Environment terminology · MLC-0121

Environment terms: O (831)

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• Ordinal dataIntegers designating the rank, order, or counts.
• Ordinal scaleMeasurement scale consisting of qualitative categories whose values have a distinct order but no numerical...
• Ordinal scale dataData classified into exhaustive, mutually exclusive, and ordered or ranked categories.
• Ordinal variableA quantitative variable whose attributes are ordered but for which the numerical differences between adjacent...
• Ordinary high water mark1. Line on the shore established by the fluctuations of water and indicated by physical characteristics such...
• Ordinary olefinic groupUnconjugated olefinic groups that are not specifically activated either by being part of a larger functional...
• OrdinationA general class of multivariate statistical procedures used to create categories (or groups) of similar...
• Ore1. The naturally occurring material from which a mineral or minerals of economic value can be extracted...
• Ore deposit1. Designates a natural occurrence of an ore in sufficient extent and degree of concentration to invite...
• Ore dry grindingProcess in which the gold ore is ground and heated (dried) prior to additional preheating or prior to...
• Ore mill1. Includes any ore mill, sampling works, concentration, and any crushing, grinding, or screening plant used...
• Ore preheatingProcess in which ground gold ore is preheated prior to entering the roaster.
• Ore pretreatment processAffected source that includes roasting operations and autoclaves that are used to pre-treat gold mine ore at...
• Oregon closed basinsThe drainage of the Great Basin that discharges into the state of Oregon. California, Nevada, Oregon. Area =...
• Oregon-Washington coastalThe drainage into the drainage boundary to the Smith River Basin boundary, excluding the Columbia River...
• OrganelleAn organelle is a subcellular structure that has one or more specific jobs to perform in the cell, much like...
• Organic1. 1. Referring to or derived from living organisms.
• Organic active ingredientCarbon-containing active ingredients used in pesticides, excluding metalloorganic active ingredients.
• Organic agricultureA concept and practice of agricultural production that focuses on production without the use of synthetic...
• Organic analysisChemical analysis of organic, i.e. carbon-chain containing, compounds.
• Organic carbon/water partition coefficient (K(oc))Ratio of chemical sorbed to organic carbon (component of suspended particles and sediment) to the chemical...
• Organic chemicalAnimal or plant-produced substances containing mainly carbon, hydrogen, nitrogen, and oxygen.
• Organic chemical or compoundAn organic chemical or compound is a substance produced by animals or plants that contains mainly carbon...
• Organic Chemicals/Compounds1. Animal or plant-produced substances containing mainly carbon, hydrogen, nitrogen, and oxygen.
• Organic coating1. Any coating used in a surface coating operation, including dilution solvents, from which volatile organic...
• Organic compound1. Molecule that contains atoms of the element carbon, usually combined with itself and with atoms of one or...
• Organic compounds, see Organic compound
• Organic constituent wet air pollution controlUsing water to remove organic constituents that are entrained in air streams exhausted from process tanks or...
• Organic contaminant1. Carbon-based chemical, such as solvents and pesticides, which can get into water through runoff from...
• Organic contaminants, see Organic contaminant
• Organic debrisParticles of vegetation or other biological material that can degrade water quality by decreasing dissolved...
• Organic enrichment pollutant categoryAll biochemical oxygen demand (BOD) and chemical oxygen demand (COD) pollutant parameters. Section 3.3.2 of...
• Organic fertilizerOrganic material such as manure or compost, applied to cropland as a source of plant nutrients.
• Organic groundwater contaminationGroundwater contamination with organic chemicals
• Organic groupStructures that contain primarily carbon, hydrogen, and oxygen atoms.
• Organic hazardous air pollutant1. HAP listed in section 112(b) of the CAA that are measured according to the procedures of Method 18 or...
• Organic hazardous air pollutant content1. Mass of organic HAP per mass of coating material.
• Organic hazardous air pollutant mass fractionRatio of the mass of organic HAP to the mass of a material in which it is contained, expressed as kg of...
• Organic hazardous air pollutant overall control efficiencyTotal efficiency of a control system, determined either by:(1) The product of the capture efficiency as...
• Organic hazardous air pollutant solventHAP that is a volatile organic liquid used for dissolving or dispersing constituents in a coating or contact...
• Organic liquid1. (1) Any non-crude oil liquid or liquid mixture that contains 5 percent by weight or greater of the organic...
• Organic liquids distribution operationCombination of activities and equipment used to store or transfer organic liquids into, out of, or within a...
• Organic litterMaterial derived from living plant organisms, such as leaves and branches.
