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Glossary: B
Back Pressure:
A pressure that can cause water to backflow into the water supply when a user's
waste water system is at a higher pressure than the public system.
Backflow/Back Siphonage:
A reverse flow condition created by a difference in water pressures that causes
water to flow back into the distribution pipes of a drinking water supply from
any source other than the intended one.
Background Level:
1. The concentration of a substance in an environmental media (air, water, or
soil) that occurs naturally or is not the result of human activities. 2. In
exposure assessment the concentration of a substance in a defined control area,
during a fixed period of time before, during, or after a data-gathering
operation..
Backwashing:
Reversing the flow of water back through the filter media to remove entrapped
solids.
Barrel Sampler:
Open-ended steel tube used to collect soil samples.
BACT - Best Available Control Technology:
An emission limitation based on the maximum degree of emission reduction
(considering energy, environmental, and economic impacts) achievable through
application of production processes and available methods, systems, and
techniques. BACT does not permit emissions in excess of those allowed under any
applicable Clean Air Act provisions. Use of the BACT concept is allowable on a
case by case basis for major new or modified emissions sources in attainment
areas and applies to each regulated pollutant.
Bacteria:
(Singular: bacterium) Microscopic living organisms that can aid in pollution
control by metabolizing organic matter in sewage, oil spills or other
pollutants. However, bacteria in soil, water or air can also cause human, animal
and plant health problems.
Bactericide:
A pesticide used to control or destroy bacteria, typically in the home, schools,
or hospitals.
Baffle:
A flat board or plate, deflector, guide, or similar device constructed or placed
in flowing water or slurry systems to cause more uniform flow velocities to
absorb energy and to divert, guide, or agitate liquids.
Baffle Chamber:
In incinerator design, a chamber designed to promote the settling of fly ash and
coarse particulate matter by changing the direction and/or reducing the velocity
of the gases produced by the combustion of the refuse or sludge.
Baghouse Filter:
Large fabric bag, usually made of glass fibers, used to eliminate intermediate
and large (greater than 20 PM in diameter) particles. This device operates like
the bag of an electric vacuum cleaner, passing the air and smaller particles
while entrapping the larger ones.
Bailer:
A pipe with a valve at the lower end, used to remove slurry from the bottom or
side of a well as it is being drilled, or to collect groundwater samples from
wells or open boreholes. 2. A tube of varying length.
Banking:
A system for recording qualified air emission reductions for later use in
bubble, offset, or netting transactions. (See: emissions trading.)
Bar Screen:
In wastewater treatment, a device used to remove large solids.
Barrier Coating(s):
A layer of a material that obstructs or prevents passage of something through a
surface that is to be protected; e.g., grout, caulk, or various sealing
compounds; sometimes used with polyurethane membranes to prevent corrosion or
oxidation of metal surfaces, chemical impacts on various materials, or, for
example, to prevent radon infiltration through walls, cracks, or joints in a
house.
Bed Load:
Sediment particles resting on or near the channel bottom that are pushed or
rolled along by the flow of water.
Bench-scale Tests:
Laboratory testing of potential cleanup technologies (See: treatability
studies.)
Benefit-Cost Analysis:
An economic method for assessing the benefits and costs of achieving alternative
health-based standards at given levels of health protection.
Benthic/Benthos:
An organism that feeds on the sediment at the bottom of a water body such as an
ocean, lake, or river.
Bentonite:
A colloidal clay, expansible when moist, commonly used to provide a tight seal
around a well casing.
Beryllium:
An metal hazardous to human health when inhaled as an airborne pollutant. It is
discharged by machine shops, ceramic and propellant plants, and foundries.
Best Available Control Measures (BACM):
A term used to refer to the most effective measures (according to USEPA
guidance) for controlling small or dispersed particulates and other emissions
from sources such as roadway dust, soot and ash from woodstoves and open burning
of rush, timber, grasslands, or trash.
Best Available Control Technology (BACT):
For any specific source, the currently available technology producing the
greatest reduction of air pollutant emissions, taking into account energy,
environmental, economic, and other costs.
Best Available Control Technology (BACT):
The most stringent technology available for controlling emissions; major sources
are required to use BACT, unless it can be demonstrated that it is not feasible
for energy, environmental, or economic reasons.
Best Demonstrated Available Technology (BDAT):
As identified by USEPA, the most effective commercially available means of
treating specific types of hazardous waste. The BDATs may change with advances
in treatment technologies.
