BEO Moussala – A New Facility for Complex Environment Studies - Sustainable Development in Mountain Regions: Southeastern Europe - page 131

Fig. 11.6 Typical aerosol size distribution in ambient air at BEO Moussala

spectra (Penev et al., 2007 ). All of them have been developed in INRNE. The air
turbine allows 1,500-1,800 m 3 per hour passing through the fibre filter, which is
type FPP-15-1.5 with high efficiency: 94-99%. The filter size is 50 50 cm. The

filter, after the sampling, is pressed to the pill with a diameter 57 mm, and a thickness
of 15 mm. The appearance in the atmosphere of Be 7 is a result of deep spallation
reaction as a process of interactions between the high energy cosmic particles with
the atmosphere. Be 7 quantity gives information for powerful atmospheric process -
intrusion of high atmospheric layers. From the results obtained during the recent
years several conclusions could be drawn:

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- Be 7 integral quantity for a specific place is determined by several factors - mainly
by atmospheric processes (including intrusion from stratosphere to troposphere),
changes in the intensity of cosmic rays (solar and galactic).
- Be 7 quantity (as a tracer for air masses origin) could serve as additional
information for short-term meteorological prognoses

Only activity of the U-Th products was detected in the aerosols at peak Moussala
including Be 7 , which is well-known product of the cosmic rays. Typical products of
the human activity, like Cs 137 and I 131 , have not been detected.