| Abandoned Well | A well whose use has been permanently discontinued or which is in a state of such disrepair that it cannot be used for its intended purpose. | Abatement | Reducing the degree or intensity of, or eliminating pollution. | Abatement Debris | Waste from remediation activities. | Abiotic | Nonliving,Not caused by or resulting from the activity of living organisms. | Aboveground storage tanks | Any tank or other container that is aboveground, partially buried, bunkered, or in a subterranean vault. This includes floating fuel systems. | Absorbed Dose | The amount of a substance that penetrates an exposed organism's absorption barriers (e.g.,, skin, lung tissue, gastrointestinal tract) through physical or biological processes. The term is synonymous with internal dose. | Absorption | The uptake of water, other fluids, or dissolved chemicals by a cell or an organism (e.g. Tree roots absorb dissolved nutrients in soil). | Absorption Barrier | Any of the exchange sites of the body that permit uptake of various substances at different rates (e.g. skin, lung tissue, and gastrointestinal-tract wall). | Accelerated Growth | On a plot of bacterial growth versus time, the point at which the bacteria begin to divide, and the population increase is gradual. | Accident Site | The location of an unexpected occurrence, failure or loss, either at a plant or along a transportation route, resulting in a release of hazardous materials. | Acclimatization | The physiological and behavioral adjustments of an organism to changes in its environment. | Accumulation | Accumulation refers to change in mass or moles within a system with respect to time. This change can be either positive or negative and accordingly accumulation is positive or negative. | Accuracy | Accuracy is a degree, or measurement, of closeness to a target value. Accuracy should not be confused with precision. A sample is accurate if the absolute value of the bias of the total sampling error is within a specified acceptable level of accuracy. | Acid | A corrosive solution with a pH less than 7. | Acid Aerosol | Acidic liquid or solid particles small enough to become airborne. High concentrations can irritate the lungs and have been associated with respiratory diseases like asthma. | Acid Deposition | A complex atmospheric phenomenon that occurs when sulfur and nitrogen compounds are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form (e.g. acid rain). | Acid Mine Drainage | Drainage of water from areas that have been mined for coal or other mineral ores. The water has a low pH because of its contact with sulfur-bearing material and is harmful to aquatic organisms. | Acid Neutralizing Capacity | Measure of ability of a base (e.g., water or soil) to resist changes in pH. | Acid Rain | Precipitation having a ph lower than the natural range of ~5.2 - 5.6; caused by sulfur and nitrogen acids derived from anthropogenic emissions. | Acidic | The condition of water or soil that contains a sufficient amount of acidic substances to lower the pH below 7.0. | Acidity | A measure of how acid a solution may be. A solution with a pH of less than 7.0 is considered acidic. | ACScale Sound Level | A measurement of sound approximating the sensitivity of the human ear, used to note the intensity or annoyance level of sounds. | Action Levels | Regulatory levels recommended by EPA for enforcement by FDA and USDA when pesticide residues occur in food or feed commodities for reasons other than the direct application of the pesticide. Action levels are set for inadvertent residues. | Activated Carbon | A highly adsorbent form of carbon used to remove odors and toxic substances from liquid or gaseous emissions. In waste treatment, it is used to remove dissolved organic matter from waste drinking water. | Activated Sludge | Product that results when primary effluent is mixed with bacteria-laden sludge and then agitated and aerated to promote biological treatment, speeding the breakdown of organic matter in raw sewage undergoing secondary waste treatment. | Activated Sludge Process | An sewage treatment process by which bacteria that feed on organic wastes are continuously circuated and put in contact with organic waste in the presence of oxygen to increase the rate of decomposition. | Activator | A chemical added to a pesticide to increase its activity. | Active Ingredient | An agent that is specifically intended to kill, repel, or otherwise deter a target organism. Active ingredients are listed on pesticide product labels. | Acute Exposure | A single exposure to a toxic substance which may result in severe biological harm or death. Acute exposures are usually characterized as lasting no longer than a day, as compared to longer, continuing exposure over a period of time. | Acute Toxicity | The ability of a substance to cause severe biological harm or death soon after a single exposure or dose. Also, any poisonous effect resulting from a single short-term exposure to a toxic substance. | Adaptation | Changes in an organism's physiological structure or function or habits that allow it to survive in new surroundings. | Add-on Control Device | An air pollution control device that reduces the pollution in an exhaust gas. The control device usually does not affect the process being controlled and thus is "add-on" technology. | Adequately Wet | Asbestos containing material that is sufficiently mixed or penetrated with liquid to prevent the release of particulates. | Administered Dose | In exposure assessment, the amount of a substance given to a test subject (human or animal) to determine dose-response relationships. Since exposure to chemicals is usually inadvertent, this quantity is often called potential dose. | Administrative Order | A legal document signed by EPA directing an individual, business, or other entity to take corrective action or refrain from an activity. It describes the violations and actions to be taken, and can be enforced in court. | Administrative Order by Consent for Response Activity and Site Redevelopment | A three party agreement between the state, a liable party under NREPA Part 201, and a non-liable party that has an interest in the property. | Administrative Order On Consent | A legal agreement signed by EPA and an individual, business, or other entity through which the violator agrees to pay for correction of violations, take the required corrective or cleanup actions, or refrain from an activity. | Administrative Procedures Act | A law that spells out procedures and requirements related to the promulgation of regulations. | Administrative Record | All documents which EPA considered or relied on in selecting the response action at a Superfund site, culminating in the record of decision for remedial action or, an action memorandum for removal actions. | Adsorb | Accumulation of a substance at an interface, i.e. is held at or on the surface.
A chemical process where a molecule attaches loosely to the surface of another phase, without becoming incorporated into that phase. | Adsorption | Removal of a pollutant from air or water by collecting the pollutant on the surface of a solid material; e.g., an advanced method of treating waste in which activated carbon removes organic matter from waste-water. | Adulterants | Chemical impurities or substances that by law do not belong in a food, or pesticide. | Adulterated | The addition of inactive ingredients to a food that cause the food to have toxic effects when ingested. | Advance (of a beach) | A continuing seaward movement of the shoreline. Also Progression. | Advanced Wastewater Treatment | Any treatment of sewage that goes beyond the secondary or biological water treatment stage and includes the removal of nutrients such as phosphorus and nitrogen and a high percentage of suspended solids. (See primary, secondary treatment.) | Advection | Advection is one of the two processes by which solutes are transported in a fluid. Advective transport is the bulk movement of solute as a direct result of cocurrent movement of the fluid elements. | Adverse Effects Data | FIFRA requires a pesticide registrant to submit data to EPA on any studies or other information regarding unreasonable adverse effects of a pesticide at any time after its registration. | Advisory | A non-regulatory document that communicates risk information to those who may have to make risk management decisions. | Aerated Lagoon | A holding and/or treatment pond that speeds up the natural process of biological decomposition of organic waste by stimulating the growth and activity of bacteria that degrade organic waste. | Aeration | A process which promotes biological degradation of organic matter in water. The process may be passive (as when waste is exposed to air), or active (as when a mixing or bubbling device introduces the air). | 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. (See: anaerobic). | Aerobic Organisms | Organisms that survive in oxygen-rich environments and use oxygen as the terminal electron acceptor. | Aerobic Respiration | The breakdown of organic chemicals by molecular oxygen to form gaseous carbon dioxide. | Aerobic Treatment | Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth. (Such processes include extended aeration, trickling filtration, and rotating biological contactors). | Aerosol | A finely divided material suspended in air or other gaseous environment. | Affected Landfill | Under the Clean Air Act, landfills that meet criteria for capacity, age, and emissions rates set by the EPA. They are required to collect and combust their gas emissions. | Affected Public | 1.The people who live and/or work near a hazardous waste site. 2. The human population adversely impacted following exposure to a toxic pollutant in food, water, air, or soil. | Afterburner | In incinerator technology, a burner located so that the combustion gases are made to pass through its flame in order to remove smoke and odors. It may be attached to or be separated from the incinerator proper. | Age Tank | A tank used to store a chemical solution of known concentration for feed to a chemical feeder. Also called a day tank. | Agent | Any physical, chemical, or biological entity that can be harmful to an organism(synonymous with stressor). | Aggradation | The general smoothing of the earth's surface by deposition due to air or aquatic transport of material. | Agricultural Pollution | Farming wastes, including runoff and leaching of pesticides and fertilizers; erosion and dust from plowing; improper disposal of animal manure and carcasses; crop residues, and