Pia Anttila, Kevin Barrett, John Derome, Risto Hillamo, Liisa Jalkanen, Sirkku Juntto, Jaakko Jurvelin, Eero Kubin, Tuomas Laurila, Antti-Jussi Lindroos, Heikki Lättilä, Timo Mäkelä, Minna Mäkinen, Tuomo Pakkanen, Jarmo Poikolainen, Antti Reissell, Aleksei Ryaboshapko, Helena Saari, Juha-Pekka Tuovinen, Aki Virkkula
Since the early 1970s, the Finnish Meteorological Institute has made measurements
of wet deposition and average atmospheric sulphur dioxide concentrations at
the institutes stations in Sodankylä and Kevo (Utsjoki). Also the National
Board of Waters and the Environment has long series of deposition observations
from a few stations in northern Finland. However, the monitoring of average
levels did not sufficiently clarify the special characteristics of air quality
in Lapland. Consequently, actual concern over the quality of the air in Lapland
began to be expressed as recently as the late 1980s, when the first reliable
information concerning the immense emissions from the Kola Peninsula was obtained
(Figs. 21 and 22).
Starting in the autumn of 1989, measurements of the concentrations
of atmospheric sulphur dioxide have been made
as 24-hour averages at Värriö (Salla) and Oulanka (Kuusamo). Ozone
and nitrogen dioxide measurements by continuously registering devices
have also been included in the measurements carried out at Oulanka.
Continuous measurement of sulphur dioxide concentrations has been
carried out at Jäniskoski, east of Lake Inarijärvi, since the spring of
1990.
Measurement of heavy metals in wet deposition was commenced at
Utsjoki and Kuusamo in 1990. In 1991, these were joined by the
continuous measurement of sulphur dioxide and ozone concentrations at
Sammaltunturi, in western Lapland; in 1992 the same measurements
began to be made at Raja-Jooseppi, east of Inari. The Sammaltunturi
station is in the process of being upgraded into a more versatile
measurement station in compliance with the requirements of the World
Meteorological Organisation. The impact on Lapland of the emissions
from the Kola Peninsula is at its worst in the eastern part of the Inari region.
This is the region for
which the Sevettijärvi air-quality measurement station was established
in the autumn of 1991 to meet the requirements of the Lapland Forest
Damage Project. The costs of building the station were shared by the
Forest and Park Service, the Meteorological Institute, the METLA, and
the municipality
of Inari.
The measurements carried out at the station are more specialized than normally
as the aim is to obtain a more comprehensive picture of the properties of the
pollution load affecting the region. Following the above development work, Lapland
now possesses Finlands densest and best-equipped measurement network for monitoring
air quality (Fig. 23). The information
obtained concerning the quality of the air in this northern region is supplemented
by measurements done by the Norwegians over their territory. The material used
in this project comprises data obtained from the aforementioned air-quality
measurement stations, the Lapland Forest Damage Projects deposition measurements,
and numerous separate studies connected to the air quality in Lapland.
When the winds blow in from the north and the west, the air they bring from
the Arctic and the North Atlantic is very clean. Southerly winds bring in pollutants
from southern Finland and from continental Europe. Despite the occasional peak,
the average of estimated atmospheric sulphur dioxide concentrations almost throughout
Lapland remain within the range of 1-5 µg/m3, which is clearly below the level
believed to be critical for forest ecosystems (Fig.
24). The year-round, reoccurring short-term exposure, which is characteristic
of the situation in Lapland, does not, however, stand out with sufficient clarity
in the critical level defined in terms of the annual mean.
The acidity of the deposition in Lapland is regulated by the sulphuric
acid formed from sulphur dioxide. Oxides of nitrogen, on the other hand,
are almost without any acidifying significance. The deposition in Lap
land has but little neutralising components. Consequently, the annual
acid deposition does come to roughly half of that recorded in southern
Finland. The annual acid load imposed on the soil in Lapland can rise to
levels as high as 15-20 meqv/m2; i.e. close to the critical level.
Atmospheric sulphur dioxide accumulates on vegetation in the form of
dry deposition. The amount of dry deposition is proportional to the
atmospheric concentrations of sulphur dioxide. Since high sulphur
dioxide concentrations have been recorded in the Inari region of Lapland
also during the grow-ing season, the accumulation of sulphur dioxide
can be expected to have a major role in the overall load imposed on the
region. Calculations indicate that as much as over 60% of the total
deposition of sulphur in the Inari region is accounted for
by dry deposition. However, dry deposition is difficult to determine. For
the present, it has
not been possible to confirm whether it plays an important role in
Lapland.
The sulphur dioxide emissions from the Kola Peninsula have a distinct impact
over a radius of a couple of hundred kilometres from the emission sources. Around
half of the sulphur deposition in central Lapland originates from the Kola Peninsula
(Fig. 25).
Depositions of nickel and copper have risen dramatically in the vicinity of
the Kola Peninsula smelters. The amounts quickly decrease with increasing distance
away from the smelters; on the Finnish side of the border, the values recorded
are close to the background values. On the eastern side of Lake Inarijärvi,
the concentrations of nickel and copper in the bark of pine trees are three-to-five
times greater than in western Lapland. Slight increases in copper and nickel
concentrations have been detected in the bark of pine trees and in mosses at
distances of 100-200 kilometres from the Kola emissions sources. The deposition
of chrome originating from Tornio, at the tip of the Gulf of Bothnia on the
Finno-Swedish border, shows up in mosses at distances of over 100 kilometres
from the source (Fig. 26a-e).
Ozone concentrations in the spring are high throughout Finland. This
is the time of the year when the pollutants that have accumulated in the
atmosphere over the winter form ozone under the influence of the spring
sunshine. During the summer the ozone concentrations are especially
high in the southern and central parts of the country, the regions most
heavily afflicted by long range transportation of pollutants and domestic
emissions. When the atmospheric concentrations of ozone over Lapland
are compared to the guideline values applied internationally, it becomes
apparent that damage to the vegetation can result, especially in the
regions southern parts.
On average, the air over Sevettijärvi is very clean: 50% of the sulphur dioxide
concentration hourly averages in 1992 and 1993 were below 1 µg/m3. Once or twice
a month there were pollution episodes with the pollution load originating from
the Kola Peninsula smelters. These lasted a few hours, during which time the
sulphur dioxide concentrations exceeded 100 µg/m3 (Fig.
27a and b). Often these episodes were accompanied by impaired visibility
and a rise in the relative humidity of the air. Easterly winds were responsible
for 60-70% of the exposure to sulphur dioxide.
The particles contained in the air over Lapland proved to be acidic
when examined in the course of this project. This is due to the fact that
the sulphuric acid formed from the sulphur dioxide does not become
diluted in the atmosphere because of lack of ammonium. Heavy-metal
analyses made of the particle samples revealed that especially nickel,
copper, cadmium, lead, zinc and vanadium are carried over to Sevet
tijärvi from the Kola Peninsula smelters. Zinc and lead are also brought
to Sevettijärvi by southerly winds during pollution episodes.
