A Glossary


Common  Environmental
             A Glossary
              Compiled by

             EPA Region IV
              Atlanta, Ga.
       U.S. Environmental Protection Agency
            Washington, D.C.


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   The word-, and terms ridi'i <,\: n 'his fjlo^if. ;>v U'-ed  in d.sai->srii; and
v-ntine about the en\iiopir."Ht  We haw exier^.d !i-,' •   tn-M v.;*rds generally
understood and defined  :-K,'\vli,:rc Midi as v, \,i;   •./ air, but  have  included
certain common woids v.hi<'v  nh;lc  not poviiia! to ''v environment, occur
frequently in environment  ur rvdentickle.  The
glossary ako explains  ttn. nc.'inini! of woids such  as dnst and abatement as
fiey apply to  the  environment  r\er>  thou»h  definitions of such  words are
found in  ordinary dictionary's.
   In sum, we  have endeavored in a  single listing to compile and define the
most common words  and terms essential to the  study, understanding  and
solution of environmental problems. Where so many  words and terms are
concerned, it is sometimes  difficult to settle upon  definitions acceptable to
users who represent a  great  vaiiety of pursuits  and  interests. This is particu-
larly true of the newer words generated by science and technology. It may be
recalled that Dr. Samuel Johnson once described a compiler of dictionaries
as a "harmless drudge" and observed: "Dictionaries are  like  watches; the
worst is better than none, and the best cannot be expected  to go quite true."
   We do not expect this glossary to be used extensively by technicians and
professionals in environmental control. It was not designed for that  purpose.
Rather, it is our hope that  it will stimulate and improve a student's under-
standing  of man's  environment  and  the interrelationship of the forces  and
elements  that comprise it.
  So many good people helped compile this glossary it would be impossible
to list them all, but sincere  thanks go to each. Employees  of EPA's Region
IV  deserve special mention  for contributing words for inclusion.

  Specific credit  should be given  to  my  major  sources:  Paul  Sarnoff's
delightful  The New York Times Encyclopedic Dictionary of the Environ-
ment, Herbert Hanson's Dictionary oj Ecology, the American Society of Civil
Engineers' Glossary—Water and Sewage  Control Engineering, Veatch and
Humphrys' Water ami Water Use Terminology and a myriad of other equally
good, but  untraceable sources.

  My especial thanks go to Charles Pou for his patience and moral support,
to Dr. Walter Bishop, my mentor, and to Daisy Sawicki  for her beautiful
typing and for uncomplainingly  correcting my misspelling of "eutrophication"
all the way through.
                                                               G. J. S.


                                                                        air  curtain
abatement: The method of reducing the
   degree or intensity of pollution,  also
   the use of such a method.

absorption:  The penetration  of  a  sub-
   stance into  or through  another.  For
   example, in air pollution control, ab-
   sorption is the dissolving of a soluble
   gas, present in an emission, in a liquid
   which can be extracted.

accelerator: In  radiology,  a device for
   imparting  high velocity  to  charged
   particles such as electrons or protons.
   These fast  particles  can  penetrate
   matter and  are known as radiation.

acclimation:  The physiological  and be-
   havioral  adjustments of an  organism
   to changes  in its  immediate  environ-

acclimatization: The acclimation or adap-
   tation of  a  particular  species   over
   several  generations   to  a  marked
   change in the environment.

activated carbon:  A  highly adsorbent
   form of carbon, used to remove odors
   and   toxic  substances  from  gaseous
   emissions.  In  advanced  waste treat-
   ment,  activated  carbon  is  used  to
   remove   dissolved   organic   matter
   from waste water.

activated sludge: Sludge that  has  been
   aerated  and  subjected  to  bacterial
   action, used to remove organic matter
   from sewage.

activated sludge  process: The process  of
   using biologically active  sewage sludge
   to hasten  breakdown of organic mat-
   ter in raw  sewage  during secondary
   waste  treatment.

acute toxicity:  Any poisonous effect  pro-
   duced within a short  period  of  time,
   usually up  to 24-96 hours,  resulting
   in severe biological  harm and often
adaptation:  A  change  in  structure  or
   habit of an  organism  that  produces
   better adjustment to the environment.

adsorption: The adhesion of a substance
   to the surface of  a solid  or liquid.
   Adsorption  is  often  used to  extract
   pollutants by causing them to be  at-
   tached to such adsorbents as activated
   carbon or silica gel. Hydrophobic, or
   water-repulsing  adsorbents,  are  used
   to extract  oil from waterways in  oil

adulterants: Chemicals or substances that
   by law do not belong in a food, plant,
   animal or pesticide formulation. Adul-
   terated products are subject to seizure
   by the Food  and Drug Administration.

advanced waste  treatment: Waste water
   treatment  beyond  the   secondary  or
   biological stage that includes removal
   of nutrients  such as phosphorus and
   nitrogen and a high percentage of sus-
   pended  solids. Advanced waste treat-
   ment, known as tertiary treatment, is
   the  "polishing stage" of waste water
   treatment and produces  a high quality

aeration: The process of  being  supplied
   or impregnated with air. Aeration is
   used in  waste  water   treatment  to
   foster biological  and chemical  puri-

aerobic: This refers to life or processes
   that can  occur only in the  presence
   of oxygen.

aerosol: A suspension of  liquid or solid
   particles in the air.

afterburner:  An air pollution  abatement
   device  that  removes undesirable  or-
   ganic gases  through incineration.

agricultural  pollution:  The  liquid  and
   solid wastes from  all types of farm-
   ing,  including runoff from pesticides,
   fertilizers  and feedlots; erosion and
   dust from  plowing, animal manure
   and  carcasses  and crop residues and
   debris.  It  has been  estimated  that
   agricultural  pollution in the  U.S.  has
   amounted  to more than  2Vz billion
   tons per year.

air  curtain:  A  method for mechanical
   containment  of  oil   spills.  Air  is
   bubbled  through  a  perforated  pipe

air mass
   causing an  upward  water flow  that
   retards the spreading of oil. Air  cur-
   tains are also used as barriers  to  pre-
   vent fish  from  entering  a polluted
   body  of water.

air mass: A widespread body of air with
   properties that were established while
   the air was situated over a particular
   region  of  the  earth's  surface and  that
   undergoes specific modifications while
   in transit  away from  that  region.

air monitoring: See monitoring.

air  pollution: The presence of contami-
   nants in the air in concentrations  that
   prevent the normal dispersive ability
   of the air and  that interfere directly
   or indirectly  with man's health, safety
   or comfort or with the full use  and
   enjoyment of his property.

air  pollution episode: The occurrence of
   abnormally high concentrations of air
   pollutants  usually  due  to  low winds
   and temperature  inversion and  accom-
   panied by an  increase  in illness  and
   death.  See inversion.

air  quality control region:  An area desig-
   nated  by the   Federal   government
   where  two or  more  communities—
   either  in  the  same or  different states
   —share a common air pollution prob-
air  quality criteria: The levels of pollu-
   tion and lengths of exposure at which
   adverse effects on health  and  welfare
air   quality  standards:  The  prescribed
   level  of pollutants in the  outside air
   that cannot  be exceeded  legally  dur-
   ing  a specified  time  in  a specified
   geographical  area.

algal bloom: A  proliferation of living
   algae on the surface  of lakes,  streams
   or ponds. Algal blooms are stimulated
   by phosphate enrichment.

alpha particle: A positively  charged  par-
   ticle  emitted  by certain  radioactive
   materials.  It  is  the  least  penetrating
   of the  three  common  types  of  radi-
   ation  (alpha, beta and gamma)  and
   usually not dangerous  to plants,  ani-
   mals  or  man.

ambient air: Any  unconfined portion  of
   the atmosphere; the outside air.
anadromous:  Type  of fish  that  ascend
   rivers from the sea to spawn.

anaerobic:  Refers  to life  or  processes
   that occur in the absence of oxygen.

anticoagulant: A chemical that  interferes
   with blood clotting,  often used as a

anti-degradation  clause: A  provision  in
   air  quality and water  quality laws
   that prohibits deterioration  of  air  or
   water quality in  areas where the pol-
   lution   levels  are  presently   below
   those allowed.

aquifer: An underground bed or stratum
   of earth,  gravel  or porous stone that
   contains water.

aquatic plants: Plants  that grow in water
   either floating on the surface, growing
   up  from  the  bottom of  the body  of
   water or  growing  under  the  surface
   of  the  water.

area source: In  air pollution, any small
   individual fuel combustion source,  in-
   cluding  any  transportation sources.
   This  is  a  general  definition;  area
   source is  legally and precisely defined
   in  Federal   regulations.  See   point

asbestos: A  mineral fiber with countless
   industrial uses;  a hazardous  air  pollu-
   tant when inhaled.

