Document Type : Research Paper
The University of Guilan, P.O. Box 3489, Rasht, IRAN
After almost three decades of intensive research on acidic deposition, it is still an important environmental issue in Europe '- and North America. Furthermore, anthropogenic emissions of the major pollutants involved _ sulfur dioxide (S02) and nitrogen oxides (NO) __ are increasing rapidly as industrialization proceeds and the use of fossil fuels increases in new geographical areas, including parts of eastern and southern Asia, southern Africa, and South America. These pollutants and their transformation products have long atmospheric lifetimes and can be carried by weather systems to distances of up to a few thousand kilometers from their point of emission. This causes acid deposition far from the primary source of pollution, thus making it a regional problem and an international transboundary issue. Considerable
advances in the understanding of acidic emissions, transportation, deposition and consequent effects on ecosystems have allowed the development of the concept of “Critical loads", which has become an integral part of international negotiations aimed at controlling emission levels within Europe. Abatement strategies based on the critical load concept resulted in substantial decreases of acidic emissions, which have led to a lower degree of environmental degradation and even recovery in deposition. Some ecosystems in eastern Asia, where a regional acid monitoring network [El-WET) is some ecosystems in eastern Asia, a regional acid already established implementation of some abatement strategies is under consideration. Economic progress in the Caspian region is associated with an increase in the oil and gas production, industrialization and a higher demand for energy and food production. On the basis of previous experiences, such a progress will definitely lead to a considerable increase in emissions of acidifying pollutants. It is important that the environmental impacts of these emissions are estimated and taken into account in the planning process. The impact study is especially very crucial for the highly"
sensitive ecosystem of the southern Caspian watershed. If less polluting techniques are applied in the region, environmental problems, like those experienced in Europe and North America may be lessened. A rational strategy for limiting the adverse effects of acidifying pollutants should include consideration of critical loads and critical levels. So far, only preliminary estimates of critical loads are available for some parts of the regionand there is a real need for regionalresearch programs in this regard.
Experience from policy actions, especially in the European region, could also be very useful for the Caspian states. There is, indeed, an obligation for environmental
scientists to promote communication and cooperation with policymaking and decision-making sectors of the Caspian societies hoping that they can have better, if not the best, policy options to prevent further environmen-tal deterioration.
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