As a consequence of human land use, population growth, and industrialization, wilderness and other natural areas can be threatened by air pollution, climate change, and exotic diseases or pests. Air pollution in the form of acidic deposition is comprised of sulfuric and nitric acids and ammonium derived from emissions of sulfur dioxide, nitrogen oxides, and ammonia. These compounds are largely emitted to the atmosphere by fossil fuel burning and agricultural activities. Once acid compounds enter sensitive ecosystems, they can acidify soil and surface waters,causing a series of ecological changes (Driscoll et al., 2003; Watmough et al., 2005). Acidic deposition has contributed to declining availability of Ca, Mg, and K in the soils of acid-sensitive forest ecosystems by leaching Ca, Mg, and K from foliage and from soil in the primary rooting zone. Acid deposition can also mobilize aluminum in soils affecting soil solution and drainage waters (National Acid Precipitation Assessment Program, 1998).
Elliott, Katherine J.; Vose, James M.; Knoepp, Jennifer D.; Johnson, Dale W.; Swank, William T.; Jackson, William. 2008. Simulated effects of sulfur deposition on nutrient cycling in class I wilderness areas. Journal of Environmental Quality. 37: 1419-1431