• Organic manganese compoundsCommon organic manganese compounds include pesticides, such as maneb or mancozeb, and methylcyclopentadienyl...
• Organic materialSubstances containing plant or animal substance. In the context of milking equipment this usually refers to...
• Organic material decaySource of most of the methane gas in the atmosphere
• Organic matter1. The organic fraction that includes plant and animal residue at various stages of decomposition, cells and...
• Organic monitoring device1. Instrument used to indicate the concentration level of organic compounds exiting a control device based on...
• Organic peroxidesOrganic compounds containing the bivalent -o-o-structure which may be considered to be a structural...
• Organic pesticide chemicalSum of all organic active ingredients listed in § 455.20(b) which are manufactured at a facility subject to...
• Organic pesticide chemical sumSum of all organic active ingredients listed in § 455.20(b) which are manufactured at a facility subject to...
• Organic removal deviceDevices such as decanters, strippers, or thin-film evaporation units.
• Organic soilSoil at least partly derived from living matter, such as decayed plant material.
• Organic soil contaminationIntroduction into soil of organic chemicals in a concentration that makes the medium unfit for its next...
• Organic solvent-based green tire sprayAny mold release agent and lubricant applied to the inside or outside of green tires that contains more than...
• Organic turf managementTurf managed without the use of inorganic fertilizers or pesticides.
• Organic wasteWastes and/or used materials that contain organic pollutants, but not a significant quantity of oil and...
• Organic waste applicationUse of organic material designated as waste material to enhance something, such as provide added nutrients to...
• Organic zinc specialty coatingAny coating derived from zinc dust incorporated into an organic binder that contains more than 960 grams of...
• Organically grownFood, feed crops, and livestock grown within an intentionally-diversified, self-sustaining agro-ecosystem. In...
• Organics1. A term used to refer to chemical compounds made from carbon molecules. These compounds may be natural...
• Organic-water separator1. Waste management unit, generally a tank used to separate oil or organics from water. An oil-water or...
• Organism1. Any living being, whether plant, mammal, bird, insect, reptile, fish, crustacean, aquatic or estuarine...
• Organism developmentProcesses that involve and promote formation of more mature organs, organ systems, or organisms; general...
• Organization1. The owner of the station, sample, and result information.
• Organization & position managementOrganization and Position Management designs, develops, and implements organizational and position structures...
• Organization administratorsOrganization administrators control access rights to ECMS for each organization by maintaining organizational...
• Organization codeThe eight digit code identifying the organization responsible for the data. It identifies the owner of the...
• Organization ID (Name)A unique identifier assigned to the Organization.
• Organization nameName identifying the organization responsible for the data. It identifies the owner of the data and is used...
• OrganolepticAffecting or involving a sense organ such as that of taste, smell, or sight.
• Organonitrogen herbicideA group of herbicides consisting of a nitrogen ring with associated functional groups and including such...
• Organophosphate insecticideA class of insecticides derived from phosphoric acid. They tend to have high acute toxicity to vertebrates...
• Organophosphate pesticideOrganic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is...
• Organophosphate pesticide exposureExposure to organophosphates used as pesticides
• Organophosphate pesticidesA group of approximately 40 closely related pesticides that affect functioning of the nervous system...
• OrganophosphatesPesticides that contain phosphorus; short-lived, but some can be toxic when first applied.
• OrganophyllicA substance that easily combines with organic compounds.
• OrganotinsChemical compounds used in anti-foulant paints to protect the hulls of boats and ships, buoys, and pilings...
• Oriented strandboardComposite panel produced from thin wood strands cut from whole logs, formed into resinated layers (with the...
• Orifice(OR-uh-fiss) An opening (hole) in a plate, wall or partition. An orifice flange or plate placed in a pipe...
• Orifice meterUsed for measuring flow rate in a pipe; it measures the pressure decrease across its hole to determine how...
• Orifice plateA flow measurement device for liquids or gases that uses a restrictive orifice plate consisting of a machined...
• Origanum spp.Marjoram (Origanum spp.); Marjoram, pot (Origanum onites L.); Marjoram, sweet (Origanum majorana L.); Oregano...
• Origin and authorityTitle V permits must specify the origin and authority for each term or condition. This consists of a citation...
• Original AHERA Inspection/Original Inspection/InspectionExamination of school buildings arranged by Local Education Agencies to identify...
• Original cost1. The amount paid for the initial purchase of an asset.
• Original data submitterPerson who possesses all rights to exclusive use or compensation under FIFRA section 3(c)(1)(F) in a study...
