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Glossary Terms

Back to the overview of the Oil and Chemical Spill Glossary.


The process by which one substance draws into itself another substance. Example: a sponge picking up water; an oil absorbent pulling in petroleum products. Compare with adsorption.
A substance that donates hydrogen ions that can be accepted by a base. Acids have a pH below 7. Contrast with base.
Acute health effects usually develop rapidly after a short-term exposure to hazardous chemicals. Acute effects have a short duration. Contrast with chronic.
The process by which one substance is attracted to and adheres to the surface of another substance without actually penetrating its internal structure. Compare with absorption.
Acute Exposure Guideline Level, a level of concern representing the adverse health effects of a hazardous substance on members of the general public. The AEGLs are developed by the National Research Council’s National Advisory Committee on AEGLs (
aerial observation
Viewing a spill from a helicopter, fixed-wing aircraft, or vessel to assess the character and extent of pollutant spilled on the water. See also overflight.
Living, growing, and reproducing in an environment with air or oxygen present (e.g., aerobic bacteria). Contrast with anaerobic.
Fine liquid droplets (or solid particles) suspended in a gas.
Likely to react rapidly or violently with dry air or moist air; may generate toxic and corrosive fumes upon exposure to air, or may catch fire.
Automatic Identification System. A system used by ships and vessel traffic systems for identifying vessels at sea, particularly when the ships are not in sight (e.g., at night, in fog, in radar blind arcs or shadows, or at distance). AIS provides a means for ships to exchange ID, position, course, speed, and other data with all other nearby ships and vessel traffic system stations.
A general description given to strong bases, including the hydroxides and carbonates of the "alkali metal" or group 1A of the Periodic Table. Examples include sodium hydroxide and potassium hydroxide. A synonym for the strong alkalis is caustics.
Having a high concentration of hydroxide ions in aqueous solution (i.e., a pH greater than 7). Strongly alkaline aqueous solutions are very corrosive to skin, metal, and other materials. See also base.
A "crash" of a vessel with a fixed object. Contrast with collision.
Computer model that predicts the area potentially affected by a toxic gas release, fire, or explosion; ALOHA is a component of the CAMEO software suite. Find out more about ALOHA on the NOAA OR&R website (
ambient temperature and pressure
Typical outdoor temperature and pressure.
Fish that spend most of their life in saltwater but migrate to freshwater to spawn (breed and lay eggs). Examples include salmon, river herring (alewife), and striped bass. Contrast with catadromous.
Living, growing, and reproducing in an environment without air or oxygen (e.g., anaerobic bacteria). Contrast with aerobic.
Ammonium nitrate-fuel oil mixtures used in commercial explosives.
Lit. "without water." A chemical shipped or stored without water, rather than in solution, is in anhydrous form (anhydrous ammonia is a common example).
Having to do with or caused by humans.
American Petroleum Institute ( A national trade association that represents all aspects of the U.S. oil and natural gas industry, from exploration through marketing.
API gravity
The density of petroleum liquids expressed in degrees according to an American Petroleum Institute (API) recommended scale. The measuring scale is calibrated in terms of degrees API. The higher the API gravity, the lower the density of the compound. Crude oil is classified as light, medium or heavy, according to its measured API gravity. API gravity is dependent on temperature and barometric pressure, and therefore generally is measured at 16° C and 1 atmospheric pressure. Oils with low specific gravity have high API gravity and vice versa. API specific gravity can be calculated using the following formula: API Gravity = (141.5/Specific gravity at 16° C) - 131.5.
In an aqueous solution, a substance is dissolved in water.
See Assessment and Restoration Division.
aromatic hydrocarbons
Hydrocarbons characterized by unsaturated ring structures of the carbon atoms. Commercial petroleum aromatics are benzene, toluene and xylenes. Aromatics are the heaviest, have the highest boiling points and are the most toxic of the crudes.
Thick, viscous, petroleum-based mixture used to surface roads, for roofing, and in other products.
Can cause unconsciousness or death by displacing oxygen from the air; especially dangerous in confined spaces.
See Natural Resource Damage Assessment.
Assessment and Restoration Division (ARD)
A division of NOAA’s Office of Response and Restoration (OR&R) that works to protect and restore coastal natural resources injured by hazardous substances, such as waste sites, oil and chemical spills, and ship groundings. Formerly the Coastal Protection and Restoration Division (CPRD).
Atlantic Intracoastal Waterway
The portion of the Intracoastal Waterway located along the Atlantic coast of the U.S. It is a navigable inland waterway extending from Key West, Florida to Boston, Massachusetts. See also Intracoastal Waterway.
Agency for Toxic Substances and Disease Registry ( Federal public health agency that provides health information related to toxic substances.
autoignition temperature
Minimum temperature at which a substance ignites when no ignition source (e.g., spark or flame) is present.


ballast tanks
Special tanks on large ships that are used to provide stability needed when a ship is carrying less than a full load of cargo and to keep it at the proper depth in the water. When the ship is loaded with cargo, the ballast tanks are emptied and its contents (usually sea water) are released to surrounding waters; when the ship is empty, the ballast tanks are filled with water (or other substance like soil or sand) to keep it upright.
A unit of volume used for crude oil or other petroleum products. A barrel is equal to exactly 42 U.S. gallons or approximately 35 Imperial (UK) gallons.
barrier or containment barrier
With respect to oil spill cleanup, any non-floating structure which is constructed to contain or divert spilled oil. Barriers are generally improvised and, unlike booms, are usually left in place until the cleanup program is complete. Sorbent materials may be used in the barrier construction to simultaneously recover spilled oil. Barriers are most frequently used in streams or ditches too shallow for conventional floating booms, and are almost always staked downstream of the spill site.
A substance that accepts hydrogen ions donated by an acid. Bases have a pH greater than 7. Contrast with acid.
bathymetric survey
The process of gathering information about navigable waters in order to map the sea floor elevations (topography) and the variations of water depth.
Abbreviation for barrel.
Animals dwelling on the bottom of a water body. These organisms inhabit the sediment on lake, river, or ocean bottoms, as well as the sediment in marshes, tidal flats, and other wetlands. Associated with sediments on the bottom of a water body. Contrast with pelagic.
(1) A raised shoulder or dike around a tank or tank farm, providing a reservoir should any oil be discharged from the tanks. (2) A low impermanent, nearly horizontal or landward-sloping beach, shelf, ledge, or narrow terrace on the back-shore of a beach, formed of material thrown up and deposited by storm waves; it is generally bounded on one side or the other by a beach ridge or beach scarp. Some beaches have no berm, others may have one or several.
The lowest point of a ship’s inner hull. Water, waste oil, and other pollutants tend to collect in the bilge, and if flushed while at sea, the oil can form a slick on the ocean’s surface and in turn cause incidental oiling of passing birds.
The property of a material to decompose naturally.
The chemical breakdown of materials by living organisms in the environment. Biodegradation depends on certain microorganisms, such as bacteria, yeast, and fungi, which break down molecules for use as food energy. Certain chemical structures are more susceptible to microbial breakdown than others; vegetable oils, for example, will biodegrade more rapidly than petroleum oils.
biological agent
Microorganisms (primarily bacteria) added to the water column or soil to increase the rate of biodegradation of spilled oil. Alternatively, nutrients added to the water (in the form of fertilization) to increase the growth and biodegradation capacity of microorganisms already present. Also, a type of weapon of mass destruction.
The act of adding fertilizers or other materials to contaminated environments, such as oil spill sites, to accelerate the natural biodegradation process. Three main types of bioremediation technologies are currently being developed or applied for treatment of oil spills: addition of fertilizer to oiled shorelines, addition of microbial products to oiled shorelines, and addition of fertilizer and/or microbial products to open-water oil slicks.
Member of the invertebrate class Bivalvia, including the shellfish groups with two hinged shells, such as oysters.
black oil
A black or very dark brown layer of oil. Depending on the quantity spilled, oil tends to quickly spread out over the water surface to a thickness of about 1 millimeter (0.04 inches). However, from the air, it is impossible to tell how thick a black oil layer is.
Boiling Liquid Expanding Vapor Explosion. BLEVEs typically occur in closed storage tanks that contain a liquefied gas, usually a gas that has been liquefied under pressure. A common BLEVE scenario happens when a container of liquefied gas is heated by fire, increasing the pressure within the container until the tank ruptures and fails. When the container fails, the chemical is released in an explosion. If the chemical is above its boiling point when the container fails, some or all of the liquid will flash-boil—that is, instantaneously become a gas. If the chemical is flammable, a burning gas cloud called a fireball may occur if a significant amount of the chemical flash-boils. Potential BLEVE hazards include thermal radiation, overpressure, hazardous fragments, smoke, and toxic byproducts from the fire. See also liquefied gases, liquified natural gas, and liquified petroleum gas.
An uncontrolled flow of gas, oil, or other fluids from a well into the atmosphere or into an underground formation. A well may blow out when formation pressure exceeds the pressure applied to it by the column of drilling fluid.
boiling point
The maximum temperature at which a substance’s liquid phase can exist in equilibrium with its vapor phase. Above the boiling point, a liquid vaporizes completely. The boiling point depends on a chemical’s composition and the applied pressure. As pressure increases, the boiling point of a substance also increases. The boiling point is also the temperature at which the vapor pressure of a liquid is equal to the applied atmospheric pressure.
boom (containment)
A temporary floating barrier used to contain an oil spill. Booms are used to reduce the possibility of polluting shorelines and other resources, and to help make recovery easier. Booms help to concentrate oil in thicker surface layers so that skimmers, vacuums, or other collection methods can be used more effectively. They come in many shapes and sizes, with various levels of effectiveness in different types of water conditions.
boom failure
Failure of a boom to contain oil due to excessive winds, waves or currents, or improper deployment. Boom failure may be manifested in oil under-flow, oil splash-over or structural breakage.
Water with a salinity less than ocean or seawater (about 35 ppt) and greater than freshwater (0 ppt).
brown oil
Typically a 0.1mm - 1.0mm thick layer of water-in-oil emulsion (thickness can vary widely depending on wind and current conditions).
bulk carrier
An ocean-going vessel specifically designed to transport large quantities of a single product, such as grain or coal.
bunker fuel (or bunkers)
Heavy, residual fuel oil used for a vessel’s own engines or boilers. Bunker fuel gets its name from the containers on ships and in ports that it is stored in, called bunkers. Bunker A (a lighter fuel oil, such as No. 2 fuel) is distilled from crude oil; bunker B is relatively viscous oil (No. 4 or No. 5 fuel); and bunker C is very viscous (No. 6 fuel). Since No. 6 is the most common, "bunker fuel" is often used as a synonym for No. 6.
A floating object that is generally anchored to the bottom of the sea. It is often used as a navigational aid and to mark a mooring location.


