Laboratory Terms M

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

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Macropores: Secondary soil features such as root holes or desiccation cracks that can cre...
Magnetic Separation: Use of magnets to separate ferrous materials from mixed municipal waste stream.
Major Modification: This term is used to define modifications of major stationary sources of emis...
Major Stationary Sources: Term used to determine the applicability of Prevention of Significant Deterio...
Majors: Larger publicly owned treatment works (POTWs) with flows equal to at least on...
Man-Made Beta Particle and Photon Emitters: All radionuclides emitting beta particles and/or photons listed in Maximum Pe...
Management Plan: Under the Asbestos Hazard Emergency Response Act (AHERA), a document that eac...
Managerial Controls: Methods of nonpoint source pollution control based on decisions about managin...
Mandatory Recycling: Programs which by law require consumers to separate trash so that some or all...
Manifest: A one-page form used by haulers transporting waste that lists EPA identificat...
Manifest System: Tracking of hazardous waste from "cradle-to-grave" (generation through dispos...
Manual Separation: Hand sorting of recyclable or compostable materials in waste.
Manufactured Gas Plant: A Manufactured Gas Plant, or MGP, was an industrial plant that produced gas, ...
Manufacturers Formulation: A list of substances or component parts as described by the maker of a coatin...
Manufacturing Use Product: Any product intended (labeled) for formulation or repackaging into other pest...
Margin of Exposure MOE: The ratio of the no-observed adverse-effect-level to the estimated exposure d...
Margin of Safety: Maximum amount of exposure producing no measurable effect in animals (or stud...
Marine Sanitation Device: Any equipment or process installed on board a vessel to receive, retain, trea...
Marsh: A type of wetland that does not accumulate appreciable peat deposits and is d...
Material Category: In the asbestos program, broad classification of materials into thermal surfa...
Material Safety Data Sheet MSDS: A compilation of information required under the OSHA Communication Standard o...
Material Type: Classification of suspect material by its specific use or application; e.g., ...
Materials Recovery Facility MRF: A facility that processes residentially collected mixed recyclables into new ...
Maximally Exposed Individual: The person with the highest exposure in a given population.
Maximum Acceptable Toxic Concentration: For a given ecological effects test, the range (or geometric mean) between th...
Maximum Available Control Technology MACT: The emission standard for sources of air pollution requiring the maximum redu...
Maximum Contaminant Level: The maximum permissible level of a contaminant in water delivered to any user...
Maximum Contaminant Level Goal MCLG: Under the Safe Drinking Water Act, a non-enforceable concentration of a drink...
Maximum Exposure Range: Estimate of exposure or dose level received by an individual in a defined pop...
Maximum Residue Level: Comparable to a U.S. tolerance level, the Maximum Residue Level the enforceab...
Maximum Tolerated Dose: The maximum dose that an animal species can tolerate for a major portion of i...
Measure of Effect Measurement Endpoint: A measurable characteristic of ecological entity that can be related to an as...
Measure of Exposure: A measurable characteristic of a stressor (such as the specific amount of mer...
Mechanical Aeration: Use of mechanical energy to inject air into water to cause a waste stream to ...
Mechanical Separation: Using mechanical means to separate waste into various components.
Mechanical Turbulence: Random irregularities of fluid motion in air caused by buildings or other non...
Media: Specific environments--air, water, soil--which are the subject of regulatory ...
Medical Surveillance: A periodic comprehensive review of a worker's health status; acceptable eleme...
Medical Waste: Any solid waste generated in the diagnosis, treatment, or immunization of hum...
Medium-size Water System: A water system that serves 3,300 to 50,000 customers.
Meniscus: The curved top of a column of liquid in a small tube.
Mercury: Mercury is a naturally occurring element that is found in air, water and soil...
Mercury Hg: Heavy metal that can accumulate in the environment and is highly toxic if bre...
Mesotrophic: Reservoirs and lakes which contain moderate quantities of nutrients and are m...
Metabolites: Any substances produced by biological processes, such as those from pesticides.
Metalimnion: The middle layer of a thermally stratified lake or reservoir. In this layer t...
Methane: A colorless, nonpoisonous, flammable gas created by anaerobic decomposition o...
Methanol: An alcohol that can be used as an alternative fuel or as a gasoline additive....
Method 18: An EPA test method which uses gas chromatographic techniques to measure the c...
Method 24: An EPA reference method to determine density, water content and total volatil...
Method 25: An EPA reference method to determine the VOC concentration in a gas stream.
Method Detection Limit MDL: The minimum concentration that can be measured and reported with 99 percent c...