debris. | Agroecosystem | Land used for crops, pasture, and livestock; the adjacent uncultivated land that supports other vegetation and wildlife; and the associated atmosphere, the underlying soils, groundwater, and drainage networks. | AHERA Designated Person | A person designated by a Local Education Agency to ensure that the AHERA requirements for asbestos management and abatement are properly implemented. | Air Binding | Situation where air enters the filter media and harms both the filtration and backwash processes. | Air Changes Per Hour | The movement of a volume of air in a given period of time; if a house has one air change per hour, it means that the air in the house will be replaced in a one-hour period. | Air Cleaning | Indoor-air quality-control strategy to remove various airborne particulates and/or gases from the air. Most common methods are particulate filtration, electrostatic precipitation, and gas sorption. | Air Contaminant | Any particulate matter, gas, or combination thereof, other than water vapor. (See: Air Pollutant.) | Air Curtain | A method of containing oil spills. Air bubbling through a perforated pipe causes an upward water flow that slows the spread of oil. It can also be used to stop fish from entering polluted water. | 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 protected from another water system in a treatment plant or other location. The open gap protects the drinking water from contamination by backflow or back siphonage. | Air Handling Unit | Equipment that includes a fan or blower, heating and/or cooling coils, regulator controls, condensate drain pans, and air filters. | Air Mass | A large body of air with similar temperature and moisture characteristics as a result of having come from the same source region. | Air Padding | Pumping dry air into a container to assist with the withdrawal of liquid or to force a liquefied gas such as chlorine out of the container. | Air Permeability | The degree to which a given material or substance will permit the passage of air. Important to the design of soil-gas surveys. Measured in darcys or centimeters-per-second. | Air Plenum | Any space used to convey air in a building, furnace, or structure. The space above a suspended ceiling is often used as an air plenum. | Air Pollutant | Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. | Air Pollution Control Device | Mechanism or equipment that cleans emissions generated by a source (e.g., an incinerator, industrial smokestack, or an automobile exhaust system) by removing pollutants that would otherwise be released to the atmosphere. | Air Pollution Episode | A period of abnormally high concentration of air pollutants, often due to low winds and temperature inversion, that can cause illness and death. (See: Episode, Pollution.). | Air Quality Criteria | The levels of pollution and lengths of exposure above which adverse health and welfare effects may occur. | Air Quality Standards | The level of pollutants prescribed by regulations that are not be exceeded during a given time in a defined area. | Air Sparging | Injecting air or oxygen into an aquifer to strip or flush volatile contaminants as air bubbles up through the ground water and is captured by a vapor extraction system. | Air Stripping | A treatment system that removes volatile organic compounds (VOCs) from contaminated ground water or surface water by forcing an airstream through the water and causing the compounds to evaporate. | Air Toxics | Any air pollutant for which a national ambient air quality standard (NAAQS) does not exist that may reasonably be anticipated to cause cancer; respiratory, cardiovascular or other serious or irreversible chronic or acute health effects in humans. | Air/Oil Table | The surface between the vadose zone and ambient oil; the pressure of oil in the porous medium is equal to atmospheric pressure. | Airborne Particulates | Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year (dust, emissions, combustion products, etc.). | Airborne Release | Release of any pollutant into the air. | Alachlor | A herbicide, marketed under the trade name Lasso, used mainly to control weeds in in corn, soybeans, peanuts, cotton, woody fruits, and certain ornamentals. | Alar | Trade name for daminozide, a pesticide that makes apples redder, firmer, and less likely to drop off trees before growers are ready to pick them. It is also used to a lesser extent on peanuts, tart cherries, concord grapes, and other fruits. | Aldicarb | An insecticide sold under the trade name Temik. It is made from ethyl isocyanate. | Algae | Simple rootless plants that grow in sunlit waters in proportion to the amount of available nutrients. They can affect water quality adversely by lowering the dissolved oxygen in the water. They are food for fish and small aquatic animals. | Algal Blooms | Sudden spurts of algal growth, which can affect water quality adversely and indicate potentially hazardous changes in local water chemistry. | Algicide | Substance or chemical used specifically to kill or control algae. | Aliphatic | Organic compound that is an alkane or alkene or alkyne or their derivative. | Aliquot | A measured portion of a sample taken for analysis. One or more aliquots make up a sample. (See: Duplicate.). | Alkaline | The condition of water or soil which contains a sufficient amount of alkali substance to raise the pH above 7.0. | Alkalinity | 1. The capacity of bases to neutralize acids. An example is lime added to lakes to decrease acidity. 2. A water's ability to resist changes in pH on the addition of acid. | Allergen | A substance that causes an allergic reaction in individuals sensitive to it. | Alluvial | Relating to and/or sand deposited by flowing water. | Alongshore | Parallel to and near the shoreline; same as LONGSHORE. | Alternative Compliance | A policy that allows facilities to choose among methods for achieving emission-reduction or risk-reduction instead of command and control regulations that specify standards and how to meet them. | Alternative Remedial Contract Strategy Contractors | Government contractors who provide project management and technical services to support remedial response activities at National Priorities List sites. | Ambient Air | Any unconfined portion of the atmosphere: open air, surrounding air. | Ambient Measurement | A measurement of the concentration of a substance or pollutant within the immediate environs of an organism; taken to relate it to the amount of possible exposure. | Ambient Medium | Material surrounding or contacting an organism (e.g., outdoor air, indoor air, water, or soil, through which chemicals or pollutants can reach the organism. (See: Biological medium, Environmental medium.) | Amphoteric | Substances with the ability to act as either an acid or a base. | Amplitude | The vertical distance that a wave causes water to be displaced from a mean value. An ocean wave has an amplitude equal to the vertical distance from STILLWATER LEVEL to wave crest. | Amprometric Titration | A way of measuring concentrations of certain substances in water using an electric current that flows during a chemical reaction. | 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 organic matter caused by microorganisms in an oxygen-free environment. | Anaerobic Respiration | Respiration that can only occur in the absence of oxygen or nitrate. | Analysis | Separation and measurement of component parts. | Analyte | The chemical for which a sample is analyzed. | Analytical Error | This error component arises from imperfections in the analysis (chemical or
physical) operation. It includes errors associated with such activities as chemically extracting the
analyte from the sample matrix, instrumentation error, operator errors, moisture analysis, gravimetric
errors, and other measurement errors. | Animal Dander | Tiny scales of animal skin, a common indoor air pollutant. | Anion | A negatively charged ion. | Anisotropy | Having properties which vary depending on the direction of measurement. | Annular Space, Annulus | The space between two concentric tubes or casings, or between the casing and the borehole wall. | Anoxic Denitrification | Conversion of oxidised forms of nitrogen, such as NO3- to nitrogen gas (N2) by anaerobic bacteria. | Anoxic Environment | An environment that contains low concentrations of oxygen. | Anti-Degradation Clause | Part of federal air quality and water quality requirements prohibiting deterioration where pollution levels are above the legal limit. | Applicable or Relevant and Appropriate Requirements | Any state or federal statute that pertains to protection of human life and the environment in addressing specific conditions or use of a particular cleanup technology at a Superfund site. | Applied Dose | In exposure assessment, the amount of a substance in contact with the primary absorption boundaries of an organism (e.g., skin, lung tissue, gastrointestinal track) and available for absorption. | Aqueous Solubility | The maximum concentration of a chemical that will dissolve in pure water at a reference temperature. | Aquiclude | A confining layer in an aquifer that is essentially impermeable to water flow. | Aquifer | The water-yeilding earthen layer where water is stored. The geologic formation, thorough which water can flow horizontally and be pumped. | Aquifer test | A test to determine hydraulic properties of an aquifer. | Aquitard | Geological formation that may contain groundwater but is not capable of transmitting significant quantities of it under normal hydraulic gradients. May function as confining bed. | Architectural Coatings | Coverings such as paint and roof tar that are used on exteriors of buildings. | Area of Concern | An environment identified as a potential pollution risk. | Area of Review | In the UIC program, the area surrounding an injection well that is reviewed during the permitting process to determine if flow between aquifers will be induced by the injection operation. | Area Source | Any source of air pollution that is released over a relatively small area but which cannot be classified as a point source. Such sources may include vehicles and other small engines, small businesses and household activities, or biogenic sources. | Aromatics | A type of hydrocarbon, such as benzene or toluene, with a specific type of ring structure. Aromatics are sometimes added to gasoline in order to increase octane. Some aromatics are toxic. | Arsenicals | Pesticides containing arsenic. | Artesian Aquifer or Well | Water held under pressure in porous rock or soil