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

Irrigation Efficiency
The amount of water stored in the crop root zone compared to the amount of irrigation water applied.

Irrigation Return Flow
Surface and subsurface water which leaves the field following application of irrigation water.

Irritant
A substance that can cause irritation of the skin, eyes, or respiratory system. Effects may be acute from a single high level exposure, or chronic from repeated low-level exposures to such compounds as chlorine, nitrogen dioxide, and nitric acid.

Isoconcentration
More than one sample point exhibiting the same isolate concentration.

Isopleth
The line or area represented by an isoconcentration.

Isotope
A variation of an element that has the same atomic number of protons but a different weight because of the number of neutrons. Various isotopes of the same element may have different radioactive behaviors, some are highly unstable..

Isotropy
The condition in which the hydraulic or other properties of an aquifer are the same in all directions.

Jar Test
A laboratory procedure that simulates a water treatment plant's coagulation/flocculation units with differing chemical doses, mix speeds, and settling times to estimate the minimum or ideal coagulant dose required to achieve certain water quality goals.

Karst
A geologic formation of irregular limestone deposits with sinks, underground streams, and caverns.

Kinetic Energy
Energy possessed by a moving object or water body.

Kinetic Rate Coefficient
A number that describes the rate at which a water constituent such as a biochemical oxygen demand or dissolved oxygen rises or falls, or at which an air pollutant reacts.

Laboratory Animal Studies
Investigations using animals as surrogates for humans.

Lagoon
1. A shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater; also used for storage of wastewater or spent nuclear fuel rods. 2. Shallow body of water, often separated from the sea by coral reefs or sandbars.

Land Application
Discharge of wastewater onto the ground for treatment or reuse. (See irrigation.)

Land Ban
Phasing out of land disposal of most untreated hazardous wastes, as mandated by the 1984 RCRA amendments.

Land Disposal Restrictions
Rules that require hazardous wastes to be treated before disposal on land to destroy or immobilize hazardous constituents that might migrate into soil and ground water.

Land Farming (of Waste)
A disposal process in which hazardous waste deposited on or in the soil is degraded naturally by microbes.

Landfills
1. Sanitary landfills are disposal sites for non-hazardous solid wastes spread in layers, compacted to the smallest practical volume, and covered by material applied at the end of each operating day. 2. Secure chemical landfills are disposal sites for hazardous waste, selected and designed to minimize the chance of release of hazardous substances into the environment.

Landscape
The traits, patterns, and structure of a specific geographic area, including its biological composition, its physical environment, and its anthropogenic or social patterns. An area where interacting ecosystems are grouped and repeated in similar form.

Landscape Characterization
Documentation of the traits and patterns of the essential elements of the landscape.

Landscape Ecology
The study of the distribution patterns of communities and ecosystems, the ecological processes that affect those patterns, and changes in pattern and process over time.

Landscape Indicator
A measurement of the landscape, calculated from mapped or remotely sensed data, used to describe spatial patterns of land use and land cover across a geographic area. Landscape indicators may be useful as measures of certain kinds of environmental degradation such as forest fragmentation.

Langelier Index (LI)
An index reflecting the equilibrium pH of a water with respect to calcium and alkalinity; used in stabilizing water to control both corrosion and scale deposition.

Large Quantity Generator
Person or facility generating more than 2200 pounds of hazardous waste per month. Such generators produce about 90 percent of the nation's hazardous waste, and are subject to all RCRA requirements.

Large Water System
A water system that services more than 50,000 customers.

Laser Induced Fluorescence
A method for measuring the relative amount of soil and/or groundwater with an in-situ sensor.

Latency
Time from the first exposure of a chemical until the appearance of a toxic effect.

Lateral Sewers
Pipes that run under city streets and receive the sewage from homes and businesses, as opposed to domestic feeders and main trunk lines.

Laundering Weir
Sedimention basin overflow weir.

LC 50-Lethal Concentration
Median level concentration, a standard measure of toxicity. It tells how much of a substance is needed to kill half of a group of experimental organisms in a given time. (See LD 50.)

LD 50- Lethal Dose
The dose of a toxicant or microbe that will kill 50 percent of the test organisms within a designated period. The lower the LD 50, the more toxic the compound.

Ldlo
Lethal dose low; the lowest dose in an animal study at which lethality occurs.

Leachate
Water that collects contaminants as it trickles through wastes, pesticides or fertilizers. Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil.

Leachate Collection System
A system that gathers leachate and pumps it to the surface for treatment.

Leaching
The process by which soluble constituents are dissolved and filtered through the soil by a percolating fluid. (See leachate.)

