Influence of acidic atmospheric deposition on soil solution composition in the Daniel Boone National Forest, Kentucky, USA

Abstract

Acid atmosperic depositoin may enter an environmental ecosystem in a variety of forms and pathways, but the most common components include sulfuric and nitric acids formed when rainwater interacts with sulfur (SO₃) and nitrogen (NO₃) emmissions. For many soils and watersheds sensitive to acid deposition, the predominant chromic effect appears to be a low pH loss of base cations, and a shift int he mineral phase controlling the activity of Al⁴⁺ and/or SO²₄ in solutoin. Soil solutions from lysimeters at various depths were taken at two sites in the Daniel Boone National Forest, Kentucky, USA, to evaluate potential impacts caused by acid deposition. The sites chosen were in close proximity to coal burning power plants near Wolfe and McCreary counties and contained soils form the Rayne and Wernock series respectively. Physiochemical characteristics of hte siols revealed that both sites contained appreciable amounts of exchangeble acidity in the surface horizons, and that their base saturation levels were sufficiently low to be impacted adversely by acididc inputs. Soil solution data indicated that the sites were periodically subjected to relatively high NO^-₃ and SO^2-₄ inputs, which may have influenced spatial and temporal variation in Al and pH. As a consequence, the formation of Al-hydroxy-sulfate minerals such as jurganite, alunite and basaluminite were thermodynamically favored over gibbsite. Given these conditions, long-term changes in soil solution chemistry from acid deposisiton are acknowledged.

Citation

Barton, C.D.; Karathanasis, A.D.; Chalfant, G. 2002. Influence of acidic atmospheric deposition on soil solution composition in the Daniel Boone National Forest, Kentucky, USA. Environmental Geology (2002) 41:672-682