Glossary of Environmental Terms
- The reduction in degree or intensity of pollution.
- acid rain
- Precipitation which has a pH of less than 5.6.
- Any poisonous effect produced within a short period of time, resulting in
severe biological harm and often death.
- The liquid and solid wastes from farming, including: runoff from
pesticides, fertilizers, and feedlots; erosion and dust from plowing; animal
manure and carcasses.
- air pollution
- The presence of contaminant substances in the air
that do not disperse properly and interfere with human health.
- air shed
- The limited space above a particular area defined by natural features as
well as by political or legal boundaries.
- air toxics
- Generally defined as air pollutants known or suspected to cause cancer or
other serious health problems. They also may disrupt reproductive processes,
cause birth defects and can cause serious environmental and ecological problems.
- Simple rootless plants that grow in bodies of water in relative proportion
to the amounts of nutrients available. Algal blooms reduce the amount of
dissolved oxygen in lakes and rivers and can result in fish kills.
- ambient air
- Any unconfined portion of the atmosphere; the outside air.
- Migratory fish that ascend rivers from the sea to spawn, like salmon.
- An underground bed or layer of earth, gravel or porous stone that contains
water. The depth of this layer can vary from a few feet to several hundred feet
below the ground.
- A mineral (magnesium silicate) that has been processed so it is used to fire
proof buildings, insulate electrical wires, and make brake linings in cars.
Asbestos can cause cancer if inhaled or ingested.
- The layer of air surrounding the earth.
- Using living organisms to measure the effect of a substance, factor or
- biochemical oxygen demand (BOD)
- The dissolved oxygen required to decompose organic matter in water. It is a
measure of pollution since heavy waste loads have a high demand for oxygen.
- Able to be broken down into simpler products by microscopic plants and
- carbon monoxide (CO)
- A colorless, odorless, highly toxic by-product of incomplete fossil fuel
combustion. It is one of the major air pollutants. Cars give off a lot of
- Capable of causing cancer.
- Green pigment found in plant cells.
- Not wasting, and renewing when possible, the human and natural resources of
- To pollute something, or make it dirty.
- dissolved oxygen (DO)
- A measure of the amount of oxygen available for biochemical activity in a
given amount of water. Low DO levels are generally due to inadequate waste
- dissolved solids
- Total disintegrated organic and inorganic material contained in water.
- The study of relationships between living things and their surroundings.
- A community of living things interacting with one another and with their
physical environment, such as a rain forest, pond or estuary.
- Waste material discharged into the environment, it can be treated or
- Waste substances discharged into the air.
- The wearing away of land surface by wind or water. Erosion occurs naturally
from weather or run-off but can be intensified by landclearing practices.
- Special environments at the mouth of coastal rivers where fresh water meets
sea water. These brackish water ecosystems shelter and feed marine life, birds
- Water loss from soil including evaporation and transpiration from the
surfaces of plants.
- fossil fuels
- Fuels such as oil, natural gas, and coal that are made from decayed plants
and animals that lived millions of years ago. These fuels are made of hydrogen
and carbon (hydrocarbons).
- greenhouse gas
- Gases such as carbon dioxide and methane that trap heat in the atmosphere.
These gases are emitted from a variety of natural sources like forest fires, and
human sources like the combustion of gasoline and natural gas.
- The mass of water in the ground that fills saturated zones of material such
as sand, gravel or porous rock.
- hazardous waste
- Waste materials that are inherently dangerous in contact, handling and
disposal. They may be toxic, explosive, caustic, or ignitable. Substances
classified as hazardous under state or federal law are subject to special
handling, shipping, storage, and disposal requirements. Radioactive materials
and some biological wastes are also considered hazardous.
- heavy metals
- Elements with high molecular weights which are generally toxic in low
concentrations to plant and animal life. Examples include mercury, chromium,
cadmium, arsenic, and lead.
- Compounds found in fossil fuels that contain carbon and hydrogen in various
combinations. They are major air pollutants and some may be carcinogenic. Fossil
fuels, glues, paints, and solvents contain hydrocarbons. Most people use the
terms "hydrocarbon" and "volatile organic compounds" (or VOCs) to mean the same
- hydrologic cycle
- The cyclical movement of water from the ocean to the atmosphere by
evaporation through rain to the earth's surface, through runoff and groundwater
to streams, and back to the sea.