Centigrade (Celsius in Europe). Temperature based on 0° C for the temperature at which water freezes and 100° C for the temperature at which water boils. Conversion to Centigrade from the Fahrenheit temperature scale is by the following formula: C = 5/9F - 32, where F is the temperature in Fahrenheit degrees. Contrast with F (Fahrenheit).
A suite of software programs developed by NOAA and EPA. CAMEO supports a number of information management functions, such as retrieval of chemical-specific information to support emergency response activities, threat zone calculation and plotting for risk assessment, organization and management of EPCRA information, and storage and computer display of area maps. Find out more about CAMEO on the NOAA OR&R website ( See also ALOHA.
Captain of the Port (COTP)
The lead federal security officer at U.S. ports.
A chemical substance or agent capable of causing or producing cancer.
CAS number
Or CAS #. Chemical Abstracts Service Registry number. This chemical identification number, in the format XXX-XX-X, is assigned by the American Chemical Society (
Fish that spend at least part of their lives in freshwater but migrate to saltwater to spawn (breed and lay eggs). An example is the American eel. Contrast with anadromous.
A substance that speeds up (catalyzes) a chemical reaction between other substances without itself being chemically changed or consumed. Catalysts are widely used in the chemical industry. For example, an iron/aluminum catalyst is used to synthesize ammonia and a platinum catalyst is used to manufacture nitric acid. Contrast with inhibitor.
To act as a catalyst.
Strongly basic, with high pH. Very corrosive. See also base.
Centers for Disease Control and Prevention ( Federal agency that conducts research and provides information about environmental health and other public health threats.
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (, as amended by the Superfund Amendments and Reauthorization Act (SARA) in 1986, often referred to as Superfund. The federal statute establishes liability for site cleanup, prescribes a procedure for identifying and ranking contaminated sites, provides a funding mechanism for site cleanups, reduces uncontrolled releases of hazardous substances, establishes cleanup procedures that provide protection for humans and the environment, and restores injured natural resources through provisions administered by the natural resource trustees. See also Superfund.
The group of wholly aquatic mammals that includes whales and dolphins.
See U.S. Coast Guard.
chemical agents
Those elements, compounds, or mixtures that disperse, dissolve, emulsify, neutralize, or otherwise mitigate the adverse effects of a pollutant or remove it from the environment. Examples include dispersants, biological additives, burning agents, and sinking agents. Also, a type of weapon of mass destruction.
chemical dispersant
See dispersant.
Of long duration, or frequently recurring. Chronic health effects become apparent and/or continue for some time after exposure to hazardous chemicals. Contrast with acute.
The removal and/or treatment of oil, hazardous substances, and/or the waste or contaminated materials generated by a spill incident. Cleanup includes restoration of the site and its natural resources.
Clean Water Act (CWA)
The law (also called the Federal Water Pollution Control Act of 1972) that established the framework for restoring and maintaining the chemical, physical, and biological integrity of U.S. waters. The CWA generally prohibits discharges of oil and hazardous substances into coastal or ocean waters. The 1973 amendments mandated the development of a National Contingency Plan (NCP).
Coastal Protection and Restoration Division (CPRD)
See Assessment and Restoration Division (ARD).
A "crash" between two moving objects, such as two vessels. Contrast with allision.
Can be ignited and burned. Combustible liquids have flash points between 100 - 200° F (37.8 - 93.3° C).
Also burning. A chemical reaction between oxygen and another element or compound that is rapid and exothermic enough to generate heat and light.
Command Post
See Incident Command Post.
The combination of two or more elements into a distinct chemical material.
The amount of a chemical present in a given weight or volume of air. Concentration of a gas in air may be expressed in units such as parts per million (by volume) or milligrams per cubic meter.
Hydrocarbons that are gases under reservoir conditions and that become liquid when temperature or pressure is reduced. A mixture of pentanes and higher hydrocarbons.
The process of preventing the spread of oil beyond the area where it has been spilled in order to minimize pollution and facilitate recovery.
containment barrier
See barrier.
contingency plan
A document used by (1) federal, state, and local agencies to guide their planning and response procedures regarding spills of oil, hazardous substances, or other emergencies; (2) a document used by industry as a response plan to spills of oil, hazardous substances, or other emergencies occurring upon their vessels or at their facilities. A contingency plan usually consists of guidelines developed for a specific industrial facility or an entire region to increase the effectiveness, efficiency and speed of cleanup operations in the event of a chemical or oil spill.
convergence line or zone
A line or area on the water surface where floating material, such as oil, can collect. A convergence can be located at the interface between two different types or bodies of water, or it can be caused by a significant depth change, tidal changes, or other common phenomena. Convergences are common in the marine environment.
Liquid or solid that can destroy human skin or lung tissue or corrode metals.
See Captain of the Port.
Treatments applied to shorelines and waterways (such as manual removal of oil, low- to high-pressure washing, use of dispersants, etc.) intended to contain, clean up, or otherwise reduce the adverse effects of spilled oil on the environment.
The amount of oil or other pollutant occupying the shore or water surface.
Coastal Resource Coordinator, now known as a Regional Resource Coordinator (RRC). The point of contact for the efforts of NOAA OR&R’s Assessment and Restoration Division (ARD). RRCs are NOAA environmental scientists who assess ecological risk and environmental and economic injury from contamination at hazardous waste sites or spill incidents, and coordinate among trustee agencies.
crude oil
An unrefined petroleum, usually liquid, consisting of a mixture of hydrocarbons. It generally ranges in gravity from 9° API to 55° API and in color from yellow to black. Crude oils may be referred to as heavy, medium, or light, according to API gravity. Crude oil may be refined into any of hundreds of components, such as commercial gasoline, kerosene, heating oils, diesel oils, lubricating oils, waxes, and asphalts.
Very low temperature.


See Damage Assessment Center.
Damage Assessment Center (DAC)
One of three offices within NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP). DAC is responsible for assessing the impact to NOAA trust resources from releases of oil and hazardous materials to achieve the goal of restoration. DAC staff determines what resources have been injured and lost to the public, and identifies resources that should be restored.
Damage Assessment, Remediation, and Restoration Program (DARRP)
A NOAA program that collaborates with other agencies, industry, and citizens to protect and restore coastal and marine resources threatened or injured by oil spills, releases of hazardous substances, and vessel groundings (
See Damage Assessment, Remediation, and Restoration Program.
The breakdown of a material or substance by heat, chemical reaction, electrolysis, decay, or other processes.
Rapid, sharp combustion with sudden evolution of flame. The flame front travels relatively slowly (subsonic speeds), as compared to a supersonic detonation. Contrast with detonation.
The deactivation of equipment, personnel, and other resources involved in response operations.
The ratio of the mass (weight) of a substance to the volume it occupies. For example, if 1 cubic foot of a substance weighs 10 pounds, its density is 10 pounds per cubic foot. The units used to express density can vary; however, it is often expressed as grams per cubic centimeter (e.g., the density of water is 1.0 g/cm3).
A natural or synthetic agent that suspends emulsified oils, greases, and fats in solution and, by doing this, acts as a cleaning agent. Examples of detergents include soaps and various alcohols, sulfonated organics like dodecylbenzene, and various alkylates.
An explosion where the flame front travels at supersonic speeds as a shock wave. Contrast with deflagration.
Department of Homeland Security ( The U.S. federal agency whose primary mission is to help prevent, protect against, and respond to acts of terrorism on U.S. soil.
A chemical that causes oil to break into small droplets by reducing the surface tension between the water and oil. Once formed, these droplets can be dispersed and degraded in the environment at a faster rate than would occur as a surface slick. Use of dispersants is subject to federal and state approval.
(1) The movement of spilled oil from the water surface down into the upper layers of the water column, caused either by natural wave action or by the application of chemical dispersants made for this purpose. (2) The movement of molecules or finely divided particles through a gaseous or liquid medium (e.g., the spreading of a chemical cloud in the atmosphere).
The process of oil dissolving into the water column. The extent of dissolution depends on the oil’s solubility in water.
Department of Defense ( The U.S. department that provides military forces needed to deter war and to protect the security of the country.
Department of the Interior ( The U.S. department that protects and provides access to the country’s natural and cultural heritage, and honors its trust responsibilities to Indian Tribes and its commitments to island communities.
Department of Transportation ( The U.S. department that oversees federal highway, air, railroad, maritime, and other transportation administration functions.
DOT label
Required Department of Transportation (DOT) hazard warning label for a chemical (e.g., "Flammable Liquid," "Corrosive").
A device used to remove sediment from the bottom of a water body.
drift card
A thin, postcard-sized piece of painted wood released into the sea for use in studying currents. A drift card usually identifies the date and place of release, and requests that the finder return it with date and place of recovery.