Lead (Pb)
A heavy metal that is hazardous to health if breathed or swallowed. Its use in gasoline, paints, and plumbing compounds has been sharply restricted or eliminated by federal laws and regulations. (See heavy metals.)

Lead Service Line
A service line made of lead which connects the water to the building inlet and any lead fitting connected to it.

Legionella
A genus of bacteria, some species of which have caused a type of pneumonia called Legionaires Disease.

Lethal Concentration 50
Also referred to as LC50, a concentration of a pollutant or effluent at which 50 percent of the test organisms die; a common measure of acute toxicity.

Lethal Dose 50
Also referred to as LD50, the dose of a toxicant that will kill 50 percent of test organisms within a designated period of time; the lower the LD 50, the more toxic the compound.

Level of Concern (LOC)
The concentration in air of an extremely hazardous substance above which there may be serious immediate health effects to anyone exposed to it for short periods

Life Cycle of a Product
All stages of a product's development, from extraction of fuel for power to production, marketing, use, and disposal.

Lifetime Average Daily Dose
Figure for estimating excess lifetime cancer risk.

Lifetime Exposure
Total amount of exposure to a substance that a human would receive in a lifetime (usually assumed to be 70 years).

Lift
In a sanitary landfill, a compacted layer of solid waste and the top layer of cover material.

Lifting Station
(See pumping station.)

Light-Emitting Diode
A long-lasting illumination technology used for exit signs which requires very little power

Limestone Scrubbing
Use of a limestone and water solution to remove gaseous stack-pipe sulfur before it reaches the atmosphere.

Limit of Detection (LOD)
The minimum concentration of a substance being analyzed test that has a 99 percent probability of being identified.

Limited Degradation
An environmental policy permitting some degradation of natural systems but terminating at a level well beneath an established health standard.

Limiting Factor
A condition whose absence or excessive concentration, is incompatible with the needs or tolerance of a species or population and which may have a negative influence on their ability to thrive.

Limnology
The study of the physical, chemical, hydrological, and biological aspects of fresh water bodies.

Lindane
A pesticide that causes adverse health effects in domestic water supplies and is toxic to freshwater fish and aquatic life.

Liner
1. A relatively impermeable barrier designed to keep leachate inside a landfill. Liner materials include plastic and dense clay. 2. An insert or sleeve for sewer pipes to prevent leakage or infiltration.

Lipid Solubility
The maximum concentration of a chemical that will dissolve in fatty substances. Lipid soluble substances are insoluble in water. They will very selectively disperse through the environment via uptake in living tissue.

Liquefaction
Changing a solid into a liquid.

Liquid Injection Incinerator
Commonly used system that relies on high pressure to prepare liquid wastes for incineration by breaking them up into tiny droplets to allow easier combustion.

List
Shorthand term for EPA list of violating facilities or firms debarred from obtaining government contracts because they violated certain sections of the Clean Air or Clean Water Acts. The list is maintained by The Office of Enforcement and Compliance Monitoring.

Listed Waste
Wastes listed as hazardous under RCRA but which have not been subjected to the Toxic Characteristics Listing Process because the dangers they present are considered self-evident.

Lithology
Mineralogy, grain size, texture, and other physical properties of granular soil, sediment, or rock.

Litter
1. The highly visible portion of solid waste carelessly discarded outside the regular garbage and trash collection and disposal system. 2. leaves and twigs fallen from forest trees.

Littoral Zone
1. That portion of a body of fresh water extending from the shoreline lakeward to the limit of occupancy of rooted plants. 2. A strip of land along the shoreline between the high and low water levels.

Local Education Agency (LEA)
In the asbestos program, an educational agency at the local level that exists primarily to operate schools or to contract for educational services, including primary and secondary public and private schools. A single, unaffiliated school can be considered an LEA for AHERA purposes.

Low Density Polyethylene (LOPE)
Plastic material used for both rigid containers and plastic film applications.

Low Emissivity (low-E) Windows
New window technology that lowers the amount of energy loss through windows by inhibiting the transmission of radiant heat while still allowing sufficient light to pass through.

Low NOx Burners
One of several combustion technologies used to reduce emissions of Nitrogen Oxides (NOx.)

Low-Level Radioactive Waste (LLRW)
Wastes less hazardous than most of those associated with a nuclear reactor; generated by hospitals, research laboratories, and certain industries. The Department of Energy, Nuclear Regulatory Commission, and EPA share responsibilities for managing them. (See high-level radioactive wastes.)

Lower Detection Limit
The smallest signal above background noise an instrument can reliably detect.

Lower Explosive Limit (LEL)
The concentration of a compound in air below which the mixture will not catch on fire.

Lowest Acceptable Daily Dose
The largest quantity of a chemical that will not cause a toxic effect, as determined by animal studies.

