RELATIONSHIPS BETWEEN AQUEOUS ALUMINUM AND ACIDIC DEPOSITION IN FORESTED WATERSHEDS OF NORTH-AMERICA AND NORTHERN EUROPE

There are important interregional differences in the concentrations of aqueous labile aluminum in soil waters and surface waters of forested watersheds in eastern North America and northern Europe. These variations in labile aluminum are a function of several interacting factors, including soil base saturation, solution pH, anion chemistry, pH-dependent solubility and adsorption relationships, and soil hydrology. The highest concentrations of labile aluminum are found in watersheds characterized by soils with <10-15% base saturation and elevated concentrations of strong acid anions. For such sites, there is a strong positive relationship between acidic deposition, as a source of mobile anions, and aluminum mobilization. Future increases or decreases in mobile strong acid anions at these types of watersheds are likely to produce corresponding changes in both the concentrations of labile aluminum and the potential for aluminum toxicity to organisms. © 1990, American Chemical Society. All rights reserved.