Copy of `EPA - Environmental Terms Glossary`

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EPA - Environmental Terms Glossary Category: Earth and Environment Date & country: 13/09/2007, USA Words: 1829

Media
Specific environments--air, water, soil--which are the subject of regulatory concern and activities.

Medical Surveillance
A periodic comprehensive review of a worker's health status; acceptable elements of such surveillance program are listed in the Occupational Safety and Health Administration standards for asbestos.

Medical Waste
Any solid waste generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biologicals, excluding hazardous waste identified or listed under 40 CFR Part 261 or any household waste as defined in 40 CFR Sub-section 261.4 (b)(1).

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 (Hg)
Heavy metal that can accumulate in the environment and is highly toxic if breathed or swallowed. (See:heavy metals.)

Mesotrophic
Reservoirs and lakes which contain moderate quantities of nutrients and are moderately productive in terms of aquatic animal and plant life.

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 there is a rapid decrease in temperature with depth. Also called thermocline.

Methane
A colorless, nonpoisonous, flammable gas created by anaerobic decomposition of organic compounds. A major component of natural gas used in the home.

Methanol
An alcohol that can be used as an alternative fuel or as a gasoline additive. It is less volatile than gasoline; when blended with gasoline it lowers the carbon monoxide emissions but increases hydrocarbon emissions. Used as pure fuel, its emissions are less ozone-forming than those from gasoline. Poisonous to humans and animals if ingested.

Method 18
An EPA test method which uses gas chromatographic techniques to measure the concentration of volatile organic compounds in a gas stream.

Method 24
An EPA reference method to determine density, water content and total volatile content (water and VOC) of coatings.

Method 25
An EPA reference method to determine the VOC concentration in a gas stream.

Method Detection Limit (MDL)
See limit of detection.

Methoxychlor
Pesticide that causes adverse health effects in domestic water supplies and is toxic to freshwater and marine aquatic life.

Methyl Orange Alkalinity
A measure of the total alkalinity in a water sample in which the color of methyl orange reflects the change in level.

Microbial Growth
The amplification or multiplication of microorganisms such as bacteria, algae, diatoms, plankton, and fungi.

Microbial Pesticide
A microorganism that is used to kill a pest, but is of minimum toxicity to humans.

Microclimate
1. Localized climate conditions within an urban area or neighborhood. 2. The climate around a tree or shrub or a stand of trees.

Microenvironmental Method
A method for sequentially assessing exposure for a series of microenvironments that can be approximated by constant concentrations of a stressor.

Microenvironments
Well-defined surroundings such as the home, office, or kitchen that can be treated as uniform in terms of stressor concentration.

Million-Gallons Per Day (MGD)
A measure of water flow.

Minimization
A comprehensive program to minimize or eliminate wastes, usually applied to wastes at their point of origin. (See waste minimization.)

Mining of an Aquifer
Withdrawal over a period of time of ground water that exceeds the rate of recharge of the aquifer.

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 not exceed NAAQS emission levels.

Minors
Publicly owned treatment works with flows less than 1 million gallons per day. (See majors.)

Miscellaneous ACM
Interior asbestos-containing building material or structural components, members or fixtures, such as floor and ceiling tiles; does not include surfacing materials or thermal system insulation.

Miscellaneous Materials
Interior building materials on structural components, such as floor or ceiling tiles.

Miscible Liquids
Two or more liquids that can be mixed and will remain mixed under normal conditions.

Missed Detection
The situation that occurs when a test indicates that a tank is 'tight' when in fact it is leaking.

Mist
Liquid particles measuring 40 to 500 micrometers (pm), are formed by condensation of vapor. By comparison, fog particles are smaller than 40 micrometers (pm).

Mitigation
Measures taken to reduce adverse impacts on the environment.

Mixed Funding
Settlements in which potentially responsible parties and EPA share the cost of a response action.

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 activated sludge treatment in an aeration tank.

Mixed Metals
Recovered metals not sorted into categories such as aluminum, tin, or steel cans or ferrous or non-ferrous metals.

Mixed Municipal Waste
Solid waste that has not been sorted into specific categories (such as plastic, glass, yard trimmings, etc.)

Mixed Paper
Recovered paper not sorted into categories such as old magazines, old newspapers, old corrugated boxes, etc.

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, buses, airplanes, and locomotives.