ebb tide
The stage of the tide when the water recedes to what is commonly called low tide. Contrast with flood tide. See also low tide.
The organisms in a community and the nonliving environment with which they interact.
A marine, flowering plant (Zostera marina) that grows subtidally in sand and mud. Eelgrass beds are an important habitat and nursery for fish, shellfish, and waterfowl.
The outflow of water, with or without pollutants, usually from a pipe.
Emergency Operations Center (EOC)
See Incident Command Post.
Emergency Response Division (ERD)
A division of NOAA’s Office of Response and Restoration (OR&R) that provides scientific expertise to support oil and chemical spill responses in U.S. coastal waters. ERD specialists also offer tools, training, and information to emergency responders and planners. Formerly the Hazardous Materials Response Division (HAZMAT).
The formation of a mixture of water and oil, which can be mixed only when energy is applied. Different oils exhibit different tendencies to emulsify, and emulsification is more likely to occur under high energy conditions (strong winds and waves). An emulsified mixture of water in oil is commonly called “mousse.”
A mechanical mixture of two liquids that do not naturally mix, such as oil and water. A water-in-oil emulsion is sometimes created when oil spills on water. See also mousse.
endangered species
A plant or animal that is in immediate danger of becoming extinct and needs protection to survive. Compare with threatened species.
A chemical reaction that must absorb heat from its surroundings in order to proceed. Contrast with exothermic, in which heat is produced by the forward reaction.
To incorporate with and carry along.
The loss of oil from containment when it is pulled under a boom by a strong current. Entrainment typically occurs from booms deployed perpendicular to currents greater than 1 knot (0.5 meter per second).
environmental sensitivity
The susceptibility of a local environment or area to any disturbance that might decrease its stability or result in short- or long-term adverse impact. Environmental sensitivity generally includes physical, biological, and socio-economic parameters.
environmental trade-off
The relinquishment of one environmental benefit for another regarded as more desirable.
Emergency Operations Center. See Command Post/Center.
Environmental Protection Agency ( A U.S. federal agency that works to protect human health and safeguard the natural environment (air, water, and land).
Environmental Response Management Application (ERMA)
The Emergency Planning and Community Right-to-Know Act “Title III of SARA”). Defines 378 chemicals as Extremely Hazardous Substances (EHSs) and requires planning for and reporting of EHS releases from facilities.
See Emergency Response Division.
An online mapping tool that integrates both static and real-time data (such as ESI maps, ship locations, weather, and ocean currents) in a centralized, easy-to-use format for environmental responders and decision makers. Learn more about ERMA on the NOAA OR&R website (
Emergency Response Planning Guideline, a level of concern representing the adverse health effects of a hazardous substance on members of the general public. The ERPGs were developed by the ERPG committee of the American Industrial Hygiene Association (
Emergency Support Function. A formal means of consolidating multiple agencies that perform similar or like functions into a single, cohesive unit to allow for the better management of emergency response functions. For example, the responsibilities of Emergency Support Function 10, Hazardous Materials (ESF-10) include coordination in response to an actual or potential release of hazardous materials resulting from a natural or technological disaster. An ESF is activated only if the National Response Plan is activated.
Environmental Sensitivity Index. A system of mapping a region’s shoreline types and biological and human use resources, based on their sensitivity to oiling. ESI maps help spill responders and planners identify vulnerable coastal locations before a spill happens, so that protection priorities can be established and cleanup strategies identified in advance. See also ESI maps.
ESI maps
Maps used by the On-Scene Commander and oil spill response team that designate areas of biological, social, and economic importance in a given region. These maps often prioritize sensitive areas so that in the event of an extensive spill, these areas can be protected or cleaned up first. Sensitivity maps usually contain other information useful to the response team, such as the location of shoreline access areas, landing strips, roads, communities, and the composition and steepness of shoreline areas. Maps of this type often form an integral part of local or regional contingency plans. See also ESI.
Of, relating to, or occurring in an estuary.
The general location where a river meets the sea and freshwater mixes with saltwater. Estuaries often contain salt-marshes and other wetlands, which are important habitat for many species.
The process by which a substance is converted from liquid to vapor. In the case of oil, the rate of evaporation depends on the volatility of various hydrocarbon constituents, temperature, wind and water turbulence, and the spreading rate of the slick. Evaporation is the most important process in the weathering of most oils.
exclusion booming
The deployment of floating booms to prevent spilled oil from entering a sensitive area. See also boom.
A term used to describe the generation of heat from a chemical reaction. Contrast with endothermic, in which heat is taken in from the surroundings.
A chemical or physical process in which the rate at which energy is being generated exceeds its ability to escape to its surrounding environment. The hazards of an explosion can include a shock wave, especially near the point of explosion, and projectiles generated by the shock wave.
A material synthesized or mixed deliberately to allow the very rapid release of chemical energy (i.e., an explosion). Also, a chemical substance that is intrinsically unstable and liable to detonate under conditions that might reasonably be encountered.
explosive limits
Or flammability limits. The lower explosive limit is the lowest concentration of a vapor in air that catches fire when exposed to a source of ignition. The upper explosive limit is the highest concentration of the vapor in air that catches fire when exposed to a source of ignition. The flash point and explosive limits of a substance are often used as measures of its flammability hazard in a given situation.


Fahrenheit. Temperature scale based on 32° F for the temperature at which water freezes and 212° F for the temperature at which water boils (180° difference). Conversion to Fahrenheit from the Centigrade temperature scale is by the following formula: F = 9/5C + 32, where C is the temperature in Centrigrade degrees. Contrast with C (Centigrade/Celsius)
A unit of length equal to 1.8 meters or 6 feet; used to measure water depth.
Federal On-Scene Coordinator (FOSC)
The federal official responsible for monitoring or directing responses to all oil spills and hazardous substance releases reported to the federal government. The FOSC is an agent of either the U.S. Coast Guard or the U.S. Environmental Protection Agency (EPA), depending on where the incident occurs. U.S. Coast Guard FOSCs have responsibility for coastal waters and the Great Lakes, while EPA FOSCs have primary responsibility for spills and releases to inland areas and waters.
Federal Emergency Management Agency ( The U.S. federal agency tasked with disaster mitigation, preparedness, response, and recovery planning.
field deployment exercise
An opportunity to demonstrate new and developing spill response techniques and technologies to a broad target audience.
With respect to oil spills, the procedure for determining the chemical character of an oil. Most oils have a characteristic balance of components, so oils from different samples can be compared and matched.
fire hazard
A hazard category that includes chemicals described as flammable, combustible liquid, pyrophoric, or oxidizers (as defined by 29 CFR § 1910.1200).
fish kill
The sudden death of fish due to pollutants or reduced dissolved oxygen in a water body.
A substance’s tendency to ignite or take flame. Flammability is closely related to the volatility of a substance (and is not its relative ability to burn in the presence of oxygen with the evolution of heat). See flammability limits. See also flash point.
flammability limits
Or explosive limits. The lower flammability limit is the lowest concentration of a vapor in air that catches fire when exposed to a source of ignition. The upper flammability limit is the highest concentration of the vapor in air that catches fire when exposed to a source of ignition. The flash point and flammability limits of a substance are often used as measures of its flammability hazard in a given situation.
Easily ignited; burns readily. The U.S. Department of Transportation ( defines flammable liquids as those liquids that have a flash point below 100° F (37.8° C).
flammable range
Range of concentration (of a gas in air) between the lower and upper explosive limits (LEL and UEL). Gas in the flammable range will burn rapidly or explode when ignited because it has been premixed to the right mixture of fuel and air for burning to occur. If the concentration falls below the LEL, then there is not enough fuel in the air to sustain a fire or an explosion—it is too lean. If the concentration rises above the UEL, then there is not enough oxygen to sustain a fire or an explosion—it is too rich (much like an engine that cannot start because it has been flooded with gasoline).
flash point
The lowest temperature at which a liquid gives off enough vapor to be ignited at its surface.
flood tide
The stage of the tide when the water rises to what is commonly called high tide. Contrast with ebb tide. See also high tide.
Use of a water stream to make oil flow to a desired location or recovery device.
See Forward Operations Base.
Field Operations Guide. The FOG is a handy pocket guide to the Incident Command System (ICS).
Organisms that serve as food. Small fish are forage for larger fish and for fish-eating birds.
Forward Operations Base (FOB)
A base established to support small quick response teams, such as a damage assessment team. The short-term base is typically operated only for a few days.
See Federal On-Scene Coordinator.
Accumulation of oil or other materials, such as debris, that makes a device inefficient or inoperative.
freezing point
Also melting point. The temperature at which the solid and liquid phases of a substance exist in equilibrium. The freezing point depends on the chemical composition and the applied pressure. The “normal freezing point” is defined at a pressure of 1 atmosphere. For example, the normal freezing point of water is 0° C (32° F).
fuel oil grade
Numerical ratings ranging from 1 to 6. The lower the grade number, the thinner the oil is and the more readily it evaporates. A high number indicates a relatively thick, heavy oil. No. 1 and 2 fuel oils are solids, which must be liquefied by heating. Kerosene, coal oil and range oil are all No. 1 oils. No. 3 oil is no longer used as a standard term.
fuel oils
Refined petroleum products having specific gravity in the range from 0.85 to 0.98 and flash points greater than 55° C. This group of products includes furnace, auto diesel and stove oils (No. 2 fuels); plant to industrial heating fuels (No. 4 fuels oils); and various bunker fuels (No. 5 and No. 6 fuel oils).
Dense, smoke-like vapors given off by fuming materials, such as very reactive liquids, gases, or molten metals (for example, concentrated hydrochloric acid or sulfur monochloride).
See U.S. Fish and Wildlife Service.


