Environmental Engineering Reference
In-Depth Information
Glossary
Allochthonous Originating from outside the boundaries of the system, as opposed to autochthonous.
Anion A negatively charged ion, such as bicarbonate, sulfate, or nitrate. A positively charged ion is called a
cation.
Anthropocene The geological epoch in which human influences have become globally important, conventionally
set to begin at the Industrial Revolution (late eighteenth century).
Anthropogenic Arising from human actions.
Assimilation Used in a general sense to mean uptake, but also in a more specific sense in energetics to refer to
the amount of energy that is taken up by an organism. For autotrophs, assimilation is equal to gross primary
production; for heterotrophs, assimilation is equal to ingestion minus egestion.
Autochthonous Originating from within the boundaries of the system, as opposed to allochthonous.
Autotrophic Used to describe both organisms and ecosystems. Autotrophic organisms are those that synthesize
organic matter de novo from inorganic materials, via either photosynthesis or chemosynthesis. Net autotrophic
ecosystems are those where total gross primary production exceeds total respiration. The opposite of autotro-
phic is heterotrophic.
Biogeochemistry The study of the physical, chemical, geological, and biological processes that determine the
chemical composition of the environment.
Biomass The mass of living tissues.
Catabolism The breakdown of complex molecules by living organisms to form simpler ones and release energy.
Cation A positively charged ion, such as calcium, ammonium, or sodium ions. A negatively charged ion is called
an anion.
Chelation The coordinate bonding of a metal with a molecule, usually of organic matter.
Chemoautotrophy Primary production in which chemical energy provides the energy needed to fix inorganic car-
bon into organic matter (contrasted with photosynthesis, in which light provides the necessary energy).
Examples of chemoautotrophic reactions include nitrification and sulfide oxidation.
Chemosynthesis Fixation of inorganic carbon into organic matter using oxidation of inorganic chemical com-
pounds as a source of energy (contrasted with photosynthesis, in which light provides the necessary energy).
Chronosequence A sequence of study sites differing in age (e.g., since disturbance, emergence from the sea, etc.),
but as similar as possible with respect to other factors. Used to study long-term dynamics of ecosystems.
Denitrification A form of anaerobic respiration in which nitrate is converted into dinitrogen gas (N
2
) by bacteria.
Denitrification represents a loss of reactive (i.e., useful) nitrogen from ecosystems.
Detritus Dead organic matter, usually restricted to particulate organic matter.
Disturbance Alteration of the three-dimensional structure of an ecological system or part of the system.
Electron donor/acceptor The chemical compounds participating in an oxidation-reduction (redox) reaction that
contribute or accept an electron, respectively, in the reaction (see the Appendix).
Energetics The study of energy flow through populations, communities, and ecosystems.
Engineering (ecological engineering) The direct or indirect modulation of resource availability by organisms.
Epilimnion The mixed zone that forms the upper part of a stratified lake. The metalimnion (or thermocline) and
hypolimnion lie beneath the epilimnion.
Eutrophic Having high primary production, usually as a result of high nutrient inputs. Eutrophication is the pro-
cess by which productivity is increased, often to undesirable levels, through increased nutrient inputs.