• Original engine configurationEngine configuration at time of initial sale.
• Original engine manufacturer1. Entity which originally manufactured the nonroad engine.
• Original equipment manufacturer1. The manufacturer that originally produced the vehicle or heavy-duty engine (e.g., Ford, Mercedes Benz...
• Original equipment manufacturer product (fiberglass)Bonded wool fiberglass insulation manufactured for OEM entities that fabricate the insulation into parts used...
• Original equipment partPart present in or on an engine at the time an urban bus is originally sold to the ultimate purchaser.
• Original generation pointWhere regulated medical or other material first becomes waste.
• Original industriesThose industries which were required to report to TRI beginning in reporting year 1988, SIC codes 20 through...
• Original locomotive manufacture1. Event of freshly manufacturing a locomotive or locomotive engine. The date of original manufacture is the...
• Original locomotive remanufacture1. First remanufacturing of a locomotive or locomotive engine at which the locomotive or locomotive engines...
• Original model yearModel year in which a vehicle/engine was originally certified by the original equipment manufacturer, as...
• Original production years oldA vehicle's age, determined by subtracting the calendar year in which it was originally manufactured from the...
• ORIS codeA plant identification number assigned by the Energy Information Administration (EIA) that is used to...
• ORISPL codeA plant identification number assigned by the Energy Information Administration (EIA) that is used to...
• Ornamental plant1. Trees, shrubs, and other plantings in and around habitations generally, but not necessarily located in...
• OrnithineNaturally occurring amino acid found in meat, fish, dairy and eggs. Ornithine is one of the key reactants in...
• Orographic effect(Effect) related to, or caused by, physical geography (such as mountains or sloping terrain).
• OrographyBranch of physical geography that deals with mountains.
• Oropharynx1. The part of the pharynx between the soft palate and the upper portion of the epiglottis.
• Orphan landDisturbed land surfaces resulting from surface mining that were inadequately reclaimed by the operator and...
• Orphan radioactive sourceFound or abandoned radioactive sources are described as "orphan" when their identifying marks have been...
• Orphan shareThe financial responsibility assigned to a potentially responsible party (PRP) who is insolvent or defunct...
• OrthophotoA corrected and standardized aerial photo; generally at a scale of 1:24,000.
• Orthotolidine(or-tho-TOL-uh-dine) Orthotolidine is a calorimetric indicator of chlorine residual. If chlorine is present...
• OrtsteinOrtstein is a cemented horizon that consists of spodic materials.
• Oryctolagus cuniculusEuropean Rabbit
• Oryza spp.Rice is produced worldwide and is the primary staple for more than half the world's population.
• Oryzias latipesJapanese Medaka (fish)
• Oscillating hydrofoilSimilar to an airplane wing but in water; yaw control systems adjusts their angle relative to the water...
• Oscillating water columnPartially submerged structure that encloses a column of air above a column of water; a collector funnels...
• Oscillating wave surge converterAny of several devices that capture wave energy directly without a collector by using relative motion between...
• OscillationShift in position of various high and low pressure systems that in climate terms is usually defined as an...
• Osmosis1. The passage of a liquid from a weak solution to a more concentrated solution across a semipermeable...
• Osmotic activityOsmotic Activity is a passive process in which water diffuses across a cell membrane in response to a...
• OssificationThe formation of bone or of a bony substance; the conversion of fibrous tissue or of cartilage into bone or a...
• OsteichthyesBony fishes
• Osteoporosis1. Severe loss of bone mass, density, and strength. Although usually an age-related disorder, osteoporosis...
• Osteoporosis agentMedications used to either prevent or treat osteoporosis.
• OsteosclerosisHardening or abnormal density of bone
• OtherFlows such as water properties such as biological oxygen demand, chemical oxygen demand or total organic...
• Other centralized non-potable reuseThe use of recycled water for non-potable applications other than landscape and agriculture where the source...
• Other cleanup activityOCA sites are sites that have completed the Superfund remedial assessment process (site assessment process)...
• Other cleanup activity siteOCA sites are sites that have completed the Superfund remedial assessment process (site assessment process)...
• Other coatingCoating steel products with metals other than zinc or terne metal by the hot dip process including the...
• Other containerOpen or closed receptacle. This includes, but is not limited to, a bucket, a box, a carton, and a vehicle or...
• Other disposalIncludes any amount of an EPCRA Section 313 chemical released to land that does not fit the categories of...
• Other ferrous metalFerrous metals from strapping, furniture, and metal found in tires and consumer electronics. Excludes the...
