Effects of Acid Deposition

Summary

From the view point of the receiving ecosystem, a distinction is made between precipitation deposition and interception deposition. Long term mean values for both kinds of deposition are given for a deciduous and a coniferous forest in Central Europe (Soiling region). Interception deposition exceeds precipitation deposition especially in the coniferous forest. The acidity deposited is to more than 75% due to SO_2, NO_X contributes less than 20%. Only less than 22% of the acidity is neutralized before reaching the ecosystem. Less than 18% of the acidity is buffered in the ecosystem down to 1 m soil depth. The main fraction of the acidity passes through the ecosystem and will finally acidify the hydrosphere. The two aspects of soil acidification are discussed shortly: leaching of nutrients and release of toxins. Heavy metals from deposition accumulate in the biotic part of the ecosystem. From a balance consideration, taking into account emission rates, deposition rates and the kind and rates of possible reactions of strong acids in the ecosphere, it is concluded that the emission of strong acid formers like SO₂ and NO_X leads to the poisening of the ecosphere.