A-Scale sound level: The measurement of
   sound  approximating   the   auditory
   sensitivity of  the  human  ear. The
   A-Scale sound level  is used to  meas-
   ure  the relative noisiness  or  annoy-
   ance  of common sounds.

assimilation:  Conversion  or  incorpora-
   tion of absorbed nutrients into proto-
   plasm.  Also refers to the ability of a
   body of water  to  purify itself of or-
   ganic pollution.

atmosphere:  The layer of air surrounding
   the earth.

atomic pile:  A nuclear reactor.

attractant: A chemical or agent that lures
   insects  or  other  pests  by  olfactory

attrition: Wearing or grinding down  by
   friction. One of the three basic con-

                                                                 biological  control
   tributing processes  of  air  pollution,
   the others  are vaporization  and com-

audiometer: An instrument  for  measur-
   ing hearing sensitivity.

autotrophic:   Self-nourishing;   denoting
   those organisms capable of construct-
   ing  organic  matter  from  inorganic
backfill:  The  material  used  to  refill  a
   ditch  or  other  excavation,  or  the
   process  of doing so.

background level:  With  respect  to air
   pollution,  amounts of pollutants  pres-
   ent in the ambient air due to natural

background radiation:  Normal radiation
   present  in the lower atmosphere  from
   cosmic  rays  and from  earth  sources.

bacteria:   Single-celled   microorganisms
   that lack  chlorophyll. Some  bacteria
   are capable of causing human, animal
   or plant diseases, others are essential
   in  pollution  control  because  they
   break down organic  matter in the air
   and  in  the  water.

baffle:  Any  deflector  device  used  to
   change  the  direction of flow  or the
   velocity of water, sewage or products
   of  combustion  such  as  fly  ash  or
   coarse  paniculate matter.   Also  used
   in deadening sound.

baghouse:  An   air pollution   abatement
   device  used  to trap particulates  by
   filtering  gas  streams  through   large
   fabric bags,  usually made of  glass

baling: A means of reducing  the volume
   of solid waste by compaction.

ballistic  separator:  A machine that sep-
   arates  inorganic from organic matter
   in a composting process.

band application: With  respect to pesti-
   cides, the application of the chemical
   over or  next to each row of plants
   in a field.

bar  screen:  In waste water treatment, a
   screen  that removes large floating and
   suspended solids.

basal application: With  respect to pesti-
   cides, the application of the pesticide
   formulation  on stems  or  trunks  of
   plants  just above  the soil line.

basin: See river basin.

benthic region:  The  bottom  of a  body
   of  water.  This region  supports the
   benthos,  a type of life that not  only
   lives  upon,  but  contributes  to  the
   character of  the bottom.

benthos: The plant and animal life whose
   habitat is the  bottom of a  sea,  lake
   or river.

beryllium:  A  metal that when airborne
   has adverse effects on human  health;
   it has  been declared  a hazardous  air
   pollutant.  It  is primarily  discharged
   by operations such as machine shops,
   ceramic  and  propellant  plants   and

beta  particle:   An  elementary  particle
   emitted by radioactive decay that may
   cause skin  burns. It  is easily stopped
   by a thin  sheet of  metal.

bioassay:  The employment  of living or-
   ganisms  to determine the  biological
   effect of  some substance,  factor  or

biochemical oxygen demand  (BOD): A
   measure  of  the amount  of  oxygen
   consumed  in  the biological  processes
   that  break  down  organic  matter in
   water.   Large  amounts  of  organic
   waste use  up  large   amounts  of  dis-
   solved  oxygen, thus  the greater the
   degree  of  pollution,  the greater the
biodegradable: The process  of decompos-
   ing quickly as a result of  the action
   of microorganisms.

biological  control: A  method  of  con-
   trolling pests by means 'of introduced

biological  oxidation
   or naturally occurring predatory orga-
   nisms,  sterilization  or  the  use of in-
   hibiting hormones,  etc., rather  than
   by mechanical  or chemical means.

biological  oxidation:  The  process by
   which  bacterial and other  microorga-
   nisms feed on  complex organic mate-
   rials  and  decompose  them.   Self-
   purification  of  waterways  and  acti-
   vated sludge and trickling  filter waste
   water treatment  processes  depend on
   this  principle.   The process  is  also
   called  biochemical  oxidation.

biomonitoring:  The use of living orga-
   nisms to test the suitability of effluent
   for  discharge  into receiving  waters
   and  to test the quality of such waters
   downstream from a discharge.

biospbere:  The portion of the earth and
   its atmosphere capable of supporting
biostabiiizer: A machine used to convert
   solid waste  into  compost by grinding
   and  aeration.

biota: All  the  species  of plants and ani-
   mals occurring within a certain  area.

bloom:  A  proliferation  of living algae
   and/or  other  aquatic  plants on the
   surface  of  lakes or ponds.  Blooms
   are  frequently  stimulated  by  phos-
   phate enrichment.

BOD: See biochemical  oxygen demand.

BOD5:  The amount of dissolved oxygen
   consumed in five days by biological
   processes breaking down organic mat-
   ter  in  an  effluent. See  biochemical
   oxygen  demand.

bog:  Wet, spongy  land  usually  poorly
   drained, highly acid and rich in plant

boom: A  floating  device that is used  to
   contain oil on a body of water.

botanical   pesticide:  A  plant-produced
   chemical used to control pests;  for ex-
   ample, nicotine, strychnine or orpyre-

brackish water: A mixture  of fresh and
   salt  water.

breeder: A nuclear reactor that produces
   more fuel than it consumes.
broadcast  application:  With  respect to
   pesticides, the application of a chem-
   ical  over  an  entire  field,  lawn  or
   other area.

burial  ground  (graveyard): A place for
   burying  unwanted  radioactive  mate-
   rials to prevent radiation escape, the
   earth or  water  acting  as a  shield.
   Such materials must  be  placed in
   water-tight,  noncorrodible containers
   so  the  radioactive  material  cannot
   leach out  and invade  underground
   water supplies.
cadmium: See heavy metals.

carbon dioxide (CO2): A colorless, odor-
   less, nonpoisonous gas that  is a nor-
   mal part of the ambient air. CO2 is a
   product of fossil fuel combustion, and
   some  researchers have theorized that
   excess CO2  raises  atmospheric  tem-

carbon   monoxide  (CO):  A  colorless,
   odorless,  highly toxic gas that is a
   normal byproduct of incomplete fossil
   fuel   combustion.  CO,  one  of  the
   major air pollutants,  can  be harmful
   in small amounts if breathed over a
   certain period of time.

carcinogenic: Cancer producing.

catalytic   converter:  An  air  pollution
   abatement device that removes organ-
   ic contaminants  by  oxidizing  them
   into carbon dioxide  and water through
   chemical  reaction.  Can  be  used  to
   reduce nitrogen oxide emissions  from
   motor vehicles.

caustic soda: Sodium hydroxide (NaOH),
   a strongly alkaline,  caustic substance
   used  as  the  cleaning agent in some

cells: With  respect to  solid waste  dis-

                                                                 coliform  organism
   posal, earthen compartments in which
   solid  wastes  are dumped, compacted
   and  covered  over  daily with  layers
   of earth.

centrifugal  collector:   Any  of   several
   mechanical  systems using centrifugal
   force to remove aerosols from a gas

cfs: Cubic feet per second,  a measure of
   the amount of water passing a given

channelization:  The  straightening  and
   deepening of streams to permit water
   to move faster,  to  reduce flooding or
   to drain marshy  acreage  for farming.
   However, channelization reduces the
   organic waste assimilation capacity of
   the  stream  and  may   disturb  fish
   breeding  and  destroy  the   stream's
   natural beauty.

chemical   oxygen  demand   (COD):  A
   measure of  the amount  of  oxygen
   required to oxidize organic  and  oxi-
   dizable  inorganic   compounds   in
   water.  The  COD test, like the BOD
   test,  is  used  to  determine the degree
   of pollution  in  an  effluent.

chemosterilant:   A  pesticide   chemical
   that   controls   pests  by  destroying
   their  ability  to  reproduce.

chilling  effect: The lowering of the earth's
   temperature  due to  the increase of
   atmospheric  particulates  that inhibit
   penetration of the sun's energy.

chlorinated hydrocarbons:   A  class  of
   generally long-lasting,  broad-spectrum
   insecticides of which the best known
   is  DDT, first used for insect  control
   during  World War  II. Other  similar
   compounds  include aldrin,  dieldrin,
   heptachlor, chlordane, lindane, endrin,
   mirex,   benzene  hexachloride  (BHC),
   and toxaphene.  The qualities of per-
   sistence  and  effectiveness against  a
   wide variety of insect pests were long
   regarded as highly desirable  in  agri-
   culture, public health and home  uses.
   But later research  has revealed that
   these same qualities may represent  a
   potential hazard through  accumulation
   in  the  food chain  and persistence in
   the environment.

chlorination: The application of  chlorine
   to drinking water, sewage or  indus-
   trial waste for disinfection or  oxida-
   tion of undesirable compounds.

chlorinator:  A   device   for  adding  a
   chlorine-containing gas  or liquid to
   drinking or waste water.

chlorine-contact   chamber:   In  a  waste
   treatment plant, a  chamber in  which
   effluent  is disinfected by chlorine be-
   fore it is discharged  to  the receiving
chlorosis: Yellowing or whitening of nor-
   mally green  plant parts. It  can  be
   caused by  disease organisms,  lack of
   oxygen  or  nutrients in the  soil or by
   various  air pollutants.

chromium: See heavy metals.

chronic: Marked  by  long  duration  or
   frequent recurrence, as a disease.

clarification: In  waste water  treatment,
   the  removal  of turbidity  and  sus-
   pended  solids  by settling, often aided
   by  centrifugal  action and chemically
   induced coagulation.

clariner: In  waste  water  treatment,  a
   settling  tank  which mechanically re-
   moves settleable  solids  from wastes.

coagulation: The clumping of particles in
   order to settle out impurities; often
   induced by chemicals such as lime or

coastal  zone:  Coastal waters  and adja-
   cent lands that  exert  a measurable
   influence on the  uses of the  sea  and
   its ecology.