A mixture of volatile, flammable liquid hydrocarbons used primarily for internal combustion engines, and characterized by a flash point of approximately - 40° C and a specific gravity from 0.65 to 0.75.
Geographic Information System (GIS)
Software that joins maps showing geographic features to observational data or databases.
See Gulf Intracoastal Waterway.
See Geographic Information System.
Global Positioning System (GPS)
A satellite-based radio navigation system developed by the U.S. Department of Defense. The system is formed by 24 satellites orbiting the earth at very high altitude, and their corresponding receivers on the earth. The GPS satellites transmit signals that allow one to determine the latitude and longitude of a receiver on earth by computing the time difference for signals from different satellites to reach the receiver. GPS is used in air, land and sea navigation, mapping, surveying and other applications where precise positioning is necessary.
See Global Positioning System.
Gulf Intracoastal Waterway (GICW)
The portion of the Intracoastal Waterway located along the Gulf Coast of the U.S. It is a navigable inland waterway running approximately 1050 mi (1700 km) from Carrabelle, Florida, to Brownsville, Texas. See also Intracoastal Waterway.


The place where a plant or animal species naturally lives and grows.
hazard class
One of 9 categories of hazardous materials used in DOT placards (DOT hazard label). The hazard class indicates the most important hazard of a given material (e.g., Explosives or Poison Gas). While some materials meet the criteria for more than one class, each material is assigned just one class.
hazardous chemical
Any chemical that is a physical or health hazard as defined in 29 CFR § 1910.1200(c).
hazardous material
Any substance or material in a quantity or form that may be harmful to humans, animals, crops, water systems, or other elements of the environment, if accidentally or intentionally released. Hazardous materials include: explosives, gases (compressed, liquefied, or dissolved), flammable and combustible liquids, flammable solids or substances, oxidizing substances, poisonous and infectious substances, radioactive materials, and corrosives.
Hazardous Materials Response Division (HAZMAT)
See Emergency Response Division (ERD).
hazardous substances
Substances designated as hazardous under CERCLA. CERCLA includes substances listed under the Clean Water Act, the Clean Air Act, the Resource Conservation and Recovery Act (RCRA), and the Toxic Substances Control Act (TSCA) Section 7. See also CERCLA.
See Emergency Response Division (ERD).
heavy crude
Crude oil with a high specific gravity and a low API gravity due to the presence of a high proportion of heavy hydrocarbon fractions and metallic content. Contrast with light crude. See also crude oil.
One hectare is equal to 10,000 square meters, or 2.471 acres.
herding agent
A chemical agent that confines or controls the spread of a floating oil film by increasing its viscosity.
high explosive
Or primary explosive. An explosive that is readily detonated by heat, friction, or shock. High explosives vary widely in their sensitivity to these forms of initiating energy.
highly flammable
Designation applying to (a) substances with flash points below 100° F, and (b) mixtures that include substances with flash points below 100° F. Materials designated as highly flammable include pyrophoric solids and substances that present an exceptional flammability hazard, in that they may suddenly and dangerously increase the intensity of a fire.
high tide (high water)
The highest level reached by the water during one tidal cycle. Contrast with low tide.
At a given temperature, the ratio of water vapor in the air to the maximum amount that can be held in the air at that temperature.
hydraulic dispersion
One of various shoreline cleanup techniques which utilizes a water stream at either low or high pressure to remove stranded oil. These techniques are most suited to removal of oil from coarse sediments, rocks and man-made structures, although care must be taken to avoid damage to intertidal flora and fauna.
A large class of molecules containing only carbon and hydrogen. Common in petroleum products and other oils. The largest source of hydrocarbons is petroleum crude oil.
Lit. "Water-loving." Refers to substances that attract and retain water, and to wettable solids whose surfaces readily attract water. Contrast with hydrophobic.
Lit. "Water hating." Refers to substances that repel water and are not easily wetted or emulsified (fats, waxes, oils, metal powders, and many inorganic compounds). Contrast with hydrophilic. To be useful in combating oil spills, sorbents need to be both oleophilic (oil-attracting) and hydrophobic (water-repellent).


See Incident Command System.
Immediately Dangerous to Life and Health, a level of concern for adult workers; estimate of the highest concentration of an airborne contaminant from which escape is possible without permanent injury. The IDLHs were established by the National Institute for Occupational Safety and Health (NIOSH;
Intermediate Fuel Oil. A type of bunker fuel (ship’s fuel), IFOs are classified into different grades as specified by a universally adopted system of measurement. The most common intermediate fuel oil grades are called IFO-180 and IFO-380. The lower the number, the better the quality of the fuel.
ignition point
Minimum temperature at which a substance ignites when no ignition source (e.g., spark or flame) is present.
Incident Action Plan (IAP)
An oral or written plan containing general objectives reflecting the overall strategy for managing an incident. An IAP identifies operational resources and assignments and may include attachments that provide additional direction. An IAP is prepared for each of the operational periods that divide up the response timetable.
Incident Commander (IC)
Under the Incident Command System, the official with overall responsibility for managing the response to an incident, and defining the objectives for the response. S/he is responsible for ensuring human health and safety, providing information to stakeholders, and coordinating with participating agencies. In certain cases, multiple agencies may share command as a Unified Command.
Incident Command Post
The location from which the Incident Commander oversees all response operations. There is generally just one ICP for each incident, but it may change locations during the incident. Every incident must have some form of ICP, which may be located in a vehicle, trailer, tent, or inside a building.
Incident Command System (ICS)
A standard system for managing the response to a significant incident, especially one so large that many agencies are involved in the response. The system is designed to flexibly grow and shrink along with the incident, allowing more people and resources to be smoothly added into the system when required, then released when no longer needed. Under the National Response Plan (NRP), ICS is the command and management component of the National Incident Management System (NIMS).
incompatible substances
Substances that react together, if mixed.
Not chemically reactive (e.g., neon).
Taking into the body by the mouth.
A route of chemical exposure in which a toxic material is breathed into the body.
Substance added to a polymerizable substance to slow down or prevent a polymerization reaction. The inhibitor level in a substance can drop over time, making a reaction possible. Contrast with catalyst.
Harm or adverse effects to aquatic organisms and the habitats they require to complete their life cycle.
Injury Assessment Coordinator (IAC)
A NOAA staff member who collects information, samples, and evidence to support natural resource damage assessments. IACs document the severity, geographic extent, and likely duration of injury to NOAA trust resources. The goal of an IAC’s efforts is to determine the appropriate amount and type of restoration required to restore injured NOAA trust resources and compensate the public for their lost use.
Compounds that do not contain the element carbon, as well as the following carbon-containing compounds: the carbon oxides, the carbides, carbon disulfide, phosgene, cyanides of metals, and carbonyl sulfide. Contrast with organic.
in situ burn (ISB)
A response technique that involves the controlled burning of oil that has spilled from a pipeline, vessel, or facility, at the location of the spill. On open water, the oil is first encircled by a specially-designed fire containment boom and is then ignited. In oiled marshes, firebreaks are constructed around the area to be burned, then the oiled marshland is ignited. When conducted properly, in situ burning may significantly reduce the amount of time that oil remains in the environment and may minimize its adverse effects.
International Bird Rescue Research Center (IBRRC)
California-based organization with experts in the field of oiled bird rehabilitation. Typically, hired by the responsible party to operate a wildlife rehabilitation effort when there are large numbers of oiled birds during a spill. These rehabilitation efforts are coordinated with the U.S. Fish and Wildlife Service and the State Parks and Wildlife Department.
The area between the low tide mark and the high tide mark. Also called the littoral zone.
Intracoastal Waterway
A 3,000-mile (4,800-km) recreational and commercial waterway along the Atlantic and Gulf coasts of the U.S. The waterway consists of two non-contiguous segments: the Gulf Intracoastal Waterway, extending from Brownsville, Texas to Carrabelle, Florida, and the Atlantic Intracoastal Waterway, extending from Key West, Florida to Boston, Massachusetts.
Integrated Ocean Observing System. A system for observations, modeling, and analysis of marine and ocean variables to support operational ocean services. IOOS is designed to meet seven societal goals, including improved prediction of climate change and weather, effective mitigation of the effects of natural hazard, safe and efficient marine transportation, homeland security, reduction of public health risks, protection and restoration of healthy coastal ecosystems, and sustainable use of ocean and coastal resources. IOOS is a major U.S. contribution to the Global Ocean Observing System (GOOS).
See in situ burn.


See Joint Information Center.
Joint Information Center (JIC)
A facility established within or near the Incident Command Post where the Information Officer and staff can coordinate and provide information on the incident to the public, media and other agencies. The JIC is normally staffed with representatives from the FOSC, SOSC, and RP.


A unit of speed equal to 0.51 meters/second, 1 nautical mile per hour, or approximately 1.2 miles per hour.


A shallow sound, pond, or lake generally near but separated from or communicating with the open sea. A shallow freshwater pond or lake generally near or communicating with a larger body of fresh water.
The location of a place on earth north or south of the Equator. Latitude is a measurement in degrees ranging from 0° at the Equator (low latitude) to 90° at the poles (90° N for the North Pole or 90° S for the South Pole; high latitude). Each degree of latitude is further sub-divided into 60 minutes, each of which is divided into 60 seconds. A latitude is thus specified as 13° 19' 43" N. Contrast with longitude.
See lower explosive limit.
level of concern (LOC)
"Threshold concentration" of an airborne pollutant, usually the concentration above which a hazard to people is believed to exist.
light crude
Crude oil with a low specific gravity and high API gravity due to the presence of a high proportion of light hydrocarbon fractions and low metallic compound. Contrast with heavy crude. See also crude oil.
The pumping or transferring of oil from cargo compartments of a tank vessel to another vessel and/or barge.
Able to dissolve, be dissolved in, or absorb lipids (fats).
liquefied gases
Gases that have been changed into liquid form. Examples include butane, butylene, ethane, ethylene, propane and propylene.
liquefied natural gas (LNG)
Natural gas that has been liquified by cooling the gas. Liquification greatly reduces the volume of the material, making it much more cost-efficient to transport over long distances. LNG is transported by specially designed cryogenic sea vessels and road tankers, and stored in specially designed tanks. LNG is a mixture of gases; the main component is methane.
liquefied petroleum gas (LPG)
A mixture of hydrocarbon gases that has been liquified by either pressure or refrigeration. LPG may be composed primarily of either propane or butane. LPG is transported over long distances by specially designed sea vessels and road tankers, either under pressure, semi-pressurized, or fully refrigerated.
The tilt of a vessel to port or starboard, usually measured in degrees from the vertical.
See liquefied natural gas.
See level of concern.
The location of a place on earth east or west of a north-south line called the Prime Meridian, which runs through Greenwich, England. Longitude is given as a measurement ranging from 0° at the Prime Meridian to +180° eastward and -180° westward. Each degree of longitude is further sub-divided into 60 minutes, each of which is divided into 60 seconds. A longitude is thus specified as 23° 27' 30" E. Contrast with latitude.
Local On-Scene Coordinator (for example, a representative of a city, county or tribal government).
lower explosive limit (LEL)
Or lower flammability limit. Lowest concentration of a flammable vapor in air at which explosion or combustion can occur.
low tide (low water)
The lowest level reached by the water during one tidal cycle. Contrast with high tide.
See liquefied petroleum gas.
Louisiana State University.