• Other ferrous metals, see Other ferrous metal
• Other gas 1 fuelGaseous fuel that is not natural gas or refinery gas and does not exceed a maximum mercury concentration of...
• Other glass1. Refers to glass from furniture, appliances, and consumer electronics. Excludes glass from transportation...
• Other habitatThis includes other habitats not listed here such as chaparral, bogs, kelp beds, or estuarine shoreline.
• Other identifierAlternative code identifying the TMDL Report (an example could be a state assigned identifier that is...
• Other lead-emitting operationAny lead-acid battery manufacturing plant operation from which lead emissions are collected and ducted to the...
• Other metalsA metal is an element characterized by a tendency to give up electrons and by good thermal and electrical...
• Other motor vehicleSelf-propelled vehicle designed for transporting persons or property on a street or highway that has a gross...
• Other motor vehicle assembly plantFacility which assembles other motor vehicles, including coating facilities and processes.
• Other non-distribution system plumbing problemA coliform contamination problem in a public water system with more than one service connection that is...
• Other nonferrous foundryFacility that melts nonferrous metals other than aluminum, copper, or copper-based alloys and pours the...
• Other nonferrous foundry hazardous air pollutantAny compound of the following metals: chromium, lead, and nickel, or any of these metals in the elemental...
• Other nonferrous metalNonferrous metals (lead, copper, and zinc) from appliances, consumer electronics, and nonpackaging aluminum...
• Other nonferrous metals, see Other nonferrous metal
• Other oilOils with a boiling range equal to or greater than 401 °F that are generally intended for use as a...
• Other Pacific IslanderA person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands. It...
• Other paper1. Refers to paper from books, third class mail, other commercial printing, paper towels, paper plates and...
• Other pesticide chemicalsChemicals registered as pesticides but which are produced and marketed mostly for other purposes, i.e...
• Other plastic1. Refers to plastic from appliances, furniture, trash bags, cups, eating utensils, sporting and recreational...
• Other plasticsRecyclable plastic from appliances, eating utensils, plates, containers, toys, and various kinds of...
• Other pressLithographic press, letterpress press, or screen printing press that does not meet the definition of...
• Other Process/Wastestream DetailsThe Other Process/Wastestream Detail(s) help identify the specific wastestream or process operation to which...
• Other reactant1. Molecule linked to one or more sequences of monomer units but which, under the relevant reaction...
• Other recyclablesRefers to household hazardous waste, oil filters, fluorescent tubes, mattresses, consumer electronics...
• Other regulated materialUntil December 31, 2020 and for the purposes of this subchapter, “ORM-D material” means a material such as a...
• Other requirementMandatory or voluntary codes of conduct and performance standards, either externally or internally created...
• Other restricted accessAreas other than electrical substations that are at least 0.1 kilometer (km) from a residential/commercial...
• Other sensitive ground water areaStates may also identify other areas in the State in addition to ground water protection areas that are...
• Other significant evidenceFactually significant information that relates to the uses of the pesticide and its adverse risk to man or to...
• Other solid waste1. Refers to nonhazardous solid wastes, other than municipal solid waste, covered under Subtitle D of the...
• Other urban or built up landTypically consists of uses such as golf driving ranges, zoos, urban parks, cemeteries, waste dumps...
• Other useIf a waterbody has been assessed for “other” this means it fits into another category other than swimming...
• Other wastewater treatmentWastewater treatment technology that is either not captured by other technology codes or is unspecified.
• Other water quality parameters evaluatedWater quality parameters that are meeting state or tribal specific water quality standards and/or thresholds...
• Other wood1. Refers to wood from furniture, cabinets from consumer electronics, and other nonpackaging wood products...
• Other-lead completeCleanup has been completed by a lead other than Fund-lead, FF-lead, PRP lead, or mixed lead.
• Other-lead underwayCleanup has been begun by a lead other than Fund-lead, FF-lead, PRP lead, or mixed lead.
• Otherwise toxic chemical useAny use of a toxic chemical, including a toxic chemical contained in a mixture or other trade name product or...
• Otherwise use1. Any use of a toxic chemical, including a toxic chemical contained in a mixture or other trade name product...
• Otherwise use as a chemical processing aidAn EPCRA Section 313 chemical that is added to a reaction mixture to aid in the manufacture or synthesis of...
• Otherwise use as a manufacturing aidAn EPCRA Section 313 chemical that aids the manufacturing process but does not become part of the resulting...
• Otherwise use for ancillary or other useAn EPCRA Section 313 chemical that is used at a facility for purposes other than aiding chemical processing...
