Laboratory Terms A

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

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A-Scale Sound Level: A measurement of sound approximating the sensitivity of the human ear, used t...
Abandoned Well: A well whose use has been permanently discontinued or which is in a state of ...
Abatement: Reducing the degree or intensity of, or eliminating, pollution.
Abatement Debris: Waste from remediation activities.
Absorbed Dose: In exposure assessment, the amount of a substance that penetrates an exposed ...
Absorber: Any material that stops ionizing radiation. Lead, concrete, and steel attenua...
Absorption: The process of taking in. The uptake of water, other fluids, or dissolved che...
Absorption Barrier: Any of the exchange sites of the body that permit uptake of various substance...
Accident Site: The location of an unexpected occurrence, failure or loss, either at a plant ...
Acclimatization: The physiological and behavioral adjustments of an organism to changes in its...
Acequia: Acequias were important forms of irrigation in the development of agriculture...
Acid: A corrosive substance with a pH less than 7.
Acid Aerosol: Acidic liquid or solid particles small enough to become airborne. High concen...
Acid Deposition: A complex chemical and atmospheric phenomenon that occurs when emissions of s...
Acid Mine Drainage: Drainage of water from areas that have been mined for coal or other mineral o...
Acid Neutralizing Capacity: Measure of ability of a base (e.g. water or soil) to resist changes in pH.
Acidic: The condition of water or soil that contains a sufficient amount of acid subs...
Action Levels: 1. Regulatory levels recommended by EPA for enforcement by FDA and USDA when ...
Activated Carbon: A highly adsorbent form of carbon used to remove odors and toxic substances f...
Activated Sludge: Product that results when primary effluent is mixed with bacteria-laden sludg...
Activator: A chemical added to a pesticide to increase its activity.
Active Ingredient: In any pesticide product, the component that kills, or otherwise controls, ta...
Activity Plans: Written procedures in a school's asbestos-management plan that detail the ste...
Acute Effect: An adverse effect on any living organism which results in severe symptoms tha...
Acute Exposure: A single exposure to a toxic substance which may result in severe biological ...
Acute Toxicity: The ability of a substance to cause severe biological harm or death soon afte...
Adaptation: Changes in an organism's physiological structure or function or habits that a...
Add-on Control Device: An air pollution control device such as carbon absorber or incinerator that r...
Adequately Wet: Asbestos containing material that is sufficiently mixed or penetrated with li...
Administered Dose: In exposure assessment, the amount of a substance given to a test subject (hu...
Administrative Order: A legal document signed by EPA directing an individual, business, or other en...
Administrative Order On Consent: A legal agreement signed by EPA and an individual, business, or other entity ...
Administrative Procedures Act: A law that spells out procedures and requirements related to the promulgation...
Administrative Record: All documents which EPA considered or relied on in selecting the response act...
Adsorption: Removal of a pollutant from air or water by collecting the pollutant on the s...
Adulterants: Chemical impurities or substances that by law do not belong in a food, or pes...
Adulterated: 1. Any pesticide whose strength or purity falls below the quality stated on i...
Advanced Treatment: A level of wastewater treatment more stringent than secondary treatment; requ...
Advanced Wastewater Treatment: Any treatment of sewage that goes beyond the secondary or biological water tr...
Adverse Effects Data: FIFRA requires a pesticide registrant to submit data to EPA on any studies or...
Advisory: A non-regulatory document that communicates risk information to those who may...
Aerated Lagoon: A holding and/or treatment pond that speeds up the natural process of biologi...
Aeration: A process which promotes biological degradation of organic matter in water. T...
Aeration Tank: A chamber used to inject air into water.
Aerobic: Life or processes that require, or are not destroyed by, the presence of oxygen.
Aerobic Treatment: Process by which microbes decompose complex organic compounds in the presence...
Aerosol: 1. Small droplets or particles suspended in the atmosphere, typically contain...
Affected Landfill: Under the Clean Air Act, landfills that meet criteria for capacity, age, and ...
