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EPA - Environmental Terms Glossary Category: Earth and Environment Date & country: 13/09/2007, USA Words: 1829

Sterilizer
One of three groups of anti-microbials registered by EPA for public health uses. EPA considers an antimicrobial to be a sterilizer when it destroys or eliminates all forms of bacteria, viruses, and fungi and their spores. Because spores are considered the most difficult form of microorganism to destroy, EPA considers the term sporicide to be synonymous with sterilizer.

Storage
Temporary holding of waste pending treatment or disposal, as in containers, tanks, waste piles, and surface impoundments.

Storm Sewer
A system of pipes (separate from sanitary sewers) that carries water runoff from buildings and land surfaces.

Stratification
Separating into layers.

Stratigraphy
Study of the formation, composition, and sequence of sediments, whether consolidated or not.

Stratosphere
The portion of the atmosphere 10-to-25 miles above the earth's surface.

Stressors
Physical, chemical, or biological entities that can induce adverse effects on ecosystems or human health.

Strip-Cropping
Growing crops in a systematic arrangement of strips or bands that serve as barriers to wind and water erosion.

Strip-Mining
A process that uses machines to scrape soil or rock away from mineral deposits just under the earth's surface.

Structural Deformation
Distortion in walls of a tank after liquid has been added or removed.

Subchronic
Of intermediate duration, usually used to describe studies or periods of exposure lasting between 5 and 90 days.

Subchronic Exposure
Multiple or continuous exposures lasting for approximately ten percent of an experimental species lifetime, usually over a three-month period.

Submerged Aquatic Vegetation
Vegetation that lives at or below the water surface; an important habitat for young fish and other aquatic organisms.

Subwatershed
Topographic perimeter of the catchment area of a stream tributary.

Sulfur Dioxide (SO2)
A pungent, colorless, gasformed primarily by the combustion of fossil fuels; becomes a pollutant when present in large amounts.

Sump
A pit or tank that catches liquid runoff for drainage or disposal.

Superchlorination
Chlorination with doses that are deliberately selected to produce water free of combined residuals so large as to require dechlorination.

Supercritical Water
A type of thermal treatment using moderate temperatures and high pressures to enhance the ability of water to break down large organic molecules into smaller, less toxic ones. Oxygen injected during this process combines with simple organic compounds to form carbon dioxide and water.

Superfund
The program operated under the legislative authority of CERCLA and SARA that funds and carries out EPA solid waste emergency and long-term removal and remedial activities. These activities include establishing the National Priorities List, investigating sites for inclusion on the list, determining their priority, and conducting and/or supervising cleanup and other remedial actions.

Supplemental Registration
An arrangement whereby a registrant licenses another company to market its pesticide product under the second company's registration.

Supplier of Water
Any person who owns or operates a public water supply.

Surface Impoundment
Treatment, storage, or disposal of liquid hazardous wastes in ponds.

Surface Runoff
Precipitation, snow melt, or irrigation water in excess of what can infiltrate the soil surface and be stored in small surface depressions; a major transporter of non-point source pollutants in rivers, streams, and lakes..

Surface Uranium Mines
Strip mining operations for removal of uranium-bearing ore.

Surface Water
All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc.)

Surface-Water Treatment Rule
Rule that specifies maximum contaminant level goals for Giardia lamblia, viruses, and Legionella and promulgates filtration and disinfection requirements for public water systems using surface-water or ground-water sources under the direct influence of surface water. The regulations also specify water quality, treatment, and watershed protection criteria under which filtration may be avoided.

Surfacing ACM
Asbestos-containing material that is sprayed or troweled on or otherwise applied to surfaces, such as acoustical plaster on ceilings and fireproofing materials on structural members.

Surfacing Material
Material sprayed or troweled onto structural members (beams, columns, or decking) for fire protection; or on ceilings or walls for fireproofing, acoustical or decorative purposes. Includes textured plaster, and other textured wall and ceiling surfaces.

Surfactant
A detergent compound that promotes lathering.

Surrogate Data
Data from studies of test organisms or a test substance that are used to estimate the characteristics or effects on another organism or substance.

Surveillance System
A series of monitoring devices designed to check on environmental conditions.

Susceptibility Analysis
An analysis to determine whether a Public Water Supply is subject to significant pollution from known potential sources.

Suspect Material
Building material suspected of containing asbestos; e.g., surfacing material, floor tile, ceiling tile, thermal system insulation.

Suspended Loads
Specific sediment particles maintained in the water column by turbulence and carried with the flow of water.

