Laboratory Terms S

A glossary of science, chemistry, environmental and laboratory terms.

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Sacrifical Anode: An easily corroded material deliberately installed in a pipe or intake to giv...
Safe: Condition of exposure under which there is a practical certainty that no harm...
Safe Water: Water that does not contain harmful bacteria, toxic materials, or chemicals, ...
Safe Yield: The annual amount of water that can be taken from a source of supply over a p...
Safener: A chemical added to a pesticide to keep it from injuring plants.
Salinity: The percentage of salt in water.
Salt Water Intrusion: The invasion of fresh surface or ground water by salt water. If it comes from...
Salts: Minerals that water picks up as it passes through the air, over and under the...
Salvage: The utilization of waste materials.
Sampling Frequency: The interval between the collection of successive samples.
Sanctions: Actions taken by the federal government for failure to provide or implement a...
Sand Filters: Devices that remove some suspended solids from sewage. Air and bacteria decom...
Sanitary Sewers: Underground pipes that carry off only domestic or industrial waste, not storm...
Sanitary Survey: An on-site review of the water sources, facilities, equipment, operation and ...
Sanitary Water: Water discharged from sinks, showers, kitchens, or other non-industrial opera...
Sanitation: Control of physical factors in the human environment that could harm developm...
Saprolite: A soft, clay-rich, thoroughly decomposed rock formed in place by chemical wea...
Saprophytes: Organisms living on dead or decaying organic matter that help natural decompo...
Saturated Zone: The area below the water table where all open spaces are filled with water un...
Saturation: The condition of a liquid when it has taken into solution the maximum possibl...
Science Advisory Board SAB: A group of external scientists who advise EPA on science and policy.
Scrap: Materials discarded from manufacturing operations that may be suitable for re...
Scrap Metal Processor: Intermediate operating facility where recovered metal is sorted, cleaned of c...
Screening: Use of screens to remove coarse floating and suspended solids from sewage.
Screening Risk Assessment: A risk assessment performed with few data and many assumptions to identify ex...
Scrubber: An air pollution device that uses a spray of water or reactant or a dry proce...
Secondary Drinking Water Regulations: Non-enforceable regulations applying to public water systems and specifying t...
Secondary Effect: Action of a stressor on supporting components of the ecosystem, which in turn...
Secondary Materials: Materials that have been manufactured and used at least once and are to be us...
Secondary Standards: National ambient air quality standards designed to protect welfare, including...
Secondary Treatment: The second step in most publicly owned waste treatment systems in which bacte...
Secure Maximum Contaminant Level: Maximum permissible level of a contaminant in water delivered to the free flo...
Sediment: Topsoil, sand, and minerals washed from the land into water, usually after ra...
Sediment Yield: The quantity of sediment arriving at a specific location.
Sedimentation: Letting solids settle out of wastewater by gravity during treatment.
Sedimentation Tanks: Wastewater tanks in which floating wastes are skimmed off and settled solids ...
Sediments: Soil, sand, and minerals washed from land into water, usually after rain. The...
Seed Protectant: A chemical applied before planting to protect seeds and seedlings from diseas...
Seepage: Percolation of water through the soil from unlined canals, ditches, laterals,...
Selective Pesticide: A chemical designed to affect only certain types of pests, leaving other plan...
Semi-Confined Aquifer: An aquifer partially confined by soil layers of low permeability through whic...
Semivolatile Organic Compounds: Organic compounds that volatilize slowly at standard temperature (20 degrees ...
Senescence: The aging process. Sometimes used to describe lakes or other bodies of water ...
Septic System: An on-site system designed to treat and dispose of domestic sewage. A typical...
Septic Tank: An underground storage tank for wastes from homes not connected to a sewer li...
Service Connector: The pipe that carries tap water from a public water main to a building.
Service Line Sample: A one-liter sample of water that has been standing for at least 6 hours in a ...
Service Pipe: The pipeline extending from the water main to the building served or to the c...
Set-Back: Setting a thermometer to a lower temperature when the building is unoccupied ...
Settleable Solids: Material heavy enough to sink to the bottom of a wastewater treatment tank.
Settling Chamber: A series of screens placed in the way of flue gases to slow the stream of air...
Settling Tank: A holding area for wastewater, where heavier particles sink to the bottom for...
Sewage: The waste and wastewater produced by residential and commercial sources and d...
Sewage Sludge: Sludge produced at a Publicly Owned Treatment Works, the disposal of which is...
Sewer: A channel or conduit that carries wastewater and storm-water runoff from the ...
Sewerage: The entire system of sewage collection, treatment, and disposal.
Shading Coefficient: The amount of the sun's heat transmitted through a given window compared with...
Shale: Shale is a sedimentary rock that is fine-grained. It has flakes of clay miner...