Affected Public: 1.The people who live and/or work near a hazardous waste site. 2. The human p...
Afterburner: In incinerator technology, a burner located so that the combustion gases are ...
Age Tank: A tank used to store a chemical solution of known concentration for feed to a...
Agent: Any physical, chemical, or biological entity that can be harmful to an organi...
Agent Orange: A toxic herbicide and defoliant used in the Vietnam conflict, containing 2,4,...
Agricultural Pollution: Farming wastes, including runoff and leaching of pesticides and fertilizers; ...
Agricultural Waste: Poultry and livestock manure, and residual materials in liquid or solid form ...
Agroecosystem: Land used for crops, pasture, and livestock; the adjacent uncultivated land t...
AHERA Designated Person ADP: A person designated by a Local Education Agency to ensure that the AHERA requ...
Air: The surface between the vadose zone and ambient oil; the pressure of oil in t...
Air Binding: Situation where air enters the filter media and harms both the filtration and...
Air Changes Per Hour ACH: The movement of a volume of air in a given period of time; if a house has one...
Air Cleaning: Indoor-air quality-control strategy to remove various airborne particulates a...
Air Contaminant: Any particulate matter, gas, or combination thereof, other than water vapor.
Air Curtain: A method of containing oil spills. Air bubbling through a perforated pipe cau...
Air Exchange Rate: The rate at which outside air replaces indoor air in a given space.
Air Gap: Open vertical gap or empty space that separates drinking water supply to be p...
Air Handling Unit: Equipment that includes a fan or blower, heating and/or cooling coils, regula...
Air Mass: A large volume of air with certain meteorological or polluted characteristics...
Air Padding: Pumping dry air into a container to assist with the withdrawal of liquid or t...
Air Permeability: Permeability of soil with respect to air. Important to the design of soil-gas...
Air Plenum: Any space used to convey air in a building, furnace, or structure. The space ...
Air Pollutant: Any substance in air that could, in high enough concentration, harm man, othe...
Air Pollution: The presence of contaminants or pollutant substances in the air that interfer...
Air Pollution Control Device: Mechanism or equipment that cleans emissions generated by a source (e.g. an i...
Air Pollution Episode: A period of abnormally high concentration of air pollutants, often due to low...
Air Quality Criteria: The levels of pollution and lengths of exposure above which adverse health an...
Air Quality Standards: The level of pollutants prescribed by regulations that are not be exceeded du...
Air Sparging: Injecting air or oxygen into an aquifer to strip or flush volatile contaminan...
Air Stripping: A treatment system that removes volatile organic compounds (VOCs) from contam...
Air Toxics: Any air pollutant for which a national ambient air quality standard (NAAQS) d...
Airborne Particulates: Total suspended particulate matter found in the atmosphere as solid particles...
Airborne Release: Release of any pollutant into the air.
Alachlor: A herbicide, marketed under the trade name Lasso, used mainly to control weed...
Alar: Trade name for daminozide, a pesticide that makes apples redder, firmer, and ...
Aldicarb: An insecticide sold under the trade name Temik. It is made from ethyl isocyan...
Algae: Simple rootless plants that grow in sunlit waters in proportion to the amount...
Algal Blooms: Sudden spurts of algal growth, which can affect water quality adversely and i...
Algicide: Substance or chemical used specifically to kill or control algae.
Aliquot: A measured portion of a sample taken for analysis. One or more aliquots make ...
Alkaline: The condition of water or soil which contains a sufficient amount of alkali s...
Alkalinity: The capacity of bases to neutralize acids. An example is lime added to lakes ...
Allergen: A substance that causes an allergic reaction in individuals sensitive to it.
Alluvial: Relating to and/or sand deposited by flowing water.
Alternate Method: Any method of sampling and analyzing for an air or water pollutant that is no...
Alternative Compliance: A policy that allows facilities to choose among methods for achieving emissio...