confined by impermeable geological formations. | Asbestos | A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction. | Asbestos Abatement | Procedures to control fiber release from asbestos-containing materials in a building or to remove them entirely, including removal, encapsulation, repair, enclosure, encasement, and operations and maintenance programs. | Asbestos Assessment | In the asbestos-in-schools program, the evaluation of the physical condition and potential for damage of all friable asbestos containing materials and thermal insulation systems. | Asbestos Program Manager | A building owner or designated representative who supervises all aspects of the facility asbestos management and control program. | Asbestos-Containing Waste Materials | Mill tailings or any waste that contains commercial asbestos and is generated by a source covered by the Clean Air Act Asbestos NESHAPS. | Asbestosis | A disease associated with inhalation of asbestos fibers. The disease makes breathing progressively more difficult and can be fatal. | Assay | Determination of the purity of a substance or the amount of any particular constituent of a mixture. | Assemblage | An association of interacting populations of organisms in a given waterbody. Examples of assemblages used for biological assessments include : algae, amphibians, birds, fish, herps (reptiles and amphibians), macroinvertebrates (insects, crayfish, clams, snails, etc.), and vascular plants. | Assessment Endpoint | In ecological risk assessment, an explicit expression of the environmental value to be protected; includes both an ecological entity and specific attributed thereof. Entity. | 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 materials without deleterious effects and without damage to aquatic life or humans who consume the water. | Association of Boards of Certification | An international organization representing boards which certify the operators of waterworks and wastewater facilities. | Atmospheric emissions | Release or discharge of fumes, dust or particulates into the air. | Atomic Number | The number of protons in the nucleus of an atom. | Atomic Weight | Of an element, is the average atomic mass for the naturally occurring element. | Attainment Area | An area considered to have air quality as good as or better than the national ambient air quality standards as defined in the Clean Air Act. An area may be an attainment area for one pollutant and a non-attainment area for others. | Attenuation | The process by which a compound is reduced in concentration over time, through absorption, adsorption, degradation, dilution, and/or transformation. an also be the decrease with distance of sight caused by attenuation of light by particulate pollution. | Attractant | A chemical or agent that lures insects or other pests by stimulating their sense of smell. | Attrition | Wearing or grinding down of a substance by friction. Dust from such processes contributes to air pollution. | Autotrophic Organisms | Primary producers that obtain their carbon from inorganic sources. | Availability Session | Informal meeting at a public location where interested citizens can talk with EPA and state officials on a one-to-one basis. | Available Chlorine | A measure of the amount of chlorine available in chlorinated lime, hypochlorite compounds, and other materials used as a source of chlorine when compared with that of liquid or gaseous chlorines. | Avoided Cost | The cost a utility would incur to generate the next increment of electric capacity using its own resources; many landfill gas projects' buy back rates are based on avoided costs. | Awash | Being intermittently washed over by waves. | Back Pressure | A pressure that can cause water to backflow into the water supply when a user's waste water system is at a higher pressure than the public system. | Backfill | To refill an excavated area with fill or soil; or, the material itself that is used to refill an excavated area. | Backflow/Back Siphonage | A reverse flow condition created by a difference in water pressures that causes water to flow back into the distribution pipes of a drinking water supply from any source other than the intended one. | Background Level | The concentration of a substance in an environmental media (air, water, or soil) that occurs naturally or is not the result of human activities. | Backwashing | Reversing the flow of water back through the filter media to remove entrapped solids. | Baffle | A flat board or plate, deflector, guide, or similar device constructed or placed in flowing water or slurry systems to cause more uniform flow velocities to absorb energy and to divert, guide, or agitate liquids. | Baffle Chamber | In incinerator design, a chamber designed to promote the settling of fly ash and coarse particulate matter by changing the direction and/or reducing the velocity of the gases produced by the combustion of the refuse or sludge. | Baghouse Filter | Large fabric bag, usually made of glass fibers, used to eliminate intermediate and large (greater than 20 PM in diameter) particles. This device operates like the bag of an electric vacuum cleaner. | Bailer | A pipe with a valve at the lower end, used to remove slurry from the bottom or side of a well as it is being drilled, or to collect ground-water samples from wells or open boreholes. | Baling | Compacting solid waste into blocks to reduce volume and simplify handling. | Ballistic Separator | A machine that sorts organic from inorganic matter for composting. | Band Application | The spreading of chemicals over, or next to, each row of plants in a field. | Banking | A system for recording qualified air emission reductions for later use in bubble, offset, or netting transactions. (See: Emissions trading.) | Barrel Sampler | Open-ended steel tube used to collect soil samples. | Basal Application | In pesticides, the application of a chemical on plant stems or tree trunks just above the soil line. | Basalt | Consistent year-round energy use of a facility; also refers to the minimum amount of electricity supplied continually to a facility. | Base-Neutralizing Capacity | The ability of a water to resist changes in pH due to the addition of a base. | Baseflow | A portion of the streamflow that would be present even during periods of drought. | Baseline Environmental Assessment | An evaluation of environmental conditions which exist at a facility at the time of purchase, occupancy, or foreclosure that reasonably defines the existing conditions. | Basin | Larger systems that include lakes, rivers, the surrounding land, and even the groundwater lying in the geological materials below the land. | Batch System | Batch system or a Closed system is one in which there is no transfer of material across the system boundary , during the time interval of interest. | Beach erosion | The carrying away of beach materials by wave action, currents, or wind. | Bean Sheet | Common term for a pesticide data package record. | Bed Load | Sediment particles resting on or near the channel bottom that are pushed or rolled along by the flow of water. | Bedrock | A general term for the rock layer that lies beneath soil, loose sediments, or other unconsolidated material. Groundwater often is found in the bedrock layer. | BEN-EPA's Computer model | EPA's computer model for analyzing a violator's economic gain from not complying with the law. | Bench-scale Tests | Laboratory testing of potential cleanup technologies (See: Treatability studies.) | Benefit-Cost Analysis | An economic method for assessing the benefits and costs of achieving alternative health-based standards at given levels of health protection. | Benthic Organism | Any of a diverse group of aquatic plants and animals that live on the bottom of marine and/or fresh water. Presence or absence of certain benthic organisms can be used as an indicator of water quality. | Benthic Zone | The bottom sediments of a lake. | Bentonite | A colloidal clay, expansible when moist, commonly used to provide a tight seal around a well casing. | Berm | A ledge, wall or mound of soil used to prevent the migration of contaminants. | Beryllium | An metal hazardous to human health when inhaled as an airborne pollutant. It is discharged by machine shops, ceramic and propellant plants, and foundries. | Best Available Control Measures | A term used to refer to the most effective measures (according to EPA guidance) for controlling small or dispersed particulates and other emissions from various sources. | Best Available Control Technology | An emission limitation based on the maximum degree of emission reduction (considering energy, environmental, and economic impacts) achievable through application of production processes and available methods, systems, and techniques. | Best Demonstrated Available Technology | The most effective commercially available means of treating specific types of hazardous waste. The BDATs may change with advances in treatment technologies. | Best Management Practice | Methods that have been determined to be the most effective, practical means of preventing or reducing pollution from non-point sources. | Bias | The systematic or persistent distortion of a measurement process that causes errors in one
direction along a metric away the true value; that is, bias is a function of systematic error (e.g., the