Suspended Solids
Small particles of solid pollutants that float on the surface of, or are suspended in, sewage or other liquids. They resist removal by conventional means.

Suspension
Suspending the use of a pesticide when EPA deems it necessary to prevent an imminent hazard resulting from its continued use. An emergency suspension takes effect immediately; under an ordinary suspension a registrant can request a hearing before the suspension goes into effect. Such a hearing process might take six months.

Suspension Culture
Cells growing in a liquid nutrient medium.

Swamp
A type of wetland dominated by woody vegetation but without appreciable peat deposits. Swamps may be fresh or salt water and tidal or non-tidal. (See wetlands.)

Synergism
An interaction of two or more chemicals that results in an effect greater than the sum of their separate effects.

Synthetic Organic Chemicals (SOCs)
Man-made (anthropogenic) organic chemicals. Some SOCs are volatile; others tend to stay dissolved in water instead of evaporating.

Systemic Pesticide
A chemical absorbed by an organism that interacts with the organism and makes the organism toxic to pests.

Tail Water
The runoff of irrigation water from the lower end of an irrigated field.

Tailings
Residue of raw material or waste separated out during the processing of crops or mineral ores.

Tailpipe Standards
Emissions limitations applicable to mobile source engine exhausts.

Tampering
Adjusting, negating, or removing pollution control equipment on a motor vehicle.

Technical Assistance Grant (TAG)
As part of the Superfund program, Technical Assistance Grants of up to $50,000 are provided to citizens' groups to obtain assistance in interpreting information related to clean-ups at Superfund sites or those proposed for the National Priorities List. Grants are used by such groups to hire technical advisors to help them understand the site-related technical information for the duration of response activities.

Technology-Based Limitations
Industry-specific effluent limitations based on best available preventive technology applied to a discharge when it will not cause a violation of water quality standards at low stream flows. Usually applied to discharges into large rivers.

Technology-Based Standards
Industry-specific effluent limitations applicable to direct and indirect sources which are developed on a category-by-category basis using statutory factors, not including water-quality effects.

Teratogen
A substance capable of causing birth defects.

Teratogenesis
The introduction of nonhereditary birth defects in a developing fetus by exogenous factors such as physical or chemical agents acting in the womb to interfere with normal embryonic development.

Terracing
Dikes built along the contour of sloping farm land that hold runoff and sediment to reduce erosion.

Tertiary Treatment
Advanced cleaning of wastewater that goes beyond the secondary or biological stage, removing nutrients such as phosphorus, nitrogen, and most BOD and suspended solids.

Therapeutic Index
The ratio of the dose required to produce toxic or lethal effects to the dose required to produce nonadverse or therapeutic response.

Thermal Pollution
Discharge of heated water from industrial processes that can kill or injure aquatic organisms.

Thermal Stratification
The formation of layers of different temperatures in a lake or reservoir.

Thermal System Insulation (TSI)
Asbestos-containing material applied to pipes, fittings, boilers, breeching, tanks, ducts, or other interior structural components to prevent heat loss or gain or water condensation.

Thermal Treatment
Use of elevated temperatures to treat hazardous wastes. (See incineration; pyrolysis.)

Thermocline
The middle layer of a thermally stratified lake or reservoir. In this layer, there is a rapid decrease in temperatures in a lake or reservoir.

Threshold
The lowest dose of a chemical at which a specified measurable effect is observed and below which it is not observed.

Threshold
The dose or exposure level below which a significant adverse effect is not expected.

Threshold Level
Time-weighted average pollutant concentration values, exposure beyond which is likely to adversely affect human health. (See environmental exposure)

Threshold Limit Value (TLV)
The concentration of an airborne substance to which an average person can be repeatedly exposed without adverse effects. TLVs may be expressed in three ways (1) TLV-TWA--Time weighted average, based on an allowable exposure averaged over a normal 8-hour workday or 40-hour work- week; (2) TLV-STEL--Short-term exposure limit or maximum concentration for a brief specified period of time, depending on a specific chemical (TWA must still be met); and (3) TLV-C--Ceiling Exposure Limit or maximum expos…

Threshold Odor
(See Odor threshold)

Threshold Planning Quantity
A quantity designated for each chemical on the list of extremely hazardous substances that triggers notification by facilities to the State Emergency Response Commission that such facilities are subject to emergency planning requirements under SARA Title III.

Thropic Levels
A functional classification of species that is based on feeding relationships (e.g. generally aquatic and terrestrial green plants comprise the first thropic level, and herbivores comprise the second.)

Tidal Marsh
Low, flat marshlands traversed by channels and tidal hollows, subject to tidal inundation; normally, the only vegetation present is salt-tolerant bushes and grasses. (See wetlands.)

