Acidification and Arctic Haze - The Changing Arctic Environment: The Arctic Messenger - page 91

al lichen-dominated heaths have essentially disappeared from areas anywhere close to the
smelters.
Arctic freshwater bodies also vary in their ability to resist the effects of acidifying in-
puts primarily due to differences in how well they are endowed with a natural buffering
capacity from such constituents as bicarbonates and organic acids. Northern Norway has
a particularly high proportion of acid-sensitive lakes due to natural underlying catchment
geology. It is therefore not surprising that around 1990, critical loads for northern Europe
were being exceeded over large areas, especially where natural, local and long-range (from
Kola smelters) acidification converged. However, the 2006 AMAP report noted improve-
ments in freshwater chemistry in the Barents Region and predicted that continued imple-
mentation of the Gothenburg Protocol should greatly reduce the extent to which critical
loads are exceeded in northern European freshwaters.
Long-term monitoring data have revealed that short-term pulses of highly polluted air
are particularly significant. For example, in the 1990s, up to 30% of the total sulphate de-
posited at a remote station in Finland arrived over a period of only five days. This is ecolo-
gically important because many plants, such as Scots pine andmature mountain birch trees,
are particularly sensitive to sudden high-concentration pulses of atmospheric sulphur diox-
ide, especially during the growing season. Freshwater ecosystems are also very sensitive
to pulses of highly acidic water. In the Arctic, these conditions are most likely to occur in
spring, when the entire winter's deposition of acidifying substances can be released through
snowmelt over just a few days. In the Kola Peninsula region, where metal emissions are
at least as toxic to freshwater and terrestrial ecosystems as is acidification, the high-con-
centration pulse associated with spring melt delivers metals and acids to the ecosystem at
the same time. Studies in Finland and Norway suggest that the strength of the acidity peak
in northern lakes during the period of snowmelt is more important to invertebrate survival
than is the annual or seasonal acidity (pH).
What does the future hold? There are some indications that the volume of emissions
from Russian sources may be increasing. Providing that this does not emerge as an upward
trend, we should be able to expect that increased Arctic environmental degradation res-