Laboratory Terms

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

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Data Call-In: A part of the Office of Pesticide Programs (OPP) process of developing key re...
Data Quality Objectives DQOs: Qualitative and quantitative statements of the overall level of uncertainty t...
Day Tank: Another name for deaerating tank.
DDT: The first chlorinated hydrocarbon insecticide chemical name
Dead End: The end of a water main which is not connected to other parts of the distribu...
Deadmen: Anchors drilled or cemented into the ground to provide additional reactive ma...
Decant: To draw off the upper layer of liquid after the heaviest material (a solid or...
Decay Products: Degraded radioactive materials, often referred to as "daughters" or "progeny"...
Dechlorination: Removal of chlorine from a substance.
Decomposition: The breakdown of matter by bacteria and fungi, changing the chemical makeup a...
Decontamination: Removal of harmful substances such as noxious chemicals, harmful bacteria or ...
Deep-Well Injection: Deposition of raw or treated, filtered hazardous waste by pumping it into dee...
Deflocculating Agent: A material added to a suspension to prevent settling.
Defluoridation: The removal of excess flouride in drinking water to prevent the staining of t...
Defoliant: An herbicide that removes leaves from trees and growing plants.
Degasification: A water treatment that removes dissolved gases from the water.
Degree-Day: A rough measure used to estimate the amount of heating required in a given ar...
Delegated State: A state (or other governmental entity such as a tribal government) that has r...
Delist: Use of the petition process to have a facility's toxic designation rescinded.
Demand-side Waste Management: Prices whereby consumers use purchasing decisions to communicate to product m...
Demineralization: A treatment process that removes dissolved minerals from water.
Denitrification: The biological reduction of nitrate to nitrogen gas by denitrifying bacteria ...
Dense Non-Aqueous Phase Liquid DNAPL: Non-aqueous phase liquids such as chlorinated hydrocarbon solvents or petrole...
Density: A measure of how heavy a specific volume of a solid, liquid, or gas is in com...
Depletion Curve: In hydraulics, a graphical representation of water depletion from storage-str...
Depressurization: A condition that occurs when the air pressure inside a structure is lower tha...
Dermal Absorption: Process by which a chemical penetrates the skin and enters the body as an int...
Dermal Exposure: Contact between a chemical and the skin.
Dermal Toxicity: The ability of a pesticide or toxic chemical to poison people or animals by c...
DES: A synthetic estrogen, diethylstilbestrol is used as a growth stimulant in foo...
Desalination: [Desalinization] (1) Removing salts from ocean or brackish water by using var...
Desiccant: A chemical agent that absorbs moisture; some desiccants are capable of drying...
Design Capacity: The average daily flow that a treatment plant or other facility is designed t...
Design Value: The monitored reading used by EPA to determine an area's air quality status; ...
Designated Pollutant: An air pollutant which is neither a criteria nor hazardous pollutant, as desc...
Designated Uses: Those water uses identified in state water quality standards that must be ach...
Designer Bugs: Popular term for microbes developed through biotechnology that can degrade sp...
Destination Facility: The facility to which regulated medical waste is shipped for treatment and de...
Destratification: Vertical mixing within a lake or reservoir to totally or partially eliminate ...
Destroyed Medical Waste: Regulated medical waste that has been ruined, torn apart, or mutilated throug...
Destruction and Removal Efficiency DRE: A percentage that represents the number of molecules of a compound removed or...
Destruction Facility: A facility that destroys regulated medical waste.
Desulfurization: Removal of sulfur from fossil fuels to reduce pollution.
Detectable Leak Rate: The smallest leak (from a storage tank), expressed in terms of gallons- or li...
Detection Criterion: A predetermined rule to ascertain whether a tank is leaking or not. Most volu...
Detection Limit: The lowest concentration of a chemical that can reliably be distinguished fro...
Detention Time: 1. The theoretical calculated time required for a small amount of water to pa...
Detergent: Synthetic washing agent that helps to remove dirt and oil. Some contain compo...
Development Effects: Adverse effects such as altered growth, structural abnormality, functional de...
Dewater: 1. Remove or separate a portion of the water in a sludge or slurry to dry the...
Diatomaceous Earth Diatomite: A chalk-like material (fossilized diatoms) used to filter out solid waste in ...
Diazinon: An insecticide. In 1986, EPA banned its use on open areas such as sod farms a...
Dibenzofurans: A group of organic compounds, some of which are toxic.
Dicofol: A pesticide used on citrus fruits.
Diffused Air: A type of aeration that forces oxygen into sewage by pumping air through perf...
Diffusion: The movement of suspended or dissolved particles (or molecules) from a more c...
Digester: In wastewater treatment, a closed tank; in solid-waste conversion, a unit in ...
Digestion: The biochemical decomposition of organic matter, resulting in partial gasific...
Dike: A low wall that can act as a barrier to prevent a spill from spreading.
Diluent: Any liquid or solid material used to dilute or carry an active ingredient.