Ecologically, mangroves are defined as an assemblage of tropical trees and shrubs that inhabit the coastal intertidal zone. A mangrove community is composed of plant species specially adapted to survive the variable flooding and salinity stress conditions of the coastal environment. Mangroves provide protected habitat for many land and marine animals. The many species of mangroves are found in about 20 plant families.
Marine Debris Program (MDP)
A division of NOAA’s Office of Response and Restoration (OR&R) that supports national and international efforts to research, prevent, and reduce the impacts of marine debris.
Marine Safety Unit (MSU)
In the U.S. Coast Guard, a subordinate office to a Sector office. For example, MSU Valdez reports directly to Sector Anchorage.
Marine Science Technician (MST)
U.S. Coast Guard Marine Science Technicians (MSTs) conduct marine-safety activities, such as investigating pollution incidents, monitoring pollution cleanups, conducting foreign-vessel boardings to enforce pollution and navigation safety laws, conducting harbor patrols for port safety and security, inspecting waterfront facilities and supervising the loading of explosives on vessels. They may be assigned to the National Strike Force for oil and hazardous-material response. MSTs are also the Coast Guard’s safety and environmental health experts ashore.
Mass is a physical property related to weight. Mass is a measure of the amount of a substance that occupies a given space. While the weight of a given amount of a substance is a measure of the force by which it is attracted by gravity (and is less on the moon than on the earth), the substance’s mass is independent of gravity.
Material Safety Data Sheet (MSDS)
Product data sheet prepared under 29 CFR § 1910.1200 by the manufacturer or marketer of a hazardous material; describes product, its hazards, and safe handling and response procedures.
See Marine Debris Program.
mechanical removal
Includes the use of pumps, skimmers, booms, earth-moving equipment, and other mechanical devices to contain the discharge of oil and to recover the discharge from the water or adjoining shorelines.
melting point
Also freezing point. The temperature at which the solid and liquid phases of a substance exist in equilibrium. Depends on chemical composition and applied pressure.
Completely soluble.
To create, restore, or enhance a natural system, such as an estuary or wetland, to maintain the functional characteristics and processes of that system.
A coastal management concept requiring developers to replace developed areas with equivalent natural areas or to reengineer other areas to resemble areas prior to development.
A uniform or nonuniform blend of two or more substances. Examples include blood, milk, petroleum products, and alloys.
Minerals Management Service. The U.S. federal agency that manages the nation’s natural gas, oil and other mineral resources on the outer continental shelf, and collects, accounts for, and disburses revenues from federal mineral leases (onshore and offshore) on federal and Indian lands.
molecular weight
The sum of the weights of all the atoms in a molecule.
A chemical entity composed of one or more elements in the form of atoms.
One of the molecules that link together to make a polymer. For example, the monomer of natural rubber is isoprene. Monomers may be naturally occurring or synthetic. See also polymerization.
A water-in-oil emulsion that resembles chocolate mousse in color and texture. These emulsions are often very stable, and often have a pudding-like consistency. Typically, a mousse forms when relatively fresh oil is exposed to strong wave action. Mousse colors can range from orange or tan to dark brown. A mousse may contain up to 75 percent water, and may have a volume up to four times that of the original oil. See also emulsion.
See Material Safety Data Sheet.
U.S. Coast Guard Marine Safety Office. As of the mid-2000s, nearly all MSOs have been combined with groups and other units to form Sectors.
See Marine Science Technician.
See Marine Safety Unit.
A chemical or radiation source that alters an organism’s DNA, affecting transmission of inherited characteristics from one generation to the next.
mystery spill
An oil or chemical spill for which no source or responsible party (RP) has been identified.


National Fire Protection Association (NFPA)
A private, non-profit organization that produces technical data related to fire protection and prevention, including the widely used “NFPA diamond” containing codes representing chemical hazards. (
National Incident Management System (NIMS)
An incident management system established by the Secretary of Homeland Security that integrates effective practices in emergency preparedness and response into a comprehensive national framework. NIMS was developed so that responders from different jurisdictions and disciplines can work together better to respond to natural disasters and emergencies, including acts of terrorism. NIMS benefits include a unified approach to incident management; standard command and management structures; and emphasis on preparedness, mutual aid, and resource management.
National Institute for Occupational Safety and Health (NIOSH)
The federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury. NIOSH is part of the Centers for Disease Control and Prevention (CDC). (
National Priorities List (NPL)
The NPL identifies locations throughout the U.S. where hazardous wastes have been found in the environment and the initial evaluation shows a significant risk of harm to human health or ecology. NPL sites are frequently called "Superfund" sites, because Superfund money can be used by EPA to investigate and clean up these sites.
National Response Center (NRC)
The central Federal clearinghouse for information on hazardous chemical spills and other oil or hazardous substance releases. Responsible parties should contact the NRC ( in order to fulfill reporting requirements for spills of oil and hazardous substances (hotline: 1-800-424-8802).
National Response Plan (NRP)
The national plan administered by the Department of Homeland Security to respond to national emergencies, such as terrorist attacks, natural disasters, or other large-scale emergencies.
National Response Team (NRT)
A planning, policy, and coordinating body consisting of representatives from 16 federal agencies responsible for emergency response to pollution incidents (e.g., an oil spill or major chemical release). The NRT ( provides national level policy guidance prior to an incident and can provide assistance during an incident.
National Weather Service (NWS)
NOAA’s National Weather Service ( provides weather, hydrologic, and climate forecasts and warnings for the U.S., its territories, adjacent waters, and ocean areas.
Natural Resource Damage Assessment (NRDA)
Investigation performed by trustees to identify and plan the restoration of natural resources injured by oil spills and hazardous substance releases. The goal of NRDA is to restore natural resources.
nautical mile
A unit of length equal to 1852 meters or 1.15 land miles or 1 minute of latitude.
The National Oil and Hazardous Substances Pollution Contingency Plan, more commonly called the National Contingency Plan. The U.S. government’s blueprint for responding to both oil spills and hazardous substance releases.
The reaction between an acid and base to form a salt and water. Neutralization is often rapid, vigorous, and exothermic (heat-producing).
See National Fire Protection Association.
NFPA codes
Numbers representing the flammability, health, reactivity (instability), and other hazards of individual chemicals; shown on the "NFPA diamond."
NFPA diamond
Standard placard used to identify the level of chemical hazard at a fixed location or in a transported container.
See National Incident Management System.
See National Institute for Occupational Safety and Health.
NOAA National Marine Fisheries Service ( NMFS recommends ways to rebuild and maintain sustainable fisheries, promote the recovery of protected species, and protect and maintain the health of coastal marine habitats.
National Oceanic and Atmospheric Administration ( An organization of the Department of Commerce, NOAA is composed of the National Ocean Service (NOS); National Weather Service; National Marine Fisheries Service; National Environmental Satellite, Data, and Information Service; and Office of Oceanic and Atmospheric Research. ERD is a portion of the Office of Response and Restoration (OR&R) under NOS.
See Emergency Response Division (ERD).
noncombustible (or non-combustible)
Non-reactive with air, even at very high temperatures.
nonflammable (or non-flammable)
Difficult to ignite.
nonpoint (or non-point) source pollution
Pollution that is generated over a relatively wide area and dispersed rather than discharged from a pipe. Common sources of nonpoint pollution include stormwater runoff, failed septic systems, and marinas. Nonpoint pollution may enter waterways from many places, such as when rainwater washes over parking lots, lawns, or farms and brings pollutants from all these sources into the water. See also point source pollution.
Not otherwise specified.
NOAA’s National Ocean Service ( NOS works to observe, understand, and manage U.S. coastal and marine resources.
Irritating; may cause temporary impairment.
See National Priorities List.
See National Response Center.
See Natural Resource Damage Assessment.
NRDA Trustees
Comprised of representatives from various state agencies that advise state and federal oil spill cleanup officials regarding the protection and restoration of natural resources threatened or damaged by an oil spill.
See National Response Plan.
See National Response Team.
Essential chemicals needed by plants and animals for growth. Excessive amounts of nutrients, nitrogen, and phosphorus, for example, can lead to degradation of water quality and growth of excessive amounts of algae. Some nutrients can be toxic at high concentrations.
See National Weather Service.


observation buoy
A platform for sensors that can be used during spill response to provide environmental data (e.g., winds, currents, water level, temperature, etc.). The data obtained may be used to predict the trajectory of a spill, forecast weather, and plan response operations.
Occupational Safety and Health Administration (OSHA)
Federal agency within the U. S. Department of Labor with the responsibility of ensuring worker safety and health. (
Office of Response and Restoration (OR&R)
NOAA’s Office of Response and Restoration ( includes the Emergency Response Division (ERD), which provides scientific expertise to support oil and chemical spill responses in U.S. coastal waters; the Assessment and Restoration Division (ARD), which works to protect and restore coastal natural resources injured by hazardous substances; and the Marine Debris Program (MDP), which supports national and international efforts to research, prevent, and reduce the impacts of marine debris.
Crude oil and refined petroleum products (e.g., motor oils, fuels, lubricants, etc.). The term also refers to vegetable oils, animal fats, and other non-petroleum oils, but these non-petroleum products rarely prompt an emergency response.
oil boom
See boom.
oil film
A slick thinner than .0001 inch and may be classified as follows:
Term Gal/

sq mile
"barely visible" 25 barely visible
"silvery" 50 silvery sheen
"slightly colored" 100 trace of color
"brightly colored" 200 bright bands of color
"dull" 666 turns dull brown
"dark" 1,332 much darker brown

Note: Each 1" thickness of oil equals 5.61 gallons per square yard or 17,378,709 gallons per square mile.

