Land degradation has been identified as a crucial and increasing environmental problem in the region, the most severe forms being the irreversible processes of erosion, acidification, and pollution. Soil compaction, loss of organic matter, overgrazing, improper irrigation, salinization, and waterlogging are other, less common forms of land degradation in the region (EEA, 1995a). Parts of Europe also suffer from desertification. Both physical and chemical degradation are expected to continue unless low-input agriculture and erosion control measures are widely adopted (CEC, 1992).
Soil erosion is increasing in Europe. Mediterranean areas are particularly susceptible, and parts of CEE and the CIS have also been widely affected. For example, 56 per cent of agricultural lands in Russia are subject to erosion of different types (Min. of Env. Prot. and Nat. Res. of the Russ. Fed., 1995a); equivalent figures for the Ukraine and Kazakstan are 34 per cent and 42 per cent respectively (Min. of Env. Prot. of Ukraine, 1994; Min. of Ecol. and Biol. Res., Kazakstan, 1993). West of the Urals, an estimated 12 per cent (115 million hectares) of the total land area is affected by water erosion and 4 per cent by wind erosion (EEA, 1995a). Major problems include the loss of humus, production losses, the cost of replacing lost nutrients, and damage to areas that receive the eroded materials (EEA, 1995a).
Pollution of land from a variety of contaminants (heavy metals, persistent organic pollutants, nitrates, phosphates, artificial radionuclides, and so on) is widespread, though the area affected is not accurately determined. Among other effects, pollutants may lower plant yields; enter food chains and water supplies, rendering them unfit for human consumption; and inhibit soil micro-organisms, thereby disturbing natural decomposition processes.
Pesticides and fertilizers are major sources of these pollutants. Industrial processes, fossil fuel combustion, waste and wastewater sludge disposal, and accidental release contribute significantly (EEA, 1995a). The Chernobyl disaster is a case in point. After the event in 1986, over 23 per cent of the territory of Belarus alone was affected by radioactive fallout (Republic of Belarus, 1995). Large areas remain contaminated more than 10 years after the event, including 430,000 hectares of the worst affected areas of Belarus, Russia, and the Ukraine, which remain an "alienation zone," and a further 9.4 million hectares of agricultural land that remain contaminated with long-lived radionuclides (IAEA, 1996). Additional, less well-known cases of serious radionuclide soil contamination in eastern Europe and the CIS countries are associated with other nuclear installations and test sites.
Other serious cases of contamination include oil and heavy-metal pollution of soils around abandoned military sites in the CIS countries, and oil leakages into land and aquatic ecosystems during oil extraction and transportation activities in western Siberia. It is estimated that some 7-20 per cent of all oil extracted ends up in these ecosystems (Mnatsakanian, 1994).
Acidification is frequently a transboundary problem. Whereas the main emission sources are in north-western and central Europe, the greatest impacts are in the industrialized, densely populated zone that extends from Poland and the Czech Republic through Germany and the Benelux countries to the United Kingdom and Scandinavia. Present loads of acidic deposition are higher than critical loads in roughly 60 per cent of Europe, with central parts of Europe receiving 20 times more acidity than the ecosystem s critical loads (EEA, 1995a).
Sulphur deposition predominates in the more northerly countries whereas nitrogen leaching and associated problems are typical for central Europe and the Netherlands. Although long-term trends in acid deposition are not yet available, there is an indication that the Long Range Transboundary Air Pollution (LRTAP) Convention prepared under the auspices of the United Nations Economic Commission for Europe (UN-ECE) is effectively reducing sulphur-related acidification in the region, as discussed later in this section (EEA, 1995a).
In agricultural areas, the application of chemicals has tended to offset acid deposition, but outside these areas the effects are not mitigated. Acid deposition is a problem in most countries in western Europe where soils have low buffering capacity. At present, 30 per cent of the forested area of Europe is thought to be degraded from this, with a further 15 per cent at risk if acid deposition continues (EEA, 1995a). Acidification of soil and water has been particularly serious in the Scandinavian countries because of prevailing winds and the high natural acidity of soils (EEA, 1995a; Bernes, 1993).
A third of Europe s 300 million hectares of drylands suffers some degree of desertification and the reduction in biological and economic productivity that goes with it (UNEP, 1992a). Desertified areas are mainly uncultivated and abandoned lands (15 million hectares), drylands (13 million hectares), and irrigated lands (1.6 million hectares) (UNEP, 1992a). Changes in agricultural practices, particularly the intensification of land use, are thought to have been the prime causes (EEA, 1995a). The affected areas are mainly in southern and central Europe and the southern parts of the Former Soviet Union (FSU) (UNEP, 1996).
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