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Glossary
acid anion: Negatively charged ion that does not react with hydrogen ion in
the pH range of most natural waters.
acid-base chemistry: The reaction of acids (proton donors) with bases (proton acceptors). In the context of this report, this means the reactions
of natural and anthropogenic acids and bases, the result of which is
described in terms of pH and acid-neutralizing capacity of the system.
acid-neutralizing capacity (ANC): The equivalent capacity of a solution to
neutralize strong acids. The components of ANC include weak bases
(carbonate species, dissociated organic acids, alumino-hydroxides,
borates, and silicates) and strong bases (primarily OH − ). ANC can
be measured in the laboratory by the Gran titration procedure or
defined as the difference in the equivalent concentrations of the
base cations and the mineral acid anions. It is a key indicator of
the ability of water to neutralize the acid or acidifying inputs it
receives. This ability depends largely on associated biogeophysical
characteristics.
acidic deposition: Transfer of acids and acidifying compounds from the
atmosphere to terrestrial and aquatic environments via rain, snow,
sleet, hail, cloud droplets, particles, and gas exchange.
acidic lake or stream: A lake or stream in which the acid-neutralizing capacity is less than or equal to zero.
acidification: The decrease of acid-neutralizing capacity in water or base saturation in soil caused by natural or anthropogenic processes.
acidified: Pertaining to a natural water that has experienced a decrease in
acid-neutralizing capacity or a soil that has experienced a reduction
in base saturation.
algae: Photosynthetic, often microscopic and planktonic, organisms occurring in marine and freshwater ecosystems.
algal bloom: A reproductive explosion of algae in a lake, river, or ocean.
alpine: The biogeographic zone made up of slopes above the tree line characterized by the presence of rosette-forming herbaceous plants and low,
shrubby, slow-growing woody plants.
analyte: A chemical species that is measured in a water sample.
anion: A negatively charged ion.
Glossary
acid anion: Negatively charged ion that does not react with hydrogen ion in
the pH range of most natural waters.
acid-base chemistry: The reaction of acids (proton donors) with bases (proton acceptors). In the context of this report, this means the reactions
of natural and anthropogenic acids and bases, the result of which is
described in terms of pH and acid-neutralizing capacity of the system.
acid-neutralizing capacity (ANC): The equivalent capacity of a solution to
neutralize strong acids. The components of ANC include weak bases
(carbonate species, dissociated organic acids, alumino-hydroxides,
borates, and silicates) and strong bases (primarily OH − ). ANC can
be measured in the laboratory by the Gran titration procedure or
defined as the difference in the equivalent concentrations of the
base cations and the mineral acid anions. It is a key indicator of
the ability of water to neutralize the acid or acidifying inputs it
receives. This ability depends largely on associated biogeophysical
characteristics.
acidic deposition: Transfer of acids and acidifying compounds from the
atmosphere to terrestrial and aquatic environments via rain, snow,
sleet, hail, cloud droplets, particles, and gas exchange.
acidic lake or stream: A lake or stream in which the acid-neutralizing capacity is less than or equal to zero.
acidification: The decrease of acid-neutralizing capacity in water or base saturation in soil caused by natural or anthropogenic processes.
acidified: Pertaining to a natural water that has experienced a decrease in
acid-neutralizing capacity or a soil that has experienced a reduction
in base saturation.
algae: Photosynthetic, often microscopic and planktonic, organisms occurring in marine and freshwater ecosystems.
algal bloom: A reproductive explosion of algae in a lake, river, or ocean.
alpine: The biogeographic zone made up of slopes above the tree line characterized by the presence of rosette-forming herbaceous plants and low,
shrubby, slow-growing woody plants.
analyte: A chemical species that is measured in a water sample.
anion: A negatively charged ion.