In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 22, No. 20 ( 2022-11-01), p. 13783-13796
Abstract:
Abstract. Secondary organic aerosol (SOA) constitutes a large
fraction of atmospheric aerosol. To assess its impacts on climate and air
pollution, knowledge of the number of phases in internal mixtures of
different SOA types is required. Atmospheric models often assume that
different SOA types form a single phase when mixed. Here, we present visual
observations of the number of phases formed after mixing different
anthropogenic and biogenic SOA types. Mixing SOA types generated in
environmental chambers with oxygen-to-carbon (O/C) ratios between 0.34 and 1.05, we found 6 out of 15 mixtures of two SOA types to result in two phase particles. We demonstrate that the number of phases depends on the
difference in the average O/C ratio between the two SOA types (Δ(O/C)). Using a threshold Δ(O/C) of 0.47, we can predict the phase
behavior of over 90 % of our mixtures, with one- and two-phase particles
predicted for Δ(O/C)〈0.47 and Δ(O/C)≥0.47,
respectively. This threshold ΔO/C value provides a simple parameter
to predict whether mixtures of fresh and aged SOA form one- or two-phase particles in the atmosphere. In addition, we show that phase-separated SOA
particles form when mixtures of volatile organic compounds emitted from real
trees are oxidized.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-22-13783-2022
DOI:
10.5194/acp-22-13783-2022-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2069847-1
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