atmosphere, absorb sufficient energy and are heated to the point of incandescence. The energy emitted in this incandescence is measured, and quantitatively determine the mass of the particle. SP2 operates in a single particle mode, measuring the light scattering and incandescence of each particle. Through the time delay between the two signals, the mixing state of BC particles can be obtained. SP2 is different from the traditional filter-based method which could provide more accurate information on single BC particle properties. First, SP2 could count the BC particles individually, so BC number concentration could be given; second, SP2 measures the mass of each BC particle, which could be converted to particle size; finally, SP2 could give the information on BC mixing state, which is important for estimating the aerosol effect on climate change.The observation taken at Wuqing in December 2009 shows that the average number concentration of BC is 1504 cm-3, with the maximum 5050 cm-3 and the minimum 46. 8 cm-3. The number of BC particles occupies 57. 2% of the aerosol particles measured by SP2. The average number concentration of non-absorbing aerosol is 1124 cm-3, with the maximum 3311 cm-3 and the minimum 70. 7 cm-3. The average mass concentration of BC is 8. 15 μg/m3. 51. 5% of BC particles are thickly coated. On a clear windy day, the daily average number concentration is 215 cm-3 ,the mass concentration is 1.17 μg/m3, and 40. 2% of them are mixed. However in the seriously polluted case, the daily average number concentration is 3169 cm-3 ,the mass concentration reaches 17. 2 μg/m3, and the ratio of mixed BC also increases to 78. 7%.%该文介绍了单颗粒黑碳测量仪的观测原理,该仪器利用红外波段的连续激光束对黑碳粒子加热并使之燃烧,通过粒子发出的散射光信号和黑碳粒子燃烧时发出的光信号,来分析每一个黑碳粒子的特性,并通过两种信号的时间差判断黑碳粒子的混合状态.其原理有别于传统的黑碳气溶胶观测方法,可以提供单个黑碳气溶胶粒子特性信息.2009年12月使用单颗粒黑碳测量仪在天津市武清地区进行了为期近1个月的观测.结果表明:粒径为50～500 nm的气溶胶粒子中,黑碳气溶胶粒子占57.2％,平均数浓度为1504 cm-3,黑碳气溶胶粒子的平均质量浓度为8.15 μg/m3,包衣较厚的混合型黑碳气溶胶粒子占黑碳气溶胶粒子的51.5％.
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