Best Management Practice (BMP):
Methods that have been determined to be the most effective, practical means of
preventing or reducing pollution from non-point sources.
Bioaccumulants:
Substances that increase in concentration in living organisms as they take in
contaminated air, water, or food because the substances are very slowly
metabolized or excreted. (See: biological magnification.)
Bioassay:
A test to determine the relative strength of a substance by comparing its effect
on a test organism with that of a standard preparation.
Bioavailability:
Degree of ability to be absorbed and ready to interact in organism metabolism.
Biochemical Oxygen Demand (BOD):
A measure of the amount of oxygen consumed in the biological processes that
break down organic matter in water. The greater the BOD, the greater the degree
of pollution.
Bioconcentration:
The accumulation of a chemical in tissues of a fish or other organism to levels
greater than in the surrounding medium.
Biodegradable:
Capable of decomposing under natural conditions.
Biodiversity:
Refers to the variety and variability among living organisms and the ecological
complexes in which they occur. Diversity can be defined as the number of
different items and their relative frequencies. For biological diversity, these
items are organized at many levels, ranging from complete ecosystems to the
biochemical structures that are the molecular basis of heredity. Thus, the term
encompasses different ecosystems, species, and genes.
Biological Contaminants:
Living organisms or derivates (e.g. viruses, bacteria, fungi, and mammal and
bird antigens) that can cause harmful health effects when inhaled, swallowed, or
otherwise taken into the body.
Biological Control:
In pest control, the use of animals and organisms that eat or otherwise kill or
out-compete pests.
Biological Integrity:
The ability to support and maintain balanced, integrated, functionality in the
natural habitat of a given region. Concept is applied primarily in drinking
water management.
Biological Magnification:
Refers to the process whereby certain substances such as pesticides or heavy
metals move up the food chain, work their way into rivers or lakes, and are
eaten by aquatic organisms such as fish, which in turn are eaten by large birds,
animals or humans. The substances become concentrated in tissues or internal
organs as they move up the chain. (See: bioaccumulants.)
Biological Measurement:
A measurement taken in a biological medium. For exposure assessment, it is
related to the measurement is taken to related it to the established internal
dose of a compound.
Biological Medium:
One of the major component of an organism; e.g. blood, fatty tissue, lymph nodes
or breath, in which chemicals can be stored or transformed. (See: ambient
medium, environmental medium.)
Biological Oxidation:
Decomposition of complex organic materials by microorganisms. Occurs in
self-purification of water bodies and in activated sludge wastewater treatment.
Biological Oxygen Demand (BOD):
An indirect measure of the concentration of biologically degradable material
present in organic wastes. It usually reflects the amount of oxygen consumed in
five days by biological processes breaking down organic waste.
Biological pesticides:
Certain microorganism, including bacteria, fungi, viruses, and protozoa that are
effective in controlling pests. These agents usually do not have toxic effects
on animals and people and do not leave toxic or persistent chemical residues in
the environment.
Biological Stressors:
Organisms accidentally or intentionally dropped into habitats in which they do
not evolve naturally; e.g. gypsy moths, Dutch elm disease, certain types of
algae, and bacteria.
Biological Treatment:
A treatment technology that uses bacteria to consume organic waste.
Biologically Effective Dose:
The amount of a deposited or absorbed compound reaching the cells or target
sites where adverse effect occur, or where the chemical interacts with a
membrane.
Biomass:
All of the living material in a given area; often refers to vegetation.
Biome:
Entire community of living organisms in a single major ecological area. (See:
biotic community.)
Biomonitoring:
1. The use of living organisms to test the suitability of effluents for
discharge into receiving waters and to test the quality of such waters
downstream from the discharge. 2. Analysis of blood, urine, tissues, etc. to
measure chemical exposure in humans.
Bioremediation:
Use of living organisms to clean up oil spills or remove other pollutants from
soil, water, or wastewater; use of organisms such as non-harmful insects to
remove agricultural pests or counteract diseases of trees, plants, and garden
soil.
Biosensor:
Analytical device comprising a biological recognition element (e.g. enzyme,
receptor, DNA, antibody, or microorganism) in intimate contact with an
electrochemical, optical, thermal, or acoustic signal transducer that together
permit analyses of chemical properties or quantities. Shows potential
development in some areas, including environmental monitoring.