Oil Pollution Act of 1990 (OPA90)
OPA90 amended the Clean Water Act to strengthen the nation’s ability to prevent and respond to oil spills. It applies to oil-carrying vessels, offshore facilities, onshore facilities, and deepwater ports that could potentially spill oil into U.S. navigable waters or the adjoining shorelines. See also Clean Water Act.
Oil Spill Removal Organization -or- Oil Spill Response Organization (OSRO)
An environmental service company that specializes in environmental problems, such as oil and chemical spills.
oil trajectory
See trajectory.
oil snares
See pom-poms.
oily debris
Can include sorbent pads/boom, protective clothing/gear, soil, sand, rocks, logs, kelp, plastics, mousse, oil/water mixture and animal carcasses.
Oil-attracting, having a strong affinity for oil. To be useful in combating oil spills, sorbents need to be both oleophilic and hydrophobic (water-repellent). Contrast with hydrophobic.
Or fuming sulfuric acid. The mixture of sulfuric acid and sulfur trioxide.
On-Scene Coordinator (OSC)
The person responsible for the spill response activities of a single or group of agencies. This person is responsible for coordinating that agency’s or group’s activities with those of the other OSCs through the Incident Command System (ICS) and the Incident Commander (IC). There may be more than one OSC at a spill (e.g., Federal OSC, State OSC, and Responsible Party OSC), but only one IC.
on-water recovery
The recovery of spilled pollutant while it is still on the water, rather than when it reaches a shoreline. On-water recovery includes using skimmers on oil slicks and netting systems for tarballs and highly viscous oils.
See Oil Pollution Act of 1990.
Generally, compounds that contain the element carbon, except for some carbon-containing compounds that are considered to be inorganic (carbon oxides, carbides, carbon disulfide, phosgene, the cyanides of the metals, and carbonyl sulfide). Contrast with inorganic.
See Office of Response and Restoration.
See On-Scene Coordinator.
See Occupational Safety and Health Administration.
The State of California’s Office of Spill Prevention and Response (OSPR) ( Housed within the Department of Fish and Game, OSPR is the lead state agency charged with oil spill prevention and response within California’s marine environment.
See Oil Spill Removal/Response Organization.
A flight by an airplane or helicopter over an area of water or shoreline, generally done to assess the character and extent of pollutant spilled on the water. See also aerial observation.
Increase of pressure within a container beyond the pressure the container is designed to contain; can lead to explosion of the container.
A chemical reaction in which oxygen bonds to an element or compound. By extension, a reaction in which one element or compound rises to a higher oxidation state while another drops to a lower oxidation state (the term is used in this sense even when no oxygen whatever is present). Contrast with reduction.
Or oxidizing agent. Substance that yields oxygen readily to support a fire.
oxidizing agent
Or oxidizer. Substance that yields oxygen readily to support a fire. Contrast with reducing agent.


Polynuclear aromatic hydrocarbon; also called polycyclic aromatic hydrocarbon, a component of oil. PAHs are associated with demonstrated toxic effects.
Isolated, roughly circular patches of oil ranging in size from a few feet across to hundreds of yards (or meters) in diameter. Sheen may or may not also be present.
Polychlorinated biphenyls. A group of synthetic, organic chlorinated aromatic hydrocarbons having various applications in industry. PCBs are highly toxic, poisonous, and potentially carcinogenic (capable of causing cancer) environmental pollutants known to cause skin diseases. They tend to accumulate in animal tissues and are suspected of causing birth defects and cancer.
Refers to fish and animals that live in the open sea, away from the sea bottom. Contrast with benthic.
The movement of spilled oil into shoreline sediments.
Can slowly react with oxygen in the air or with oxidizers (oxidizing agents) to eventually form potentially explosive, white crystalline peroxides.
A term used to describe a substance that will remain in the environment for a long period of time without being broken down into simpler chemicals or reduced to acceptable levels by natural physical or chemical biological processes.
personal protective equipment (PPE)
Any gear, clothing, or other equipment used to protect personnel from known and or suspected hazards on a site.
Hydrocarbon materials found naturally underground, including crude oil, condensate, natural gasoline, natural gas liquids, liquefied petroleum gas, and liquid petroleum products.
Measure of the acidity or alkalinity of a solution. At room temperature, a solution having a pH of 7 is neutral (neither acidic nor basic). Solutions with pHs greater than 7 are basic (alkaline); solutions with pHs below 7 are acidic.
The group of marine mammals that includes seals, walruses, and sealions.
place of refuge
An area of sheltered water for a ship in distress or needing repairs.
Point of contact.
point source pollution
Pollution originating at a particular place, such as a grounded ship or a sewage treatment plant, outfall, or other discharge pipe. See also non-point source pollution.
Any material entering the water which is not a normal part of the local environment, or which is in a concentration that is not normal to the local environment.
Pollution report. An initial report of a pollution incident (e.g., a spill or a potential release of an oil or chemical), issued by the U.S. Coast Guard.
The product of polymerization. Proteins, starches, cellulose and natural rubber are naturally occurring polymers; polystyrene, nylon, Teflon®, and synthetic rubber are synthetic polymers. See also polymerization.
Can react with itself. Polymerization reactions typically generate heat and could cause container to overpressurize, possibly leading to a fire or explosion.
Chemical reaction in which small molecules join to form larger molecules; polymerization reactions typically release heat, and can cause containers to overpressurize.
Also called oil snares. Pom-pom shaped absorbents made of synthetic fibers that "attract" oil. Pom-poms are used individually or tied on long ropes and used to catch oil as it leaches from beaches and rocky areas. Strings of pom-poms are effective in collecting oil in rock or difficult to reach areas where the tide rises and falls.
pooled oil
Fresh oil or mousse that has accumulated to a thickness exceeding 1 cm.
pour point
The lowest temperature at which oil is observed to flow. At ambient temperatures that are below an oil’s pour point, the oil will tend to be a semi-solid. An oil that is near or below its pour point generally cannot be pumped without heating, cannot be chemically dispersed, and will not readily penetrate into substrates such as gravel or cobble beaches.
Parts per billion. A unit of concentration used where low levels of concentration are significant, such as that of a gas or vapor in air (as molecules of chemical per billion molecules of air).
See Personal Protective Equipment.
Parts per million. A unit of concentration often used when measuring levels of pollutants in air and water. One ppm is 1 part in 1,000,000, which can be approximated by one teaspoon in 1,300 gallons. The common unit mg/liter is equal to ppm.
Parts per thousand. A unit of concentration often used to record the salinity of seawater. One ppt is 1 part in 1,000.
Build up of pressure within a closed container. May cause container to explode.
Small spherical or cylindrical pellets used in the fertilizer and explosive industry because they are convenient to handle (e.g., ammonium nitrate prills, often coated with wax because this salt tends to cake when hydrated).
Pounds per square inch; a unit of pressure measurement.
Pounds per square inch gauge; pressure relative to atmospheric pressure.
Any substance that ignites in the presence of air at or below ambient temperatures. Many pyrophoric materials react with moisture in the air to generate flammable hydrogen gas and enough heat to ignite the hydrogen. These are extremely dangerous fire hazards that are generally stored under an inert atmosphere or in a solvent like ether or kerosene that excludes air.
The manufacture of fireworks, signal flares, and so on, involving the mixture of different chemicals to achieve various visual and auditory effects. Chemicals used in pyrotechnics include many explosive inorganic compounds such as potassium nitrate, metal perchlorates, dichromate, powdered metals, and phosphorus.