Sharps: Hypodermic needles, syringes (with or without the attached needle), Pasteur p...
Shock Load: The arrival at a water treatment plant of raw water containing unusual amount...
Short-Circuiting: When some of the water in tanks or basins flows faster than the rest; may res...
Sick Building Syndrome: Building whose occupants experience acute health and/or comfort effects that ...
Signal: The volume or product-level change produced by a leak in a tank.
Signal Words: The words used on a pesticide label--Danger, Warning, Caution--to indicate le...
Significant Deterioration: Pollution resulting from a new source in previously "clean" areas.
Significant Municipal Facilities: Those publicly owned sewage treatment plants that discharge a million gallons...
Significant Non-Compliance: significant violations.)
Significant Potential Source of Contamination: A facility or activity that stores, uses, or produces compounds with potentia...
Significant Violations: Violations by point source dischargers of sufficient magnitude or duration to...
Silt: Sedimentary materials composed of fine or intermediate-sized mineral particles.
Silviculture: Management of forest land for timber.
Single-Breath Canister: Small one-liter canister designed to capture a single breath. Used in air pol...
Sink: Place in the environment where a compound or material collects.
Sinking: Controlling oil spills by using an agent to trap the oil and sink it to the b...
SIP Call: EPA action requiring a state to resubmit all or part of its State Implementat...
Site: An area or place within the jurisdiction of the EPA and/or a state.
Site Assessment Program: A means of evaluating hazardous waste sites through preliminary assessments a...
Site Inspection: The collection of information from a Superfund site to determine the extent a...
Site Remediation: Cleanup techniques used to remove or contain a toxic spill or hazardous mater...
Site Safety Plan: A crucial element in all removal actions, it includes information on equipmen...
Siting: The process of choosing a location for a facility.
Skimming: Using a machine to remove oil or scum from the surface of the water.
Slow Sand Filtration: Passage of raw water through a bed of sand at low velocity, resulting in subs...
Sludge: A semi-solid residue from any of a number of air or water treatment processes...
Sludge Digester: Tank in which complex organic substances like sewage sludges are biologically...
Slurry: A watery mixture of insoluble matter resulting from some pollution control te...
Small Quantity Generator: Persons or enterprises that produce 220-2200 pounds per month of hazardous wa...
Smelter: A facility that melts or fuses ore, often with an accompanying chemical chang...
Smog: Air pollution typically associated with oxidants.
Smoke: Particles suspended in air after incomplete combustion.
Soft Detergents: Cleaning agents that break down in nature.
Soft Water: Any water that does not contain a significant amount of dissolved minerals su...
Soil Adsorption Field: A sub-surface area containing a trench or bed with clean stones and a system ...
Soil and Water Conservation Practices: Control measures consisting of managerial, vegetative, and structural practic...
Soil Conditioner: An organic material like humus or compost that helps soil absorb water, build...
Soil Erodibility: An indicator of a soil's susceptibility to raindrop impact, runoff, and other...
Soil Gas: Gaseous elements and compounds in the small spaces between particles of the e...
Soil Moisture: The water contained in the pore space of the unsaturated zone.
Soil Sterilant: A chemical that temporarily or permanently prevents the growth of all plants ...
Solder: Metallic compound used to seal joints between pipes. Until recently, most sol...
Sole-Source Aquifer: An aquifer that supplies 50-percent or more of the drinking water of an area.
Solid Waste: Non-liquid, non-soluble materials ranging from municipal garbage to industria...
Solid Waste Disposal: The final placement of refuse that is not salvaged or recycled.
Solid Waste Management: Supervised handling of waste materials from their source through recovery pro...
Solidification and Stabilization: Removal of wastewater from a waste or changing it chemically to make it less ...
Solubility: The amount of mass of a compound that will dissolve in a unit volume of solut...
Soot: Carbon dust formed by incomplete combustion.
Sorption: The action of soaking up or attracting substances; process used in many pollu...
Source Area: The location of liquid hydrocarbons or the zone of highest soil or groundwate...
Source Characterization Measurements: Measurements made to estimate the rate of release of pollutants into the envi...
Source Reduction: Reducing the amount of materials entering the waste stream from a specific so...
Source Separation: Segregating various wastes at the point of generation (e.g., separation of pa...
Source-Water Protection Area: The area delineated by a state for a Public Water Supply or including numerou...
Sparge or Sparging: Injection of air below the water table to strip dissolved volatile organic co...
Special Local-Needs Registration: Registration of a pesticide product by a state agency for a specific use that...
Special Review: Formerly known as Rebuttable Presumption Against Registration (RPAR), this is...
Special Waste: Items such as household hazardous waste, bulky wastes (refrigerators, pieces ...
Species: 1. A reproductively isolated aggregate of interbreeding organisms having comm...
Specific Conductance: Rapid method of estimating the dissolved solid content of a water supply by t...