average measured mass differs from the true mass by +0.034 g). | Bimetal | Beverage containers with steel bodies and aluminum tops; handled differently from pure aluminum in recycling. | Bin vent filter | Used on Minergy storage silos to minimize emission of particulate matter. | Bioaccumulants | Substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted. | Bioassay | A test to determine the relative strength of a substance by comparing its effect on a test organism with that of a standard peparation. | Bioavailability | Degree of ability to be absorbed and ready to interact in organism metabolism. | Biochemical Oxygen Demand | A measure of the amount of oxygen consumed in the biological processes that break down organic matter in water. The greater the BOD, the greater the degree of pollution. | Bioconcentration | The accumulation of a chemical in tissues of a fish or other organism to levels greater than in the surrounding medium. | Biodegradable | Capable of decomposing under natural conditions. | Biodiversity | Refers to the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequencies. | Biological Assessment (bioassessment) | Using biomonitoring data of samples of living organisms to evaluate the condition or health of a place (e.g., a stream, wetland, or woodlot). | Biological Contaminants | Living organisms or derivates(e.g., viruses, bacteria, fungi, and mammal and bird) antigens that can cause harmful health effects when inhaled, swallowed, or otherwise taken into the body. | Biological Control | In pest control, the use of animals and organisms that eat or otherwise kill or out-compete pests. | Biological Indicators of Exposure Study | A study designed to use biomedical testing or the measurement of a chemical (analyte), its metabolite, or another marker of exposure in human body fluids or tissues in order to validate human exposure to a hazardous substance. | Biological Integrity | The ability to support and maintain balanced, integrated, functionality in the natural habitat of a given region. Concept is applied primarily in drinking water management. | Biological Magnification | Refers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. | Biological Measurement | A measurement taken in a biological medium. For exposure assessment, it is related to the measurement is taken to related it to the established internal dose of a compound. | Biological Medium | One of the major component of an organism; e.g., blood, fatty tissue, lymph nodes or breath, in which chemicals can be stored or transformed. | Biological Oxidation | Decomposition of complex organic materials by microorganisms. Occurs in self-purifi- cation of water bodies and in activated sludge wastewater treatment. | Biological Oxygen Demand | The amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. | Biological Stressors | Organisms accidently or intentionally dropped into habitats in which they do not evolve naturally; e.g. gypsy moths, Dutch elm disease, certain types of algae, and bacteria. | Biological Treatment | A treatment technology that uses bacteria to consume organic waste. | Biological Uptake | The transfer of hazardous substances from the environment to plants, animals, and humans. | Biologically Effective Dose | The amount of a deposited or absorbed compound reaching the cells or target sites where adverse effect occur, or where the chemical interacts with a membrane. | Biologicals | Vaccines, cultures and other preparations made from living organisms and their products, intended for use in diagnosing, immunizing, or treating humans or animals, or in related research. | Biomagnification | The process that results in the accumulation of a chemical in an organism at higher levels than are found in its own food. | Biomass | All of the living material in a given area; often refers to vegetation. | Biome | Entire community of living organisms in a single major ecological area. | Biomonitoring | The use of living organisms to test the suitability of effluents for discharge into receiving waters and to test the quality of such waters downstream from the discharge. | Bioremediation | Use of living organisms to clean up oil spills or remove other pollutants from soil, water, or wastewater; use of organisms such as non-harmful insects to remove agricultural pests or counteract diseases of trees, plants, and garden soil. | Biosensor | Analytical device comprising a biological recognition element (e.g., enzyme, DNA) in intimate contact with an electrochemical, optical, thermal, or acoustic signal transducer that together permit analyses of chemical properties or quantities. | Biostabilizer | A machine that converts solid waste into compost by grinding and aeration. | Biota | The animal and plant life of a given region. | Biotechnology | Techniques that use living organisms or parts of organisms to produce a variety of products (from medicines to industrial enzymes) to improve plants or animals or to develop microorganisms to remove toxics from bodies of water, or act as pesticides. | Biotic Community | A naturally occurring assemblage of plants and animals that live in the same environment and are mutually sustaining and interdependent. (See: Biome.) | Biotransformation | Conversion of a substance into other compounds by organisms; includes biodegredation. | Bioturbation | The natural activity of living organisms, such as worms, to move particles and porewater from inside soil or sediment beds toward the surface and circulate them in the upper layers. | Blackwater | Water that contains animal, human, or food waste. | Bloom | A proliferation of algae and/or higher aquatic plants in a body of water; often related to pollution, especially when pollutants accelerate growth. | Body Burden | The amount of a chemical stored in the body at a given time, especially a potential toxin in the body as the result of exposure. | Bog | A type of wetland that accumulates appreciable peat deposits. Bogs depend primarily on precipitation for their water source, and are usually acidic and rich in plant residue with a conspicuous mat of living green moss. | Boom | A floating device used to contain oil on a body of water. | Borehole | Hole made by inserting a hollow tube with drilling equipment to draw up a core of soil. The soil samples are collected for testing to determine the site geology and to learn if the soil has been contaminated. | Boring (or Soil Boring) | A circular hole made in the ground by an auger or mechanical drill rig to collect soil samples deep in the ground. Representative samples are collected for testing to see if the subsoil has been contaminated. Sometimes these borings are converted into groundwater monitoring wells. | Boring logs | The record of formations penetrated, drilling progress, record of depth of water, location of contaminants, and other recorded information having to do with the drilling well. | Botanical Pesticide | A pesticide whose active ingredient is a plant-produced chemical such as nicotine or strychnine. Also called a plant-derived pesticide. | Bottom Ash | The non-airborne combustion residue from burning pulverized coal in a boiler; the material which falls to the bottom of the boiler and is removed mechanically; a concentration of non-combustible materials, which may include toxics. | Bottom Land Hardwoods | Forested freshwater wetlands adjacent to rivers in the southeastern United States, especially valuable for wildlife breeding, nesting and habitat. | Bounding Estimate | An estimate of exposure, dose, or risk that is higher than that incurred by the person in the population with the currently highest exposure, dose, or risk. | Brackish | Mixed fresh and salt water. | Break water | A structure that protects a shoreline, harbor, anchorage, or basin from waves. | Breakdown products | Most contaminants are combinations of specific substances. Contaminants are degraded, or separated, into these individual substances through chemical or physical means. | Breakpoint Chlorination | Addition of chrlorine to water until the chlorine demand has been satisfied. | Breakthrough | A crack or break in a filter bed that allows the passage of floc or particulate matter through a filter; will cause an increase in filter effluent turbidity. | Breathing Zone | Area of air in which an organism inhales. | Brine Mud | Waste material, often associated with well-drilling or mining, composed of mineral salts or other inorganic compounds. | British Thermal Unit | A measure of the amount of energy produced from a material that is being combusted. | Brownfield | Abandoned, idled, or under-used industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived environmental contamination. | Brownfield Plan | A plan approved by the local governing body that includes the specific brownfield properties. | Brownfield Revelopment Authority | A local governing body that provides decision making and control of brownfield redevelopment projects. | Bubble | Under the bubble concept, sources can control more than required at one emission point where control costs are relatively low in return for a comparable relaxation of controls at a second emission point where costs are higher. | Buffer | A solution or liquid whose chemical makeup is such that it minimizes changes in pH when acids or bases are added to it. | Buffering Capacity | The ability of a water to resist change in pH when an acid or base is added. | Building Related Illness | Diagnosable illness whose cause and symptoms can be directly attributed to a specific pollutant source within a building (e.g., Legionnaire's disease, hypersensitivity, pneumonitis.) | Bulk head | A shoreline protection structure or partition intended to retain land from sliding into a water body. | Bulk Sample | A small portion (usually thumbnail size) of a suspect asbestos-containing building material collected by an asbestos inspector for laboratory analysis to determine asbestos content. | Cadmium | A heavy metal that accumulates in the environment. | Cap | A layer of clay, or other impermeable material installed over the top of a closed landfill to prevent entry of rainwater and minimize leachate. | Capacity Assurance Plan | A statewide plan which supports a state's ability to manage the hazardous waste generated within its boundaries over a twenty year period. | Capillary Action | The process of soil drawing water above its static level. | Capillary Fringe | The porous material just above the water table which may hold water by capillarity (a property of surface tension that draws water upwards) in the smaller void spaces. | Capture Efficiency | The fraction of organic vapors generated by a process that are directed to an abatement or recovery device. | Carbon Absorber | An add-on control device that uses activated carbon to absorb volatile organic compounds from a gas stream. (The VOCs are later recovered from the carbon.) | Carbon Adsorption | A treatment system that removes contaminants from ground water or surface water by forcing it through tanks containing activated carbon treated to attract the contaminants. | Carbon Monoxide | A colorless, odorless, poisonous gas produced by incomplete fossil fuel combustion. | Carbon Tetrachloride | Compound consisting of one carbon atom ad four chlorine atoms, once widely used as a industrial raw material, as a solvent, and in the production of CFCs. Use as a solvent ended when it was discovered to be carcinogenic. | Carcinogen | Any substance that can cause or aggravate cancer. | Carrier | Any material or system that can facilitrate the movement of a pollutant into the body or cells. | Carrying Capacity | On a plot of bacterial growth versus time, the point at which the bacteria begin to die faster than they reproduce. | Cask | A thick-walled container (usually lead) used to transport