Beschreibung:
<jats:p>Abstract. Probing sources of atmospheric pollution in complex environments often leads to the measurement and sampling of a mixture of different aerosol types due to fluctuations of the emissions or the atmospheric transport situation. Here, we present the AERosol and TRACe gas Collector (AERTRACC), a system for sampling various aerosol types independently on separate sampling media,
controlled by parallel online measurements of particle, trace gas, and
meteorological variables, like particle number or mass concentration,
particle composition, trace gas concentration, and wind direction and
speed. AERTRACC is incorporated into our mobile laboratory (MoLa) which
houses online instruments that measure various physical and chemical aerosol
properties, as well as trace gas concentrations. Based on preparatory online
measurements with the whole MoLa setup, suitable parameters measured by
these instruments are used to define individual sampling conditions for each
targeted aerosol type using a dedicated software interface. Through
evaluation of continuously online-measured data with regard to the sampling
conditions, the sampler automatically switches between sampling and
non-sampling for each of up to four samples, which can be collected in
parallel. The particle phase and gas phase of each aerosol type, e.g., source emissions and background, are sampled onto separate filters with PM1 and PM10 cutoffs and thermal desorption tubes, respectively.
Information on chemical compounds in the sampled aerosol is obtained by means of
thermal desorption chemical ionization mass spectrometry (TD-CIMS) as the
analysis method. The design, operation, and characterization of the sampler
are presented. For in-field validation, wood-fired pizza oven emissions were
sampled as targeted emissions separately from ambient background. Results
show that the combination of well-chosen sampling conditions allows more
efficient and effective separation of source-related aerosols from the
background, as seen by the increases of particle number and mass concentration
and concentration of organic aerosol types, with minimized loss of sampling
time compared to alternative sampling strategies.
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