Environmental Engineering Reference
In-Depth Information
as the midlatitude cyclonic models used in
weather forecasting to general circulation models
which attempt to represent global circulation
patterns.
atmospheric turbidity
A measure of the dustiness or
dirtiness of the atmosphere as indicated by the
reduction in solar radiation passing through it.
atom
The smallest unit of an element that retains the
characteristics of that element.
autovariation
Environmental change produced when
one component of the
environment
responds
automatically to change in another.
C
Carbon
A non-metallic element which exists in a
variety of forms in the environment. It is chemically
mobile, readily combines with other elements and
is present in all organic substances.
carbon cycle
A natural bio-geochemical cycle which
works to maintain a balance between the release
of carbon compounds from their sources and their
absorption in
sinks
.
carbon cycle models
Computer based models which
simulate the workings of the carbon cycle.
carbon dioxide
One of the variable gases, currently
making up 0.0353 per cent of the atmosphere by
volume, but growing. Despite its low volume, it is
important to life on earth because of its
participation in
photosynthesis
and its contribution
to the
greenhouse effect
.
carbon tax
A policy which would tax fossil fuels
according to the amount of carbon they contained,
the ultimate aim being to reduce
carbon dioxide
emissions and slow the enhancement of the
greenhouse effect
.
carbon tetrachloride
A solvent and cleaning agent
identified as contributing to the depletion of the
ozone
layer.
carrying capacity
The maximum number of organisms
that can be supported by a particular environment.
cash cropping
Growing crops for monetary return
rather than direct food supply. (See also
subsistence
farming
.)
catalyst
A substance which facilitates a chemical
reaction, yet remains unchanged when the reaction
is over. Being unchanged, it can continue to
promote the same reaction again and again, as long
as the reagents are available, or until the catalyst
itself is removed. This is a catalytic chain reaction.
Central Electricity Generating Board (CEGB)
The
English public utility identified in the 1970s and
1980s as the main source of acid rain falling in
Scandinavia.
chemical models
Models which simulate chemical
processes. In studies of the atmospheric
environment they are being developed to investigate
the role of trace gases in the circulation of the
atmosphere.
chlorine monoxide
A compound containing chlorine
and oxygen, which has been implicated in the
destruction of
stratospheric ozone
.
B
Biodiversity Convention
A document outlining policies
aimed at combining the preservation of natural
biological diversity with
sustainable development
of biological resources. A product of
UNCED
.
biogeophysical feedback mechanism
The hypothesis
developed to explain
degradation induced drought
in the
Sahel.
Overgrazing and woodcutting
increased the surface
albedo
which in turn
disrupted the regional radiation balance. Reduced
surface heating retarded convective activity and
limited precipitation. With less precipitation,
vegetation cover decreased and the
albedo
of the
surface was further enhanced. This is an example
of positive
feedback
.
biomass
The total living organic matter in a given area.
biosphere
The zone of terrestrial life including the
earth's surface plus the lowest part of the
atmosphere and the upper part of the soil layer.
bromofluorocarbon
A group of chemicals containing
bromine, fluorine and
carbon
. Similar in properties
and use to
chlorofluorocarbons
. They decompose
to release bromine which contributes to the
destruction of the
ozone
layer.
Brundtland Commission
see
World Commission on
Environment and Development
.
buffering agents
Materials which reduce changes in
pH
when an
acid
or
alkali
is added to a solution
or mixture. Alkaline or basic materials are
capable of reducing or neutralizing acidity, for
example, and natural buffering agents such as
limestone help to reduce the environmental
impact of
acid rain
.
'business-as-usua' scenario
A scenario, based on the
maintenance of the status quo, used to predict the
future status of environmental issues.
