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|Alewell, C: Acid inputs into the soils from acid rain in Rengel Z.: Handbook of Soil Acidity, Marcel Dekker Inc.,New York, 83-115 (2003)|
Regarding acid rain industrialized regions of the world show very different trends for future development of sulfur, nitrogen and proton deposition. While in Europe as well as North America a significant decrease in sulfur and proton but only a slight decrease in nitrogen deposition can be noted, Northeast Asia is only starting to face the deleterious problems of acid rain. Because of the long range transboundary transport of emissions of SO2 and NOx, international cooperation (in case of the United States national cooperation between states) has been the only successful way in applying abatement strategies. It can be concluded that reduction in sulfur emissions in North America and Europe were achieved due to available technical options. In contrast, abatement strategies for nitrogen emissions rely mainly on changes in human behavior (e.g. less motor vehicle use, consuming less meat to reduce livestock numbers) and energy use (e.g. more usage of wind, solar and water energy; energy saving strategies). Thus, decrease in nitrogen emissions have been less successful so far. The good news for ammonia abatement strategies are that countries will directly benefit from their own efforts, because there is hardly any long range transport involved. Thus, there is hope for the future that site and country specific abatement strategies will be brought into action without the decades of delay connected with international political cooperation.
The scientific proof of the detrimental effects of acid rain on biota or soils is not easy to give. However, there is plenty of evidence that acid rain causes soil and water acidification, is connected to forest decline, has a negative effect on biodiversity, a detrimental effect on human health and can even cause extinction of plant and animal species.
A recovery from the deleterious effects of acid rain after 25 years of decreased sulfur and proton deposition in Europe and North America is up to know only reported for the reversal of chemical trends in aquatic systems. However, biological recovery (recovery of trees, aquatic species etc.) as well as reversal of soil acidification has not been noted yet.