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Glossary
anthropogenic: Of, relating to, derived from, or caused by humans or related
to human activities or actions.
atmosphere: The gaseous envelope surrounding Earth. The dry atmosphere
consists almost entirely of nitrogen and oxygen, together with trace
gases, including carbon dioxide and ozone.
autecology: Study of the ecology of individual species, as opposed to the
entire community of species.
base cation: An alkali or alkaline earth metal cation (Ca 2+ , Mg 2+ , K + , Na + ).
base saturation: The proportion of total soil cation exchange capacity that
is occupied by exchangeable base cations, that is, by Ca 2+ , Mg 2+ , K + ,
and Na + .
benthic macroinvertebrates: Animals without backbones that inhabit the
bottom substrates of streams.
bioaccumulation: The phenomenon wherein toxic elements are progressively
amassed in greater quantities as individuals farther up the food chain
ingest matter containing those elements.
biological effects: Changes in biological (organismal, populational,
community-level) structure or function in response to some causal
agent; also referred to as biological response.
calibration: Process of checking, adjusting, or standardizing operating characteristics of instruments or coefficients in a mathematical model
with empirical data of known quality. The process of evaluating the
scale readings of an instrument with a known standard in terms of the
physical quantity to be measured.
catchment: An area that collects and drains rainwater (also called a
watershed).
cation: A positively charged ion.
cation exchange capacity: The total exchangeable cations that a soil can
adsorb.
chronic acidification: The decrease of acid-neutralizing capacity in a lake
or stream over a period of decades or longer, generally in response to
gradual leaching of ionic constituents.
circumneutral: Close to neutrality with respect to pH (neutral pH = 7); in
natural waters, pH 6–8.
climate: Climate in a narrow sense is usually defined as the “average weather”
or, more rigorously, as the statistical description in terms of the mean
and variability of relevant quantities over a period of time ranging from
months to thousands or millions of years. These quantities are most
often surface variables such as temperature, precipitation, and wind.
Climate in a wider sense is the state, including a statistical description, of the climate system. The classical period of time is 30 years, as
defined by the World Meteorological Organization (WMO).
Glossary
anthropogenic: Of, relating to, derived from, or caused by humans or related
to human activities or actions.
atmosphere: The gaseous envelope surrounding Earth. The dry atmosphere
consists almost entirely of nitrogen and oxygen, together with trace
gases, including carbon dioxide and ozone.
autecology: Study of the ecology of individual species, as opposed to the
entire community of species.
base cation: An alkali or alkaline earth metal cation (Ca 2+ , Mg 2+ , K + , Na + ).
base saturation: The proportion of total soil cation exchange capacity that
is occupied by exchangeable base cations, that is, by Ca 2+ , Mg 2+ , K + ,
and Na + .
benthic macroinvertebrates: Animals without backbones that inhabit the
bottom substrates of streams.
bioaccumulation: The phenomenon wherein toxic elements are progressively
amassed in greater quantities as individuals farther up the food chain
ingest matter containing those elements.
biological effects: Changes in biological (organismal, populational,
community-level) structure or function in response to some causal
agent; also referred to as biological response.
calibration: Process of checking, adjusting, or standardizing operating characteristics of instruments or coefficients in a mathematical model
with empirical data of known quality. The process of evaluating the
scale readings of an instrument with a known standard in terms of the
physical quantity to be measured.
catchment: An area that collects and drains rainwater (also called a
watershed).
cation: A positively charged ion.
cation exchange capacity: The total exchangeable cations that a soil can
adsorb.
chronic acidification: The decrease of acid-neutralizing capacity in a lake
or stream over a period of decades or longer, generally in response to
gradual leaching of ionic constituents.
circumneutral: Close to neutrality with respect to pH (neutral pH = 7); in
natural waters, pH 6–8.
climate: Climate in a narrow sense is usually defined as the “average weather”
or, more rigorously, as the statistical description in terms of the mean
and variability of relevant quantities over a period of time ranging from
months to thousands or millions of years. These quantities are most
often surface variables such as temperature, precipitation, and wind.
Climate in a wider sense is the state, including a statistical description, of the climate system. The classical period of time is 30 years, as
defined by the World Meteorological Organization (WMO).