Model Plant
A hypothetical plant design used for developing economic, environmental, and energy impact analyses as support for regulations or regulatory guidelines; first step in exploring the economic impact of a potential NSPS.

Modified Bin Method
Way of calculating the required heating or cooling for a building based on determining how much energy the system would use if outdoor temperatures were within a certain temperature interval and then multiplying the energy use by the time the temperature interval typically occurs.

Modified Source
The enlargement of a major stationary pollutant sources is often referred to as modification, implying that more emissions will occur.

Moisture Content
1.The amount of water lost from soil upon drying to a constant weight, expressed as the weight per unit of dry soil or as the volume of water per unit bulk volume of the soil. For a fully saturated medium, moisture content indicates the porosity. 2. Water equivalent of snow on the ground; an indicator of snowmelt flood potential.

Molecule
The smallest division of a compound that still retains or exhibits all the properties of the substance.

Molten Salt Reactor
A thermal treatment unit that rapidly heats waste in a heat-conducting fluid bath of carbonate salt.

Monitoring
Periodic or continuous surveillance or testing to determine the level of compliance with statutory requirements and/or pollutant levels in various media or in humans, plants, and animals.

Monitoring Well
1. A well used to obtain water quality samples or measure groundwater levels. 2. A well drilled at a hazardous waste management facility or Superfund site to collect ground-water samples for the purpose of physical, chemical, or biological analysis to determine the amounts, types, and distribution of contaminants in the groundwater beneath the site.

Monomictic
Lakes and reservoirs which are relatively deep, do not freeze over during winter, and undergo a single stratification and mixing cycle during the year (usually in the fall).

Montreal Protocol
Treaty, signed in 1987, governs stratospheric ozone protection and research, and the production and use of ozone-depleting substances. It provides for the end of production of ozone-depleting substances such as CFCS. Under the Protocol, various research groups continue to assess the ozone layer. The Multilateral Fund provides resources to developing nations to promote the transition to ozone-safe technologies.

Moratorium
During the negotiation process, a period of 60 to 90 days during which EPA and potentially responsible parties may reach settlement but no site response activities can be conducted.

Morbidity
Rate of disease incidence.

Mortality
Death rate.

Most Probable Number
An estimate of microbial density per unit volume of water sample, based on probability theory.

Muck Soils
Earth made from decaying plant materials.

Mudballs
Round material that forms in filters and gradually increases in size when not removed by backwashing.

Mulch
A layer of material (wood chips, straw, leaves, etc.) placed around plants to hold moisture, prevent weed growth, and enrich or sterilize the soil.

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 of contact with, or proximity to, a variety of airborne agents and other substances.

Multiple Use
Use of land for more than one purpose; e.g., grazing of livestock, watershed and wildlife protection, recreation, and timber production. Also applies to use of bodies of water for recreational purposes, fishing, and water supply.

Multistage Remote Sensing
A strategy for landscape characterization that involves gathering and analyzing information at several geographic scales, ranging from generalized levels of detail at the national level through high levels of detail at the local scale.

Municipal Discharge
Discharge of effluent from waste water treatment plants which receive waste water from households, commercial establishments, and industries in the coastal drainage basin. Combined sewer/separate storm overflows are included in this category.

Municipal Sewage
Wastes (mostly liquid) orginating from a community; may be composed of domestic wastewaters and/or industrial discharges.

Municipal Sludge
Semi-liquid residue remaining from the treatment of municipal water and wastewater.

Municipal Solid Waste
Common garbage or trash generated by industries, businesses, institutions, and homes.

Mutagen-Mutagenicity
An agent that causes a permanent genetic change in a cell other than that which occurs during normal growth. Mutagenicity is the capacity of a chemical or physical agent to cause such permanent changes.

National Estuary Program
A program established under the Clean Water Act Amendments of 1987 to develop and implement conservation and management plans for protecting estuaries and restoring and maintaining their chemical, physical, and biological integrity, as well as controlling point and nonpoint pollution sources.

National Municipal Plan
A policy created in 1984 by EPA and the states in 1984 to bring all publicly owned treatment works (POTWs) into compliance with Clean Water Act requirements.

National Priorities List (NPL)
EPA's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund. The list is based primarily on the score a site receives from the Hazard Ranking System. EPA is required to update the NPL at least once a year. A site must be on the NPL to receive money from the Trust Fund for remedial action.

