Laboratory Terms T

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

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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...
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 $50,00...
Technical-Grade Active Ingredient TGA: A pesticide chemical in pure form as it is manufactured prior to being formul...
Technology-Based Limitations: Industry-specific effluent limitations based on best available preventive tec...
Technology-Based Standards: Industry-specific effluent limitations applicable to direct and indirect sour...
Tentatively Identified Compounds TICs: TICs or Tentatively Identified Compounds are those which can be detected by a...
Teratogen: A substance capable of causing birth defects.
Teratogenesis: The introduction of nonhereditary birth defects in a developing fetus by exog...
Terracing: Dikes built along the contour of sloping farm land that hold runoff and sedim...
Tertiary Treatment: Advanced cleaning of wastewater that goes beyond the secondary or biological ...
Theoretical Maximum Residue Contribution: The theoretical maximum amount of a pesticide in the daily diet of an average...
Therapeutic Index: The ratio of the dose required to produce toxic or lethal effects to the dose...
Thermal Pollution: Discharge of heated water from industrial processes that can kill or injure a...
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, ...
Thermal Treatment: Use of elevated temperatures to treat hazardous wastes.
Thermocline: The middle layer of a thermally stratified lake or reservoir. In this layer, ...
Threshold: The lowest dose of a chemical at which a specified measurable effect is obser...
Threshold Level: Time-weighted average pollutant concentration values, exposure beyond which i...
Threshold Limit Value TLV: The concentration of an airborne substance to which an average person can be ...
Threshold Planning Quantity: A quantity designated for each chemical on the list of extremely hazardous su...
Thropic Levels: A functional classification of species that is based on feeding relationships...
Tidal Marsh: Low, flat marshlands traversed by channels and tidal hollows, subject to tida...
Tillage: Plowing, seedbed preparation, and cultivation practices.
Time-weighted Average TWA: In air sampling, the average air concentration of contaminants during a given...
Tire Processor: Intermediate operating facility where recovered tires are processed in prepar...
Tires: As used in recycling, passenger car and truck tires (excludes airplane, bus, ...
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 pro...
Tonnage: The amount of waste that a landfill accepts, usually expressed in tons per mo...
Topography: The physical features of a surface area including relative elevations and the...
Total Dissolved Phosphorous: The total phosphorous content of all material that will pass through a filter...
Total Dissolved Solids TDS: All material that passes the standard glass river filter; now called total fi...
Total Petroleum Hydrocarbons TPH: Measure of the concentration or mass of petroleum hydrocarbon constituents pr...
Total Pressure: In flowing air, the sum of the static and velocity pressures.
Total Recovered Petroleum Hydrocarbon: A method for measuring petroleum hydrocarbons in samples of soil or water.
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, d...
Total Trihalomethanes TTHM: Total Trihalomethanes (TTHM) are the total amount of trihalomethanes allowed ...
Toxaphene: Chemical that causes adverse health effects in domestic water supplies and is...
Toxic Chemical: Any chemical listed in EPA rules as "Toxic Chemicals Subject to Section 313 o...
Toxic Chemical Release Form: Information form required of facilities that manufacture, process, or use (in...
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 inges...
Toxic Release Inventory: Database of toxic releases in the United States compiled from SARA Title III ...
Toxic Substance: A chemical or mixture that may present an unreasonable risk of injury to heal...
Toxic Waste: A waste that can produce injury if inhaled, swallowed, or absorbed through th...
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 a...
Toxicity Assessment: Characterization of the toxicological properties and effects of a chemical, w...
Toxicity Testing: Biological testing (usually with an invertebrate, fish, or small mammal) to d...
Toxicological Profile: An examination, summary, and interpretation of a hazardous substance to deter...
Transboundary Pollutants: Air pollution that travels from one jurisdiction to another, often crossing s...
Transfer Station: Facility where solid waste is transferred from collection vehicles to larger ...
Transient Water System: A non-community water system that does not serve 25 of the same nonresidents ...
Transmission Lines: Pipelines that transport raw water from its source to a water treatment plant...
Transmissivity: The ability of an aquifer to transmit water.
Transpiration: The process by which water vapor is lost to the atmosphere from living plants...
Transportation Control Measures TCMs: Steps taken by a locality to reduce vehicular emission and improve air qualit...
Transporter: Hauling firm that picks up properly packaged and labeled hazardous waste from...
Trash: Material considered worthless or offensive that is thrown away. Generally def...
Trash-to-Energy Plan: Burning trash to produce energy.
Treatability Studies: Tests of potential cleanup technologies conducted in a laboratory
Treated Regulated Medical Waste: Medical waste treated to substantially reduce or eliminate its pathogenicity,...
Treated Wastewater: Wastewater that has been subjected to one or more physical, chemical, and bio...
Treatment: (1) Any method, technique, or process designed to remove solids and/or pollut...
Treatment Plant: A structure built to treat wastewater before discharging it into the environm...
Treatment Storage and Disposal Facility: Site where a hazardous substance is treated, stored, or disposed of. TSD faci...
Tremie: Device used to place concrete or grout under water.
Trial Burn: An incinerator test in which emissions are monitored for the presence of spec...
Trichloroethylene TCE: A stable, low boiling-point colorless liquid, toxic if inhaled. Used as a sol...
Trickle Irrigation: Method in which water drips to the soil from perforated tubes or emitters.
Trickling Filter: A coarse treatment system in which wastewater is trickled over a bed of stone...
Trihalomethanes THM: Trihalomethanes (THM) is a family of organic compounds named as derivative of...
Troposhpere: The layer of the atmosphere closest to the earth's surface.
Trust Fund: A fund set up under the Comprehensive Environmental Response, Compensation an...
Tube Settler: Device using bundles of tubes to let solids in water settle to the bottom for...
Tuberculation: Development or formation of small mounds of corrosion products on the inside ...
Tundra: A type of treeless ecosystem dominated by lichens, mosses, grasses, and woody...
Turbidimeter: A device that measures the cloudiness of suspended solids in a liquid; a meas...
Turbidity: 1. Haziness in air caused by the presence of particles and pollutants. 2. A c...

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