COD: See chemical oxygen demand.

coefficient  of  haze (COH):  A measure-
   ment of visibility interference in  the

coffin:  A thick-walled  container  (usually
   lead) used for transporting radioactive

COH: See coefficient of haze.

coliform index:  An index of  the  purity
   of water based on a count of its coli-
   form bacteria.

coliform organism: Any  of a number of
   organisms  common to the intestinal
   tract  of man  and  animals   whose

combined  sewers
   presence in  waste water  is an indi-
   cator of pollution and of potentially
   dangerous  bacterial contamination.

combined  sewers:  A  sewerage  system
   that carries both sanitary sewage and
   storm   water   runoff.  During  dry
   weather, combined  sewers  carry  all
   waste  water to  the  treatment  plant.
   During a storm,  only part of the flow
   is  intercepted because of plant over-
   loading;  the remainder goes  untreated
   to the  receiving  stream.

combustion: Burning. Technically, a rapid
   oxidation accompanied by the release
   of energy  in  the form  of  heat  and
   light. It is one  of the three basic con-
   tributing factors  causing  air pollution,
   the others  are  attrition and  vaporiza-
comminution:   Mechanical  shredding or
   pulverizing  of  waste,  a process  that
   converts it  into  a  homogeneous  and
   more manageable material.  Used in
   solid waste management and  in the
   primary  stage  of waste  water  treat-
comminutor: A device  that grinds  solids
   to make them  easier to  treat.

compaction: Reducing the bulk of solid
   waste by rolling  and tamping.

compost:  Relatively stable  decomposed
   organic material.

composting: A controlled process of de-
   grading organic matter by microorga-
   nisms.  (1)   mechanical—a method in
   which  the   compost  is  continuously
   and  mechanically mixed and aerated.
   (2)  ventilated cell—compost is  mixed
   and  aerated by being dropped through
   a  vertical  series of  ventilated  cells.
   (3)  windrow—an open-air method in
   which  compostable material  is  placed
   in  windrows, piles or ventilated bins
   or  pits  and occasionally turned  or
   mixed. The process may be anaerobic
   or aerobic.

contact pesticide:  A chemical  that kills
   pests on contact with the body,  rather
   than by  ingestion (stomach  poison).

contrails:  Long narrow clouds caused by
   the  disturbance  of  the  atmosphere
   during   passage  of  high-flying  jets.
   Proliferation of  contrails  may  cause
   changes  in  the  weather.

coolant:  A  substance,  usually  liquid or
   gas, used for cooling  any part of a
   reactor in  which heat is  generated,
   including the core, the reflector, shield
   and  other  elements   that  may  be
   heated by absorption of radiation.

cooling tower:  A device to remove excess
   heat  from  water used in  industrial
   operations,  notably  in  electric  power

core:  The  heart  of a nuclear  reactor
   where energy is  released.

cover material: Soil that is used to cover
   compacted  solid  waste in a sanitary

cultural  eutrophication: Acceleration by
   man of the natural  aging process of
   bodies of water.

curie: A  measure of radioactivity.

cutie-pie:  A portable instrument equipped
   with a direct reading  meter used to
   determine the  level  of radiation in
   an  area.

cyclone collector:  A device used  to  col-
   lect large-size particulates from  pol-
   luted  air by centrifugal force.
DDT:  The  first  of the  modern chlori-
   nated hydrocarbon  insecticides whose
   chemical name is l,l,l-tricholoro-2,2-
   bis  (p-chioriphenyl)-ethane.  It has a
   half-life of  15  years, and  its residues
   can become concentrated in the  fatty
   tissues of certain organisms,  especially
   fish. Because of  its  persistence in  the
   environment and its ability to  accu-
   mulate  and  magnify  in  the  food
   chain,  EPA has  banned the  registra-
   tion and interstate  sale of DDT  for
   nearly all  uses  in  the United  States
   effective  December  31, 1972.

                                                              dry limestone process
decibel  (dB): A unit of sound measure-

decomposition:  Reduction   of  the  net
   energy level  and change in chemical
   composition  of  organic matter  be-
   cause  of  the actions of  aerobic  or
   anaerobic microorganisms.

dermal  toxiciry: The  ability of a pesti-
   cide  chemical to poison  an  animal or
   human by skin  absorption.

desalinization: Salt removal from sea or
   brackish  water.

desiccant: A  chemical  agent that may be
   used to remove  moisture from plants
   or insects causing them  to wither and
detergent: Synthetic washing agent  that,
   like  soap, lowers the surface tension
   of water,  emulsifies  oils  and  holds
   dirt  in suspension.  Environmentalists
   have   criticized  detergents  because
   most contain large  amounts of phos-
   phorus-containing   compounds  that
   contribute  to the   eutrophication  of

diatomaceous earth (diatomite):  A  fine
   siliceous   material   resembling  chalk
   used in waste water treatment plants
   to filter  sewage effluent  to remove
   solids.  May also be used as inactive
   ingredients in  pesticide  formulations
   applied as dust or  powder.

diffused air:  A type of sewage aeration.
   Air is  pumped into  the sewage through
   a perforated  pipe.

digester:  In  a  waste  water  treatment
   plant,  a  closed  tank that   decreases
   the  volume  of  solids  and  stabilizes
   raw  sludge by  bacterial action.

digestion:  The biochemical decomposition
   of organic matter.  Digestion of  sew-
   age sludge takes place in tanks where
   the sludge decomposes,  resulting  in
   partial gasification,  liquefaction  and
   mineralization of pollutants.

dilution ratio: The  ratio of the volume
   of water of  a  stream to the volume
   of incoming waste.  The  capacity  of a
   stream to assimilate waste  is partial-
   ly dependent upon   the dilution ratio.

disinfection: Effective killing by chemical
   or physical processes of  all  organisms
   capable of causing infectious disease.
   Chlorination is the disinfection meth-
   od  commonly employed  in  sewage
   treatment processes.

dispersant:  A  chemical  agent  used to
   break  up  concentrations  of organic
   material.  In cleaning oil  spills,  dis-
   persants  are used to disperse oil from
   the water surface.

dissolved  oxygen (DO):  The oxygen  dis-
   solved in water or  sewage.  Adequate-
   ly dissolved  oxygen  is necessary for
   the  life  of  fish and  other aquatic
   organisms and for  the prevention of
   offensive  odors.  Low dissolved oxy-
   gen  concentrations  generally  are  due
   to  discharge   of   excessive  organic
   solids having high BOD, the result of
   inadequate waste  treatment.

dissolved  solids:  The  total amount of
   dissolved  material,  organic and inor-
   ganic,  contained  in water or  wastes.
   Excessive dissolved solids make water
   unpalatable  for drinking and  unsuit-
   able for industrial  uses.

distillation:  The  removal of  impurities
   from liquids  by  boiling. The  steam,
   condensed back into  liquid,  is almost
   pure water; the pollutants  remain in
   the concentrated residue.

dose: In  radiology,  the quantity of en-
   ergy or  radiation  absorbed.

dosimeter  (dosemeter):   An  instrument
   used to measure  the  amount of radi-
   ation a person  has received.

dredging:   A  method   for   deepening
   streams,  swamps or coastal waters by
   scraping  and removing solids from the
   bottom. The resulting mud is  usually
   deposited in  marshes  in  a  process
   called filling. Dredging and  filling can
   disturb natural ecological cycles.  For
   example, dredging can destroy  oyster
   beds and other aquatic life:  filling can
   destroy  the   feeding  and  breeding
   grounds for many fish species.

dry limestone process:  A  method of con-
   trolling air pollution caused by sulfur
   oxides. The polluted gases are exposed
   to  limestone   which  combines  with
   oxides of sulfur to form manageable

dump: A land site where solid waste  is
   disposed of  in  a manner  that  does
   not protect the environment.

dust: Fine-grain paniculate matter that
   is capable of being suspended in air.

dustfall jar: An open-mouthed container
   used to collect large particles that fall
   out of the  air. The particles are  mea-
   sured and analyzed.

dystrophic lakes:  Lakes  between eutro-
   phic and swamp stages of aging. Such
   lakes are shallow and have high hu-
   mus content, high organic matter con-
   tent,   low  nutrient  availability  and
   high BOD.
 ecological impact: The total effect of an
    environmental  change,  either natural
    or man-made,  on  the  ecology  of the

 ecology:  The  interrelationships of living
    things to one another and to their en-
    vironment  or the study of  such inter-

 economic poisons: Those  chemicals  used
    to control  insects, rodents,  plant dis-
    eases, weeds and other pests, and also
    to defoliate economic crops such  as

 ecosphere: See biosphere.

 ecosystem: The interacting system  of  a
    biological  community  and  its  non-
    living environment.

 effluent:  A  discharge of  pollutants  into
    the environment,  partially or  com-
    pletely treated  or  in its natural state.
    Generally used in regard to discharges
    into waters.

 electrodialysis:  A  process   that  uses
    electrical current  and an arrangement
   of permeable  membranes to separate
   soluble  minerals from water.  Often
   used  to  desalinize  salt or  brackish
electrostatic precipitator: An air pollution
   control device that removes participate
   matter  by  imparting  an   electrical
   charge to particles in a gas stream for
   mechanical collection on an electrode.

emergency  episode:  See  air   pollution

emission:  See  effluent.  (Generally  used
   in regard to discharges into air.)
emission factor: The average  amount of
   a  pollutant  emitted from each type of
   polluting source  in   relation   to  a
   specific amount of material processed.
   For  example, an emission factor for
   a  blast  furnace  (used to  make iron)
   would be a number of pounds of par-
   ticulates  per ton of raw materials.

emission inventory: A  list of  air  pollu-
   tants emitted  into a community's  at-
   mosphere,  in  amounts (usually  tons)
   per day, by type of  source.  The emis-
   sion inventory is basic to the establish-
   ment of  emission standards.
emission standard: The maximum amount
   of a pollutant legally permitted to be
   discharged  from a single source, either
   mobile or stationary.
enrichment: The  addition of  nitrogen,
   phosphorus and carbon compounds or
   other nutrients  into  a lake or other
   waterway  that  greatly  increases the
   growth potential for algae  and other
   aquatic  plants.  Most frequently, en-
   richment results from the   inflow of
   sewage effluent or  from agricultural
environment:  The sum  of  all external
   conditions  and influences affecting the
   life, development and, ultimately,  the
   survival of an organism.
environmental impact statement: A docu-
   ment prepared  by  a Federal agency
   on  the  environmental impact  of its
   proposals  for  legislation   and  other
   major  actions  significantly  affecting
   the  quality of the human environment.
   Environmental  impact statements are
   used as  tools for decision making and
   are  required by the National Environ-
   mental Policy Act.

