Environmental Engineering Reference
In-Depth Information
Spatial resolution:
the smallest identifiable element in a sequence.
Speciation:
a process over time where one species evolves into a different species, or one
species diverges to become two or more species.
Specific heat capacity:
a measure of the heat energy required to increase the temperature
of a unit quantity of a substance by a unit of temperature.
Specific retention:
the volume of water retained after a saturated geologic material has
been drained under the force of gravity.
Specific yield:
that portion of interconnected pore space permitting groundwater flow
through a geologic strata. Also termed effective porosity.
Sprawl:
haphazard pattern of urbanization affecting large metropolitan areas; creates
more automobile dependence and longer commutes to work.
Spreading basin:
a form of artificial groundwater recharge where water is spread over a
large surface area composed of permeable material and permitted to seep into the
ground and migrate into an aquifer below.
Stabilization:
a remedial method involving the addition and mixing of a substance
designed to immobilize or entomb contamination. Also referred to as solidification.
Stormwater:
nonpoint pollution in urban areas initiated by wet-weather events.
Strata:
layers of rock or sediment having internally consistent characteristics distinguish-
ing them from contiguous layers.
Stratigraphic column:
a vertical chronological succession of geologic units or formations
specific to a given location.
Stratification:
the layering of sediments as they are formed and deposited; also referred
to as bedding.
Stratigraphy:
the study of rock layers or unconsolidated sediment and strata; particularly
their ages, composition, and relationship with other layers.
Strike:
the attitude or trend of a particular deposit of geologic material.
Sulfur dioxide:
SO
2
; occurs naturally through volcanic eruptions and anthropogenically
through the combustion of fossil fuels and some industrial processes. Sulfur diox-
ide is a pollutant and a component of smog.
Substitution:
a pollution prevention term used to describe the use of a less toxic or poten-
tially harmful substance instead of a more toxic or harmful substance; in ecology,
when one or more organisms/species are replaced by others.
Surface risk:
the probability any given site will contaminate the environment given the
best available data from public sources.
Surface water:
water at the surface of Earth.
Sustainability:
human activities that do not inflict excessive levels of damage upon
the environment; the environment is given adequate time to repair itself from
prior damages; and, these efforts will help return physical systems to dynamic
equilibrium.
Sustainable development:
in urban watersheds this concept encompasses those activi-
ties designed to achieve and maintain dynamic equilibrium within and between
the major physical systems performing their work in the atmosphere, biosphere,
hydrosphere, and lithosphere.
Teratogen:
a chemical capable of causing an adverse effect on a developing fetus.
Threshold:
in landscapes, the point at which instability occurs.
Threshold effect value:
the lowest tested dose of a chemical or substance causing a harm-
ful or adverse health effect. Also referred to as lowest-observed-adverse-effect
level.
Total porosity:
the sum of effective porosity and specific retention.
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