- An atmospheric condition occurring when a layer of cool air is trapped by a
layer of warm air and is unable to rise. Inversions spread polluted air
horizontally rather than vertically so that contaminating substances cannot be
- Liquid that has percolated through solid waste or other matter, extracting
dissolved or suspended materials from it.
- mobile source
- A moving source of pollution, such as a car or truck.
- nitrogen oxides
- Gases that form when the nitrogen and oxygen in the atmosphere are burned
with fossil fuels at high temperatures.
- non-point source
- Water contaminant that cannot be traced to a specific point of origin, but
rather comes from many different non-specific sources.
- Essential elements or compounds in the development of living things. Oxygen,
nitrogen and phosphorous are examples.
- organic chemicals
- Chemical compounds containing carbon. Historically organic compounds were
obtained from vegetable or animal sources. Today, many organic chemicals are
synthesized in a laboratory.
- The mouth of a sewer, drain or conduit where effluent is discharged into
- Pungent, colorless, toxic gas that is the major component of smog. It is
formed when sunlight triggers chemical reactions involving hydrocarbons and
oxides of nitrogen.
- Fine particles such as dust, smoke, fumes, or smog found in emissions and
- Polychlorinated biphenyls. Found in transformers and capacitors, these
organic compounds are very persistent in the environment where they accumulate
- Chemicals used to destroy or control insects, weeds or unwanted growths.
- In water terms, the extent or boundary of the spread of underground soil or
water contamination. In air, a visible emission from a flue or chimney.
- point source
- A stationary location where pollutants are discharged.
- A contaminant that adversely alters the physical, chemical, or biological
properties of the environment.
- To make the land, water, or air dirty and unhealthy.
- Processes used to reduce the amount of pollution in water before it enters
the sewers or treatment plant.
- Colorless, odorless radioactive gas formed by the decay of radium.
- To act in response to something. For example, a chemical can change, or
react, if added to another chemical.
- remedial action
- Work done at a hazardous waste site to clean up or control the contamination
found at the site.
- respiratory system
- A body's system for breathing, including the nose, throat, and lungs.
- resource recovery
- The process of obtaining materials or energy, particularly from solid
- river basin
- The land area drained by a river and its tributaries.
- Water from precipitation or irrigation that flows over the ground surface
and returns to streams. It can collect pollutants from the air or land and carry
them to the receiving waters.
- Fine particles of soil.
- septic tank
- An enclosure that stores and processes wastes where no sewer
system exists. Bacteria decompose the organic matter into sludge,
which is pumped off periodically.
- A product of the treatment process as particles in waste are
converted to solids.
- solid waste
- Useless, unwanted or discarded material with insufficient liquid content to
be free flowing. It may be agricultural, commercial, industrial, institutional,
municipal, or residential in nature.
- A substance used to dissolve another substance.
- Lack of motion in a mass of air or water, which tends to hold pollutants.
- stationary source
- A non-moving source of pollution, such as a factory smokestack.
- The layer of air that extends from about 10 to 30 mile above the surface of
- sulfur dioxide
- A colorless gas that can that can bother the lungs. It is formed when fossil
fuels that contain sulfur are burned. It is also given off when volcanoes erupt.
- total dissolved solids
- The total amount of solid material dissolved in one liter of
- Describes something that can be poisonous or deadly if it is eaten touched,
or inhaled in large enough amounts.
- The quality or degree of being poisonous or harmful to plant or animal life.
- Hazy air due to the presence of particles and pollutants; a similar cloudy
condition in water due to suspended silt or organic matter.
- Storm water from city streets, usually carrying litter and organic wastes.
- Atmospheric air circulation determined by wind speed and mixing height. The
degree of ventilation is an indication of how well air pollution will be
- Any substance that evaporates at low temperature.
- volatile organic compounds
- VOCs are made of carbon, oxygen, hydrogen, chlorine, and other atoms that
can form gases easily. They are found in nature as well as in some glue, paint,
solvents, and other products. They help form ozone near the ground, which may
harm our health and even cause cancer.
- water pollution
- The addition of enough harmful or objectionable material to damage water
- The area drained by a given stream.
- water table
- The upper level of groundwater.
- Areas such as tidal flats or swamps covered by shallow water, or where the
water table is at or near the surface.