Environmental Engineering Reference
In-Depth Information
Backwater:
A body of water in which the flow is slowed or turned back by
an obstruction such as a bridge or dam, an opposing current, or the
movement of the tide.
Bacteria:
Single-celled microscopic organisms.
Bank:
The sloping ground that borders a stream and confines the water in
the natural channel when the water level, or flow, is normal.
Bank storage:
The change in the amount of water stored in an aquifer adja-
cent to a surface water body resulting from a change in stage of the
surface water body.
Barrier bar:
An elongate offshore ridge, submerged at least at high tide and
built up by the action of waves or currents.
Base low:
The sustained low low of a stream, usually groundwater inflow
to the stream channel.
Basic:
The opposite of acidic; refers to water that has a pH greater than 7.
Basin and range physiography:
A region characterized by a series of gener-
ally north-trending mountain ranges separated by alluvial valleys.
Bed material:
Sediment comprising the streambed.
Bed sediment:
The material that temporarily is stationary in the bottom of a
stream or other watercourse.
Bedload:
Sediment that moves on or near the streambed and is in almost
continuous contact with the bed.
Bedrock:
A general term used for solid rock that underlies soils or other
unconsolidated material.
Benthic invertebrates:
Insects, mollusk, crustaceans, worms, and other
organisms without a backbone that live in, on, or near the bottom of
lakes, streams, or oceans.
Benthic organism:
A form of aquatic life that lives on or near the bottom of
stream, lakes, or oceans.
Bioaccumulation:
The biological sequestering of a substance at a higher
concentration than that at which it occurs in the surrounding envi-
ronment or medium. Also, the process whereby a substance enters
organisms through gills, epithelial tissues, diet, or other means.
Bioavailability:
The capacity of a chemical constituent to be taken up by liv-
ing organisms either through physical contact or by ingestion.
Biochemical:
Refers to chemical processes that occur inside or are mediated
by living organisms.
Biochemical oxygen demand (BoD):
Amount of oxygen required by bacteria
to stabilize decomposable organic matter under aerobic conditions.
Biochemical process:
A process characterized by, produced by, or involving
chemical reactions in living organism.
Biodegradation:
Transformation of a substance into new compounds
through biochemical reactions or the actions of microorganisms
such as bacteria.
Biological treatment:
A process that uses living organisms to bring about
chemical changes.
