摘要
对2010年10月和11月北京市区粒径小于2．5pm（PM2，）和2．5～10μm之间（PM2.5-10）的气溶胶粒子质量浓度进行了观测和分析，同时研究了同期的Angstrom指数和散射系数等气溶胶特性参数的变化。结果表明，不同粒径颗粒物的质量浓度与气溶胶特性参数的逐时日变化明显。PM：，质量浓度在凌晨5时至6时取得最小值，夜间20时至21时取得最大值；PM2.5-10质量浓度则在9时至10时和20时至21时出现双蜂。气溶胶Angstrom指数在下午明显高于上午，最大值出现在16时左右；散射系数高峰出现在17时至18时。2010年10月7—9日出现了显著的灰霾天气，灰霾天气下PM2.5，和PM2.5-10质量浓度均有明显增加。细粒子增多是导致PM25增加和Angstrom指数增大的主要原因。另外，灰疆天气期间散射系数迅速增大，非灰霾天（10月11日）的散射系数只有灰霾天（10月8日）的1．27％。
In order to trace and explore the change of the characteris- tic parameters of the behaviors and features of the aerosol since the days of 2008 Beijing Olympic Games, we began to conduct the inves- tigation and measurements of the particulate mass concentrations with the diameters below 2.5 ptm （PM2.5） and those between 2.5 μm and 10μm （PM2.5-10） in the campus of Beijing Institute of Technology from Oct. to Nov. , 2010, by using a TSI Aerosol Particulate Sizer. In particular, we have put our research focus on observing and pursu- ing the aerosol properties, such as Angstrom exponent and scattering coefficient during the same period. The mass concentration of PM2.5 proves to be the lowest from 5：00 to 6：00 every morning with the size of about 63.37 μg/m3 while the peak value used to appear from 20： 00 to 21：00 with the average size of 97.48 μg/m3. We have also ob- served and traced the bimodality shape with the mass concentration being PM2.5_10. To be accurate, the two big values were found equal to 82.43 μg/m3 and 101.56 μg/m3 from 9：00 to 10：00 in the morn- ing and 20：00 to 21：00 in the evening, respectively, the consequen- tial results of which might he attributed to the human activities and traffic emissions. We have also worked out the Angstrom exponent by measuring the aerosol spectral optical depths via the Cimel Solar Pho- tometer. The measuring results can be stated as follows： the values of Angstrom exponents tend to be much greater in the afternoon than in the morning, with the peak value （1. 343 ± 0. 079 ） obtained at around 16：00 in the afternoon. We have also measured the scattering coefficient by using the Ecotech M9003 integrated nephelometer, which witnessed the pick values from 17：00 to 18：00. It can be con- cluded that the augment of secondary aerosol with high scattering properties is likely to be attributed to the high scattering coefficient. It can be believed that Beijing experienced an abrupt hazy weather shock from Oct 7 to Oct. 9, 2010, for the concentrations of PM2.5 and PM2.5 10 since then have increased notably during the hazy shock, with the increments of PM2.5 being remarkably noticeable. The mass concentration of PM2.5 and PM2.5-10 in the non-hazy day of Oct. 11 was only 1.25% and 3.04% of those measured in hazy day Oct 9, respectively. Under the hazy weather conditions, the distribution of Angstrom exponent were found to reach about 1.4 due to the augment of the fine mode particles. Moreover, there occurred a sharp rise in scattering coefficient during the hazy episode, whose value in Oct 11 was only 1.27% of that measured in Oct. 8.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2014年第1期267-272,共6页
Journal of Safety and Environment
基金
国家自然科学基金重点项目(40637035)