Alternative Fuels: Substitutes for traditional liquid, oil-derived motor vehicle fuels like gaso...
Alternative Remedial Contract Strategy Contractors: Government contractors who provide project management and technical services ...
Ambient Air: Any unconfined portion of the atmosphere
Ambient Measurement: A measurement of the concentration of a substance or pollutant within the imm...
Ambient Medium: Material surrounding or contacting an organism (e.g. outdoor air, indoor air,...
Ambient Temperature: Temperature of the surrounding air or other medium.
Amprometric Titration: A way of measuring concentrations of certain substances in water using an ele...
Anaerobic: A life or process that occurs in, or is not destroyed by, the absence of oxygen.
Anaerobic Decomposition: Reduction of the net energy level and change in chemical composition of organ...
Analyte: A compound or property that is to be determined and/or analyzed.
Animal Dander: Tiny scales of animal skin, a common indoor air pollutant.
Animal Studies: Investigations using animals as surrogates for humans with the expectation th...
Anisotropy: In hydrology, the conditions under which one or more hydraulic properties of ...
Annular Space: The space between two concentric tubes or casings, or between the casing and ...
Antagonism: Interference or inhibition of the effect of one chemical by the action of ano...
Antarctic Ozone Hole: Refers to the seasonal depletion of ozone in the upper atmosphere above a lar...
Anti-Degradation Clause: Part of federal air quality and water quality requirements prohibiting deteri...
Anti-Microbial: An agent that kills microbes.
Applicable or Relevant and Appropriate Requirements ARARs: Any state or federal statute that pertains to protection of human life and th...
Applied Dose: In exposure assessment, the amount of a substance in contact with the primary...
Aqueous: Something made up of water.
Aqueous Solubility: The maximum concentration of a chemical that will dissolve in pure water at a...
Aquifer: An underground geological formation, or group of formations, containing water...
Aquifer Test: A test to determine hydraulic properties of an aquifer.
Aquitard: Geological formation that may contain groundwater but is not capable of trans...
Architectural Coatings: Coverings such as paint and roof tar that are used on exteriors of buildings.
Area of Review: In the UIC program, the area surrounding an injection well that is reviewed d...
Area Source: Any source of air pollution that is released over a relatively small area but...
Aromatics: A type of hydrocarbon, such as benzene or toluene, with a specific type of ri...
Arsenicals: Pesticides containing arsenic.
Artesian Aquifer or Well: Water held under pressure in porous rock or soil confined by impermeable geol...
Asbestos: A mineral fiber that can pollute air or water and cause cancer or asbestosis ...
Asbestos Abatement: Procedures to control fiber release from asbestos-containing materials in a b...
Asbestos Assessment: In the asbestos-in-schools program, the evaluation of the physical condition ...
Asbestos Program Manager: A building owner or designated representative who supervises all aspects of t...
Asbestos-Containing Waste Materials ACWM: Mill tailings or any waste that contains commercial asbestos and is generated...
Asbestosis: A disease associated with inhalation of asbestos fibers. The disease makes br...
Ash: The mineral content of a product remaining after complete combustion.
Assay: A test for a specific chemical, microbe, or effect.
Assessment Endpoint: In ecological risk assessment, an explicit expression of the environmental va...
Assimilation: The ability of a body of water to purify itself of pollutants.
Assimilative Capacity: The capacity of a natural body of water to receive wastewaters or toxic mater...
Association of Boards of Certification: An international organization representing boards which certify the operators...
Attainment Area: An area considered to have air quality as good as or better than the national...
Attenuation: The process by which a compound is reduced in concentration over time, throug...
Attractant: A chemical or agent that lures insects or other pests by stimulating their se...
Attrition: Wearing or grinding down of a substance by friction. Dust from such processes...
Availability Session: Informal meeting at a public location where interested citizens can talk with...
Available Chlorine: A measure of the amount of chlorine available in chlorinated lime, hypochlori...
Avoided Cost: The cost a utility would incur to generate the next increment of electric cap...

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