Aerosol Emissions from Long-Lasting Smoldering of Boreal Peatlands: Chemical Composition, Markers, and Microstructureстатья
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Дата последнего поиска статьи во внешних источниках: 4 сентября 2019 г.
Аннотация:As large-scale peat burning emissions can severely impact the environment and human health, it is crucial to assess the
characteristics of smoke aerosol at the source and at down-wind locations. From March until late summer in 2014, the
Tver region, north of the city of Moscow, was considerably affected by long-lasting peat bog fires. Peat bog smoldering
emissions from three types of smoke (underground, inside grass, and above grass) were analyzed by an extensive suite of
instrumentation that sampled and measured their optical and chemical properties. The particle composition was
characterized by organic species with high OC/EC ratios (10–20), with water-soluble organic carbon (WSOC) and
levoglucosan (Lev) comprising the largest fraction, up to 30 and 9%, respectively, of the OC. Aliphatic, aromatic,
carbonyl, and carboxylate functionalities in the underground smoke were enriched by nitro compounds, and brown carbon
(BrC) was identified by a high Absorption Angstrom Exponent (AAE) of 4.1. Organic “tar balls” in the peat smoke were
more abundant (78.5%) than individual Ca-rich (e.g., Ca-oxides or carbonates), Fe-rich (e.g., Fe-oxides), and Al-rich
(e.g., alumosilicates) particles. Peat smoke plumes affected an urban site in Moscow in August 2014, with ambient PM10
mass loadings reaching up to 97 µg m–3 and OC, EC, and ionic species accounting for a large percentage of the total
aerosol enhancement. With the transport of air masses from the peat bog region to Moscow, the OC/EC ratio and AAE
reached peak values of 7 and 1.3, respectively. Levoglucosan served as a molecular marker of the impact of peat
smoldering, approaching a maximum ambient concentration of 108 ng m–3. WSOC correlated well with Lev, indicating
secondary organic aerosol (SOA) formation associated with peat burning emissions. Spectral absorbance features showed
characteristics similar to peat burning and traffic source emissions during fire and non-fire related days, confirming the
potential effect of transported peat smoke on air quality in megacities.