                                                                          flue gas
epidemiology: The study of  diseases as
   they affect populations.

erosion:  The  wearing away  of the land
   surface by wind  or  water.  Erosion
   occurs naturally from weather or run-
   off but is  often  intensified by  man's
   land-clearing practices.

estuaries: Areas  where  the  fresh  water
   meets  salt  water.  For example, bays,
   mouths of rivers, salt marshes  and
   lagoons. Estuaries are delicate eco-
   systems;  they  serve  as  nurseries,
   spawning  and  feeding grounds  for a
   large group of  marine life and provide
   shelter and food for birds and wildlife.

eutrophication: The normally  slow  aging
   process by which  a lake evolves into
   a  bog or  marsh  and ultimately as-
   sumes a  completely  terrestrial  state
   and disappears. During eutrophication
   the lake becomes  so  rich  in nutritive
   compounds,  especially nitrogen  and
   phosphorus,  that  algae   and  other
   microscopic plant life become  super-
   abundant,  thereby "choking" the lake,
   and causing it eventually  to  dry up.
   Eutrophication may be accelerated by
   many human activities.

 eutrophic lakes:  Shallow  lakes,  weed-
   choked at the  edges  and very rich in
   nutrients.  The water  is characterized
   by large amounts of  algae, low water
   transparency,  low dissolved  oxygen
   and high BOD.

 evaporation   ponds:  Shallow,  artificial
   ponds where sewage sludge is pumped,
   permitted  to  dry and either  removed
    or buried  by more sludge.
 fabric filters: A device for removing dust
    and particulate matter from industrial
    emissions much like  a home  vacuum
   cleaner  bag.  The  most common  use
   of fabric filters is the baghouse.

fecal coliform bacteria: A group of orga-
   nisms common to the intestinal  tracts
   of man  and of animals. The presence
   of fecal coliform bacteria  in water is
   an indicator  of pollution  and of po-
   tentially dangerous bacterial contami-

feedlot: A  relatively small, confined land
   area for  raising cattle.  Although an
   economical method of fattening beef,
   feedlots concentrate  a  large amount
   of animal wastes in a small area. This
   excrement cannot  be handled  by the
   soil  as  it could be  if the  cattle were
   scattered  on  open  range.   In addition,
   runoff  from   feedlots  contributes ex-
   cessive  quantities  of nitrogen,  phos-
   phorus   and   potassium   to  nearby
   waterways, thus contributing to  eutro-

 fen: A  low-lying land area partly covered
   by water.

 filling:  The process of depositing dirt and
   mud in marshy areas to  create more
   land for real  estate development.  Fill-
   ing  can  disturb  natural  ecological
   cycles.  See dredging.

 film badge: A  piece of masked  photo-
   graphic film  worn like  a  badge by
   nuclear workers to monitor an expo-
   sure to  radiation.  Nuclear radiation
   darkens the film.

 filtration:  In waste water treatment, the
    mechanical process that removes par-
    ticulate  matter  by separating  water
    from solid material usually by passing
    it through sand.

 floe: A clump of solids formed in  sewage
    by biological or chemical  action.

 flocculation:  In  waste  water  treatment,
    the  process   of separating  suspended
    solids by chemical creation  of  clumps
    or  floes.

 flowmeter:  In waste  water   treatment, a
    meter  that indicates the rate at which
    waste  water  flows through  the plant.

 flue  gas:  A mixture  of  gases resulting
    from combustion  and  emerging  from
    a chimney.  Flue gas includes nitrogen

   oxides,  carbon  oxides,  water vapor
   and  often  sulfur  oxides or  particu-

fluorides:  Gaseous,  solid  or  dissolved
   compounds  containing  fluorine,
   emitted into the air or water from  a
   number of industrial  processes.  Fluo-
   rides in the air are a cause of vege-
   tation  damage and,   indirectly,  of
   livestock damage.

flume: A channel, either natural  or man-
   made,  which carries water.

fly ash: All solids, including ash, charred
   paper,  cinders, dust,  soot  or  other
   partially incinerated matter,  that are
   carried in  a gas stream.

fog: Liquid particles  formed by conden-
   sation  of vaporized liquids.

fogging: The application  of a  pesticide
   by rapidly  heating the  liquid chemi-
   cal,  thus forming  very fine  droplets
   with the  appearance of  smoke.  Fog-
   ging is  often  used to  destroy  mos-
   quitoes and blackflies.

food waste: Animal and  vegetable waste
   resulting  from the handling, storage,
   sale, preparation, cooking and serving
   of foods; commonly called  garbage.

fossil  fuels: Coal, oil and natural  gas;
   so-called because  they  are derived
   from  the  remains  of  ancient  plant
   and animal life.

fume:  Tiny  solid  particles  commonly
   formed by the condensation of vapors
   of solid matter.

fumigant:  A pesticide that is  burned  or
   evaporated  to form a  gas  or  vapor
   that destroys  pests.  Fumigants are
   often  used  in buildings  or  green-

fungi:  Small,  often   microscopic  plants
   without  chlorophyll.  Some  fungi  in-
   fect and cause disease  in plants  or
   animals;  other fungi  are  useful  in
   stabilizing  sewage  or   in   breaking
   down  wastes for compost.

fungicide: A pesticide chemical that kills
   fungi or  prevents  them from causing
   diseases, usually on plants of econom-
   ic importance. See pesticide.
game fish: Those  species of fish  sought
   by  sports  fishermen;  for  example,
   salmon, trout, black bass, striped bass,
   etc. Game fish  are usually more sen-
   sitive to  environmental  changes  and
   water   quality   degradation    than
   "rough" fish.

gamma ray:  Waves  of  radiant nuclear
   energy.  Gamma rays are  the most
   penetrating of the three types of radi-
   ation  and are  best stopped  by dense
   materials  such  as  lead.

garbage: See  food  waste.

garbage grinding:  A method of grinding
   food waste  by  a  household disposal,
   for example, and washing it into the
   sewer  system.  Ground garbage then
   must be disposed of as sewage sludge.

Geiger counter: An  electrical  device that
   detects the presence of radioactivity.

generator:  A device  that converts  me-
   chanical energy into electrical  energy.

germicide: A chemical or agent that kills
   microorganisms such as  bacteria  and
   prevents  them  from  causing disease.
   Such  compounds  must  be registered
   as pesticides with  EPA.

grain: A unit of weight  equivalent to 65
   milligrams or 2/1,000 of an ounce.

grain loading:  The  rate  of emission of
   particulate  matter from  a  polluting
   source.   Measurement  is   made  in
   grains  of  particulate matter per cubic
   foot of gas  emitted.

green belts: Certain  areas restricted from
   being used  for buildings and houses;
   they often serve  as separating  buffers
   between  pollution  sources  and con-
   centrations  of  population.

greenhouse effect: The heating effect of
   the atmosphere upon the earth. Light
   waves from the sun pass through the

   air  and  are  absorbed  by  the  earth.
   The  earth then  reradiates  this energy
   as heat waves that are absorbed  by
   the  air, specifically by carbon dioxide.
   The  air thus  behaves like  glass in a
   greenhouse,  allowing  the  passage  of
   light  but not of  heat.  Thus  many
   scientists theorize  that  an  increase in
   the  atmospheric concentration of CO2
   can  eventually  cause  an  increase  in
   the  earth's surface temperature.

ground  cover:  Grasses  or other  plants
   grown to keep soil from being  blown
   or washed  away.

groundwater: The  supply of  freshwater
   under  the earth's  surface in an aqui-
   fer  or  soil that  forms  the natural
   reservoir for  man's use.

groundwater runoff: Groundwater that is
   discharged  into  a stream  channel  as
   spring or  seepage water.
habitat: The sum  total of environmental
   conditions  of  a specific place  that  is
   occupied by  an organism,  a popula-
   tion  or  a community.

half-life: The  time it takes certain mate-
   rials,  such as persistent pesticides or
   radioactive isotopes, to lose half their
   strength.  For  example, the  half-life
   of DDT is 15 years;  the half-life of
   radium  is 1,580 years.

hammermill: A  broad category of high-
   speed equipment that  uses pivoted or
   fixed  hammers  or cutters  to  crush,
   grind, chip or  shred  solid wastes.

hard  water:  Water  containing  dissolved
   minerals such  as calcium,  iron  and
   magnesium. The most notable char-
   acteristic of hard water is its inability
   to lather soap. Some  pesticide  chem-
   icals will  curdle or  settle  out when
   added to hard  water.
hazardous  air pollutant:  According  to
   law, a pollutant to which no ambient
   air  quality standard is  applicable and
   that may  cause  or contribute  to  an
   increase  in mortality  or  in  serious
   illness. For example,  asbestos,  beryl-
   lium and mercury have been declared
   hazardous  air pollutants.

heat  island  effect.   An   air  circulation
   problem  peculiar to cities. Tall build-
   ings,  heat  from  pavements  and con-
   centrations of pollutants create a haze
   dome  that prevents   rising  hot  air
   from  being cooled at  its normal rate.
   A self-contained  circulation  system is
   put in motion that can be broken by
   relatively strong winds. If  such winds
   are absent, the  heat island  can trap
   high concentrations of pollutants and
   present a serious health problem.

