Acute Toxicity: The ability of a substance to
cause poisonous effects that result in severe biological harm or death
soon after a single exposure or dose. (See chronic toxicity.)
Adsorption: The adhesion of molecules of gas, liquid, or dissolved
solids to a surface.
Advisory: A nonregulatory document that communicates risk information.
Air Pollutant: Any substance in air that could, if in high enough
concentration, harm living things.
Algae: Simple rootless plants that grow in sunlit waters in relative
proportion to the amounts of light and nutrients available. They are food
for fish and small aquatic animals.
Atmospheric Deposition: Pollution from the atmosphere associated with dry deposition in the form of dust, wet deposition in the form of rain and snow, or as a result of vapor exchanges.
B
Bacteria: A group of universally distributed, rigid, essentially
unicellular microscopic organisms lacking chlorophyll. Some bacteria can
aid in pollution control by consuming or breaking down organic matter in
sewage or by similarly acting on oil spills or other water pollutants.
Bacteria in soil, water, or air can also cause human, animal, and plant
health problems.
Benthic Organism (benthos): A form of aquatic plant or animal life that is found near the bottom of a stream, lake, or ocean. Benthic populations are often indicative of sediment quality. The benthos comprise:
Bioaccumulative Substances: Substances that increase in concentration
in living organisms (that are very slowly metabolized or excreted) as they
breathe contaminated air or water, drink contaminated water, or eat contaminated
food. (See biological magnification.)
Bioassay: An evaluation using organisms to measure the effect of
a substance, factor, or condition by comparing before and after data.
Biological Magnification: Refers to the process whereby certain substances
become more concentrated in tissues at each successive stage up the food
web. (See bioaccumulative substances.)
Biomass: All the living material in a given area: often refers to
vegetation. Algal biomass is often indicative of the trophic status of
a water body.
Byproduct: Material, other than the principal product, that is generated as a consequence of an industrial process.
C
Carcinogen: Any substance that can cause or contribute to the production
of cancer.
Chlorophyll-a: The photosynthetic pigment found in most algae. Chlorophyll-a
is used to measure the rate of photosynthesis in a body of water.
Chronic Toxicity: The capacity of a substance to cause poisonous
effects in an organism after long-term exposure. (See acute toxicity).
Combined Sewers: A sewer system that carries both sewage and stormwater
runoff. Normally, its entire flow goes to a waste treatment plant, but
during a heavy storm, the stormwater volume may be so great as to cause
overflows (combined sewer overflow). When this happens, untreated mixtures
of stormwater and sewage may flow into receiving waters. Stormwater runoff
may also carry toxic chemicals from industrial areas or streets into the
sewer system.
Conventional Pollutants: Such contaminants as organic waste, sediment, acid, bacteria and viruses, nutrients, oil and grease, or heat.
D
Decay: The breakdown of organic matter by bacteria and fungi.
Dissolved Oxygen (DO): The oxygen freely available in water. Dissolved
oxygen is vital to fish and other aquatic life. Traditionally, the level
of dissolved oxygen has been accepted as the single most important indicator
of a water body's ability to support desirable aquatic life.
Drainage Basin: A water body and the land area drained by it.
Dredging: Removal of sediment from the bottom of a water body.
E
Ecosystem: The interacting system of a biological community and its
environmental surroundings.
Effluent: Wastewater--treated or untreated--that flows from a treatment
plant, sewer, or industrial outfall. Generally refers to discharges into
surface waters.
Emission: Discharges into the atmosphere from such sources as smokestacks,
residential chimneys, motor vehicles, locomotives, and aircraft.
Erosion: The wearing away of land surface by wind or water. Erosion
occurs naturally but can be caused by farming, residential or industrial
development, mining, or timber-cutting.
Eutrophication: The process of fertilization that causes high productivity
and biomass in an aquatic ecosystem. Eutrophication can be a natural process
or it can be a cultural process accelerated by an increase of nutrient
loading to a lake by human activity.
Exotic Species: Species that are not native to the Great Lakes and that have been intentionally introduced to or have inadvertently infiltrated the system. Exotics prey upon native species and compete with them for food or habitat.
F
Fertilizer: Materials, including nitrogen and phosphorus, that provide
nutrients for plants.
Food Chain: A sequence of organisms, each of which uses the next,
lower member of the sequence as a food source. Members of a chain are interdependent
so that a disturbance to one species can disrupt the entire hierarchy.
Food Web: The complex feeding network occurring within and between food chains in an ecosystem, whereby members of one food chain may belong to one or more other food chains.
G
Game Fish: Fish species caught for sport, such as trout, salmon,
or bass.
Groundwater: The supply of fresh or saline water found beneath the Earth's surface, usually in aquifers, often supplying wells and springs.
H
Habitat: The place where a population (e.g., human, animal, plant,
micro-organism) lives and its surroundings.
Heavy Metals: Metallic elements with high atomic weights (e.g., mercury,
chromium, cadmium, arsenic, and lead) that tend to be toxic and bioaccumulate.
Herbicide: A chemical pesticide designed to control or destroy plants, weeds, or grasses.
I
Indicator: An organism, species, or community whose characteristics
show the presence of specific environmental conditions.
Insecticide: A chemical specifically used to kill or control the
growth of insects.
Lampricide: A chemical used to kill sea lamprey.
Landfills: 1. Land disposal sites for nonhazardous solid wastes at
which the waste is spread in layers, compacted to the smallest practical
volume, and covered with material applied at the end of each operating
day. 2. Land disposal sites for hazardous waste designed to minimize the
chance of release of hazardous substances into the environment.
Loading: The addition of a substance to a water body.
M
Marsh: A type of wetland that does not accumulate appreciable peat
deposits and is dominated by herbaceous vegetation. Marshes may be either
freshwater or saltwater and tidal or nontidal. (See wetland.)