Tillage
Plowing, seedbed preparation, and cultivation practices.

Time-weighted Average (TWA)
In air sampling, the average air concentration of contaminants during a given period.

Tire Processor
Intermediate operating facility where recovered tires are processed in preparation for recycling.

Tires
As used in recycling, passenger car and truck tires (excludes airplane, bus, motorcycle and special service military, agricultural, off-the-road and-slow speed industrial tires). Car and truck tires are recycled into rubber products such as trash cans, storage containers, rubberized asphalt or used whole for playground and reef construction.

Tolerance Petition
A formal request to establish a new tolerance or modify an existing one.

Tolerances
Permissible residue levels for pesticides in raw agricultural produce and processed foods. Whenever a pesticide is registered for use on a food or a feed crop, a tolerance (or exemption from the tolerance requirement) must be established. EPA establishes the tolerance levels, which are enforced by the Food and Drug Administration and the Department of Agriculture.

Tonnage
The amount of waste that a landfill accepts, usually expressed in tons per month. The rate at which a landfill accepts waste is limited by the landfill's permit.

Topography
The physical features of a surface area including relative elevations and the position of natural and man-made (anthropogenic) features.

Total Dissolved Phosphorous
The total phosphorous content of all material that will pass through a filter, which is determined as orthophosphate without prior digestion or hydrolysis. Also called soluble P. or ortho P.

Total Dissolved Solids (TDS)
All material that passes the standard glass river filter; now called total filtrable residue. Term is used to reflect salinity.

Total Petroleum Hydrocarbons (TPH)
Measure of the concentration or mass of petroleum hydrocarbon constituents present in a given amount of soil or water. The word 'total' is a misnomer--few, if any, of the procedures for quantifying hydrocarbons can measure all of them in a given sample. Volatile ones are usually lost in the process and not quantified and non-petroleum hydrocarbons sometimes appear in the analysis.

Total Suspended Particles (TSP)
A method of monitoring airborne particulate matter by total weight.

Total Suspended Solids (TSS)
A measure of the suspended solids in wastewater, effluent, or water bodies, determined by tests for 'total suspended non-filterable solids.' (See suspended solids.)

Toxaphene
Chemical that causes adverse health effects in domestic water supplies and is toxic to fresh water and marine aquatic life.

Toxic Chemical
Any chemical listed in EPA rules as 'Toxic Chemicals Subject to Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986.'

Toxic Chemical Release Form
Information form required of facilities that manufacture, process, or use (in quantities above a specific amount) chemicals listed under SARA Title III.

Toxic Chemical Use Substitution
Replacing toxic chemicals with less harmful chemicals in industrial processes.

Toxic Cloud
Airborne plume of gases, vapors, fumes, or aerosols containing toxic materials.

Toxic Concentration
The concentration at which a substance produces a toxic effect.

Toxic Dose
The dose level at which a substance produces a toxic effect.

Toxic Pollutants
Materials that cause death, disease, or birth defects in organisms that ingest or absorb them. The quantities and exposures necessary to cause these effects can vary widely.

Toxic Release Inventory
Database of toxic releases in the United States compiled from SARA Title III Section 313 reports.

Toxic Substance
A chemical or mixture that may present an unreasonable risk of injury to health or the environment.

Toxic Waste
A waste that can produce injury if inhaled, swallowed, or absorbed through the skin.

Toxicant
A harmful substance or agent that may injure an exposed organism.

Toxicity
The degree to which a substance or mixture of substances can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure sometimes lasting for the entire life of the exposed organism. Subchronic toxicity is the ability of the substance to cause effects for more than one ye…

Toxicity Assessment
Characterization of the toxicological properties and effects of a chemical, with special emphasis on establishment of dose-response characteristics.

Toxicity Testing
Biological testing (usually with an invertebrate, fish, or small mammal) to determine the adverse effects of a compound or effluent.

Toxicological Profile
An examination, summary, and interpretation of a hazardous substance to determine levels of exposure and associated health effects.

Transboundary Pollutants
Air pollution that travels from one jurisdiction to another, often crossing state or international boundaries. Also applies to water pollution.

Transfer Station
Facility where solid waste is transferred from collection vehicles to larger trucks or rail cars for longer distance transport.

Transient Water System
A non-community water system that does not serve 25 of the same nonresidents per day for more than six months per year.

Transmission Lines
Pipelines that transport raw water from its source to a water treatment plant, then to the distribution grid system.

Transmissivity
The ability of an aquifer to transmit water.