radioactive material. Also called a coffin. | Catalyst | A substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed by the chemical reaction. | Catalytic Converter | An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by oxidizing them into carbon dioxide and water or reducing them to nitrogen. | Catalytic Incinerator | A control device that oxidizes volatile organic compounds (VOCs) by using a catalyst to promote the combustion process. Catalytic incinerators require lower temperatures than conventional thermal incinerators, thus saving fuel and other costs. | Categorical Exclusion | A class of actions which either individually or cumulatively would not have a significant effect on the human environment and therefore would not require preparation of an environmental assessment or environmental impact statement. | Categorical Pretreatment Standard | A technology-based effluent limitation for an industrial facility discharging into a municipal sewer system. Analogous in stringency to Best Availability Technology (BAT) for direct dischargers. | Cation | A positively charged ion. | Cementitious | Densely packed and nonfibrous friable materials. | Central Collection Point | Location were a generator of regulated medical waste consolidates wastes originally generated at various locations in his facility. The wastes are gathered together for treatment on-site or for transportation elsewhere for treatment and/or disposal. | Centrifugal Collector | A mechanical system using centrifugal force to remove aerosols from a gas stream or to remove water from sludge. | Channel Precipitation | The symbolic representation of a chemical reaction in terms of chemical formulas. | Channelization | Straightening and deepening streams so water will move faster, a marsh-drainage tactic that can interfere with waste assimilation capacity, disturb fish and wildlife habitats, and aggravate flooding. | Characteristic | Any one of the four categories used in defining hazardous waste: ignitability, corrosivity, reactivity, and toxicity. | Characterization of Ecological Effects | Part of ecological risk assessment that evaluates ability of a stressor to cause adverse effects under given circumstances. | Characterization of Exposure | Portion of an ecological risk assessment that evaluates interaction of a stressor with one or more ecological entities. | Check-Valve Tubing Pump | Water sampling tool also referred to as a water Pump. | Chemical | A chemical is any element, chemical compound or mixture of elements and/or compounds. | Chemical Case | For purposes of review and regulation, the grouping of chemically similar pesticide active ingredients (e.g., salts and esters of the same chemical) into chemical cases. | Chemical Oxygen Demand | A measure of the oxygen required to oxidize all compounds, both organic and inorganic, in water. | Chemical spill | Accident release occurring during the production, transportation or handling of hazardous chemical substances. | Chemical Stressors | Chemicals released to the environment through industrial waste, auto emissions, pesticides, and other human activity that can cause illnesses and even death in plants and animals. | Chemnet | Mutual aid network of chemical shippers and contractors that assigns a contracted emergency response company to provide technical support if a representative of the firm whose chemicals are involved in an incident is not readily available. | Chemotroph | Organisms that obtain their energy from organic or inorganic carbon rather than from light. | Chemtrec | The industry-sponsored Chemical Transportation Emergency Center; provides information and/or emergency assistance to emergency responders. | Chlorinated Hydrocarbons | Chemicals containing only chlorine, carbon, and hydrogen or any chlorinated organic compounds including chlorinated solvents. Includes DDT, aldrin, dieldrin, heptachlor, chlordane, dichloromethane, trichloromethylene, chloroform. | Chlorinated Solvent | An organic solvent containing chlorine atoms(e.g., methylene chloride and 1,1,1-trichloromethane). Uses of chlorinated solvents are include aerosol spray containers, in highway paint, and dry cleaning fluids. | Chlorofluorocarbons | A family of inert, nontoxic, and easily liquefied chemicals used in refrigeration, air conditioning, packaging, insulation, or as solvents and aerosol propellants. CFCs drift into the upper atmosphere where their chlorine components destroy ozone. | Chlorophenoxy | A class of herbicides that may be found in domestic water supplies and cause adverse health effects. | Chlorosis | Discoloration of normally green plant parts caused by disease, lack of nutrients, or various air pollutants. | Chronic Effect | An adverse effect on a human or animal in which symptoms recur frequently or develop slowly over a long period of time. | Chronic Exposure | Multiple exposures occurring over an extended period of time or over a significant fraction of an animal's or human's lifetime (Usually seven years to a lifetime.) | Chronic Toxicity | The capacity of a substance to cause long-term poisonous health effects in humans, animals, fish, and other organisms.(See: Acute toxicity.) | Circle of Influence | The circular outer edge of a depression produced in the water table by the pumping of water from a well. | Class I Area | A Class I area is one in which visibility is protected more stringently than under the national ambient air quality standards; includes national parks, wilderness areas, monuments, and other areas of special national and cultural significance. | Class I Substance | One of several groups of chemicals with an ozone depletion potential of 0.2 or higher, including CFCS, Halons, Carbon Tetrachloride, and Methyl Chloroform (listed in the Clean Air Act). | Class II Substance | A substance with an ozone depletion potential of less than 0.2. All HCFCs are currently included in this classification. | Clay Soil | Soil material containing more than 40 percent clay, less than 45 percent sand, and less than 40 percent silt. | Clean Air Act | The comprehensive federal law, which regulates air emissions. | Clean Coal Technology | Any technology not in widespread use prior to the Clean Air Act Amendments of 1990. This Act will achieve significant reductions in pollutants associated with the burning of coal. | Clean Fuels | Blends or substitutes for gasoline fuels, including compressed natural gas, methanol, ethanol, and liquified petroleum gas. | Clean Water Act | The Clean Water Act (CWA) is the cornerstone of surface water quality protection in the United States. (The Act does not deal directly with ground water nor with water quantity issues). The law employs a variety of regulatory and nonregulatory tools to sharply reduce direct pollutant discharges into waterways, finance municipal wastewater treatment facilities, and manage polluted runoff. | Cleaner Technologies Substitutes Assessment | A document that systematically evaluates the relative risk, performance, and cost trade-offs of technological alternatives; serves as a repository for all the technical data. | Cleanup | Actions taken to deal with a release or threat of release of a hazardous substance that could affect humans and/or the environment. | Cleanup Process | A comprehensive program for the clean up (or remediation) of a polluted site. It involves investigation, analysis, and development of a cleanup plan and implementation of that plan. | Climate Change | The term "climate change" is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. | Climatology | The science of studying climatic conditions. Climatic conditions studied are usually within a region of the earth over an extended period of time. | Closed-Loop Recycling | Reclaiming or reusing wastewater for non-potable purposes in an enclosed process. | Closure | The procedure a landfill operator must follow when a landfill reaches its legal capacity for solid ceasing acceptance of solid waste and placing a cap on the landfill site. | Co-fire | Burning of two fuels in the same combustion unit; e.g., coal and natural gas, or oil and coal. | Coal Cleaning Technology | A precombustion process by which coal is physically or chemically treated to remove some of its sulfur so as to reduce sulfur dioxide emissions. | Coastal Zone | Lands and waters adjacent to the coast that exert an influence on the uses of the sea and its ecology, or whose uses and ecology are affected by the sea. | Code of Federal Regulations | Document that codifies all rules of the executive departments and agencies of the federal government. It is divided into fifty volumes, known as titles. Title 40 of the CFR (referenced as 40 CFR) lists all environmental regulations. | Coefficient of Haze | A measurement of visibility interference in the atmosphere. | Coke Oven | An industrial process which converts coal into coke, one of the basic materials used in blast furnaces for the conversion of iron ore into iron. | Cold Temperature CO | A standard for automobile emissions of carbon monoxide (CO) emissions to be met at a low temperature (i.e. 20 degrees Fahrenheit). Conventional automobile catalytic converters are not efficient in cold weather until they warm up. | Coliform Index | A rating of the purity of water based on a count of fecal bacteria. | Coliform Organism | Microorganisms found in the intestinal tract of humans and animals. Their presence in water indicates fecal pollution and potentially adverse contamination by pathogens. | Collector Sewers | Pipes used to collect and carry wastewater from individual sources to an interceptor sewer that will carry it to a treatment facility. | Combined Sewer Overflows | Discharge of a mixture of storm water and domestic waste when the flow capacity of a sewer system is exceeded during rainstorms. | Combined Sewers | A sewer system that carries both sewage and storm-water runoff. During a heavy storm, the volume of water may be so great as to cause overflows of untreated mixtures of storm water and sewage into receiving waters. | Combustion | Burning accompanied by release of energy in the form of heat and light. Refers to controlled burning of waste, in which heat chemically alters organic compounds, converting into stable inorganics such as carbon dioxide and water. | Combustion Product | Substance produced during the burning or oxidation of a material. | Command-and-Control Regulations | Specific requirements prescribing how to comply with specific standards defining acceptable levels of pollution. | Comment Period | Time provided for the public to review and comment on