The recent warming is consistent with observed changes in atmospheric circulation, particularly the generally positive phase of the North Atlantic/Arctic
Oscillation (Vavrus and Harrison 2003). The NAO index generally tend to be more
often positive what results in more intense and extending farther north wind
transport. The contaminants may be thus more effectively transported to the arctic
regions. The further enhanced contaminant transport by currents is however
uncertain since from the winter of 2010 NAO index tends to be low. The contaminant flux increase may be also caused by higher precipitation. The further
global changes predictions show that the precipitation in the Arctic will increase
(Macdonald et al. 2005). Thus, the “washing” of the contaminants from the
atmosphere will be more effective (Schiedek et al. 2007).
2.2 Ocean Currents
A significant marine transport route for influxes of contaminants into the marine
arctic environment is via inflow of water from the Norwegian Atlantic Current
(NwAC) and the Norwegian Coastal Current (NCC). Transport with the NCC and
the NwAC constitutes the dominant marine pathways for some contaminants
originating from western Europe. The role of long-range oceanic transport may be
significant for soluble, conservative radionuclides (e.g., Cs-137) (Gao et al. 2004;
Johannessen et al. 2010), heavy metals (Cd, Pb) (Macdonald et al. 2005; Maccali
et al. 2013) and organic chemicals with relatively low Henry’s Law constants (e.g.
HCH) (Lohmann et al. 2007; Halsall 2004).
While the NCC and the in-shore branch of the NwAC enter the western Barents
Sea, the off-shore branch of the NwAC continues northwards. It flows into the
Arctic Ocean through the Fram Strait. This branch sub-ducts under the fresh, cold
layers of Polar Surface Water, separated by a strong vertical salinity gradient. The
Barents Sea branch of the NwAC, mixed with the waters of the NCC, continues
eastward across the Barents Sea Shelf to the Kara Sea. The warmer waters of
Atlantic origin lose their heat and form dense waters that cascades down to the sea
bottom. Thus contaminants that were transported by NwAC reach the bottom parts
of the Eurasian Basin seawaters (Karcher et al. 2010).
The positive NAO index indicating increased in the strength Atlantic Oscillation
may result in an enhanced northward delivery of contaminants from the Western
Europe to the Arctic Ocean. The Norwegian Atlantic Current changes in volume
and heat transfer are well documented (Hurrell and Deaer 2010). Higher transport
of Atlantic origin water coupled with ice cover reduction will cause larger penetration of contaminated water masses into high latitudes. The effect of NAO may
not be so certain since recently (from 2010) the NAO index is low.
Climate Change Influence on Migration of Contaminants …
79
Oscillation (Vavrus and Harrison 2003). The NAO index generally tend to be more
often positive what results in more intense and extending farther north wind
transport. The contaminants may be thus more effectively transported to the arctic
regions. The further enhanced contaminant transport by currents is however
uncertain since from the winter of 2010 NAO index tends to be low. The contaminant flux increase may be also caused by higher precipitation. The further
global changes predictions show that the precipitation in the Arctic will increase
(Macdonald et al. 2005). Thus, the “washing” of the contaminants from the
atmosphere will be more effective (Schiedek et al. 2007).
2.2 Ocean Currents
A significant marine transport route for influxes of contaminants into the marine
arctic environment is via inflow of water from the Norwegian Atlantic Current
(NwAC) and the Norwegian Coastal Current (NCC). Transport with the NCC and
the NwAC constitutes the dominant marine pathways for some contaminants
originating from western Europe. The role of long-range oceanic transport may be
significant for soluble, conservative radionuclides (e.g., Cs-137) (Gao et al. 2004;
Johannessen et al. 2010), heavy metals (Cd, Pb) (Macdonald et al. 2005; Maccali
et al. 2013) and organic chemicals with relatively low Henry’s Law constants (e.g.
HCH) (Lohmann et al. 2007; Halsall 2004).
While the NCC and the in-shore branch of the NwAC enter the western Barents
Sea, the off-shore branch of the NwAC continues northwards. It flows into the
Arctic Ocean through the Fram Strait. This branch sub-ducts under the fresh, cold
layers of Polar Surface Water, separated by a strong vertical salinity gradient. The
Barents Sea branch of the NwAC, mixed with the waters of the NCC, continues
eastward across the Barents Sea Shelf to the Kara Sea. The warmer waters of
Atlantic origin lose their heat and form dense waters that cascades down to the sea
bottom. Thus contaminants that were transported by NwAC reach the bottom parts
of the Eurasian Basin seawaters (Karcher et al. 2010).
The positive NAO index indicating increased in the strength Atlantic Oscillation
may result in an enhanced northward delivery of contaminants from the Western
Europe to the Arctic Ocean. The Norwegian Atlantic Current changes in volume
and heat transfer are well documented (Hurrell and Deaer 2010). Higher transport
of Atlantic origin water coupled with ice cover reduction will cause larger penetration of contaminated water masses into high latitudes. The effect of NAO may
not be so certain since recently (from 2010) the NAO index is low.
Climate Change Influence on Migration of Contaminants …
79