heating season: The coldest  months of
   the year when pollution emissions are
   higher in  some  areas  because of  in-
   creased fossil-fuel  consumption.

heavy  metals:  Metallic   elements  with
   high  molecular   weights,   generally
   toxic  in  low concentrations  to  plant
   and animal life. Such metals  are  often
   residual in  the environment and ex-
   hibit  biological   accumulation.   Ex-
   amples  include  mercury,  chromium,
   cadmium, arsenic  and lead.

herbicide: A  pesticide  chemical used to
   destroy  or control  the   growth  of
   weeds, bush  and  other  undesirable
   plants. See pesticide.

herbivore:  An organism  that  feeds  on

heterotrophic  organism:  Organisms de-
   pendent on organic matter  for  food.

high  density  polyethylene:  A   material
   often used  in the manufacture of plas-
   tic  bottles  that produces  toxic  fumes
   if incinerated.

hi-volume sampler: A device used in the
   measurement  and  analysis   of  sus-
   pended   particulate  pollution.   Also
   called a  Hi-Vol.

hot: A colloquial term meaning highly

humus: Decomposed organic  material.

hydrocarbons:  A  vast family  of  com-
   pounds  containing carbon and hydro-
   gen  in  various  combinations, found
   especially in fossil fuels. Some hydro-
   carbons  are  major  air  pollutants,
   some may be carcinogenic and others
   contribute to photochemical smog.

hydrogen sulflde (FLS):  A  malodorous
   gas made up of hydrogen and sulfur
   with the characteristic odor of rotten
   eggs. It is emitted  in  the natural de-
   composition of organic matter and is
   also the natural  accompaniment  of
   advanced  stages  of  eutrophication.
   H2S is  also a byproduct of  refinery
   activity  and the  combustion  of oil
   during  power  plant  operations.  In
   heavy  concentrations,  it  can  cause

hydrology: The science dealing with the
   properties, distribution and circulation
   of water and snow.
impedance:  The rate at which a  sub-
   stance can absorb and transmit sound.

implementation plan: A  document of the
   steps to be taken to ensure attainment
   of  environmental  quality  standards
   within a specified time period. Imple-
   mentation plans are required by  vari-
   ous  laws.

impoundment: A body of water, such as
   a  pond,  confined by  a dam,  dike,
   floodgate  or other barrier.

incineration:  The  controlled process  by
   which solid, liquid  or gaseous com-
   bustible   wastes  are   burned  and
   changed  into gases;  the residue  pro-
   duced contains  little  or no combus-
   tible  material.

incinerator:  An  engineered  apparatus
   used  to burn waste substances and in
   which  all  the combustion factors—
   temperature,  retention  time,  turbu-
   lence  and  combustion  air—can be

inert gas:  A gas that does not react with
   other substances  under ordinary con-

inertia)  separator: An  air pollution con-
   trol  device  that uses the principle of
   inertia  to  remove  particulate  matter
   from a stream of  air or  gas.

infiltration: The  flow  of a fluid  into  a
   substance   through  pores  or  small
   openings.  Commonly used in hydrol-
   ogy  to denote the flow of water into
   soil  material.

inoculum:  Material  such  as   bacteria
   placed  in compost or other medium
   to initiate  biological  action.

integrated pest control: A system of man-
   aging pests by using  biological, cul-
   tural and  chemical  means.

interceptor sewers: Sewers used to collect
   the flows from main and trunk sewers
   and  carry them to a central point for
   treatment and discharge.  In  a com-
   bined sewer system, where street run-
   off from rains is  allowed to enter the
   system along with sewage, interceptor
   sewers  allow  some of the sewage to
   flow  untreated directly into the receiv-
   ing stream,  to prevent the plant from
   being overloaded.

interstate  carrier  water supply: A water
   supply  whose  water may be used for
   drinking or cooking purposes  aboard
   common carriers  (planes, trains, buses
   and  ships) operating  interstate.  Inter-
   state carrier water  supplies are regu-
   lated by the Federal government.

interstate   waters:  According  to  law,
   waters  defined as: (1) rivers, lakes and
   other  waters  that  flow  across  or
   form a part of State or international
   boundaries; (2)  waters of the  Great
   Lakes;   (3)  coastal  waters — whose
   scope  has  been  defined  to  include
   ocean waters seaward to the territorial
   limits  and  waters   along  the  coast-
   line  (including   inland  streams)  in-
   fluenced by the tide.

inversion:   An  atmospheric  condition

   where  a layer  of  cool  air is trapped
   by  a layer of  warm air so  that  it
   cannot  rise. Inversions  spread pol-
   luted air horizontally rather  than ver-
   tically   so  that  contaminating  sub-
   stances cannot  be  widely  dispersed.
   An  inversion  of  several  days  can
   cause  an  air pollution  episode.

ionization  chamber:  A device  roughly
   similar  to a Geiger  counter that re-
   veals the  presence of ionizing  radia-

isotope: A variation of an element having
   the same  atomic number as the  ele-
   ment  itself,  but  having a  different
   atomic  weight  bcause  of a different
   number  of neutrons.  Different  iso-
   topes of  the same element  have  dif-
   ferent  radioactive behavior.
lagoon: In waste water treatment, a shal-
   low  pond  usually  man-made where
   sunlight,  bacterial action and  oxygen
   interact to restore  waste water to  a
   reasonable  state of purity.

lateral sewers: Pipes running underneath
   city  streets that  collect  sewage from
   homes or businesses.

LC50:   Median  lethal  concentration,  a
   standard measure  of toxicity. LC50
   indicates the concentration  of a sub-
   stance that will kill  50  percent of a
   group of experimental insects or ani-

leachate: Liquid   that  has  percolated
   through solid waste or other mediums
   and has extracted dissolved  or sus-
   pended materials from it.

leaching: The process by which soluble
   materials in the soil, such as nutrients,
   pesticide chemicals  or  contaminants,
   are  washed into a lower layer of soil
   or are  dissolved and carried away by

lead:  A heavy metal  that may  be haz-
   ardous to  human health if breathed
   or ingested.

life cycle: The phases, changes or  stages
   an  organism  passes  through  during
   its  lifetime.

lift:  In a sanitary  landfill,  a compacted
   layer of solid waste and the top layer
   of cover material.

limnology: The  study of  the physical,
   chemical,  meteorological  and biologi-
   cal aspects of fresh waters.
marsh:  A low-lying tract  of soft,  wet
   land that provides  an important eco-
   system for a  variety  of plant  and
   animal life  but often is destroyed by
   dredging and filling.

masking:  Covering over of  one  sound or
   element  by  another. Quantitatively,
   masking is  the  amount  the audibility
   threshold of one sound  is raised by
   the  presence  of  a  second  masking
   sound. Also used in regard to odors.

mechanical turbulence: The erratic move-
   ment of air caused by local obstruc-
   tions such  as  buildings.

mercury:  A heavy metal, highly toxic if
   breathed or ingested. Mercury is  re-
   sidual  in  the  environment, showing
   biological accumulation  in all  aquatic
   organisms,  especially fish  and  shell
   fish.  Chronic  exposure  to  airborne
   mercury can have  serious  effects on
   the central  nervous system.

methane:   Colorless,  nonpoisonous  and
   flammable gaseous hydrocarbon. Meth-
   ane, (CA.i),  is emitted by marshes and
   by dumps undergoing  anaerobic  de-

mgd: Millions of gallons  per day.  Mgd
   is commonly  used to express  rate of

microbes:  Minute  plant or animal  life.
   Some  disease-causing microbes  exist
   in sewage.

mist: Liquid  particles in air formed by
   condensation   of   vaporized   liquids.
   Mist particles vary  from 500 to 40
   microns in size. By  comparison, fog
   particles are smaller  than 40 microns
   in size.

mixed  liquor: A  mixture  of  activated
   sludge  and water  containing  organic
   matter  undergoing  activated  sludge
   treatment in the aeration tank.

mobile  source: A  moving  source of air
   pollution  such as  an automobile.

monitoring: Periodic  or  continuous deter-
   mination  of the amount of pollutants
   or  radioactive contamination  present
   in the  environment.

muck soils:  Soils made from decaying
   plant materials.

mulch:  A  layer  of wood  chips,  dry
   leaves,  straw, hay,  plastic  strips or
   other  material placed   on the  soil
   around plants to  retain moisture, to
   prevent weeds  from growing  and to
   enrich  soil.
   in a discolored, sunken area or death
   of the entire plant.

nitric oxide  (NO): A  gas formed in great
   part from  atmospheric nitrogen  and
   oxygen when  combustion takes place
   under h igh temperature and high pres-
   sure,  as  in internal  combustion  en-
   gines. NO  is  not  itself a  pollutant;
   however, in the ambient air,  it con-
   verts  to  nitrogen  dioxide,  a  major
   contributor  to photochemical smog.

nitrogen  dioxide  (NO2):  A   compound
   produced by  the  oxidation of nitric
   oxide  in the  atmosphere;  a  major
   contributor  to photochemical  smog.

nitrogenous  wastes: Wastes of animal or
   plant origin that contain a significant
   concentration  of nitrogen.

NO: A notation meaning oxides of nitro-
   gen. See nitric oxide.
noise:  Any  undesired   audible  signal.
   Thus, in  acoustics,  noise  is  any  un-
   desired  sound.