• Otto-cycle engineType of engine with operating characteristics significantly similar to the theoretical Otto combustion cycle...
• Outboard engine1. Assembly of a spark-ignition engine and drive unit used to propel a vessel from a properly mounted...
• Outbreak1. Synonymous with epidemic. Sometimes the preferred word, as it may escape sensationalism associated with...
• Outbreak dataCDC data on foodborne disease outbreaks define an outbreak as an incident in which two or more persons...
• Outbreak, foodborneAn incident in which two or more cases of a similar illness result from eating the same food.
• Outbreeding depressionThe deterioration in a population's fitness or other traits due to immigration of individuals from other...
• Outcome1. Changes or benefits resulting from activities and outputs. Short-term outcomes produce changes in...
• Outcome evaluation1. This form of evaluation assesses the extent to which a program achieves its outcome-oriented objectives...
• OutcropA term used in connection with a vein or lode as an essential part of the definition of apex. It does not...
• Outdoor1. The air outside of buildings, from ground level to several miles above the Earth's surface.
• Outdoor activityEvents taking place out-of-doors.
• Outdoor air1. Air taken from the external atmosphere and, therefore, not previously circulated through the system.
• Outdoor air qualityRefers to how outdoor air quality will be impacted by climate change.
• Outdoor air supply1. Air brought into a building from outside.
• Outdoor decontaminationRemoval of harmful substances such as noxious chemicals, harmful bacteria or other organisms, or radioactive...
• Outdoor electrical substationOutdoor, fenced-off, and restricted access areas used in the transmission and/or distribution of electrical...
• Outdoor pesticide useAny pesticide application that occurs outside enclosed manmade structures or the consequences of which extend...
• Outdoor recreationRecreation that takes place outside, such as skiing, hiking, bicycling and camping.
• Outdoor settled dustParticles that have settled onto outdoor objects and surfaces due to either wet or dry deposition.
• Outdoor useAny pesticide application that occurs outside enclosed manmade structures or the consequences of which extend...
• Outdoor wood fired hydronic heaterFuel burning device located outside of a building designed to burn wood or wood pellet fuel for the purpose...
• Outdoor workerIndividual whose employment requires that person to be out of doors for the majority of working hours.
• Outer Continental Shelf1. All submerged lands lying seaward and outside of the area of lands beneath navigable waters as defined in...
• Outer Continental Shelf sourceAny equipment, activity, or facility which:(1) Emits or has the potential to emit any air pollutant;(2) Is...
• Outfall1. The point where water flows from a conduit, stream, or drain.
• Outfall pipeOutfalls are pipelines or tunnels that discharge municipal or industrial wastewater, storm water, combined...
• Outfall/IntakeOutfalls are pipelines or tunnels that discharge municipal or industrial wastewater, storm water, combined...
• OutlayCharge made to the project or program that is an allowable cost in terms of costs incurred or in-kind...
• OUTLAYSCharges made to the project or program. They may be reported on a cash or accrual basis. For reports prepared...
• Outlier1. Instances that are aberrant or do not fit with other instances: instances that, compared to other members...
• Out-of-kind resourceResource of a different structural and functional type from the impacted resource.
• Output1. Product or service delivery/implementation targets you aim to produce.
• Output formatReports can be created in three different formats depending on the user's choice. HTML: This type of report...
• Output recordsIn electronic records, information generated by a computer and placed on an outside medium, such as paper...
• Output-based environmental regulationOutput-based environmental regulations (OBR) relate emissions to the productive output of a process...
• Output-based environmental regulations, see Output-based environmental regulation
• Outreach and Information DivisionOutreach and Information Division (of EPA's Office of Air, OAQPS, located in RTP, NC).
• Outreach and Special Projects StaffSee http://www.epa.gov/oswer/comments.htm. The Outreach and Special Projects Staff (OSPS) serves to...
• Outreach/Communication/EducationHow climate change related issues are communicated to the public in an effort to create a widespread...
• Outside coilThe heat-transfer (exchanger) component of a heat pump, located outdoors, from which heat is collected in the...
• Outside evaluatorAn evaluator not affiliated with the agency prior to the program evaluation.
• Outslope1. The face of the spoil or embankment sloping downward from the highest elevation to the toe.
• Outstanding natural resource watersThose waters designated as such by a Tribe or State. The State or Tribal designation shall describe the...
• OutwashGlacial outwash is the deposit of sand, silt, and gravel formed below a glacier by meltwater streams and...
• Outwash plainA braided stream deposit beyond the margin of a glacier; it is formed from meltwater flowing away from the...