a proposed EPA action or rulemaking after publication in the Federal Register. | Commingled Recyclables | Mixed recyclables that are collected together. | Comminuter | A machine that shreds or pulverizes solids to make waste treatment easier. | Common Sense Initiative | Voluntary program to simplify environmental regulation to achieve cleaner, cheaper, smarter results, starting with six major industry sectors. | Community Water System | A public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. | Comparative Risk Assessment | Process that generally uses the judgement of experts to predict effects and set priorities among a wide range of environmental problems. | Complex | A compound consisting of either complex ions with other ions of opposite charge or a neutral complex species. | Complex Ion | A metal ion with Lewis bases attached to it through coordinate covalent bonding. | Compliance Monitoring | Collection and evaluation of data, including self-monitoring reports, and verification to show whether pollutant concentrations and loads contained in permitted discharges are in compliance with the limits and conditions specified in the permit. | Compliance Schedule | A negotiated agreement between a pollution source and a government agency that specifies dates and procedures by which a source will reduce emissions and, thereby, comply with a regulation. | Composite Sample | A series of water samples taken over a given period of time and weighted by flow rate. | Composite sample | A sample created by combining several distinct subsamples. | Compounds | Substances containing two or more elements that are combined chemically. | Comprehensive Environmental Response, Compensation, and Liability Act | Federal law passed in 1980 that created a tax to fund Superfund, a trust fund used to investigate and clean up abandoned or uncontrolled hazardous waste sites. | Concentration | The relative amount of a substance mixed with another substance. An example is five ppm of carbon monoxide in air or 1 mg/l of iron in water. | Conditional Registration | Under special circumstances, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) permits registration of pesticide products that is "conditional" upon the submission of additional data. | Conditionally Exempt Generators | Persons or enterprises which produce less than 220 pounds of hazardous waste per month. Exempt from most regulation, they are required merely to determine whether their waste is hazardous, notify appropriate state or local agencies, and ship it offsite. | Conductance | A rapid method of estimating the dissolved solids content of water supply by determining the capacity of a water sample to carry an electrical current. Conductivity is a measure of the ability of a solution to carry and electrical curerent. | Cone of Depression | A depression in the water table that develops around a pumped well. | Cone of Influence | The depression, roughly conical in shape, produced in a water table by the pumping of water from a well. | Cone Penterometer Testing | A direct push system used to measure lithology based on soil penetration resistance. Sensors in the tip of the cone of the DP rod measure tip resistance and side-wall friction, transmitting electrical signals to digital processing equipment. | Confidential Business Information | Material that contains trade secrets or commercial or financial information that has been claimed as confidential by its source (e.g., a pesticide or new chemical formulation registrant). EPA has special procedures for handling such information. | Confidential Statement of Formula | A list of the ingredients in a new pesticide or chemical formulation. The list is submitted at the time for application for registration or change in formulation. | Confined Aquifer | An aquifer in which ground water is confined under pressure which is significantly greater than atmospheric pressure. | Confining Layer | The impermeable layers in an aquifer. | Consent Decree | A legal document, approved by a judge, that formalizes an agreement reached between EPA and potentially responsible parties (PRPs) through which PRPs will conduct all or part of a cleanup action at a Superfund site. | Conservation Easement | Easement restricting a landowner to land uses that are compatible with long-term conservation and environmental values. | Conservative Chemical | Most of the chemicals undergo chemical, biological or radioactive decay in the environment. Substances which do not undergo these types of reaction are called conservative substances. | Constituent(s) of Concern | Specific chemicals that are identified for evaluation in the site assessment process. | Construction Ban | If, under the Clean Air Act, EPA disapproves an area's planning requirements for correcting nonattainment, EPA can ban the construction or modification of any major stationary source of the pollutant for which the area is in nonattainment. | Consumption | Consumption is the rate of disappearance of a substance in a reaction. It can be defined as the moles or mass of a substance reacted with respect to time. Consumption terms contribute to disappearance of mass and thus are given a negative sign in a mass balance equation. | Consumptive Water Use | Water removed from available supplies without return to a water resources system, e.g., water used in manufacturing, agriculture, and food preparation. | Contaminant | Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil. | Contamination | Introduction into water, air, and soil of microorganisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the medium unfit for its next intended use. | Contamination Source Inventory | An inventory of contaminant sources within delineated State Water Protection Areas. Targets likely sources for further investigation. | Contingency Plan | A document setting out an organized, planned, and coordinated course of action to be followed in case of a fire, explosion, or other accident that releases toxic chemicals, hazardous waste, or radioactive materials. | Continuous Discharge | A routine release to the environment that occurs without interruption, except for infrequent shutdowns for maintenance, process changes, etc. | Continuous Emission Monitoring Systems | Machines that measure, on a continuous basis, how much pollution is being released into the air. For specific locations or stacks, CEMS measure the pollutants released (emitted) by that source into the air. | Continuous Opacity Monitoring Systems | Equipment used to sample and condition, analyze and provide permanent record of emissions or process parameters that reduce the transmission of light and obscure the view of a background object. | Continuous Sample | A flow of water, waste or other material from a particular place in a plant to the location where samples are collected for testing. May be used to obtain grab or composite samples. | Contour Plowing | Soil tilling method that follows the shape of the land to discourage erosion. | Control Technique Guidelines | EPA documents designed to assist state and local pollution authorities to achieve and maintain air quality standards for certain sources through reasonably available control technologies. | Control technology; control measures | Equipment, processes or actions used to reduce air pollution. The extent of pollution reduction varies among technologies and measures. | Control Volume | Control Volume is the region of space over which our attention is focussed. It is any arbitrary portion of system set out specifically for analysis. It is common to break down a larger system such as a Water Treatment Plant into smaller blocks, each being a control volume. | Controlled Reaction | A chemical reaction under temperature and pressure conditions maintained within safe limits to produce a desired product or process. | Conventional Pollutants | Statutorily listed pollutants understood well by scientists. These may be in the form of organic waste, sediment, acid, bacteria, viruses, nutrients, oil and grease, or heat. | Conventional Site Assessment | Assessment in which most of the sample analysis and interpretation of data is completed off-site; process usually requires repeated mobilization of equipment and staff in order to fully determine the extent of contamination. | Convergence | As two waves merge the wave height will increase totaling the height of both individual waves. Increased wave heights will also occur when the depth of water in which they are travelling decreases. The opposite of DIVERGENCE. | Conveyance Loss | Water loss in pipes, channels, conduits, ditches by leakage or evaporation. | Cooperative Agreement | An assistance agreement whereby EPA transfers money, property, services or any- thing of value to a state, university, non-profit, or not-for-profit organization for the accomplishment of authorized activities or tasks. | Core Program Cooperative Agreement | An assistance agreement whereby EPA supports states or tribal governments with funds to help defray the cost of non-item-specific administrative and training activities. | Corrective Action | EPA can require treatment, storage and disposal (TSDF) facilities handling hazardous waste to undertake corrective actions to clean up spills resulting from failure to follow hazardous waste management procedures or other mistakes. | Corrective Measures Implementation | Part of the RCRA Process. The CMI phase involves the design and implementation of a chosen remedy. | Cost Recovery | A legal process by which potentially responsible parties who contributed to contamination at a Superfund site can be required to reimburse the Trust Fund for money spent during any cleanup actions by the federal government. | Cost Sharing | A publicly financed program through which society, as a beneficiary of environmental protection, shares part of the cost of pollution control with those who must actually install the controls. | Cost/Benefit Analysis | A quantitative evaluation of the costs which would bve incurred by implementing an environmental regulation versus the overall benefits to society of the proposed action. | Covalent Bond | A bond formed by the sharing of a pair of electrons between atoms. | Cradle-to-Grave | A procedure in which hazardous materials are identified and followed as they are produced, treated, transported, and disposed of by a series of permanent, linkable, descriptive documents. | Criteria | Descriptive factors taken into account by EPA in setting standards for various pollutants. These factors are used to determine limits on allowable concentration