NTA:  Nitrilotriacetic acid, a  compound
   once  used  to  replace  phosphates in

nuclear power plant: Any  device,  ma-
   chine or assembly that converts  nu-
   clear energy into some form of useful
   power, such  as  mechanical  or elec-
   trical  power.   In  a  nuclear  electric
   power plant,   heat  produced  by  a
   reactor   is  generally  used  to make
   steam to drive a  turbine that  in turn
   drives an electric  generator.

nutrients: Elements or compounds essen-
   tial  as  raw materials for  organism
   growth and  development; for example,
   carbon,  oxygen,   nitrogen   and phos-
 natural gas:  A  fuel  gas occurring nat-
    urally  in  certain geologic formation.
    Natural gas is usually  a  combustible
    mixture   of   methane   and   hydro-

 natural selection: The natural process  by
    which  the  organisms best adapted  to
    their environment survive and those
    less well adapted are eliminated.

 necrosis:  Death of plant  cells  resulting
oil  spill: The accidental discharge of oil
   into oceans,  bays  or  inland  water-

   ways.  Methods  of  oil  spill  control
   include chemical dispersion, combus-
   tion,   mechanical   containment  and

oligotrophic lakes:  Deep lakes that have
   a low supply of  nutrients and  thus
   contain little organic  matter.  Such
   lakes  are characterized by high water
   transparency  and  high  dissolved

opacity:  Degree of obscuration of light.
   For  example,  a  window  has  zero
   opacity; a wall is 100 percent opaque.
   The Ringelmann system  of evaluating
   smoke density is based on opacity.

open  burning:  Uncontrolled  burning  of
   wastes in an open dump.

open dump: See dump.

organic:  Referring  to  or  derived  from
   living  organisms.  In chemistry,  any
   compound containing carbon.

organism:  Any  living  human, plant  or

organophosphates: A group of pesticide
   chemicals containing phosphorus, such
   as malathion and  parathion, intended
   to control  insects.  These  compounds
   are short-lived and,  therefore, do not
   normally  contaminate   the  environ-
   ment.  However,  some   organophos-
   phates, such  as  parathion, are  ex-
   tremely toxic when initially  applied
   and  exposure to  them  can  interfere
   with the normal processes of the ner-
   vous system, causing convulsions and
   eventually  death.  Malathion,  on  the
   other  hand,  is  low in  toxicity  and
   relatively  safe  for humans and  ani-
   mals;  it is  a common  ingredient  in
   household insecticide products.

outfall:  The mouth of  a sewer, drain  or
   conduit  where  an  effluent  is  dis-
   charged into the receiving waters.

overfire air: Air forced into  the top  of
   an incinerator to  fan  the flame.

oxidant: Any oxygen containing substance
   that  reacts  chemically in  the  air  to
   produce new substances.  Oxidants are
   the primary contributors to photo-
   chemical smog.

oxidation: A chemical reaction in which
   oxygen unites or combines with other
   elements.  Organic matter is oxidized
   by the action of aerobic bacteria; thus
   oxidation is used in waste water treat-
   ment  to break down organic wastes.

oxidation pond:  A man-made lake  or
   pond  in  which  organic wastes  are
   reduced  by  bacterial   action.   Often
   oxygen is bubbled  through the pond
   to speed the process.

ozone  (O3): A pungent,  colorless, toxic
   gas.   Ozone  is   one  component  of
   photochemical  smog  and  is consid-
   ered a major air pollutant.
package  plant: A prefabricated  or pre-
   built waste water  treatment plant.

packed  tower:  An  air  pollution control
   device in which  polluted air  is forced
   upward through a tower packed with
   crushed rock or wood  chips  while  a
   liquid  is sprayed  downward  on  the
   packing material.  The  pollutants  in
   the air stream either dissolve or chem-
   ically react with the liquid.

PAN:  Peroxyacetyl  nitrate,  a pollutant
   created by the action of sunlight on
   hydrocarbons  and nitrogen oxides in
   the air. PANS are an integral part of
   photochemical smog.

particulates:  Finely  divided  solid  or
   liquid  particles  in the  air or  in an
   emission.  Particulates  include   dust,
   smoke,  fumes, mist,  spray  and fog.

particulate  loading:  The  introduction
   of particulates  into  the ambient  air.

pathogenic: Causing or capable of caus-
   ing disease.

PCBs: Polychlorinated biphenyls, a  group
   of organic  compounds  used in  the
   manufacture  of plastics.  In  the  en-

   vironment, PCBs exhibit many of the
   same characteristics as DDT and may,
   therefore, be confused with that pesti-
   cide. PCBs are highly toxic to aquatic
   life, they persist  in  the environment
   for long periods of time, and they are
   biologically accumulative.

peat: Partially decomposed organic mate-

percolation:  Downward flow or  infiltra-
   tion  of  water through  the pores  or
   spaces of a rock or  soil.

persistent pesticides: Pesticides that will
   be  present in  the  environment  for
   longer  than   one  growing season  or
   one year after application.

pesticide: An agent used to control pests.
   This  includes  insecticides   for   use
   against harmful insects;  herbicides for
   weed  control; fungicides for control
   of  plant  diseases;   rodenticides  for
   killing rats, mice, etc.; and germicides
   used in disinfectant products, algae-
   cides, slimicides, etc. Some pesticides
   can contaminate water, air or  soil and
   accumulate in man,  animals  and the
   environment,  particularly if  they are
   misused.  Certain of these  chemicals
   have  been shown  to  interfere  with
   the  reproductive  processes  of preda-
   tory birds and possibly  other animals.

pesticide  tolerance: A  scientifically and
   legally  established  limit  for   the
   amount  of chemical residue  that can
   be permitted  to remain  in  or on  a
   harvested  food  or  feed crop  as  a
   result of the  application  of a chemi-
   cal  for  pest-control  purposes. Such
   tolerances or  safety levels, established
   federally by  EPA, are set well below
   the  point at which  residues might  be
   harmful to consumers.

pH:  A measure  of the acidity  or alka-
   linity  of a material,  liquid or solid.
   pH  is represented on a scale of  0 to
    14  with  7   representing  a  neutral
   state,  0  representing the most  acid
   and  14, the  most  alkaline.

phenols:  A group of organic compounds
   that in  very  low concentrations pro-
   duce  a  taste  and  odor  problem  in
   water.  In higher  concentrations,  they
   are  toxic to aquatic life. Phenols are
   byproducts   of   petroleum   refining,
   tanning  and  textile,  dye  and  resin

phosphorus: An element that while essen-
   tial to life, contributes  to  the  eutro-
   phication of lakes  and other  bodies
   of water.

photochemical oxidants:  Secondary  pol-
   lutants formed by  the  action of  sun-
   light  on  the oxides of nitrogen  and
   hydrocarbons in the air; they are the
   primary  contributors  to photochemi-
   cal smog.

photochemical  smog:  Air  pollution as-
   sociated  with  oxidants  rather  than
   with  sulfur  oxides, particulates,  etc.
   Produces   necrosis,   chlorosis    and
   growth  alterations  in  plants  and is
   an  eye  and respiratory  irritant  in

phytoplankton:  The  plant portion  of

phytotoxic:  Injurious  to plants.

pig:  A  container  usually made of  lead
   used  to  ship or   store  radioactive

pile: A  nuclear reactor.

plankton: The floating or  weakly  swim-
   ming plant and animal life in a body
   of water,  often microscopic  in size.

plume:  The visible emission from a flue
   or chimney.

point source: In air pollution, a stationary
   source of  a  large individual emission,
   generally of an industrial nature.  This
   is a  general  definition; point source is
   legally and  precisely  denned in  Fed-
   eral  regulations. See area source.

pollen:  A fine  dust produced  by  plants;
   a natural or background air pollutant.

pollutant: Any introduced gas, liquid or
   solid that  makes a resource  unfit for
   a specific purpose.

pollution:  The presence  of  matter  or
   or energy  whose  nature,  location or
   quantity produces  undesired environ-
   mental effects.

polyelectrolytes: Synthetic chemicals used
   to  speed  flocculation  of   solids  in

                                                                        raw sewage
potable water:  Water suitable  for drink-
   ing or  cooking purposes  from  both
   health  and aesthetic considerations.

ppm: Parts per million.  The  unit  com-
   monly used  to represent the degree of
   pollutant  concentration  where  the
   concentrations are small. Larger con-
   centrations  are  given  in percentages.
   Thus  BOD  is  represented  in  ppm
   while  suspended solids  in  water are
   expressed in percentages. In air, ppm
   is usually a volume/volume  ratio; in
   water, a weight/volume ratio.

precipitate—A  solid that separates  from
   a  solution because of some chemical
   or  physical change  or the formation
   of such a solid.

precipitators: In pollution  control work,
   any of a number of air pollution con-
   trol devices usually using mechanical/
   electrical means to collect particulates
   from an emission.

pretreatment:  In waste  water treatment,
   any process used to reduce pollution
   load before the waste water is  intro-
   duced  into a  main  sewer system or
   delivered to  a  treatment plant  for
   substantial  reduction  of the pollution

primary  treatment:  The  first  stage  in
   waste water treatment  in  which sub-
   stantially  all  floating  or  settleable
   solids  are  mechanically removed by
   screening and sedimentation.

process weight:  The total weight  of all
   materials, including  fuels, introduced
   into a  manufacturing  process. The
   process weight  is used to  calculate
   the  allowable  rate   of emission  of
   pollutant matter from  the process.

 pulverization:  The  crushing  or grinding
    of material into small  pieces.

pumping  station:  A  station  at   which
    sewage is pumped  to a higher level.
    In  most sewer systems  pumping  is
    unnecessary;  waste   water flows by
    gravity to  the treatment plant.

 putrescible:  Capable  of  being decom-
    posed  by  microorganisms with suffi-
    cient  rapidity to cause nuisances from
    odors, gases, etc. For example, kitchen
    wastes or dead animals.
quench  tank: A water-filled tank  used
   to cool incinerator residues.
rad: A  unit of measurement of any kind
   of radiation  absorbed by man.

