| Περίληψη: | A new experimental methodology was developed to measure the non-volatile particle number concentration, using a thermodenuder (TD). The TD was coupled with a high resolution
time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle
sizer (SMPS) that provided the number size distribution of the aerosol in the range from
10 to 500 nm.
The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (98 %) of secondary organic aerosol (SOA) as well as freshly
nucleated particles, using the TD temperature of 400 C.
This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of non-volatile particles from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80% of the particles survived the intense heating, suggesting that nearly
all biomass burning particles had a non-volatile core. These particles consisted mostly from black carbon (BC), while organic aerosol (OA) were responsible for another 40 %.
Organics that survived through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) that had not evaporated, contributing 90% of the organic mass
concentration, while the other 10% was hydrocarbon-like OA (HOA) and cooking OA
(COA). For periods that traffic contribution was dominant, mostly during the rush hour,
50-60% of the particles had a non-volatile core, while the rest evaporated at 400 0C. The remaining particles consisted mostly from BC, with an 80% contribution, while organics were responsible for another 15-20 %. Organics were mostly HOA and OOA, with a
contribution of >95% to the organic mass concentration, while <5% was from BBOA
and COA.
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