levels, and to limit the number of violations per year. | Criteria Air Pollutants | A group of very common air pollutants regulated by EPA on the basis of criteria (information on health and/or environmental effects of pollution. | Critical Effect | The first adverse effect, or its known precursor, that occurs as a dose rate increases. Designation is based on evaluation of overall database. | Cross Contamination | The movement of underground contaminants from one level or area to another due to invasive subsurface activities. | Cryptosporidium | A protozoan microbe associated with the disease cryptosporidiosis in man. The disease can be transmitted through ingestion of drinking water or person-to-person and can cause acute diarrhea, abdominal pain, vomiting, fever, and can be fatal. | Cubic Feet Per Minute | A measure of the volume of a substance flowing through air within a fixed period of time. With regard to indoor air, refers to the amount of air, in cubic feet, that is exchanged with outdoor air in a minute's time; i.e., the air exchange rate. | Cultural Eutrophication | Increasing rate at which water bodies "die" by pollution from human activities. | Cumulative Ecological Risk Assessment | Consideration of the total ecological risk from multiple stressors to a given eco-zone. | Cumulative Exposure | The sum of exposures of an organism to a pollutant over a period of time. | Current | The part of a fluid body (air or water) that moves continuously in a certain direction. | Cutie-Pie | An instrument used to measure radiation levels. | Cyclone Collector | A device that uses centrifugal force to remove large particles from polluted air. | Cyclone furnace | The type of furnace used in the Minergy Clear Horizons process. It is where the wastewater sludge (and coal and limestone flux) is combusted to form the glass aggregate. | Data quality objective (DQO) process | A systematic planning tool to facilitate the planning of
environmental data collection activities (see: U.S. EPA, 1994, 1996a, 1996c, 1997, 2000a, and
2000d). The DQO process allows planners to focus their planning efforts by specifying the intended
use of the data, the decision criteria, and the decision maker’s tolerable decision error rates. Data
quality objects are the qualitative and quantitative outputs from the DQO process. | Data Quality Objectives | Statements of the overall level of uncertainty that a decision-maker will accept in results or decisions based on environmental data. They provide the statistical framework for planning and managing environmental data operations. | Data Quality Objectives | Qualitative and quantitative statements derived from the DQO
process that clarify study objectives, define the appropriate types of data, and specify tolerable levels
of potential decision errors that will be used as the basis for establishing the quality and quantity of
the data needed to support decisions. | Datum | A chosen point used as a basis for calculating or measuring. | Day Tank | Another name for deaerating tank. (See: Age tank). | Death Rate | The number of organisms that die per unit time divided by the number of organisms alive at the beginning of that time period. | Debris | Broken, scattered remains; rubble; pieces of rubbish or litter. | Decant | To draw off the upper layer of liquid after the heaviest material (a solid or another liquid) has settled. | Decay Products | Degraded radioactive materials, often referred to as "daughters" or "progeny"; radon decay products of most concern from a public health standpoint are polonium-214 and polonium-218. | Decontamination | Removal of harmful substances such as noxious chemicals, harmful bacteria or other organisms, or radioactive material from exposed individuals, rooms and furnishings in buildings, or the exterior environment. | Deep-Well Injection | Deposition of raw or treated, filtered hazardous waste by pumping it into deep wells, where it is contained in the pores of permeable subsurface rock. | Deflation | The removal of loose material from a beach or other land surface by wind or wave action. | Defoliant | An herbicide that removes leaves from trees and growing plants. | Deforestation | Those practices or processes that result in the change of forested lands to non-forest uses. | Delegated State | A state (or other governmental entity such as a tribal government) that has received authority to administer an environmental regulatory program in lieu of a federal counterpart. The term does not connote any transfer of federal authority to a state. | Delist | Use of the petition process to have a facility's toxic designation rescinded. | Denitrification | The biological reduction of nitrate to nitrogen gas by denitrifying bacteria in soil. | Denitrification | The process in which nitrate is reduced by bacteria to nitrogen gas and lost from the system. | Dense Non-Aqueous Phase Liquid | Non-aqueous phase liquids that sink through the water column until they reach a confining layer. Because they are at the bottom of aquifers instead of floating on the water table, typical monitoring wells do not indicate their presence. | Density | A measure of how heavy a specific volume of a solid, liquid, or gas is in comparison to water. | Depletion Curve | In hydraulics, a graphical representation of water depletion from storage-stream channels, surface soil, and groundwater. A depletion curve be drawn for base flow, direct runoff, or total flow. | Depressurization | A condition that occurs when the air pressure inside a structure is lower that the air pressure outdoors. Radon may be drawn into a house more rapidly under depressurized conditions. | Dermal Absorption/Penetration | Process by which a chemical penetrates the skin and enters the body as an internal dose. | Dermal Toxicity | The ability of a pesticide or toxic chemical to poison people or animals by contact with the skin. | Desalination | 1) Removing salts from ocean or brackish water by using various technologies. 2) Removal of salts from soil by artificial means, usually leaching. | Description of Current Conditions | A document required by the EPA before a site investigation begins that includes what is known about the background and existing state of the site. | Desiccant | A chemical agent that absorbs moisture; some desiccants are capable of drying out plants or insects, causing death. | Design Value | The monitored reading used by EPA to determine an area's air quality status; e.g., for ozone, the fourth highest reading measured over the most recent three years is the design value. | Designated Pollutant | An air pollutant which is not a hazardous pollutant described in the Clean Air Act, but for which source performance standards exist. The Clean Air Act does require states to control these pollutants which include acid mist and total reduced sulfur (TRS). | Designated Uses | Those water uses identified in state water quality standards that must be achieved and maintained as required under the Clean Water Act. Uses can include cold water fisheries, public water supply, and irrigation. | Designer Bugs | Popular term for microbes developed through biotechnology that can degrade specific toxic chemicals at their source in toxic waste dumps or in ground water. | Destination Facility | The facility to which regulated medical waste is shipped for treatment and destruction, incineration, and/or disposal. | Destratification | Vertical mixing within a lake or reservoir to totally or partially eliminate separate layers of temperature, plant, or animal life. | Destruction and Removal Efficiency | A percentage that represents the number of molecules of a compound removed or destroyed in an incinerator relative to the number of molecules entering the system. For some pollutants, the RCRA removal requirement may be as stringent as 99.9999 percent. | Desulfurization | Removal of sulfur from fossil fuels to reduce pollution. | Detection Criterion | A predetermined rule to ascertain whether a tank is leaking or not. Most volumetric tests use a threshold value as the detection criterion. | Detection Limit | The lowest concentration of a chemical that can reliably be distinguished from a zero concentration. | Detergent | Synthetic washing agent that helps to remove dirt and oil. Some contain compounds which kill useful bacteria and encourage algae growth when they are in wastewater that reaches receiving waters. | Development Effects | Adverse effects such as altered growth, structural abnormality, functional deficiency, or death observed in a developing organism. | Dewater | 1. Remove or separate a portion of the water in a sludge or slurry to dry the sludge so it can be handled and disposed off. 2.Remove or drain the water from a tank or trench. | Diatom | Microscopic algae with cell walls made of silicon and of two separating halves. | Diazinon | An insecticide. In 1986, EPA banned its use on open areas such as sod farms and golf courses because it posed a danger to migratory birds. The ban did not apply to agricultural, home lawn or commercial establishment uses. | Dibenzofurans | A group of organic compounds, some of which are toxic. | Dichloro-Diphenyl-Trichloroethane | Insecticide that can collect in fatty tissues of certain animals. EPA banned registration and interstate sale of DDT for virtually all but emergency uses in the United States in 1972. | Dicofol | A pesticide used on citrus fruits. | Diethylstilbestrol | A synthetic estrogen, diethylstilbestrol is used as a growth stimulant in food animals. Residues in meat are thought to be carcinogenic. | Diffused Air | A type of aeration that forces oxygen into sewage by pumping air through perforated pipes inside a holding tank. | Diffusion | The movement of suspended or dissolved particles (or molecules) from a more concentrated to a less concentrated area. The process tends to distribute the particles or molecules more uniformly. | Digestion | The biochemical decomposition of organic matter, resulting in partial gasification, liquefaction, and mineralization of pollutants. | Dike | A low wall that can act as a barrier to prevent a spill from spreading. | Dilution Ratio | The relationship between the volume of water in a stream and the volume of incoming water. It affects the ability of the stream to assimilate waste. | Dimictic | Lakes and reservoirs that freeze over and normally go through two stratifications and two mixing cycles a year. | Dinocap | A fungicide used primarily by apple growers to control summer diseases. EPA proposed restrictions on its use in 1986 when laboratory tests