Environmental Engineering Reference
In-Depth Information
Amalgamation:
The dissolving or blending of a metal (commonly gold and
silver) in mercury to separate it from its parent material.
Ammonia:
A compound of nitrogen and hydrogen (NH
3
) that is a common
byproduct of animal waste. Ammonia readily converts to nitrate in
soils and streams.
Anadromous fish:
Migratory species that are born in freshwater, live mostly
in estuaries and ocean water, and then return to freshwater to spawn.
Anaerobic:
Pertaining to, taking place in, or caused by the absence of oxygen.
Anomalies:
As related to fish, externally visible skin or subcutaneous disor-
ders, including deformities, eroded fins, lesions, and tumors.
Anthropogenic:
Having to do with or caused by humans.
Anticline:
A fold in the Earth's crust, convex upward, whose core contains
stratigraphically older rocks.
Aquaculture:
The science of farming organisms that live in water, such as
fish, shellfish, and algae.
Aquatic:
Living or growing in or on water.
Aquatic guidelines:
Specific levels of water quality which, if reached, may
adversely affect aquatic life. These are nonenforceable guidelines
issued by a governmental agency or other institution.
Aquifer:
A geologic formation, group of formations, or part of a formation
that contains sufficient saturated permeable material to yield signifi-
cant quantities of water to springs and wells.
Arroyo:
A small, deep, flat-floored channel or gully of an ephemeral or inter-
mittent stream, usually with nearly vertical banks cut into uncon-
solidated material.
Artificial recharge:
Augmentation of natural replenishment of groundwater
storage by some method of construction, by spreading the water, or
by pumping water directly into an aquifer.
Atmospheric deposition:
The transfer of substances from the air to the sur-
face of the Earth, either in wet form (rain, fog, snow, dew, frost, hail)
or in dry form (gases, aerosols, particles).
Atmospheric pressure:
The pressure exerted by the atmosphere on any sur-
face beneath or within it; equal to 14.7 pounds per square inch at sea
level.
Average discharge:
As used by the U.S. Geological Survey, the arithmetic
average of all complete water years of record of surface water dis-
charge whether consecutive or not. The term “average” generally is
reserved for average of record and “mean” is used for averages of
shorter periods—namely, daily, monthly, or annual mean discharges.
B
Background concentration:
Concentration of a substance in a particu-
lar environment that is indicative of minimal influence by human
(anthropogenic) sources.