Method Reporting Limit MRL: The lowest amount of an analyte in a sample that can be quantitatively determ...
Methoxychlor: Pesticide that causes adverse health effects in domestic water supplies and i...
Methyl Orange Alkalinity: A measure of the total alkalinity in a water sample in which the color of met...
Microbial Growth: The amplification or multiplication of microorganisms such as bacteria, algae...
Microbial Pesticide: A microorganism that is used to kill a pest, but is of minimum toxicity to hu...
Microclimate: 1. Localized climate conditions within an urban area or neighborhood. 2. The ...
Microenvironmental Method: A method for sequentially assessing exposure for a series of microenvironment...
Microenvironments: Well-defined surroundings such as the home, office, or kitchen that can be tr...
Million-Gallons Per Day MGD: A measure of water flow.
Minimization: A comprehensive program to minimize or eliminate wastes, usually applied to w...
Mining of an Aquifer: Withdrawal over a period of time of ground water that exceeds the rate of rec...
Mining Waste: Residues resulting from the extraction of raw materials from the earth.
Minor Source: New emissions sources or modifications to existing emissions sources that do ...
Minors: Publicly owned treatment works with flows less than 1 million gallons per day.
Miscellaneous ACM: Interior asbestos-containing building material or structural components, memb...
Miscellaneous Materials: Interior building materials on structural components, such as floor or ceilin...
Miscible Liquids: Two or more liquids that can be mixed and will remain mixed under normal cond...
Missed Detection: The situation that occurs when a test indicates that a tank is "tight" when i...
Mist: Liquid particles measuring 40 to 500 micrometers (pm), are formed by condensa...
Mitigation: Measures taken to reduce adverse impacts on the environment.
Mixed Funding: Settlements in which potentially responsible parties and EPA share the cost o...
Mixed Glass: Recovered container glass not sorted into categories (e.g. color, grade).
Mixed Liquor: A mixture of activated sludge and water containing organic matter undergoing ...
Mixed Metals: Recovered metals not sorted into categories such as aluminum, tin, or steel c...
Mixed Municipal Waste: Solid waste that has not been sorted into specific categories (such as plasti...
Mixed Paper: Recovered paper not sorted into categories such as old magazines, old newspap...
Mixed Plastic: Recovered plastic unsorted by category.
Mobile Incinerator Systems: Hazardous waste incinerators that can be transported from one site to another.
Mobile Source: Any non-stationary source of air pollution such as cars, trucks, motorcycles,...
Model Plant: A hypothetical plant design used for developing economic, environmental, and ...
Modified Bin Method: Way of calculating the required heating or cooling for a building based on de...
Modified Source: The enlargement of a major stationary pollutant sources is often referred to ...
Moisture Content: 1.The amount of water lost from soil upon drying to a constant weight, expres...
Molecule: The smallest division of a compound that still retains or exhibits all the pr...
Molten Salt Reactor: A thermal treatment unit that rapidly heats waste in a heat-conducting fluid ...
Monitoring: Periodic or continuous surveillance or testing to determine the level of comp...
Monitoring Well: 1. A well used to obtain water quality samples or measure groundwater levels....
Monoclonal Antibodies: 1. Man-made (anthropogenic) clones of a molecule, produced in quantity for me...
Monomictic: Lakes and reservoirs which are relatively deep, do not freeze over during win...
Montreal Protocol: Treaty, signed in 1987, governs stratospheric ozone protection and research, ...
Moratorium: During the negotiation process, a period of 60 to 90 days during which EPA an...
Morbidity: Rate of disease incidence.
Most Probable Number: An estimate of microbial density per unit volume of water sample, based on pr...
Muck Soils: Earth made from decaying plant materials.
Mudballs: Round material that forms in filters and gradually increases in size when not...
Mulch: A layer of material (wood chips, straw, leaves, etc.) placed around plants to...
Multi-Media Approach: Joint approach to several environmental media, such as air, water, and land.
Multiple Chemical Sensitivity: A diagnostic label for people who suffer multi-system illnesses as a result o...
Multiple Use: Use of land for more than one purpose; e.g., grazing of livestock, watershed ...
Multistage Remote Sensing: A strategy for landscape characterization that involves gathering and analyzi...
Municipal Discharge: Discharge of effluent from waste water treatment plants which receive waste w...
Municipal Sewage: Wastes (mostly liquid) orginating from a community; may be composed of domest...
Municipal Sludge: Semi-liquid residue remaining from the treatment of municipal water and waste...
Municipal Solid Waste: Common garbage or trash generated by industries, businesses, institutions, an...
Mutagen: An agent that causes a permanent genetic change in a cell other than that whi...

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