No glossary entries


Electromagnetic energy or light, depending on the wavelength, which imparts energy to molecules and atoms. Radiation absorption causes ionization and bond-breaking.
In inorganic chemistry, refers to an aqueous, dissociated ionized group that acts as a fragmented, highly reactive, short-lived substance. Free radical generation can initiate polymerization and other kinds of reactions.
Spontaneously and continuously emitting ions or ionizing radiation. Radioactivity is not a chemical property, but an additional hazard apart from other properties of a material.
rapid reaction
A reaction in which chemical change becomes evident within minutes to hours after the mixing of incompatible chemicals. That evidence can be dramatic change such as fire or explosion, or more subtle effects, such as chemical heat production, evolution of gases, or deposition/disappearance of solids.
See resources at risk.
The change that takes place when two or more substances interact to form new substances.
Readily reacts with other chemicals (described in 29 CFR § 1910.1200).
The tendency of a substance to undergo chemical change. The reactivity of most substances depends on the temperature and pressure of the surroundings, and on the chemicals with which it comes in contact. Under ordinary conditions, innately reactive substances are those that react rapidly with water, air, and other common components of the environment, as well as substances that self-react (decompose or polymerize).
recoverable oil
Oil in a thick enough layer on the water to be recovered by conventional techniques and equipment. Only black or dark brown oil, mousse, and heavy sheens (which are dull brown in color) are generally considered to be thick enough to be effectively recovered by skimmers. See also on-water recovery.
In oil spill cleanup, the entire process of any operation contributing to the physical removal of spilled oil from land, water, or shoreline environments. General methods of recovery of oil from water are the use of mechanical skimmers, sorbents, and manual recovery by the cleanup work force. The main method of recovery of oil spilled on land or shorelines is excavation of oiled materials.
reducing agent
Substance that can react strongly or explosively with oxidizers. Contrast with oxidizing agent.
A reaction in which either oxygen is removed from a substance or, in a more general sense, one or more electrons is accepted from another substance. Contrast with oxidation.
Also known as cleanup, remediation is the action taken to reduce, isolate, or remove contamination from an environment with the goal of preventing exposure to people or animals. Examples include dredging to remove contaminated sediment, or capping to prevent contaminated sediment from contacting benthic organisms. Compare with restoration.
reportable quantity (RQ)
The quantity of a hazardous substance or extremely hazardous substance that, if released, must be reported to the National Response Center, the State Emergency Response Commission, and the community emergency coordinator for areas likely to be affected by the release.
residual oils
The heavier oils that remain after the distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations. Included are No. 5, a residual fuel oil of medium viscosity; Navy Special, for use in steam-powered vessels in government service and in shore power plants; and No. 6, which includes Bunker C fuel oil and is used for commercial and industrial heating and electricity generation.
resources at risk (RAR)
Economic and ecological resources threatened by a spill incident.
responder resources
All personnel and major items of equipment available, or potentially available, for assignment to incident tasks on which status is maintained.
responsible party (RP)
The person, business, or entity identified as owning the vessel or facility that caused a spill incident. The term does not imply criminal negligence.
To return a site to an approximation of its condition before alteration. In the Superfund cleanup process, restoration usually follows remediation. Compare with remediation.
The derrick and surface equipment of a drilling unit.
A layer of large, durable fragments of broken rock, concrete, or other material used as a hard, artificial shoreline facing to reduce erosion by waves or currents and thereby preserve the shape of a surface, slope, or underlying structure.
See Responsible Party.
See reportable quantity.
Regional Resource Coordinator, formerly a Coastal Resource Coordinator (CRC). The point of contact for the efforts of NOAA OR&R’s Assessment and Restoration Division (ARD). RRCs are NOAA environmental scientists who work to provide the technical foundation for assessments of ecological risk and environmental and economic injury from contamination at hazardous waste sites and to improve coordination among trustee agencies.
The Federal response organization (consisting of representatives from selected federal and state agencies) which acts as a regional body responsible for planning and preparedness before an oil spill occurs and providing advice to the FOSC in the event of a major or substantial spill.


The saltiness or dissolved salt content of a body of water. On average, seawater in the world’s oceans has a salinity of about 3.5%, or 35 parts per thousand (ppt). Fresh water (found in lakes and rivers) has less than 0.5 ppt dissolved salts.
Shoreline Cleanup Assessment Technique. A systematic method for surveying an affected shoreline after an oil spill. During oil spill response, SCAT teams systematically survey and document the affected area to provide a rapid and accurate geographic picture of shoreline oiling conditions. The information is used to develop real-time decisions regarding shoreline treatment and cleanup operations.
Scientific Support Coordinator (SSC)
The point of contact for the Scientific Support Team from NOAA OR&R’s Emergency Response Division (ERD). In accordance with the National Contingency Plan, the SSC provides the Federal On-Scene Coordinator scientific advice regarding the best course of action during a spill response. Using the resources of a Scientific Support Team, the SSC provides expertise on chemical hazards, field observations, trajectory analysis, resources at risk, environmental tradeoffs of countermeasures and cleanup methods, and information management. Additionally, the SSC provides data on weather, tides, currents, and other applicable environmental conditions. SSCs are geographically located in Coast Guard districts throughout the U.S.
Scientific Support Team (SST)
NOAA’s multi-disciplinary team of scientists, based in Seattle and led by nine regionally-based Scientific Support Coordinators (SSCs). The team provides expertise in environmental chemistry, aerial observations, pollutant transport modeling, resources at risk, environmental tradeoffs of countermeasures and cleanup, and information management. The SST also provides data on weather, tides, currents, and other applicable environmental conditions.
A shore-based operational command responsible for the execution of all Coast Guard missions within its area of responsibility (e.g., search and rescue, ensuring navigation safety, pollution response and investigation, etc.).
A general term used to describe or refer to: material in suspension in air or water; the total dissolved and suspended material transported by a stream or river; the unconsolidated sand and gravel deposits of river valleys and coastlines; and materials deposited on the floor of lakes and oceans.
Due to weathering the density of some heavy spilled oils may increase and become higher than that of the sea water, so that they sink. Oil may also be absorbed by heavy mineral particles (sand, silt, etc.) and thus sink.
sensitivity maps
See ESI maps.
Substance that can cause an allergic reaction in some people; the reaction can be severe, and breathing can be obstructed.
A very thin layer of oil (less than 0.0001 inches or 0.003 millimeters in thickness) floating on the water surface. Sheen is the most commonly observed form of oil during the later stages of a spill. Depending on thickness, sheens range in color from dull brown for the thickest sheens to rainbows, grays, silvers, and near-transparency in the case of the thinnest sheens.
shock wave
A pressure wave generated by an explosion.
shoreline assessment
A segment-by-segment survey of oiled shoreline to collect information about the shoreline habitats, type and degree of shoreline contamination, and spill-specific physical processes. The field data are collected in order to provide specific cleanup recommendations to maximize the recovery of oiled habitats and resources, while minimizing the risk of injury from cleanup efforts.
shoreline cleanup
The collection of oil stranded onshore or floating in shallow intertidal areas. Cleanup methods can include barriers and berms, manual or mechanical oil removal, the use of sorbents or vacuums, sediment reworking/tilling, vegetation cutting/removal, etc. Natural recovery is sometimes used, in which no attempt is made to remove stranded oil, when there is no effective method for cleanup or to minimize impact to the environment. The oil is left to degrade naturally. Overall, a cleanup strategy that minimizes the impact to all sensitive aspects of the environment and minimizes the amount of oily wastes is the most optimal.
shoreline sensitivity
The susceptibility of environment to any disturbance that might decrease its stability or result in short or long-term adverse impacts. Shorelines that are most susceptible to damage from stranded oil are usually equally sensitive to cleanup activities that may alter physical habitat or disturb associated flora and fauna. The most sensitive shoreline environments are marshes and lagoons, while exposed coastline, subject to heavy wave action, is generally least affected by oil and/or cleanup activities.
Side-Looking Airborne Radar (SLAR)
This aircraft-mounted device emits radiation and looks at the return signal. It looks for "damped areas," does not work well if winds are calm (there are no capillary waves to suppress) or if winds are too strong (greater than 15-20 knots). It needs ground-truthing; false positives include kelp beds, lee of bluffs, etc. However, it can cover a large area in a short amount of time and can be used at night or through clouds.
Situation Report. A written account generated by the U.S. Coast Guard, and usually issued on a daily basis, detailing the status of a spill and its response.
A floating device used to remove oil from the water’s surface by any of a variety of mechanical methods (e.g., weir, oleophilic belt or drum). Skimmers may be stationary, towed, or self-propelled. Skimmers come in a wide range of shapes and sizes, designed for different sea conditions and types of oil. Skimmers are often used in conjunction with booms to increase collection efficiency, and a reservoir or bladder to store collected oil.
skin absorption
Chemical exposure through the skin. Because the skin does not act as a reliable barrier to hazardous chemicals, it can be a route of acute poisoning. Compounds such as dimethyl sulfoxide are known to be directly absorbed into the bloodstream through the skin.
The common term used to describe a film of oil (usually less than 2 microns thick) on the water surface. Oil spilled on the water absorbs energy and dampens out surface waves, making the oil appear smoother—or slicker—than the surrounding water.
A thick or viscous mixture of solids in aqueous solution, such as sewage sludge.
Special Monitoring of Applied Response Technologies. SMART is a cooperatively designed monitoring program for dispersant and in situ burning operations.
See pom-poms.
A measure of a chemical’s ability to dissolve in water. If a chemical is highly soluble, it will dissolve easily into water.
A solute is a gas, liquid, or solid substance that is uniformly dispersed in a liquid solvent substance, forming a solution. The solvent molecules act to break the solute molecules’ attraction for one another, and also the solvent’s natural structure. For instance, water is a highly-structured substance, in the absence of any solutes. See also solution.
Mixtures of chemicals in which the components are interspersed uniformly at the molecular level. See also solute/solvent.
Any material that absorbs oil or to which oil adheres. A sorbent should be oleophilic and hydrophobic (i.e., it should absorb petroleum or products from 0 to 25 times its weight, and repel water). Sorbents are available in many forms: sheets, booms, sweeps, blankets, and loose material. Sorbents may be made of polymer beads, synthetic hydrocarbon polymers, cellulose, plastic fiber, and even straw.
sorbent barrier
A barrier which is constructed of or includes sorbent materials to simultaneously recover spilled oil during the containment process. Sorbent booms and barriers are used only when the oil slick is relatively thin since their recovery efficiency rapidly decreases once the sorbent is saturated with oil.
(1) an internationally recognized distress signal in which the letters “SOS” are repeatedly spelled out, as by radio-telegraphy (••• – – – •••); used especially by ships and aircraft. (2) Science of Oil Spills class taught by NOAA OR&R’s Emergency Response Division. SOS classes help spill responders increase their understanding of oil spill science when analyzing spills and making risk-based decisions. (A former name for the class: Environmental Spill Response Workshop.) Learn more about SOS classes on the NOAA OR&R website (
See State On-Scene Coordinator.
To release and fertilize eggs, as done by a number of aquatic species (fish, oysters, etc.) to reproduce.
specific gravity
Density expressed as the ratio of the weight of a substance, such as oil, to the weight of an equal volume of another standard substance. In the case of liquids and solids, the standard is water. In the case of natural gas or other gas materials, the standard is air. Buoyancy is intimately related to specific gravity; if a substance has a specific gravity less than that of a fluid, it will float on that fluid. The specific gravity of most crude oils and refined petroleum products is less than 1.0 and therefore, these substances generally float on water. A substance with a specific gravity greater than 1.0 will sink rather than float in water. See also density.
spill response
All actions taken in carrying out responsibilities to spills of oil and hazardous materials, e.g., receiving and making notifications; information gathering and technical advisory phone calls; preparation for and travel to and from spill sites; direction of cleanup activities; damage assessments; report writing, enforcement investigations and actions; cost recovery; and program development.
spill trajectory
See trajectory.
When crude oil or refined petroleum product is poured onto clear water surfaces, it tends to spread out to a thin film. Most crude oils spread to a thickness of some tenths of millimeter after one hour, and to only a few microns after two or three hours. In reality, oil, when spilled onto the sea, will form windrows (elongated thick patches of oil separated by areas of clear water or water covered by a thin film of oil). The spreading rate will be affected by many factors, such as oil thickness near the source of the spill; type of oil (boiling range, wax content, viscosity, presence of natural surface active compounds); sea state; weather conditions; unimpeded surface area water availability; contamination in the vicinity of the spill, by floating debris; the limitation of free water surface due to seaweed or the presence of natural or man-made structures (rock, jetties, etc.); and the modification of the pollutant composition (emulsion build-up).
See Scientific Support Coordinator.
staging area
The location where incident personnel and equipment are assigned awaiting tactical assignment.
State On-Scene Coordinator (SOSC)
Spill responder responsible for spills of oil and hazardous substances occurring in state.
A narrow line of oil, mousse, or sheen on the water surface, surrounded on both sides by clean water. Streamers result from the combined effects of wind, currents, and/or natural convergence zones. Often, heavier concentrations of mousse or sheen will be present in the center of a streamer, with progressively lighter sheen along the edges. Streamers are also often called "fingers" or "ribbons."
strike team
A set number of resources of the same kind and type that can be assembled for a specific mission. Also, one of the U.S. Coast Guard’s three National Strike Force teams that respond to oil and hazardous chemical incidents.
sublethal effect
A toxic effect that does not directly cause death, but does affect behavior, biochemical or physiological functions, or tissue integrity.
A frozen substance sublimes when it passes directly into the gas phase without first becoming liquid. Substances that sublime include solid carbon dioxide, sulfur, camphor, and naphthalene.
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA) in 1986, often referred to as Superfund. This federal statute establishes liability for site cleanup, prescribes a procedure for identifying and ranking contaminated sites, provides a funding mechanism for site cleanups, reduces uncontrolled releases of hazardous substances, establishes cleanup procedures that provide protection for humans and the environment, and restores injured natural resources through provisions administered by the natural resource trustees.
surface tension
The force of attraction between the surface molecules of liquid. Surface tension affects the rate at which spilled oil will spread over a land or water surface, or into the ground. Oils with low specific gravities are often characterized by low surface tensions and therefore faster spreading rates.
A substance that reduces surface tension of liquids. Nearly synonymous with detergent (which reduces the surface tension of water), wetting agent, and emulsifier.
A uniformly-dispersed mixture of fine particles in a liquid.
Long and relatively uniform wind-generated ocean waves that have traveled out of their generating area.


