Atmospheric Deposition Effects on Surface Waters, Soils, and Forest Productivity

Abstract

When acid rain was discovered to be a regional problem in North America in the 1970s, initial concerns focused on surface-water acidification. Some of the earliest acidic deposition research found that fish populations in some lakes and streams in the Adirondack Mountains of NY had been eliminated by acidification (Schofield, 1976). In the 1980s, research in the U.S. expanded greatly through the National Acid Precipitation Assessment Program (NAPAP) to include soils and forests, as well as aquatic ecosystems. Because little environmental monitoring had been done before the start of NAPAP, however, information on changes that led to the conditions observed in the 1970s and 1980s was limited. As a result, NAPAP research focused on assessments of current conditions, short-term experimental manipulations, reconstructions from paleolimnological evidence, and mathematical modeling, to investigate past and possible future changes caused by acidic deposition. This program yielded conclusive evidence that acidic deposition had acidified poorly buffered surface waters, resulting in the loss of fish populations and other aquatic organisms, although uncertainties remained about the extent of these effects (NAPAP, 1991). The NAPAP Integrated Assessment Report (NAPAP, 1991) also concluded that acidic deposition may have affected soil chemistry but effects on forest health were not apparent, except for high-elevation spruce-fir forests where stand dieback was attributed to acidic deposition.KeywordsForest FloorBase CationAcidic DepositionSugar MapleStream ChemistryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.