• Ovary1. One of a pair of female reproductive glands in which the ova, or eggs, are formed. The ovaries are located...
• Oven1. An appliance that is an enclosed compartment supplied with heat and used for cooking food. Toaster ovens...
• Oven cleanerAny cleaning product designed to clean and to remove dried food deposits from oven interiors.
• Over sampleWhen known or suspected circumstances are likely to prevent sampling at some base sample sites, e.g., frame...
• Over samples, see Over sample
• Over the air folder managementA BlackBerry function
• Over the counter drugs, see Over-the-Counter-Drug
• Overall control efficiencyEfficiency of a control system, calculated as the product of the capture and control device efficiencies...
• Overall data uncertaintyConfounded population and measurement uncertainty occurring in a sample.
• Overall efficiency pumpThe combined efficiency of a pump and motor together.
• Overall hazardous air pollutant control efficiencyTotal efficiency of the control system, determined by the product of the capture efficiency and the control...
• Overall organic HAP control efficiency1. Total efficiency of a control system, determined either by:(1) The product of the capture efficiency and...
• Overall organic hazardous air pollutant control efficiency1. Total efficiency of a control system, determined either by:(1) The product of the capture efficiency and...
• Overall statusThe overall support status for the Assessment Unit ID, calculated by ATTAINS.
• Overall waterbody conditionOverall Waterbody Condition refers to the overall condition of the waterbody based on its evaluated uses. If...
• Overbank depositSilt and clay deposited on a flood plain by a flooding stream.
• Overburden1. Rock and soil cleared away before mining.
• Overburdened communityMinority, low-income, tribal, or indigenous populations or geographic locations in the United States that...
• Overdraft1. The pumping of water from a groundwater basin or aquifer in excess of the supply flowing into the basin...
• Overdraft accountNOX Allowance Tracking System account, established by the Administrator under subpart F of this part, for...
• OverexploitationThe removal of individuals or biomass from a population at a rate greater than the population is able to...
• OverfilingWhen a state fails to enforce its hazardous waste program properly, EPA can overfile, or enforce a provision...
• Overfill releaseRelease that occurs when a tank is filled beyond its capacity, resulting in a discharge of the regulated...
• Overfire air1. Air forced into the top of an incinerator or boiler to fan the flames.
• Overflow rate1. One of the guidelines for the design of settling tanks and clarifiers in treatment plants. Used by...
• OverhangA rock mass jutting out from a slope, especially the upper part or edge of an eroded cliff projecting out...
• Overhead irrigation infrastructureOverhead sprinklers or sprayers and supporting system devices
• Overhead valve engine1. Otto-cycle, four stroke engine in which the intake and exhaust valves are located above the combustion...
• Overissue publications (overissues)Refers to printed publications, such as newspapers and magazines, that are defined as unsold inventory by the...
• Overland flow1. A land application technique that cleanses waste water by allowing it to flow over a sloped surface. As...
• Overland segmentPortion of the hazardous substance migration path from a source to a surface water body.
• Overlay permit1. A NPDES permit issued to a group of point source dischargers that supplements individual permits by...
• Overmature timberTrees that have attained full development, particularly in height, and are declining in vigor, health, and...
• OverrunQuantities of sheets printed over the requested number of copies.
• Oversized regulated medical wasteMedical waste that is too large for plastic bags or standard containers.
• OversprayThe amount of spray that misses its target.
• Oversubscription payment deadline30 calendar days prior to the allowance transfer deadline.
• Over-the-Counter-DrugDrug that can legally be sold without a prescription.
• Over-the-head position useMode of use of a device with a headband, in which the headband is worn such that it passes over the user's...
• Over-the-head useMode of use of a device with a headband, in which the headband is worn such that it passes over the user's...
• Overtopping devicePartially submerged structure; a collector funnels waves over the top of the structure into a reservoir...
• Overturn1. The almost spontaneous mixing of all layers of water in a reservoir or lake when the water temperature...
• Overvarnish coating operationSystem on each beverage can surface coating line used to apply a coating over ink which reduces friction for...
• Overviews & factsheetsA brief statement or summary that presents the basic facts and information about a particular entity or idea...
• OverwashThe sediment that is transported from the beach across a barrier and is deposited in an apron-like...
• OverwinterTo remain alive or viable throughout the winter.
• Ovine pulmonary adenomatosisA pulmonary disease of sheep characterized by hyperplasia and hypertrophy of septal cells of the lung.
• Ovule1. Structure containing an egg; a seed prior to fertilization.
• OvumThe female gamete, germ cells in stages between the prophase of the first maturation division and the...
