Environmental Engineering Reference
In-Depth Information
Aquifer:
Water-bearing stratum of permeable sand, rock, or gravel.
Arbitrage:
The simultaneous purchase and sale of identical or similar assets across
two or more markets in order to profit from a temporary price discrepancy.
Aromatics:
Hydrocarbons characterized by unsaturated ring structures of carbon
atoms. Commercial petroleum aromatics are benzene, toluene, and xylene
(BTX).
Asexual reproduction:
The naturally occurring ability of some plant species to
reproduce asexually through seeds, meaning that the embryos develop
without a male gamete. This ensures that the seeds will produce plants
identical to the mother plant.
Atmospheric crude oil distillation:
The refining process of separating crude oil
components at atmospheric pressure by heating to temperatures of about
600 to 750°F (depending on the nature of the crude oil and desired prod-
ucts) and subsequent condensing of the fractions by cooling.
Attenuator:
A long floating structure like a terminator, but it is oriented parallel to
the waves rather than normal to them. It rides the waves like a ship, and
movements of the device at its bow and along its length can be restrained
so as to extract energy. The theoretical advantage of the attenuator over
the terminator is that its area normal to the waves is small so the forces it
experiences are much lower.
Availability factor:
A percentage representing the number of hours a generating
unit is available to produce power (regardless of the amount of power) in a
given period, compared to the number of hours in the period.
Average stream flow:
The rate, usually expressed in cubic feet per second, at which
water passes a given point in a stream over a set period of time.
Average water conditions:
The amount and distribution of precipitation within a
drainage basin and the runoff conditions present as determined by review-
ing the area water supply records over a long period of time.
Av ia n:
Of or having to do with birds.
Av i fau na:
All birds of a given region.
Azimuth angle:
The angle between true south and the point on the horizon directly
below the sun.
B
Bagasse:
The fibrous material remaining after extraction of the juice from sugar-
cane; often burned by sugar mills as a source of energy.
Barrel:
A unit of volume equal to 42 U.S. gallons.
Barrier:
Any obstruction to fish passage (i.e., an aquatic barrier).
Baseload plants:
Electricity-generating units that are operated to meet the constant
or minimum load on the system. The cost of energy from such units is usu-
ally the lowest available to the system.
Basin:
The land surrounding and draining into a water body.
Benzene (C
6
H
6
):
An aromatic hydrocarbon present in a small proportion in some
crude oils and made commercially from petroleum by the catalytic reform-
ing of naphthenes in petroleum naphtha. Also made from coal in the