Mass Balance Approach: An analytic method, based on conservation
of mass, used to assess the quantity and cycling of contaminants throughout
a water system.
Metabolite: A substance that is the product of biological changes
to a chemical.
Monitoring: A scientifically designed system of continuing standardized measurements and observations and the evaluation thereof.
N
Nitrate: A compound containing nitrogen and oxygen that can exist
in the atmosphere or in water and that can have harmful effects on humans
and animals at high concentrations.
Nonpoint Source: Pollution sources that are diffuse and do not have
a single point of origin or are not introduced into a receiving stream
from a specific outlet. The pollutants are generally carried off land by
stormwater runoff. Commonly used categories for nonpoint sources are agriculture,
forestry, urban, mining, construction, dams and channels, and land disposal.
Nutrient: Any substance assimilated by living organisms that promotes growth. The term is generally applied to nitrogen and phosphorous, but is also applied to other essential trace elements.
Pesticide: A substance intended for preventing, destroying, repelling,
or mitigating any pest. Also, any substance or mixture of substances intended
for use as a plant regulator, defoliant, or desiccant.
Phosphorus: An essential chemical food element that can contribute
to the eutrophication of lakes and other water bodies.
Photosynthesis: A process occurring in the cells of green plants
and some micro-organisms in which solar energy is transformed into stored
chemical energy.
Phytoplankton: That portion of the plankton community comprising
tiny plants (e.g., algae, diatoms).
Plankton: Microscopic plants and animals that live in water.
Point Source: A stationary facility from which pollutants are discharged
or emitted. Also, any single identifiable source of pollution (e.g., a
pipe, ditch, ship, ore pit, factory smokestack).
Pollutant: Any substance introduced into the environment that adversely
affects the usefulness of a resource.
Pollution Prevention: Measures taken to reduce the generation of
a substance that could be harmful to living organisms if released to the
environment. Pollution prevention can be achieved in many ways.
Predator: Any organism that lives by capturing and feeding on another
animal.
Pretreatment: Processes used to reduce, eliminate, or alter pollutants
from nonresidential sources before they are discharged into publicly owned
sewage treatment systems.
Primary Waste Treatment: This treatment consists of the first steps in wastewater treatment during which screens and sedimentation tanks are used to remove most materials that float or will settle. Primary treatment results in the removal of about 30 percent of carbonaceous biochemical oxygen demand from domestic sewage.
R
Resuspension (of sediment): The remixing of sediment particles and
pollutants back into the water by storms, currents, organisms, and human
activities, such as dredging.
Retention Time: The time it takes for the volume of water in a lake
to exit through its outlet (i.e., total volume/outlet flow = retention
time).
Risk Assessment: qualitative and quantitative evaluation to define
the hazards posed to human health and/or the environment.
Run-Off: That part of precipitation, snow melt, or irrigation water that drains off land into surface water. It can carry sediments and pollutants into the receiving waters.
S
Secondary Waste Treatment: The second step in most waste treatment
systems in which bacteria consume the organic parts of the waste. It is
accomplished by bringing together waste, bacteria, and oxygen in trickling
filters or in the activated sludge process. This removes floating and settleable
solids and about 90 percent of the oxygen-demanding substances and suspended
solids. Disinfection is the final stage of secondary treatment. (See primary,
tertiary waste treatment.)
Sediments: Soil, sand, and minerals eroded from land by water or
air. Sediments settle to the bottom of surface water.
Sewage: The waste and wastewater discharged into sewers from homes
and industry.
Sewer: A channel or conduit that carries wastewater and stormwater
runoff from its source to a treatment plant or receiving stream. Sanitary
sewers carry household, industrial, and commercial waste; storm sewers
carry runoff from rain or snow; and combined sewers carry both.
Stratification (or layering): The tendency in deep water bodies for
distinct layers of water to form as a result of vertical change in temperature
and, therefore, in the density of water. During stratification, dissolved
oxygen, nutrients, and other parameters of water chemistry do not mix well
between layers, establishing chemical as well as thermal gradients.
Surface Water: All water open to the atmosphere (e.g., rivers, lakes,
reservoirs, streams, impoundments, seas, estuaries) and all springs, wells,
or other collectors that are directly influenced by surface water.
Swamp: A type of wetland that is dominated by woody vegetation and that does not accumulate appreciable peat deposits. Swamps may be freshwater or saltwater and tidal or nontidal. (See wetland.)
T
Toxic Substance (or toxicant): A substance that can cause death, disease, behavioral abnormalities, cancer, genetic mutations, physiological or reproductive malfunctions, or physical deformities in any organism or its offspring. The quantities and length of exposure necessary to cause these effects can vary widely.
U
Urban Runoff: Stormwater from city streets and adjacent domestic or commercial properties that may pickup terrestrial contamination and carry pollutants of various kinds into sewer systems and/or receiving waters.
V
Vaporization: The change of a substance from a liquid to a gas.
Volatile Substance: A substance that evaporates readily.
W
Waste Treatment Plant: A facility containing a series of tanks, screens,
filters, and other processes by which pollutants are removed from water.
Wastewater: The spent or used water from individual homes, a community,
a farm, or an industry that often contains dissolved or suspended matter.
Watershed: The land area that drains into a river, stream, reservoir
or lake.
Water Table: The level of groundwater.
Wetland: An area that is regularly saturated by surface water or
groundwater and is characterized by a prevalence of vegetation that is
adapted for life in saturated soil conditions (e.g., swamps, bogs, fens,
marshes, and estuaries).
Wildlife Refuge: An area designated for the protection of wild animals, within which hunting and fishing are either prohibited or strictly controlled.
Zooplankton: Microscopic aquatic animals.