• Own childA child under 18 years old who is a son or daughter by birth, marriage (a stepchild), or adoption. For...
• Owned propertyProperty that is owned or leased by the insured.
• Owner1. The owner or operator of any facility or activity subject to the UIC regulations.
• Owner, administrativeAn individual with rights to administer an email list through the use of system commands sent to the list...
• Owner, federalEach email list must have an EPA employee who requests and is ultimately responsible for the list.
• Owner or operator1. Any person who owns, leases, operates, controls, or supervises a facility, building, structure, or...
• Owner, silentAn individual with rights to post messages directly to a moderated list.
• Owner's manual1. Written or electronic collection of instructions provided to ultimate purchasers to describe the basic...
• Oxic horizonThe oxic horizon is a mineral subsurface horizon of sandy loam or a finer texture with a low cation-exchange...
• Oxidant1. A substance containing oxygen that reacts chemically with other materials to produce new substances...
• OxidasesAny of various enzymes that catalyze oxidations; especially: one able to react directly with molecular oxygen.
• Oxidation1. Oxidation is the addition of oxygen, removal of hydrogen, or removal of electrons from an element or...
• Oxidation control system1. Emission control system which reduces emissions from sulfur recovery plants by converting these emissions...
• Oxidation pondA man-made (anthropogenic) body of water in which waste is consumed by bacteria, used most frequently with...
• Oxidation technologyBreaks down pollutants or organic waste; e.g.,destruction of chemicals such as cyanides, phenols, and organic...
• Oxidation with filtration technologyRemediation treatment for contaminants in water.
• Oxidation-reductionA chemical reaction consisting of two half-reactions; an oxidation reaction in which a substance loses or...
• Oxidation-reduction interactionAn Oxidation-Reduction Interaction is a non-enzymatic physical interaction between atoms or radicals in which...
• Oxidation-reduction potential1. The electrical potential required to transfer electrons from one compound or element (the oxidant) to...
• Oxidation-reduction propertyTendency of a substance to change its oxidation number by gaining or losing an electron.
• Oxidation-reduction reaction1. A chemical reaction consisting of two half-reactions; an oxidation reaction in which a substance loses or...
• Oxidation-reduction (redox), see Oxidation-reduction
• Oxidation-reduction (redox) potentialA measure of an aqueous solution’s tendency to either release or accept electrons. Oxidizing systems tend to...
• Oxidative burstA process that consists of the rapid release of reactive oxygen species. The process frequently ocurrs in...
• Oxidative deaminationGenerally takes place in the liver where the removal of an amine group from a molecule such as glutamic acid...
• Oxidative phosphorylation1. Electron transfer through the cytochrome system liberating free energy which is transformed into...
• Oxidative regulationOxidative Regulation involves cellular and biochemical mechanisms that localize and control...
• Oxidative stressA disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage...
• Oxidative stress inductionOxidative Stress Induction involves initiation of activities that induce a disturbance in the...
• Oxidative stress measurement(Measurement of the) damage to biological tissues caused by superoxide and other free radicals generated as a...
• Oxides of nitrogen1. Sum of the nitric oxide and nitrogen dioxide contained in a gas sample as if the nitric oxide were in the...
• OxidizeTo chemically transform a substance by combining it with oxygen.
• Oxidized glutathioneA glutathione dimer formed by a disulfide bond between the cysteine sulfhydryl side chains during the course...
• Oxidizing agent1. Any substance, such as oxygen (O2) or chlorine (Cl2), that will readily add (take on) electrons. The...
• Oxidizing salt bath descalingRemoval of scale from semi-finished steel products by the action of molten salt baths other than those...
• OxidoreductasesThe class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a...
• OxisolsOxisols are weathered soils that are low in fertility. They are most common on the gentle slopes of...
• OxyclineZone in the water column where oxygen concentration changes rapidly with depth, often as a result of...
• OxycodoneA semisynthetic derivative of codeine.
• Oxygen analyzer systemAll equipment required to determine the oxygen content of a gas stream and used to monitor oxygen in the...
• Oxygen consumptionThe rate at which oxygen is used by tissues.
• Oxygen cycleCyclic movement of oxygen in different chemical forms from the environment, to organisms, and then back to...
• Oxygen deficient atmosphereAn oxygen-deficient atmosphere is one in which the percentage of oxygen by volume is below 19.5 percent...
• Oxygen delignification systemEquipment that uses oxygen to remove lignin from pulp after high-density stock storage and prior to the...
• Oxygen demandMeasure of the dissolved oxygen used by a system (microorganisms) in the oxidation of organic matter. (See...