Specific Yield: The amount of water a unit volume of saturated permeable rock will yield when...
Spill Prevention Containment and Countermeasures Plan SPCP: Plan covering the release of hazardous substances as defined in the Clean Wat...
Spoil: Dirt or rock removed from its original location--destroying the composition o...
Sprawl: Unplanned development of open land.
Spray Tower Scrubber: A device that sprays alkaline water into a chamber where acid gases are prese...
Spring: Ground water seeping out of the earth where the water table intersects the gr...
Spring Melt: The process whereby warm temperatures melt winter snow and ice. Because vario...
Stabilization: Conversion of the active organic matter in sludge into inert, harmless material.
Stable Air: A motionless mass of air that holds, instead of dispersing, pollutants.
Stack: A chimney, smokestack, or vertical pipe that discharges used air.
Stack Effect: Flow of air resulting from warm air rising, creating a positive pressure area...
Stage II Controls: Systems placed on service station gasoline pumps to control and capture gasol...
Stagnation: Lack of motion in a mass of air or water that holds pollutants in place.
Stakeholder: Any organization, governmental entity, or individual that has a stake in or m...
Standard Industrial Classification Code: Also known as SIC Codes, a method of grouping industries with similar product...
Standard Sample: The part of finished drinking water that is examined for the presence of coli...
Standards: Norms that impose limits on the amount of pollutants or emissions produced. E...
Start of a Response Action: The point in time when there is a guarantee or set-aside of funding by EPA, o...
State Emergency Response Commission SERC: Commission appointed by each state governor according to the requirements of ...
State Environmental Goals and Indication Project: Program to assist state environmental agencies by providing technical and fin...
State Implementation Plans SIP: EPA approved state plans for the establishment, regulation, and enforcement o...
State Management Plan: Under FIFRA, a state management plan required by EPA to allow states, tribes,...
Static Pressure: In flowing air, the total pressure minus velocity pressure, pushing equally i...
Static Water Depth: The vertical distance from the centerline of the pump discharge down to the s...
Static Water Level: 1. Elevation or level of the water table in a well when the pump is not opera...
Stationary Source: A fixed-site producer of pollution, mainly power plants and other facilities ...
Sterilization: The removal or destruction of all microorganisms, including pathogenic and ot...
Sterilizer: One of three groups of anti-microbials registered by EPA for public health us...
Storage: Temporary holding of waste pending treatment or disposal, as in containers, t...
Storm Sewer: A system of pipes (separate from sanitary sewers) that carries water runoff f...
Stratification: Separating into layers.
Stratigraphy: Study of the formation, composition, and sequence of sediments, whether conso...
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...
Strip-Cropping: Growing crops in a systematic arrangement of strips or bands that serve as ba...
Strip-Mining: A process that uses machines to scrape soil or rock away from mineral deposit...
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 expo...
Subchronic Exposure: Multiple or continuous exposures lasting for approximately ten percent of an ...
Submerged Aquatic Vegetation: Vegetation that lives at or below the water surface; an important habitat for...
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; ...
Summa Canister: A summa canister is a stainless steel electropolished (or "summa" polished) p...
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 ...
Supercritical Water: A type of thermal treatment using moderate temperatures and high pressures to...
Superfund: The program operated under the legislative authority of CERCLA and SARA that ...
Superfund Innovative Technology Evaluation SITE: EPA program to promote development and use of innovative treatment and site c...
Supplemental Registration: An arrangement whereby a registrant licenses another company to market its pe...
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 infiltrat...
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,...
Surface-Water Treatment Rule: Rule that specifies maximum contaminant level goals for Giardia lamblia, viru...
Surfacing ACM: Asbestos-containing material that is sprayed or troweled on or otherwise appl...
Surfacing Material: Material sprayed or troweled onto structural members (beams, columns, or deck...
Surfactant: A detergent compound that promotes lathering.
Surrogate Data: Data from studies of test organisms or a test substance that are used to esti...
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 signific...
Suspect Material: Building material suspected of containing asbestos; e.g., surfacing material,...
Suspended Loads: Specific sediment particles maintained in the water column by turbulence and ...
Suspended Solids: Small particles of solid pollutants that float on the surface of, or are susp...
Suspension: Suspending the use of a pesticide when EPA deems it necessary to prevent an i...
Suspension Culture: Cells growing in a liquid nutrient medium.
Swamp: A type of wetland dominated by woody vegetation but without appreciable peat ...
Synergism: An interaction of two or more chemicals that results in an effect greater tha...
Synthetic Organic Chemicals SOCs: Man-made (anthropogenic) organic chemicals. Some SOCs are volatile; others te...
System With a Single Service Connection: A system that supplies drinking water to consumers via a single service line.
Systemic Pesticide: A chemical absorbed by an organism that interacts with the organism and makes...

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