Modeling of Critical Loads for Acid Deposition in Austria

The author develops an approach to simulate acidification processes in forest soils caused by acid deposition from the atmosphere. Based on a dynamic formulation of the most important processes and external factors leading to soil acificiation the stationary solution of the equation system is derived, which serves as a basis for estimating critical loads for acid deposition. Thereby, critical loads determine the maximum exposure to one or more pollutants, which will not cause chemical changes in the soil leading to long-term harmful effects on the most sensitive ecological systems.
This method is applied to derive critical loads for the Austrian forest soils. Results indicate that acid deposition has to be considered as a potential long-term threat for the majority of Austrian forests. The most sensitive ecosystems occur in the north and north-east of Austria.
A comparison of the critical loads with current acid deposition shows an excess of the threshold limits in large parts of Austria. Certain ecosystems in the east of Austria, in particular forests in the Waldviertel and the oak forests north and south-east of Vienna, face currently an acid deposition of more than ten times above their critical loads.
Finally, a sensitivity analysis identifies the most influential parameters of the model calculations and allows thereby to derive recommendations for further research and monitoring efforts.

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