radiation:  The  emission  of fast atomic
   particles or  rays by  the  nucleus of
   an atom. Some elements are naturally
   radioactive while others become radio-
   active after  bombardment  with neu-
   trons  or  other  particles.  The  three
   major forms of  radiation are alpha,
   beta  and gamma.

radiation standards: Regulations  that in-
   clude  exposure standards,  permissible
   concentrations  and   regulations  for

radiobiology: The study of the principles,
   mechanisms  and  effects of  radiation
   on  living matter.

radioecology: The study  of the effects of
   radiation on species of  plants and
   animals in natural communities.

radioisotopes:  Radioactive  isotopes. Ra-
   dioisotopes  such  as cobalt-60 are used
   in the treatment of disease.

rasp: A device  used to  grate solid waste
    into   a  more  manageable   material,
    ridding it of much of its odor.

raw sewage: Untreated domestic  or com-
    mercial waste water.

receiving waters
receiving waters: Rivers, lakes, oceans or
   other bodies  that  receive treated or
   untreated waste waters.

recycling: The  process  by which waste
   materials are  transformed into  new
   products in  such  a manner that the
   original  products   may  lose   their

red tide: A proliferation or bloom of a
   certain type  of plankton with red-to-
   orange  coloration, that often  causes
   massive  fish  kills. Though they are a
   natural  phenomenon, blooms are be-
   lieved to be stimulated  by phosphorus
   and  other nutrients discharged  into
   waterways by man.

refuse: See solid waste.

refuse  reclamation: The process of con-
   verting  solid waste  to  saleable prod-
   ucts. For example, the  composting of
   organic solid waste yields a saleable
   soil conditioner.

rem: A measurement of  radiation dose
   to the internal tissues of man.

rep:  A unit of measurement of  any kind
   of radiation absorbed by man.

reservoir:  A pond, lake, tank  or  basin,
   natural  or  man-made,  used  for the
   storage,  regulation  and  control  of

resource recovery: The  process of obtain-
   ing materials or  energy,  particularly
   from solid waste.

reverberation: The persistence  of  sound
   in an enclosed space after the  sound
   source has stopped.

Ringelmann  chart: A series  of illustra-
   tions ranging from light grey to black
   used to measure the opacity  of  smoke
   emitted from stacks  and other sources.
   The shades  of grey simulate various
   smoke densities and are assigned num-
   bers ranging from one to five. Ringel-
   mann No. 1 is equivalent to 20  per-
   cent dense;  No.  5 is  100 percent
   dense.  Ringelmann charts  are used in
   the setting and enforcement of emis-
   sion standards.

riparian rights:  Rights of a land  owner
   to the water  on or bordering his prop-
   erty,  including  the  right  to prevent
   diversion or misuse of upstream water.
river  basin:  The  total area  drained  by
   a river  and its tributaries.

rodenticide: A  chemical or  agent used to
   destroy  or prevent damage by rats or
   other rodent pests. See pesticide.

rough fish: Those fish species  considered
   to be of  poor fighting  quality  when
   taken on  tackle  or of  poor  eating
   quality;  for  example,  gar,  suckers,
   etc. Most rough fish are  more tolerant
   of  widely  changing   environmental
   conditions than are game fish.

rubbish:  A general term  for  solid waste
   —excluding food  waste and ashes—
   taken from  residences, commercial es-
   tablishments and institutions.

runoff:  The  portion  of rainfall,  melted
   snow or  irrigation  water  that  flows
   across ground  surface and eventually
   is  returned to  streams. Runoff  can
   pick  up  pollutants  from  the air or
   the land  and carry them  to  the  re-
   ceiving  waters.
salinity:  The degree of salt in  water.

salt  water intrusion: The invasion  of salt
   water into a body  of fresh water,  oc-
   curring in either  surface or ground-
   water bodies.  When this invasion  is
   caused by  oceanic  waters, it is called
   sea water intrusion.

salvage:  The  utilization of waste mate-

sanitation: The  control of all the  factors
   in  man's  physical  environment  that
   exercise or can exercise  a deleterious
   effect on  his  physical  development,
   health and survival.

sanitary  landfill:  A site for solid waste
   disposal  using  sanitary  landfilling

sanitary landfilling: An engineered meth-
   od of solid waste  disposal on  land in
   a manner  that  protects the environ-
   ment; waste is spread  in thin layers,
   compacted  to  the smallest  practical
   volume  and  covered  with soil at the
   end of each working day.

sanitary sewers: Sewers  that carry  only
   domestic   or   commercial   sewage.
   Storm  water runoff  is  carried  in  a
   separate system. See sewer.

scrap:  Discarded  or  rejected materials
   that  result from   manufacturing  or
   fabricating  operations  and are  suit-
   able for reprocessing.

screening:  The  removal   of  relatively
   coarse  floating  and suspended solids
   by straining through racks or screens.

scrubber: An  air pollution control device
   that  uses  a  liquid spray  to   remove
   pollutants  from a  gas  stream  by ab-
   sorption  or chemical reaction. Scrub-
   bers also reduce  the  temperature of
   the  emission.

secondary treatment:  Waste water treat-
   ment, beyond  the primary stage, in
   which bacteria  consume the   organic
   parts of  the wastes. This biochemical
   action  is  accomplished  by   use  of
   trickling  filters  or  the activated sludge
   process. Effective secondary treatment
   removes  virtually  all  floating and set-
   tleable solids and approximately  90
   percent of both BOD3 and suspended
   solids.  Customarily,  disinfection  by
   chlorination is  the final stage of the
   secondary  treatment process.

sedimentation: In  waste  water treatment,
   the  settling out of solids by gravity.

sedimentation tanks: In waste water treat-
   ment, tanks where the solids  are  al-
   lowed to  settle or to float as scum.
   Scum is  skimmed off;  settled solids
   are  pumped to incinerators, digesters,
   filters or other means of disposal.

seepage:  Water that   flows  through the

selective  herbicide: A pesticide intended
   to kill only certain  types of  plants,
   especially broad-leafed weeds, and not
   harm other plants such as farm crops
   or lawn grasses. The leading herbicide
   in the  United  States is 2,4-D. A  re-
   lated but stronger chemical used most-
   ly for  brush  control  on range, pas-
   ture, and forest  lands  and on  utility
   or highway rights-of-way is  2,4,5-T.
   Uses of the latter chemical  have been
   somewhat restricted because Of labora-
   tory evidence  that it or a dioxin con-
   taminant  in  2,4,5-T can cause  birth
   defects  in test animals.

senescence: The  process of growing old.
   Sometimes used to refer to lakes near-
   ing extinction.

septic tank:  An  underground  tank used
   for the  deposition of domestic wastes.
   Bacteria in the wastes decompose the
   organic matter,  and the sludge  settles
   to  the  bottom.   The  effluent   flows
   through drains into the ground. Sludge
   is pumped out at regular intervals.

settleable  solids:  Bits of debris  and fine
   matter  heavy  enough to settle out of
   waste water.

settling chamber: In air pollution control,
   a low-cost device used to reduce the
   velocity of flue gases usually by means
   of baffles, promoting  the settling of
   fly ash.

settling tank: In waste water treatment, a
   tank  or  basin   in  which  settleable
   solids are removed by  gravity.

sewage: The total of organic waste and
   waste water generated  by residential
   and commercial establishments.

sewage lagoon: See lagoon.

sewer: Any pipe  or  conduit used to col-
   lect and carry away sewage or storm-
   water   runoff   from  the  generating
   source  to treatment plants  or receiv-
   ing streams.   A  sewer  that  conveys
   household and commercial  sewage  is
   called a sanitary sewer. If  it  trans-
   ports runoff from rain  or snow, it  is
   called  a  storm   sewer.  Often  storm
   water runoff  and  sewage are  trans-
   ported   in the same system or  com-
   bined sewers.

sewerage:   The  entire system of sewage
   collection,  treatment   and  disposal.
   Also applies to all effluent carried by
   sewers  whether it is sanitary  sewage,
   industrial  wastes  or storm water run-

shield: A wall that protects workers from
   harmful  radiation released by radio-
   active materials.

silt:  Finely  divided  particles of soil or
   rock. Often carried in cloudy suspen-
   sion in water and eventually deposited
   as sediment.

sinking: A method of controlling oil spills
   that employs  an agent to entrap oil
   droplets  and sink them to the bottom
   of  the body  of  water.  The  oil  and
   sinking  agent are eventually  biologi-
   cally degraded.

skimming:  The  mechanical  removal of
   oil  or  scum  from  the  surface of

sludge: The  construction of  solids  re-
   moved  from  sewage  during  waste
   water  treatment.  Sludge  disposal  is
   then handled by incineration, dump-
   ing or  burial.

smog:  Generally  used as an equivalent of
   air  pollution,  particularly  associated
   with oxidants.

smoke: Solid  particles generated  as a re-
   sult of the incomplete combustion of
   materials containing carbon.