Dilution Ratio: The relationship between the volume of water in a stream and the volume of in...
Dimictic: Lakes and reservoirs that freeze over and normally go through two stratificat...
Dinocap: A fungicide used primarily by apple growers to control summer diseases. EPA p...
Dinoseb: A herbicide that is also used as a fungicide and insecticide. It was banned b...
Dioxin: Any of a family of compounds known chemically as dibenzo-p-dioxins. Concern a...
Direct Discharger: A municipal or industrial facility which introduces pollution through a defin...
Direct Filtration: A method of treating water which consists of the addition of coagulent chemic...
Direct Push: Technology used for performing subsurface investigations by driving, pushing,...
Direct Runoff: Water that flows over the ground surface or through the ground directly into ...
Discharge: Flow of surface water in a stream or canal or the outflow of ground water fro...
Disinfectant: A chemical or physical process that kills pathogenic organisms in water, air,...
Disinfectant By-Product: A compound formed by the reaction of a disinfenctant such as chlorine with or...
Disinfectant Time: The time it takes water to move from the point of disinfectant application (o...
Dispersant: A chemical agent used to break up concentrations of organic material such as ...
Displacement Savings: Saving realized by displacing purchases of natural gas or electricity from a ...
Disposables: Consumer products, other items, and packaging used once or a few times and di...
Disposal: Final placement or destruction of toxic, radioactive, or other wastes; surplu...
Disposal Facilities: Repositories for solid waste, including landfills and combustors intended for...
Dissolved Oxygen DO: The oxygen freely available in water, vital to fish and other aquatic life an...
Dissolved Solids: Disintegrated organic and inorganic material in water. Excessive amounts make...
Distillation: The act of purifying liquids through boiling, so that the steam or gaseous va...
Disturbance: Any event or series of events that disrupt ecosystem, community, or populatio...
Diversion: 1. Use of part of a stream flow as water supply. 2. A channel with a supporti...
Diversion Rate: The percentage of waste materials diverted from traditional disposal such as ...
DNA Hybridization: Use of a segment of DNA, called a DNA probe, to identify its complementary DN...
Dobson Unit DU: Units of ozone level measurement. measurement of ozone levels. If, for exampl...
Domestic Application: Pesticide application in and around houses, office buildings, motels, and oth...
Dosage: 1. The actual quantity of a chemical administered to an organism or to which ...
Dose Equivalent: The product of the absorbed dose from ionizing radiation and such factors as ...
Dose Rate: In exposure assessment, dose per time unit (e.g. mg/day), sometimes also call...
Dose Response: Shifts in toxicological responses of an individual (such as alterations in se...
Dose Response Curve: Graphical representation of the relationship between the dose of a stressor a...
Dose-Response Assessment: 1. Estimating the potency of a chemical. 2. In exposure assessment, the proce...
Dose-Response Relationship: The quantitative relationship between the amount of exposure to a substance a...
Dosimeter: An instrument to measure dosage; many so-called dosimeters actually measure e...
DOT Reportable Quantity: The quantity of a substance specified in a U.S. Department of Transportation ...
Downgradient: The direction that groundwater flows; similar to "downstream" for surface water.
Downstream Processors: Industries dependent on crop production (e.g. canneries and food processors).
DP Hole: Hole in the ground made with DP equipment.
Draft: 1. The act of drawing or removing water from a tank or reservoir. 2. The wate...
Draft Permit: A preliminary permit drafted and published by EPA; subject to public review a...
Drainage: Improving the productivity of agricultural land by removing excess water from...
Drainage Basin: The area of land that drains water, sediment, and dissolved materials to a co...
Drainage Well: A well drilled to carry excess water off agricultural fields. Because they ac...
Drawdown: 1. The drop in the water table or level of water in the ground when water is ...
Dredging: Removal of mud from the bottom of water bodies. This can disturb the ecosyste...
Drilling Fluid: Fluid used to lubricate the bit and convey drill cuttings to the surface with...
Drinking Water Equivalent Level: Protective level of exposure related to potentially non-carcinogenic effects ...
Drinking Water State Revolving Fund: The Fund provides capitalization grants to states to develop drinking water r...
Drive Casing: Heavy duty steel casing driven along with the sampling tool in cased DP syste...
Drive Point Profiler: An exposed groundwater DP system used to collect multiple depth-discrete grou...
Drop-off: Recyclable materials collection method in which individuals bring them to a d...
Dual-Phase Extraction: Active withdrawal of both liquid and gas phases from a well usually involving...
Dump: A site used to dispose of solid waste without environmental controls.
Duplicate: A second aliquot or sample that is treated the same as the original sample in...
Dustfall Jar: An open container used to collect large particles from the air for measuremen...
Dynamometer: A device used to place a load on an engine and measure its performance.

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