Abstract:

The increased deposition of atmospheric nitrogen due to the air pollution has exceeded the demands of forest ecosystems in many areas.The chemical and biochemical reactions of nitrogen in soils have significant effects on the production and consumption of H⁺.The balance between the inputs and outputs of NH⁺₄ and NO^-₃ determines the rate of acidification of the soil-soil solution system. Excessive nitrogen deposition will enhance the nitrification of NH⁺₄ and the leaching of NO^-₃,which are the processes of strong acidification.An increase in the NO^-₃ concentration will increase the acidity and aluminium concentration in the soil solution.Basic cations will be leached out for accompanying the NO^-₃ leaching,resulting in the acceleration of soil acidification.Soil acidification is harmful to forest.

Key words: Atmospheric pollution, Nitrogen deposition, Forest soil, Acidification