SOX: A symbol meaning oxides of sulfur.

soft  detergents: Biodegradable detergents.

soil  conditioner:  A biologically stable or-
   ganic material such as humus or com-
   post that makes soil  more amenable
   to  the passage  of water  and to  the
   distribution of fertilizing material,  pro-
   viding  a better medium  for necessary
   soil bacteria growth.

solid waste:  Useless,  unwanted or  dis-
   carded material with insufficient liquid
   content to  be free flowing.  Also see
   waste.   (1)  agricultural—solid  waste
   that results  from  the  raising  and
   slaughtering  of   animals,   and   the
   processing  of animal products and or-
   chard and  field crops. (2) commercial
   —waste  generated by stores, offices
   and other   activities  that  do  not  ac-
   tually  turn out a product.  (3)  indus-
   trial—waste that  results  from  indus-
   trial  processes  and  manufacturing.
   (4) institutional  — waste originating
   from educational, health care and re-
   search facilities.  (5) municipal—resi-
   dential  and  commercial  solid  waste
   generated  within  a  community.  (6)
   pesticide—the residue from the  manu-
   facturing, handling or  use  of chemi-
   cals  intended  for  killing  plant  and
   animal  pests.  (7)  residential—-waste
   that  normally originates in a residen-
   tial environment. Sometimes called do-
   mestic solid waste.

solid  waste  disposal: The ultimate  dispo-
   sition of refuse that  cannot be sal-
   vaged or recycled.

solid  waste management: The purposeful,
   systematic  control  of  the generation,
   storage,  collection, transport, separa-
   tion,  processing, recycling, recovery
   and disposal of solid wastes.

sonic boom:  The tremendous booming
   sound produced as a vehicle, usually a
   supersonic  jet  airplane,  exceeds  the
   speed of sound, and the shock wave
   reaches the ground.

soot:  Agglomerations of tar-impregnated
   carbon   particles   that  form   when
   carbonaceous-material does  not  under-
   go complete  combustion.

sorption: A term including both adsorb-
   tion  and absorption. Sorption is basic
   to many processes  used to remove
   gaseous  and  particulate  pollutants
   from an emission and to clean  up oil

spoil: Dirt or  rock that has been removed
   from its original location,  specifically
   materials that have been dredged from
   the bottoms of waterways.

stabilization:  The  process of  converting
   active   organic  matter   in  sewage
   sludge  or  solid  wastes   into   inert,
   harmless material.

stabilization ponds: See lagoon, oxidation

stable air: An air mass that  remains in
   the same position rather  than moving
   in its normal  horizontal and vertical
   directions.  Stable air does not disperse
   pollutants and can lead to high build-
   ups of  air pollution.

stack: A  smokestack;  a vertical pipe or
   flue  designed  to  exhaust  gases and
   suspended  particulate  matter.

stack effect:  The  upward movement of
   hot gases  in  a stack due to the tem-
   perature difference between the gases
   and the atmosphere.

stagnation: Lack of wind in an air mass
   or lack  of  motion  in  water. Both
   cases  tend to entrap and concentrate

stationary  source:  A  pollution   emitter
   that  is  fixed  rather  than moving as
   an automobile.

storm sewer: A  conduit that collects  and
   transports rain and  snow runoff back
   to the ground  water. In a  separate
   sewerage  system, storm sewers  are
   entirely separate from those  carrying
   domestic and commercial waste water.

stratification: Separating into layers.

strip mining:  A process  in which rock and
   top soil strata overlying ore  or  fuel
   deposits  are  scraped away  by  me-
   chanical shovels. Also known as  sur-
   face  mining.

sulfur dioxide (SO2) A heavy, pungent,
   colorless gas formed primarily by the
   combustion  of fossil fuels.  SO2 dam-
   ages the  respiratory tract as  well as
   vegetation and materials and  is con-
   sidered a  major air  pollutant.

sump:  A depression  or tank that serves
   as a drain or receptacle for  liquids for
   salvage  or disposal.

surfactant:  An agent used  in  detergents
   to cause lathering. Composed of  sev-
   eral phosphate compounds, surfactants
   are a source  of external enrichment
   thought to  speed the  eutrophication
   of our lakes.

surveillance system: A monitoring system
   to determine environmental   quality.
   Surveillance systems should be estab-
   lished to monitor all aspects  of prog-
   ress  toward  attainment  of  environ-
   mental standards  and to identify po-
   tential  episodes  of  high   pollutant
   concentrations  in time  to  take  pre-
   ventive  action.

suspended solids (SS): Small particles of
   solid  pollutants in  sewage  that con-
   tribute  to turbidity and that resist
   separation by  conventional   means.
   The  examination  of suspended solids
   and the BOD  test constitute the two
   main determinations for water  qual-
   ity performed  at waste  water  treat-
   ment facilities.

synergism: The cooperative action of sep-
   arate  substances  so  that   the  total
   effect is greater than  the sum of  the
   effects of the substances acting  inde-

systemic pesticide: A pesticide chemical
   that is carried to  other  parts  of a
   plant or animal after  it is injected or
   taken up from  the  soil or body sur-
tailings:  Second grade  or  waste material
   derived when raw material is screened
   or  processed.

tertiary treatment: Waste water  treatment
   beyond the  secondary, or  biological
   stage that includes  removal of nutri-
   ents such as  phosphorus and nitrogen,
   and a high  percentage of suspended
   solids. Tertiary treatment,  also known
   as  advanced waste treatment,  pro-
   duces a high quality effluent.

thermal  pollution: Degradation of water
   quality  by  the   introduction  of  a
   heated effluent.  Primarily  a result of
   the discharge of  cooling waters  from
   industrial  processes, particularly  from
   electrical   power  generation.   Even
   small deviations  from  normal water
   temperatures can affect  aquatic  life.
   Thermal  pollution   usually  can  be
   controlled by cooling towers.

threshold dose:  The minimum  dose of a
   given substance necessary to produce
   a  measurable  physiological  or  psy-
   chological effect.

tolerance: The relative  capability of  an
   organism  to  endure an  unfavorable
   environmental factor. The amount of


   a  chemical considered  safe  on  any
   food to be eaten by man or animals.
   Also see pesticide tolerance.

topography: The configuration of a  sur-
   face area including its  relief, or rela-
   tive elevations, and the position of its
   natural and  man-made  features.

toxicant: A  substance that  kills or injures
   an organism through its chemical or
   physical  action or by  altering its en-
   vironment;  for  example,   cyanides,
   phenols,  pesticides or  heavy  metals.
   Especially  used for insect control.

toxicity: The  quality or degree of being
   poisonous  or  harmful  to   plant  or
   animal life.

trickling filter: A  device for the biologi-
   cal or secondary treatment  of waste
   water consisting  of a bed of rocks or
   stones  that support  bacterial growth.
   Sewage is  trickled over the  bed en-
   abling  the  bacteria  to break  down
   organic  wastes.

troposphere: The layer of the atmosphere
   extending  seven  to  ten miles  above
   the earth.  Vital  to  life on  earth,  it
   contains  clouds  and   moisture   that
   reach earth as  rain or  snow.

turbidimeter:  A device used to measure
   the amount of suspended solids in a

turbidity:  A thick, hazy condition  of air
   due to the presence  of  particulates or
   other pollutants,  or the similar cloudy
   condition in water due  to the suspen-
   sion of silt or finely divided organic
vapor: The gaseous phase  of substances
   that normally are  either  liquids or
   solids at atmospheric temperature and
   pressure; for example, steam and  phe-
   nolic  compounds.

vapor  plume: The  stack  effluent consist-
   ing of flue  gas  made visible by  con-
   densed  water droplets or mist.

vaporization: The change of  a substance
   from  the liquid to the  gaseous state.
   One of  three basic contributing  fac-
   tors to  air  pollution, the  others are
   attrition and  combustion.

variance: Sanction  granted  by a govern-
   ing body for delay  or  exception in
   the application of  a given law,  ordi-
   nance or regulation.

vector: Disease vector—a carrier, usually
   an arthropod, that is capable of trans-
   mitting  a pathogen from  one orga-
   nism  to another.

volatile:  Evaporating  readily  at a  rela-
   tively low temperature.
urban  runoff:  Storm  water from  city
   streets and  gutters  that usually con-
   tains a great deal of litter and organic
   and bacterial wastes.
waste: Also  see solid waste. (1) bulky
   waste—items  whose large  size  pre-
   cludes  or complicates their handling
   by  normal  collection,  processing or
   disposal  methods.  (2)   construction
   and  demolition waste—building  ma-
   terials  and rubble  resulting from con-
   struction,   remodeling,   repair   and
   demolition operations. (3) hazardous

   waste — wastes that require special
   handling to avoid illness  or injury to
   persons   or   damage  to   property.
   (4)  special waste—those wastes  that
   require   extraordinary  management.
   (5)  wood  pulp waste —  wood or
   paper fiber  residue resulting from  a
   manufacturing  process.    (6)   yard
   waste—plant  clippings, prunings  and
   other discarded material  from yards
   and  gardens.  Also  known  as  yard

waste water: Water carrying wastes from
   homes,  businesses and  industries  that
   is  a  mixture  of water and dissolved
   or suspended solids.

water pollution: The addition  of sewage,
   industrial wastes or other harmful or
   objectionable   material to   water in
   concentrations or in sufficient quan-
   tities to result  in measurable degrada-
   tion  of  water quality.

water quality criteria: The levels of pol-
   lutants  that affect the suitability of
   water  for  a  given  use.  Generally,
   water use classification includes: pub-
   lic water supply; recreation; propaga-
   tion  of  fish and other  aquatic  life;
   agricultural use  and industrial  use.

water quality standard: A plan for water
   quality  management  containing four
   major  elements: the  use  (recreation,

   drinking water, fish and wildlife prop-
   agation,  industrial or  agricultural) to
   be  made of  the water;  criteria to
   protect   those  uses;   implementation
   plans (for needed industrial-municipal
   waste  treatment  improvements)  and
   enforcement plans, and an anti-degra-
   dation statement to  protect existing
   high quality waters.

watershed: The area drained by a given

water supply system: The  system for the
   collection, treatment, storage and dis-
   tribution of potable  water  from the
   sources  of supply to  the  consumer.

water table: The upper  level of ground
zooplankton:  Planktonic  animals   that
   supply food  for  fish.