2.1 The Air Transport
The atmosphere is the fastest and most direct contaminant transport route from
distant and local sources to the Arctic (Halsall et al. 2001; Gordeev 2002;
Melnikova et al. 2003; Wania and Su 2004). This pathway is particularly efficient
for volatile and semi-volatile contaminants as persistent organic pollutants (POPs)
and some heavy metals (Hg, Pb). Transport by winds may deliver contaminants
from the south to the Arctic within a few days (Halsall et al. 1998). From the
atmosphere, the contaminants may enter marine arctic ecosystem via direct air/
water/ice exchange but the main process discharging contaminants to the sea surface is wet or dry precipitation. The atmosphere is also important for radionuclides
transport that reached higher atmosphere parts during air detonations of nuclear
bombs (particularly in 60s and 70s) and still are present in the upper stratosphere
(Crane et al. 2000; Efurd et al. 2005).
Atmospheric circulation in the Arctic is driven by Arctic Oscillation (AO) that is
correlated with North Atlantic Oscillation (NAO). North Atlantic Oscillation is
described as NAO index that is normalized air pressure difference between Iceland
and Azores. In the summer, the continental high pressure cells disappear what
results in weakening of northward transport from low latitudes. Summer transport
accounts in average for only 20 % of the annual south to north air transport (from
Norwegian Sea: 10 %, Eastern Europe/Siberia: 5 %, and Bering Sea: 5 %). In the
winter, the lower tropospheric circulation is dominated by high pressures over the
continents and low pressures over the northern Pacific (Aleutian Low) and Atlantic
Oceans (Icelandic Low). Contaminants are transported to the Arctic during the
winter by three routes—from the Norwegian Sea (40 %), Eastern Europe/Siberia
(15 %), and the Bering Sea (25 %) (Macdonald et al. 2005). Particularly in this
season, the cold condensation processes efficiently remove contaminants from the
atmosphere to the sea surface.
The Arctic aerosol composition shows an annual variation with maximal concentration values of anthropogenic components during the winter/spring season.
The winter phenomenon of “ice crystal haze’’ was discovered not to be wind-blown
dust, but air pollution from the mid-latitudes. Arctic haze is a mixture of aerosols
containing acidifying gases (SOx and NOx), coarse particles of soot, heavy metals,
polycyclic aromatic hydrocarbons (PAHs), and polychlorinated bifenyls (PCBs).
Arctic haze is concentrated in the lower troposphere (up to 3 km altitude) and is
most pronounced during the coldest months of the year (from December–April)
(Bard 1999).
The atmospheric transport apart from transport from remote globe regions also
includes local sources. Two-thirds of the heavy metals in the air in the Arctic
originate from industrial activities on the Kola Peninsula, the Norilsk industrial
complex, the Pechora Basin, the Urals and the Yakutsk region of the Russian Arctic
(Gordeev 2002). Other local sources include for instance mining activities at
Svalbard Archipelago and Greenland (Elberling et al. 2002; Dowdall et al. 2004).
78
A. Pouch and A. Zaborska
The atmosphere is the fastest and most direct contaminant transport route from
distant and local sources to the Arctic (Halsall et al. 2001; Gordeev 2002;
Melnikova et al. 2003; Wania and Su 2004). This pathway is particularly efficient
for volatile and semi-volatile contaminants as persistent organic pollutants (POPs)
and some heavy metals (Hg, Pb). Transport by winds may deliver contaminants
from the south to the Arctic within a few days (Halsall et al. 1998). From the
atmosphere, the contaminants may enter marine arctic ecosystem via direct air/
water/ice exchange but the main process discharging contaminants to the sea surface is wet or dry precipitation. The atmosphere is also important for radionuclides
transport that reached higher atmosphere parts during air detonations of nuclear
bombs (particularly in 60s and 70s) and still are present in the upper stratosphere
(Crane et al. 2000; Efurd et al. 2005).
Atmospheric circulation in the Arctic is driven by Arctic Oscillation (AO) that is
correlated with North Atlantic Oscillation (NAO). North Atlantic Oscillation is
described as NAO index that is normalized air pressure difference between Iceland
and Azores. In the summer, the continental high pressure cells disappear what
results in weakening of northward transport from low latitudes. Summer transport
accounts in average for only 20 % of the annual south to north air transport (from
Norwegian Sea: 10 %, Eastern Europe/Siberia: 5 %, and Bering Sea: 5 %). In the
winter, the lower tropospheric circulation is dominated by high pressures over the
continents and low pressures over the northern Pacific (Aleutian Low) and Atlantic
Oceans (Icelandic Low). Contaminants are transported to the Arctic during the
winter by three routes—from the Norwegian Sea (40 %), Eastern Europe/Siberia
(15 %), and the Bering Sea (25 %) (Macdonald et al. 2005). Particularly in this
season, the cold condensation processes efficiently remove contaminants from the
atmosphere to the sea surface.
The Arctic aerosol composition shows an annual variation with maximal concentration values of anthropogenic components during the winter/spring season.
The winter phenomenon of “ice crystal haze’’ was discovered not to be wind-blown
dust, but air pollution from the mid-latitudes. Arctic haze is a mixture of aerosols
containing acidifying gases (SOx and NOx), coarse particles of soot, heavy metals,
polycyclic aromatic hydrocarbons (PAHs), and polychlorinated bifenyls (PCBs).
Arctic haze is concentrated in the lower troposphere (up to 3 km altitude) and is
most pronounced during the coldest months of the year (from December–April)
(Bard 1999).
The atmospheric transport apart from transport from remote globe regions also
includes local sources. Two-thirds of the heavy metals in the air in the Arctic
originate from industrial activities on the Kola Peninsula, the Norilsk industrial
complex, the Pechora Basin, the Urals and the Yakutsk region of the Russian Arctic
(Gordeev 2002). Other local sources include for instance mining activities at
Svalbard Archipelago and Greenland (Elberling et al. 2002; Dowdall et al. 2004).
78
A. Pouch and A. Zaborska