found it caused birth defects in rabbits. | Dinoseb | A herbicide that is also used as a fungicide and insecticide. It was banned by EPA in 1986 because it posed the risk of birth defects and sterility. | Dioxin | Any of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity as contaminants in commercial products. Tests on laboratory animals indicate that it is one of the more toxic man-made compounds. | Direct Discharger | A municipal or industrial facility which introduces pollution through a defined conveyance or system such as outlet pipes; a point source. | Direct Push | Technology used for performing subsurface investigations by driving, pushing, and/or vibrating small-diameter hollow steel rods into the ground. Also known as direct drive, drive point, or push technology. | Direct Runoff | Water that flows over the ground surface or through the ground directly into streams, rivers, and lakes. | Discharge | Flow of surface water in a stream or canal or the outflow of ground water from a flowing artesian well, ditch, or spring. Can also apply to of liquid effluent from a facility or to chemical emissions into the air through designated venting mechanisms. | Disinfectant | A chemical or physical process that kills pathogenic organisms in water, air, or on surfaces. Chlorine is often used to disinfect sewage treatment effluent, water supplies, wells, and swimming pools. | Disinfectant By-Product | A compound formed by the reaction of a disinfectant such as chlorine with organic material in the water supply; a chemical byproduct of the disinfection process. | Dispersal | The movement of an animal from the location of it birth to a new area where it lives and reproduces. | Dispersant | A chemical agent used to break up concentrations of organic material such as spilled oil. | Dispersion | Dispersion is the spreading of the solute from the path that it is expected to follow according to advective hydraulics. Dispersion can be classified into two Categories: Turbulent diffusion and Hydrodynamic dispersion. | Disposables | Consumer products, other items, and packaging used once or a few times and discarded. | Disposal | Final placement or destruction of toxic, radioactive, or other wastes; surplus or banned pesticides or other chemicals; polluted soils; and drums containing hazardous materials from removal actions or accidental releases. | Dissolution Reaction | A procedure by which one substance is dissolved in another to form a solution. | Dissolved Oxygen | The oxygen freely available in water, vital to fish and other aquatic life and for the prevention of odors. DO levels are most important indicator of a water body's ability to support desirable aquatic life. | Dissolved Solids | Disintegrated organic and inorganic material in water. Excessive amounts make water unfit to drink or use in industrial processes. | Distillation | The act of purifying liquids through boiling, so that the steam or gaseous vapors condense to a pure liquid. Pollutants and contaminants may remain in a concentrated residue. | Divergence | When a wave separates creating two waves, the wave height of each wave will decrease as the distance between them increases. Decreased wave heights will also occur as the depth of water in which they are travelling increases. | Diversion Rate | The percentage of waste materials diverted from traditional disposal such as landfilling or incineration to be recycled, composted, or re-used. | Domestic Application | Pesticide application in and around houses, office buildings, motels, and other living or working areas. | Dosage/Dose | The actual quantity of a chemical administered to an organism or to which it is exposed. 2. The amount of a substance that reaches a specific tissue. | Dose Rate | In exposure assessment, dose per time unit (e.g., mg/day), sometimes also called dosage. | Dose Response | Shifts in toxicological responses of an individual (such as alterations in severity) or populations (such as alterations in incidence) that are related to changes in the dose of any given substance. | Dose Response Curve | Graphical representation of the relationship between the dose of a stressor and the biological response thereto. | Dose-Response Assessment | 1. Estimating the potency of a chemical. 2. In exposure assessment, the process of determining the relationship between the dose of a stressor and a specific biological response. | Dose-Response Relationship | The quantitative relationship between the amount of exposure to a substance and the extent of toxic injury or disease produced. | Dosimeter | An instrument to measure dosage; many so-called dosimeters actually measure exposure rather than dosage. Dosimetry is the process or technology of measuring and/or estimating dosage. | DOT Reportable Quantity | The quantity of a substance specified in a U.S. Department of Transportation regulation that triggers labeling, packaging and other requirements related to shipping such substances. | Downdrift | The predominant direction of movement of shoreline materials, such as sand. | Downgradient | The direction the groundwater flows; similar to "downstream" for surface water. | Draft | 1. The act of drawing or removing water from a tank or reservoir. 2. The water which is drawn or removed. | Drainage Basin | The area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel. | Drainage Well | A well drilled to carry excess water off agricultural fields. Because they act as a funnel from the surface to the groundwater below. Drainage wells can contribute to groundwater pollution. | Drawdown | 1. The drop in the water table or level of water in the ground when water is being pumped from a well. 2. The amount of water used from a tank or reservoir. 3. The drop in the water level of a tank or reservoir. | Dredging | Removal of mud from the bottom of water bodies. This can disturb the ecosystem and causes silting that kills aquatic life. Dredging of contaminated muds can expose biota to heavy metals and other toxins. | Drilling Fluid | Fluid used to lubricate the bit and convey drill cuttings to the surface with rotary drilling equipment. Usually composed of bentonite slurry muddy water. Can become contaminated, leading to cross contamination, and may require special disposal. | Drinking Water Equivalent Level | Protective level of exposure related to potentially non-carcinogenic effects of chemicals that are also known to cancer. | Drinking Water State Revolving Fund | Grants to help finance system infrastructure improvements, assure source-water protection, enhance operation and management of drinking-water systems, and otherwise promote local water-system compliance and protection of public health. | Drive Casing | Heavy duty steel casing driven along with the sampling tool in cased DP systems. Keeps the hole open between sampling runs and is not removed until last sample has been collected. | Drive Point Profiler | A system used to collect multiple depth-discrete groundwater samples. Ports in the tip of the probe connect to an internal stainless steel or teflon tube that extends to the surface. Samples are collected via suction or airlift methods. | Dry Scrubbing | The removal of sulfur dioxide (SO2) and toxics by using lime and minimal amounts of water to provide humidification. | Dual-Phase Extraction | Active withdrawal of both liquid and gas phases from a well usually involving the use of a vacuum pump. | Due Care | Due Care:1. prevent exacerbation of existing contamination 2. eliminate unacceptable exposure to occupants 3. take reasonable precautions against acts or omissions of a third party. | Due Care compliance Plan | Once the property is determined a facility, and the owner complies with BEA, they must comply with Due Care to maintain protection from liability. | Dustfall Jar | An open container used to collect large particles from the air for measurement and analysis. | Dystrophic Lakes | Acidic, shallow bodies of water that contain much humus and/or other organic matter; contain many plants but few fish. | Ecological Entity | In ecological risk assessment, a general term referring to a species, a group of species, an ecosystem function or characteristic, or a specific habitat or biome. | Ecological Exposure | Exposure of a non-human organism to a stressor. | Ecological Impact | The effect that a man-caused or natural activity has on living organisms and their non-living (abiotic) environment. | Ecological Indicator | A characteristic of an ecosystem that is related to a measure of biotic or abiotic variable, that can provide quantitative information on ecological structure and function. An indicator can contribute to a measure of integrity and sustainability. | Ecological Integrity | A living system exhibits integrity if, when subjected to disturbance, it sustains and organizes self-correcting ability to recover toward a biomass end-state that is normal for that system. | Ecological Risk Assessment | The application of an analytical process or model to estimate the effects of human actions(s) on a natural resource and to interpret the significance of those effects in light of the uncertainties identified in each component of the assessment process. | Ecological System | A community of organisms that interact with one another and with their physical environnent, including sunlight, rainfall, and soil nutrients. | Ecological/Environmental Sustainability | Maintenance of ecosystem components and functions for future generations. | Ecology | The science that studies the relationship of living organisms to each other and to their environment. | Ecoregion | Regions defined by similarity of climate, landform, soil, potential natural vegetation, hydrology, and other ecologically relevant variables. | Ecosystem | The biotic community and abiotic environment within a specified location and time including the chemical, physical and biological relationships among the biotic and abiotic components. | Ecosystem Structure | Attributes related to the instantaneous physical state of an ecosystem; examples include species population density, species richness or evenness, and standing crop biomass. | Ecotone | A habitat created by the juxtaposition of distinctly different habitats; an edge habitat; or an ecological zone or boundary where two or more ecosystems meet. | Effluent | Wastewater--treated or untreated--that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters. | Ejector | A device used to disperse a chemical solution into water being treated. | Electrode | Conducting body at which the electrochemical reaction occurs. |
