Acidification and Arctic Haze - The Changing Arctic Environment: The Arctic Messenger - page 90

creasing since the late 1990s and is indicative of the increasing importance for the Arctic
of emissions from Eastern Asia.
Little information was available for the Chukotka region of Russia, but it lies within
a prevailing air stream originating from industrial areas, particularly those involving coal-
fired power generation in China and India. It is possible that this area is being exposed
to increasing levels of acidifying substances. Elsewhere, air streams from North America,
Europe and Asia that are known or believed to be carrying sulphur and nitrogen are not
doing so at levels likely to cause widespread Arctic soil or freshwater acidification now
or in the near future. In Arctic Canada, the combined maximum sulphur and nitrogen de-
position (north of 60° north) is below the critical loads for soil acidity. It is not known at
this time whether this situation will show local or regional perturbation resulting from the
large-scale development of tar sands in northern Alberta.
Surprisingly, acidified soils around the Kola Peninsula smelters appear to be restricted
- more or less - to the zones of visible vegetation loss. This is not an area of high rain or
snowfall. Vegetation studies along the Barents Sea coast of Norway show that most of the
sulphur in the leaves of small tundra plants arrived in association with dust particles and
not directly from sulphur dioxide. Up to 80% of the sulphur entering the air at the Kola
sources may be quickly deposited in this way. Other supporting studies have shown that
acidic precipitation generally falls within 30-40 kilometres of the smelters. Outside this
zone, it appears that the neutralizing activity of base cations from the local geology and
from alkaline fly ash co-emitted from the source smelters are sufficient to prevent soil acid-
ification reaching levels that may result in vegetation damage.
Ecologists recognized a series of concentric zones of impact (elongated by prevailing
winds) close to the Kola smelters. Beside the smelters is the “industrial barrens” zone -
in which almost all vegetation has disappeared - followed by zones of decreasing severity
of effect. At the less impacted zones, the observed change remains significant ecologic-
ally because it is manifested through changes in plant community structure, especially with
respect to lichens. Lichens are particularly sensitive to sulphur dioxide and preindustri-