Lowest Achievable Emission Rate
Under the Clean Air Act, the rate of emissions that reflects (1) the most stringent emission limitation in the implementation plan of any state for such source unless the owner or operator demonstrates such limitations are not achievable; or (2) the most stringent emissions limitation achieved in practice, whichever is more stringent. A proposed new or modified source may not emit pollutants in excess of existing new source standards.

Macropores
Secondary soil features such as root holes or desiccation cracks that can create significant conduits for movement of NAPL and dissolved contaminants, or vapor-phase contaminants.

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 emissions with respect to Prevention of Significant Deterioration and New Source Review under the Clean Air Act.

Major Stationary Sources
Term used to determine the applicability of Prevention of Significant Deterioration and new source regulations. In a nonattainment area, any stationary pollutant source with potential to emit more than 100 tons per year is considered a major stationary source. In PSD areas the cutoff level may be either 100 or 250 tons, depending upon the source.

Majors
Larger publicly owned treatment works (POTWs) with flows equal to at least one million gallons per day (mgd) or servicing a population equivalent to 10,000 persons; certain other POTWs having significant water quality impacts. (See minors.)

Management Plan
Under the Asbestos Hazard Emergency Response Act (AHERA), a document that each Local Education Agency is required to prepare, describing all activities planned and undertaken by a school to comply with AHERA regulations, including building inspections to identify asbestos-containing materials, response actions, and operations and maintenance programs to minimize the risk of exposure.

Managerial Controls
Methods of nonpoint source pollution control based on decisions about managing agricultural wastes or application times or rates for agrochemicals.

Mandatory Recycling
Programs which by law require consumers to separate trash so that some or all recyclable materials are recovered for recycling rather than going to landfills.

Manifest
A one-page form used by haulers transporting waste that lists EPA identification numbers, type and quantity of waste, the generator it originated from, the transporter that shipped it, and the storage or disposal facility to which it is being shipped. It includes copies for all participants in the shipping process.

Manifest System
Tracking of hazardous waste from 'cradle-to-grave' (generation through disposal) with accompanying documents known as manifests.(See cradle to grave.)

Manual Separation
Hand sorting of recyclable or compostable materials in waste.

Manufacturer's Formulation
A list of substances or component parts as described by the maker of a coating, pesticide, or other product containing chemicals or other substances.

Manufacturing Use Product
Any product intended (labeled) for formulation or repackaging into other pesticide products.

Margin of Exposure (MOE)
The ratio of the no-observed adverse-effect-level to the estimated exposure dose.

Margin of Safety
Maximum amount of exposure producing no measurable effect in animals (or studied humans) divided by the actual amount of human exposure in a population.

Marine Sanitation Device
Any equipment or process installed on board a vessel to receive, retain, treat, or discharge sewage.

Marsh
A type of wetland that does not accumulate appreciable peat deposits and is dominated by herbaceous vegetation. Marshes may be either fresh or saltwater, tidal or non-tidal. (See wetlands.)

Material Category
In the asbestos program, broad classification of materials into thermal surfacing insulation, surfacing material, and miscellaneous material.

Material Safety Data Sheet (MSDS)
A compilation of information required under the OSHA Communication Standard on the identity of hazardous chemicals, health, and physical hazards, exposure limits, and precautions. Section 311 of SARA requires facilities to submit MSDSs under certain circumstances.

Material Type
Classification of suspect material by its specific use or application; e.g., pipe insulation, fireproofing, and floor tile.

Materials Recovery Facility (MRF)
A facility that processes residentially collected mixed recyclables into new products available for market.

Maximum Contaminant Level
The maximum permissible level of a contaminant in water delivered to any user of a public system. MCLs are enforceable standards.

Maximum Exposure Range
Estimate of exposure or dose level received by an individual in a defined population that is greater than the 98th percentile dose for all individuals in that population, but less than the exposure level received by the person receiving the highest exposure level.

Maximum Residue Level
Comparable to a U.S. tolerance level, the Maximum Residue Level the enforceable limit on food pesticide levels in some countries. Levels are set by the Codex Alimentarius Commission, a United Nations agency managed and funded jointly by the World Health Organization and the Food and Agriculture Organization.

Maximum Tolerated Dose
The maximum dose that an animal species can tolerate for a major portion of its lifetime without significant impairment or toxic effect other than carcinogenicity.

Measure of Exposure
A measurable characteristic of a stressor (such as the specific amount of mercury in a body of water) used to help quantify the exposure of an ecological entity or individual organism.

Mechanical Aeration
Use of mechanical energy to inject air into water to cause a waste stream to absorb oxygen.

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 nonthermal, processes.