Environmental Engineering Reference
In-Depth Information
Primary production The storage of energy through the formation of organic matter from inorganic carbon com-
pounds. Primary production includes both photosynthesis and chemosynthesis, and can be expressed as gross
primary production (GPP; all energy captured by the primary producer) or net primary production (NPP; the
energy captured by the primary producer less energy expended in its own respiration).
Radioactive isotope An isotope that decays into another element or isotope (see also isotope).
Recalcitrant Resistant to decay.
Reduction A chemical reaction in which a substance gains electrons. The opposite reaction is oxidation.
Residence time The average amount of time that a substance spends in an ecosystem before being lost, calculated
as the ratio of standing stock inside the ecosystem to the rate of input.
Resilience The ability of an ecosystem to recover after a perturbation to its original state.
Respiration The oxidation of organic matter by organisms to release energy and carbon dioxide. Respiration may
be aerobic or anaerobic.
Scale In ecosystem science, scale most commonly refers to spatial or temporal grain size (the finest resolution pos-
sible in the data set), extent (size of the entire study area or length of the study), or levels of organization (organ-
isms, populations, communities, ecosystems, landscapes) in a study.
Secondary production Production of all heterotrophs, as contrasted with primary production.
Sequestration Storage, often used in reference to carbon.
Sink An ecosystem is a sink for a material if inputs of that material exceed outputs (see source).
Source An ecosystem is a source for a material if outputs of that material exceed inputs (see sink).
Spiraling The combination of material cycling and transport, usually in a stream (see Box 5.2 in Chapter 5).
Stable isotope An isotope that is not subject to radioactive decay (see also isotope).
Stoichiometry The ratio of different elements in chemical reactions, organisms, or ecological processes. The simul-
taneous mass balance of multiple elements in ecosystems.
Substrate The organic matter used by a microorganism as its food.
Trophic cascade A mechanism by which top predators can control lower trophic levels and abiotic properties of
ecosystems through interactions propagated through the food web (see Figure 11.1 in Chapter 11).
Valence An integer that shows the number of electrons that an atom or radical will gain, lose, or share when it
reacts with other atoms.
Weathering The chemical and physical changes that result when rocks are exposed to air and water.
Zoonosis An infectious disease that is carried by both humans and some other animal species.