National Response Center
The federal operations center that receives notifications of all releases of oil and hazardous substances into the environment; open 24 hours a day, is operated by the U.S. Coast Guard, which evaluates all reports and notifies the appropriate agency.

National Response Team (NRT)
Representatives of 13 federal agencies that, as a team, coordinate federal responses to nationally significant incidents of pollution--an oil spill, a major chemical release, or a - superfund response action--and provide advice and technical assistance to the responding agency(ies) before and during a response action.

Navigable Waters
Traditionally, waters sufficiently deep and wide for navigation by all, or specified vessels; such waters in the United States come under federal jurisdiction and are protected by certain provisions of the Clean Water Act.

Necrosis
Death of plant or animal cells or tissues. In plants, necrosis can discolor stems or leaves or kill a plant entirely.

Negotiations (Under Superfund)
After potentially responsible parties are identified for a site, EPA coordinates with them to reach a settlement that will result in the PRP paying for or conducting the cleanup under EPA supervision. If negotiations fail, EPA can order the PRP to conduct the cleanup or EPA can pay for the cleanup using Superfund monies and then sue to recover the costs.

Nematocide
A chemical agent which is destructive to nematodes.

Nephelometric
Method of of measuring turbidity in a water sample by passing light through the sample and measuring the amount of the light that is deflected.

Netting
A concept in which all emissions sources in the same area that owned or controlled by a single company are treated as one large source, thereby allowing flexibility in controlling individual sources in order to meet a single emissions standard. (See bubble.)

Neutralization
Decreasing the acidity or alkalinity of a substance by adding alkaline or acidic materials, respectively.

New Source
Any stationary source built or modified after publication of final or proposed regulations that prescribe a given standard of performance.

New Source Review (NSR)
A Clean Air Act requirement that State Implementation Plans must include a permit review that applies to the construction and operation of new and modified stationary sources in nonattainment areas to ensure attainment of national ambient air quality standards.

Nitrate
A compound containing nitrogen that can exist in the atmosphere or as a dissolved gas in water and which can have harmful effects on humans and animals. Nitrates in water can cause severe illness in infants and domestic animals. A plant nutrient and inorganic fertilizer, nitrate is found in septic systems, animal feed lots, agricultural fertilizers, manure, industrial waste waters, sanitary landfills, and garbage dumps.

Nitric Oxide (NO)
A gas formed by combustion under high temperature and high pressure in an internal combustion engine; it is converted by sunlight and photochemical processes in ambient air to nitrogen oxide. NO is a precursor of ground-level ozone pollution, or smog..

Nitrification
The process whereby ammonia in wastewater is oxidized to nitrite and then to nitrate by bacterial or chemical reactions.

Nitrilotriacetic Acid (NTA)
A compound now replacing phosphates in detergents.

Nitrite
1. An intermediate in the process of nitrification. 2. Nitrous oxide salts used in food preservation.

Nitrogen Dioxide (NO2)
The result of nitric oxide combining with oxygen in the atmosphere; major component of photochemical smog.

Nitrogen Oxide (NOx)
The result of photochemical reactions of nitric oxide in ambient air; major component of photochemical smog. Product of combustion from transportation and stationary sources and a major contributor to the formation of ozone in the troposphere and to acid deposition.

Nitrogenous Wastes
Animal or vegetable residues that contain significant amounts of nitrogen.

Nitrophenols
Synthetic organopesticides containing carbon, hydrogen, nitrogen, and oxygen.

No Further Remedial Action Planned
Determination made by EPA following a preliminary assessment that a site does not pose a significant risk and so requires no further activity under CERCLA.

No Till
Planting crops without prior seedbed preparation, into an existing cover crop, sod, or crop residues, and eliminating subsequent tillage operations.

No-Observed-Effect-Level (NOEL)
Exposure level at which there are no statistically or biological significant differences in the frequency or severity of any effect in the exposed or control populations.

Noble Metal
Chemically inactive metal such as gold; does not corrode easily.

Noise
Product-level or product-volume changes occurring during a test that are not related to a leak but may be mistaken for one.

Non-Aqueous Phase Liquid (NAPL)
Contaminants that remain undiluted as the original bulk liquid in the subsurface, e.g. spilled oil. (See fee product.)

Non-Attainment Area
Area that does not meet one or more of the National Ambient Air Quality Standards for the criteria pollutants designated in the Clean Air Act.

Non-Community Water System
A public water system that is not a community water system; e.g. the water supply at a camp site or national park.