Volume 14, No. 3, April 2014, Pages 954-969 PDF(843 KB)
Seasonal Variation of Physical and Chemical Properties in TSP, PM10 and PM2.5 at a Roadside Site in Beijing and Their Influence on Atmospheric Visibility
Yan-Ju Liu1,2 Ting-Ting Zhang1, Qing-Yang Liu1, Ren-Jian Zhang3, Zhen-Quan Sun1, Mei-Gen Zhang3
1 Beijing Centre for Physical and Chemical Analysis, 100089, China
2 Beijing Milu Ecological Research Center, Beijing 100076, China
3 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
In Beijing, capital of China, decreasing visibility has become a serious problem on people’s life, thus a hot environmental concern. An urban roadside site in Beijing was chosen to collect 24-h TSP, PM10 and PM2.5 samples for one month each season from June 2009 to March 2010. The PM mass concentrations, and the concentrations of ions, EC, OC and metals in PM10 and PM2.5 were measured, and their correlation with visibility, as well as the influence of weather factors on visibility were studied. The results showed that daily mean concentrations of TSP, PM10 and PM2.5 were 75–1350 µg/m3 (mean 275.8), 29–448 µg/m3 (mean 187) and up to 300 µg/m3 (mean 92.6), with the number of days exceeding the secondary standard (GB3095-2012) representing 33.3%, 59.8% and 51.0%, respectively. All PM concentrations were higher in spring than in other seasons. Obvious seasonal variations were observed for certain ions, OC, EC and metal concentrations in PM10 and PM2.5. Average mean visibility was low (5.64 km), showing better visibility in summer than in other seasons. PM10 and PM2.5 showed stronger negative correlation with visibility giving coefficients of –0.52 and –0.50. Almost all significant correlations were negative and occurred in autumn for visibility with TSP, PM10 and PM2.5, and with ions, EC and OC in both PM10 and PM2.5. The only positive and significant correlation was found between fine OC and visibility. Negative and significant correlations were also observed for visibility with humidity in autumn and winter, and with minimum temperature in all seasons but summer.
PM; Anions; Cations; Metals; OC; EC; Weather; Visibility.