Environmental Engineering Reference
In-Depth Information
1996, the U.S. Department of Commerce introduced the chained-dollar mea-
sure. The new measure is based on the average weights of goods and services
in successive pairs of years. It is “chained” because the second year in each
pair, with its weights, becomes the first year of the next pair. The advantage of
using the chained-dollar measure is that it is more closely related to any given
period covered and is therefore subject to less distortion over time.
Characterization: Sampling, monitoring, and analysis activities to determine the
extent and nature of contamination at a facility or site. Characterization
provides the necessary technical information to develop, screen, analyze,
and select appropriate clean-up techniques.
Chemical separation: A process for extracting uranium and plutonium from dis-
solved spent nuclear fuel and irradiated targets. The fission products that
are left behind are high-level waste. Chemical separation is also known as
reprocessing .
Chips: Woody material cut into short, thin wafers. Chips are used as a raw material
for pulping and fiberboard or as biomass fuel.
Chlorofluorocarbon (CFC): Any of various compounds consisting of carbon,
hydrogen, chlorine, and fluorine used as refrigerants. CFCs are now thought
to be harmful to the Earth's atmosphere.
Christmas tree: The valves and fittings installed at the top of a gas or oil well to
control and direct the flow of well fluids.
Climate: The average weather (usually taken over a 30-year time period) for a par-
ticular region and time period. Climate is not the same as weather; rather, it
is the average pattern of weather for a particular region. Weather describes
the short-term state of the atmosphere. Climatic elements include precipita-
tion; temperature; humidity; sunshine; wind velocity; phenomena such as
fog, frost, and hail storms; and other measures of the weather.
Climate change: Sometimes is used to refer to all forms of climatic inconsistency,
but because the Earth's climate is never static the term is more properly
used to imply a significant change from one climatic condition to another.
In some cases, climate change has been used synonymously with the term
global warming ; however, scientists tend to use the term in the wider sense
to also include natural changes in the climate.
Climate effects: Impact on residential space heating and cooling (kg CO 2 /tree/year)
from trees located greater than approximately 15 m (50 ft) from a build-
ing (far trees) due to associated reductions in wind speeds and summer air
temperatures.
Closed-loop biomass: Crops grown in a sustainable manner for the purpose of opti-
mizing their value for bioenergy and bioproduct uses. This includes annual
crops such as maize and wheat and perennial crops such as trees, shrubs,
and grasses such as switchgrass.
Cloud condensation nuclei: Aerosol particles that provide a platform for the con-
densation of water vapor, resulting in clouds with higher droplet concentra-
tions and increased albedo.
Coarse materials: Wood residues suitable for chipping, such as slabs, edgings, and
trimmings.
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