Studies on Size Distribution and Mixing State of Black Carbon Aerosols in China

最近东亚工业活动的快速增长已造成该地区气溶胶的大量增加。大气气溶胶通过散射和吸收改变辐射收支。由于黑碳气溶胶（如烟尘）对太阳辐射的有效吸收，已被公认为是太阳辐射最重要的气溶胶化合物之一，是引起气候变化最重要的气溶胶化合物之一。在2006物理年，北京大学研究小组和其他一些国际研究小组在中国北京地区和珠江三角洲地区测量了BC的质量浓度、粒度分布和混合状态。同时测量了气溶胶的化学成分和其他一些参数。在物理年2007年，利用三维化学输运模型从排放源、化学生产、输运过程和去除过程等方面对这些数据进行了精确分析和解释。观测结果表明，北京地区BC浓度日变化明显，夜间最大。模式计算通过边界层高度等日变化很好地再现了这一特征。虽然发现次生气溶胶（如无机气溶胶）的日变化很大，但它们对BC的影响很小。模型计算表明，前24小时内，北京周边100公里范围内的BC浓度基本受BC排放控制。在中央，在稳定的天气尺度气象条件下，发现过去3天内最远500公里的排放通过积累影响硫酸盐等次生气溶胶的浓度。

Recent rapid growth of industrial activities in East Asia has been causing large increase in aerosols in this area. Atmospheric aerosols modify the radiation budget through scattering and absorption. Because black carbon (BC) aerosols (e.g., soot) efficiently absorb the solar radiation, they have been recognized one of the most important aerosol compounds the solar radiation, they have been recognized one of the mot important aerosol compounds for climate change.In the physical year of 2006, measurements of BC mass concentrations, size distribution, and mixing sate were in the Beijing region and Peal River Delta (PRD) region in China with Peking University Research Groups and some other international research groups. Aerosol chemical composition and some other parameters were also simultaneously measured.In the physical year of 2007, these data were precisely analyzed and interpreted from the viewpoint of emission sources, chemical production, transport processes, and removal processes using three-dimensional chemistry transport model. Observations show that BC concentrations in Beijing have a clear diurnal variation with a maximum during night. This feature was well reproduced by model calculations through diurnal variations, such as that in the boundary layer height. Although large day-to-day variations were found for secondary aerosols, such as inorganic aerosols, they were small for BC. Model calculations showed that BC concentrations were generally controlled by BC emissions within 100 km around Beijing within previous 24 hours. On the centrally, emissions as far as 500 km within previous 3 days were found to affect concentrations of secondary aerosols, such as sulfate through accumulations under stable synoptic-scale meteorological conditions.