• Oxygen depletionA deficit of dissolved oxygen in a water system due to oxidation of organic matter.
• Oxygen maximumA layer in the ocean where oxygen concentration is at a minimum, often due to a locus of high respiratory...
• Oxygen minimumRegion in the water column where oxygen is reduced (relative to surrounding waters) due to high respiration...
• Oxygen saturationThe natural or artificial reaeration or oxygenation of a water system (water sample) to bring the level of...
• Oxygen sensorA sensor in the engine exhaust system that measures the concentration of oxygen in the exhaust gas.
• Oxygen trim system1. System of monitors that is used to maintain excess air at the desired level in a combustion device. A...
• Oxygenate1. Oxygenates are hydrocarbons added to fuels to increase the oxygen content of those fuels to improve...
• Oxygenate blender1. Any person who owns, leases, operates, controls, or supervises an oxygenate blending facility, or who owns...
• Oxygenate blender recordShall include laboratory analysis reports; refiner, importer and oxygenate blender contracts; quality...
• Oxygenate blending blendstockGasoline blendstock which could become gasoline solely upon the addition of an oxygenate.
• Oxygenate blending facility1. As defined in § 80.2(ll).
• Oxygenate compoundOxygen-containing, ashless organic compound, such as an alcohol or ether, which may be used as a fuel or fuel...
• Oxygenate import facilityAny facility where oxygenate, including DFE, is imported into the United States.
• Oxygenate producerAny person who produces or imports oxygenate for gasoline in the United States, or any person who owns...
• Oxygenate production facilityAny facility where oxygenate is produced, including DFE.
• Oxygenated fuel1. Gasoline which has been blended with alcohols or ethers that contain oxygen in order to reduce carbon...
• Oxygenated fuels, see Oxygenated fuel
• Oxygenated gasolineGasoline which contains a measurable amount of oxygenate.
• Oxygenated solventAn organic solvent containing oxygen as part of the molecular structure. Alcohols and ketones are oxygenated...
• Oxygenates, see Oxygenate
• OxytocinA naturally secreted hormone that is important in milk letdown and the contraction of the smooth uterine...
• Oyster fishingHarvesting of oysters from an oyster bed. Oysters are saltwater clams, bivalve mollusks.
• Oyster reef habitatShallow and deep-water habitats with substrates consisting of mollusk shells.
• Ozonation1. (O-zoe-NAY-shun) The application of ozone to water for disinfection or for taste and odor control.
• Ozone1. Found in two layers of the atmosphere, the stratosphere and the troposphere. In the stratosphere (the...
• Ozone 8-hr (1997 standard)1. Description: Ozone 8-hr (1997 standard)
• Ozone 8-hr (2008 standard)1. Description: Ozone 8-hr (2008 standard)
• Ozone air concentrationOzone summer seasonal avg. of daily maximum 8-hour concentration in air in parts per billion, 2013.
• Ozone depleting substance1. A family of man-made compounds that includes, but are not limited to, chlorofluorocarbons (CFCs)...
• Ozone depleting substances, see Ozone depleting substance
• Ozone depletion1. Chemical destruction of the stratospheric ozone layer beyond natural reactions. Stratospheric ozone is...
• Ozone depletion potential1. A number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the...
• Ozone "hole"A large area of the stratosphere with extremely low amounts of ozone.
• Ozone inactivation technologyA technology having a high germicidal effectiveness against a wide range of pathogenic organisms including...
• Ozone in-situ chemical oxidationInvolves the injection of a mixture of air and O3 gas directly into the unsaturated and/or saturated zones.
• Ozone layer1. The layer of ozone that shields the Earth from the sun's harmful rays.
• Ozone layer depletionChemical destruction of ozone molecules in the ozone layer.
• Ozone level in airOzone summer seasonal avg. of daily maximum 8-hour concentration in air in parts per billion.
• Ozone nonattainment areaArea designated as a nonattainment area for ozone under subpart C of part 81 of this chapter.
• Ozone Policy & Strategies GroupOzone Policy & Strategies Group (of EPA).
• Ozone precursorChemical compounds, such as carbon monoxide, methane, non-methane hydrocarbons, and nitrogen oxides, which in...
• Ozone precursors, see Ozone precursor
• Ozone season day emissionsAverage day's emissions for a typical ozone season work weekday. The state shall select, subject to EPA...
• Ozone transport region1. Area established by section 184(a) of the CAA or any other area established by the Administrator pursuant...

831 of 29,894 terms in Environment terminology (MLC-0121). Request the full dataset.