Geographic Overview of the Regional Case Study Areas
Evaluation of low ANC surface waters can be aided by defining study areas that minimize intraregional differences in physiography and water chemistry. Major factors, including geology, soils, land use, vegetation, landforms, climate, and hydrology, were selected to best represent important processes distinguishing surface water chemistry among regions. Four of the case study regions currently receive high levels of acidic deposition (Adirondack Mountains, Catskill Mountains, western Virginia, and the Southern Blue Ridge), but they differ markedly in the extent of acidic waters, climate, geology, soils, land use, and vegetation. The regional case study areas receiving moderate levels of acidic deposition (Maine, Upper Midwest, and Florida) also vary widely in the major factors affecting surface water chemistry. Only among the three low deposition case study regions in the West (Sierra Nevada, Cascade Mountains, Rocky Mountains) is there a high degree of similarity in physical characteristics and lake chemistry. The diversity of physiography in the United States underscores the need for analysis of aquatic resources on a regional basis.
KeywordsAcidic Deposition Rocky Mountain Hydraulic Residence Time Bedrock Geology Regional Case Study
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