Seasonal Trend of Water-Soluble Ions at One TSP and Five PM2.5 Sampling Sites in Beijing, China - Highway and Urban Environment - page 84

Fig. 4 Average PM 2.5 concentrations (mean day and night) for each season (2006) at all five
sampling sites in Beijing
Fig. 5 PM 2.5 and TSP concentrations at site 4 for the course of the year 2006
concentrations occur especially in the coarse fraction (TSP £100 µm). This supports
the assumption that the high amount of particulate matter during this time of the year
mainly originates from long-distance transport from arid areas northwest of Beijing.
During so-called dust storms days these geogenic particles accumulate in the city
[4-6] . The high particle concentration in wintertime, however, is reflected both in the
coarse and fine fractions. During this period, heating activities, which include a high
amount of coal combustion, contribute noticeably to the high aerosol pollution.