Chemistry Reference
In-Depth Information
wildfires can have a larger impact on air quality than other common anthropogenic
sources, in both urban and rural areas. Fire emissions are not just local issue since
particle emissions can be transported over long distances, leading to regionally
elevated loadings.
In Northern Europe the concentrations of particulate matter are typically quite
small compared with the more polluted regions in Europe [
5
,
6
]. In Northern
Europe annual average PM
2.5
concentrations are ~10
gm
3
in urban areas,
whereas in Eastern and Southern Europe the concentrations are two or three times
larger [
7
]. In areas with low local emissions the composition and the mass
concentrations of fine particles are substantially affected by the long-range trans-
port (LRT) from other areas, even from thousands of kilometers away. For example
in the urban areas of Helsinki, Finland, 64-76% of the PM
2.5
mass was estimated to
originate from the LRT in 1998-2002 [
8
]. Regarding special pollution episodes, a
total of 27 pollution episodes were attributed to LRT in Southern Finland in
2001-2007 [
9
]. Half of those episodes was caused by smokes from wildfires in
Eastern Europe, and the total duration of the episodes was 26 days in 7 years time
period.
This chapter describes the episodes of wildfire particles observed in Northern
Europe in the last 10 years. Biomass fires were usually located in Russia or other
Eastern European countries but the smokes from the fires were transported to the
northern European regions. Transport of smoke plumes to Northern Europe is
typically caused by low and high pressure centers located in the northern hemi-
sphere. An anticyclonic system over northeastern Europe, the burning area, and a
low pressure center over northern Atlantic can create a strong flow from south to
north, from the fire region to Northern Europe [
10
]. Smoke episodes observed in
Northern Europe in late summer 2002 and spring 2006 were exceptionally intense
with the smoke being carried to regions as far as the European Arctic [
10
] and UK
[
11
] causing severe air quality deterioration. This chapter presents the smoke events
detected in Northern Europe in 2002-2010, the chemical and physical properties of
the observed LRT particles as well as the methods to investigate the composition
and source areas of smoke plumes.
m
2 LRT Wildifire Smoke Episodes Detected in Northern Europe
in 2002-2010
The episodes of LRT biomass burning smokes have been detected in the northern
European regions almost every year in the last 10 years (Table
1
). The episodes
were observed most extensively in Finland but also in Sweden, Norway, and
Denmark. At the seasonal level, the episodes of biomass burning smokes occurred
most likely in spring, from March to May, and in late summer in August and
September. Exceptionally in 2010, the smoke plumes were detected in Kuopio,
Finland, already at the end of July [
32
]. The duration of the episodes varied from