tank barge
Any tank vessel not equipped with means of self-propulsion, generally used for transporting petroleum products.
tank vessel
Any vessel specially constructed or converted to carry liquid bulk cargo in tanks.
Weathered oil that has formed pliable balls or patches that float on the water. Tarballs can range in diameter from 1/4 inch (a few millimeters) to a foot (0.3 meters). Tarballs can be very persistent and travel long distances on the sea surface. A tarball may eventually biodegrade on the water’s surface or accumulate in a coastal area.
To be announced.
Temporary Emergency Exposure Limit, a level of concern representing the adverse health effects of a hazardous substance on members of the general public. The TEELS are defined by the U.S. Department of Energy for use when ERPGs aren’t available (see
threatened species
A plant or animal species that is not currently endangered, but may become so if its population continues to decrease. Compare with endangered species.
Threshold Limit Value (TLV)
A level of concern representing the adverse health effects of a hazardous substance on healthy adult workers.
tidal flats
Marshy or muddy areas of the seabed, which are covered and uncovered by the rise and fall of tidal water.
tide pools
Permanent depressions in the substrate of intertidal zones, which always contain water but are periodically flushed with successive incoming tides. Tide pools are more frequently located near the high tide mark and often contain abundant flora and fauna that can be adversely affected when spilled oil becomes stranded in these areas.
See Threshold Limit Value.
Poisonous; can injure or kill people or other organisms.
The degree to which a particular substance is deemed to be harmful or deadly. May be acute (sudden) or chronic (long-term).
The direction and pattern of movement of spilled oil over time.
trajectory forecast
A prediction of the speed and direction of the movement of spilled oil or chemical on the water or in the atmosphere. Forecasts are generally produced by computer trajectory models using forecasts and/or observations of local currents and weather. An important role of NOAA’s Scientific Support Team is to produce trajectory forecasts during an incident response.
trustee (for natural resources)
Government officials who act on behalf of the public when there is injury to, destruction of, loss of, or threat to natural resources as a result of a release of a hazardous substance or a discharge of oil. Trustees include the U.S. Departments of Commerce, Interior, Defense, Agriculture, and Energy; state agencies; and Native American tribes. NOAA is the lead federal trustee for coastal and marine resources.
The loss of water clarity or transparency owing to the presence of suspended material.


See Unified Command.
See Upper Explosive Limit.
Unified Command (UC)
The group responsible for conducting response operations at the scene of an incident. It is usually comprised of the U.S. Coast Guard Federal On-Scene Coordinator (FOSC), the State On-Scene Coordinator, and a representative of the responsible party.
UN/NA number
United Nations-North America number. (Also UN Number or DOT Number.) Four-digit number identifying an individual chemical or group of chemicals with similar characteristics. Required on shipping papers; often shown on placards or labels. Often preceded by "UN": e.g., "UN1219."
Upper Explosive Limit (UEL)
Or Upper Flammability Limit. Highest concentration of a flammable vapor in air at which explosion or combustion can occur.
See U.S. Coast Guard.
USCG District
One of 9 administrative units within the U.S. Coast Guard Pacific and Atlantic areas (
U.S. Coast Guard (USCG or CG)
A military, multi-mission, maritime service that is charged with a broad scope of regulatory, law-enforcement, humanitarian, and emergency-response duties. The Coast Guard ( is responsible for responding to oil spills at sea, as well as creating regulations to prevent those spills and contingency plans to be activated should an offshore oil spill occur.
U.S. Fish and Wildlife Service (USFWS or FWS)
A bureau in the U.S. Department of the Interior that works to conserve, protect and enhance fish, wildlife, plants, and their habitats, with a particular focus on migratory birds, endangered species, certain marine mammals, and freshwater and anadromous fish. (
See U.S. Fish and Wildlife Service.
Underground storage tank.


The gas given off by a substance that is liquid (or solid) at normal temperatures and pressures.
vapor density
The ratio of the density of a gas to the density of air at the same temperature. A gas with a vapor density greater than 1.0 is heavier than air and will sink in the atmosphere. See also density.
vapor pressure
A measure of a substance’s tendency to evaporate; liquids with higher vapor pressures evaporate faster.
A measure of a fluid’s resistance to flow and spreading. Viscosity decreases as temperature increases. The viscosity of an oil influences cleanup strategies because it affects whether the oil can penetrate into a substrate, and whether it can be readily pumped or skimmed. An oil’s viscosity increases as it weathers and loses its more volatile components. Petroleum products range in viscosity by orders of magnitude. Tar, for example, is far more viscous than diesel fuel.
Thick, resistant to flow, having a high viscosity.
Volatile Organic Compound. Hydrocarbon compounds that exist in the air and contribute to the formation of smog and/or may themselves be toxic. VOCs often have an odor. Some examples include gasoline, alcohol, and the solvents used in paints. VOCs evaporate quickly and can cause nerve damage and behavioral abnormalities in mammals when inhaled.
A solid or liquid is volatile if it readily evaporates or vaporizes. Petroleum products have a wide range in volatility; for example, gasoline volatilizes so readily that it can pose a short-term risk of fire or explosion hazard. On the other hand, heavy crude oil contains few volatile hydrocarbons and is much less volatile.
Readiness to evaporate. The volatility of a given substance increases with temperature.


Can react vigorously when mixed with water or steam or when spilled into water; the reaction may generate hazardous gas or overpressurize container.
The physical and chemical changes, such as evaporation, emulsification, and biodegradation, that oil or other pollutants undergo when exposed to the environment. Weathering can change an oil’s density, viscosity (resistance to flow), rate of evaporation and dispersion into the water column, and the rate at which it may emulsify. A pollutant’s weathering behavior affects its eventual fate in the environment.
A hole drilled or bored into the earth, usually cased with metal pipe, for the production of gas or oil. A hole for the injection, under pressure, of water or gas into a subsurface rock formation.
A region where the influence of surface water or groundwater has resulted in the development of plant or animal communities adapted to aquatic or intermittently wet conditions. Wetlands include tidal flats, shallow subtidal areas, swamps, marshes, wet meadows, bogs, and similar areas.
wind chop
Short-crested waves found in harbors and lakes that may spring up quickly in a moderate breeze, and which break easily at the crest. Wind chop is usually created by wind, but may also occur by the passage of boats.
Streaks of oil that line up in the direction of the wind. Windrows typically form early during a spill when the wind speed is at least 10 knots (5.1 meters per second). Sheen is the form of spilled oil that most frequently windrows.
Weapon of Mass Destruction. A term used to describe a chemical, biological, radiological, nuclear, or explosive agent that can be used as a weapon.
Organic material, usually from dead seagrass or algae that wash up on shorelines.

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Last updated Wednesday, August 16, 2023 5:08pm PDT