Biosphere:
The portion of Earth and its atmosphere that can support life.
Biota:
The animal and plant life of a given region.
Biotechnology:
Techniques that use living organisms or parts of organisms to produce a variety
of products (from medicines to industrial enzymes) to improve plants or animals
or to develop microorganisms to remove toxics from bodies of water, or act as
pesticides.
Biotic Community:
A naturally occurring assemblage of plants and animals that live in the same
environment and are mutually sustaining and interdependent. (See:
biome.)
Biotransformation:
Conversion of a substance into other compounds by organisms; includes
biodegradation.
Blackwater:
Water that contains animal, human, or food waste.
Bloom:
A proliferation of algae and/or higher aquatic plants in a body of water; often
related to pollution, especially when pollutants accelerate growth.
BOD5:
The amount of dissolved oxygen consumed in five days by biological processes
breaking down organic matter.
Body Burden:
The amount of a chemical stored in the body at a given time, especially a
potential toxin in the body as the result of exposure.
Bog:
A type of wetland that accumulates appreciable peat deposits. Bogs depend
primarily on precipitation for their water source, and are usually acidic and
rich in plant residue with a conspicuous mat of living green moss.
Boiler:
A vessel designed to transfer heat produced by combustion or electric resistance
to water. Boilers may provide hot water or steam.
Boom:
1. A floating device used to contain oil on a body of water. 2. A piece of
equipment used to apply pesticides from a tractor or truck.
Borehole:
Hole made with drilling equipment.
Botanical Pesticide:
A pesticide whose active ingredient is a plant-produced chemical such as
nicotine or strychnine. Also called a plant-derived pesticide.
Bottom Ash:
The non-airborne combustion residue from burning pulverized coal in a boiler;
the material which falls to the bottom of the boiler and is removed
mechanically; a concentration of non-combustible materials, which may include
toxics.
Bottom Land Hardwoods:
Forested freshwater wetlands adjacent to rivers in the southeastern United
States, especially valuable for wildlife breeding, nesting and habitat.
Bounding Estimate:
An estimate of exposure, dose, or risk that is higher than that incurred by the
person in the population with the currently highest exposure, dose, or risk.
Bounding estimates are useful in developing statements that exposures, doses, or
risks are not greater than an estimated value.
Brackish:
Mixed fresh and salt water.
Breakpoint Chlorination:
Addition of chlorine to water until the chlorine demand has been satisfied.
Breakthrough:
A crack or break in a filter bed that allows the passage of floc or particulate
matter through a filter; will cause an increase in filter effluent turbidity.
Breathing Zone:
Area of air in which an organism inhales.
Brine Mud:
Waste material, often associated with well-drilling or mining, composed of
mineral salts or other inorganic compounds.
British Thermal Unit:
Unit of heat energy equal to the amount of heat required to raise the
temperature of one pound of water by one degree Fahrenheit at sea level.
Broadcast Application:
The spreading of pesticides over an entire area.
Brownfields:
Abandoned, idled, or under used industrial and commercial facilities/sites where
expansion or redevelopment is complicated by real or perceived environmental
contamination. They can be in urban, suburban, or rural areas.
Bubble:
A system under which existing emissions sources can propose alternate means to
comply with a set of emissions limitations; under the bubble concept, sources
can control more than required at one emission point where control costs are
relatively low in return for a comparable relaxation of controls at a second
emission point where costs are higher.
Bubble Policy:
(See: emissions trading.)
Buffer:
A solution or liquid whose chemical makeup is such that it minimizes changes in
pH when acids or bases are added to it.
Buffer Strips:
Strips of grass or other erosion-resisting vegetation between or below
cultivated strips or fields.
Building Cooling Load:
The hourly amount of heat that must be removed from a building to maintain
indoor comfort (measured in British thermal units (Btus).
Building Envelope:
The exterior surface of a building's construction--the walls, windows, floors,
roof, and floor. Also called building shell.
Bulk Sample:
A small portion (usually thumbnail size) of a suspect asbestos-containing
building material collected by an asbestos inspector for laboratory analysis to
determine asbestos content.
Bulky Waste:
Large items of waste materials, such as appliances, furniture, large auto parts,
trees, stumps.
Burial Ground (Graveyard):
A disposal site for radioactive waste materials that uses earth or water as a
shield.
By-product:
Material, other than the principal product, generated as a consequence of an
industrial process or as a breakdown product in a living system.
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