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Accute effects: Effects having a sudden onset and lasting a short time.

Ambient air monitoring: A systematic assessment of pollutant levels by measuring the quantity and types of certain pollutants in the surrounding, outdoor air. Note that most PAHs in ambient air are the result of man-made processes.

Ames test: A biological assay to assess the mutagenic potential of chemical compounds.

Analyte: A substance or chemical constituent that is determined in an analytical procedure.

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. However, from the air, it is impossible to tell how thick a black oil layer is.

Bioaccumulation: The uptake and retention of a bioavailable chemical from any one of or all possible external sources (water, food, substrate, air).

Bioavalability: Chemicals that are able to penetrate permeable tissues of an organism.

Bio-assay: A measurement of the effects of a substance on living organisms

Biodegradation:  The chemical breakdown of materials by a physiological environment.

BRIDGES: Biological response indicator devices for gauging environmental stressors, Project 4 of the Superfund Program. More information.

Chronic effects: Chronic health effects are characterized by prolonged or repeated exposures over many days, months or years. Symptoms may not be immediately apparent.

Crude oil (crude oil petroleum): A fossil fuel formed from plant and animal remains many million of years ago. It comprises organic compounds built up from hydrogen and carbon atoms and is, accordingly, often referred to as hydrocarbons. Crude oil is occasionally found in springs or pools but is usually drilled from wells beneath the earth's surface.

Dispersants: Chemicals that are used to break down spilled oil into small droplets
Related link: Dispersants: A Guided Tour from NOAA
Related article: Ingredients of Controversial Dispersants Used on Gulf Spill Are Secrets No More (NY Times, 6-8-10)

Emulsions: A mixture of small droplets of oil and water.

Oil plumes: These are underwater globules of oil that do not float to the surface of the ocean. Scientists say microscopic oil droplets are forming these deep water oil bubbles. The heavy use of chemical dispersants, which breaks up surface oil, is said to have contributed to the formation of these plumes. Scientists are worried that these underwater globs will pose a threat to the marine ecosystem and that the oil could be absorbed by tiny animals and enter a food chain that builds to larger fish.

Oil Trajectory: NOAA uses a model to provide information about where a spill is likely to go.
Related link: NOAA Oil Spill Trajectory Maps 

OPAHs: Oxygenated PAHs (oxy-PAHs)

Passive Sampling Device (PSD):  A method of determining airborne and water concentrations of volatile contaminants. PSDs collect samples with a small badge-like device that relies on the diffusion of compounds to a collection surface or sorbent. The diffusion barrier across the badge confers a constant, predetermined effective flow rate that is only slightly affected by temperature and unaffected by pressure (or altitude). The PSD hangs in the sampling area for periods ranging from 8 hours to one month. After the sampling period, it is capped and returned to a laboratory for analysis using traditional methods.

Petroleum: Petroleum means "rock oil", from the Greek petros/Latin petra (rock), and the Greek elaion/Latin oleum (oil). The term petroleum is nowadays used as a common denotation for crude oil (mineral oil) and natural gas, i.e., the hydrocarbons from which various oil and gas products are made. Petroleum, then, is a collective term for hydrocarbons, whether solid, liquid or gaseous.

Polycyclic aromatic hydrocarbons (PAHs): See All About PAHs

Quality Assurance: The systematic monitoring and evaluation of the various aspects of the sampling project to ensure that standards of quality are being met.

Quality Control: Periodic checks to verify that data are generated, collected, handled, analyzed, and reported according to protocol.

Slick: A thin film of oil on the water’s surface.

Sorbents: Substances that take up and hold water or oil; sorbents used in oil spill cleanup are made of oleophilic materials.

Spreading: As soon as oil is spilled, it starts to spread out over the sea surface, initially as a single slick. The speed at which this takes place depends to a great extent upon the viscosity of the oil. Slicks quickly spread to cover extensive areas of the sea surface. Spreading is rarely uniform and large variations in the thickness of the oil are typical. After a few hours the slick will begin to break up and, because of winds, wave action and water turbulence, will then form narrow bands or windrows parallel to the wind direction. The rate at which the oil spreads is also determined by the prevailing conditions such as temperature, water currents, tidal streams and wind speeds. The more severe the conditions, the more rapid the spreading and breaking up of the oil.

Tar: A black or brown hydrocarbon material that ranges in consistency from a heavy liquid to a solid.

Tarball: Dense, black sticky spheres of hydrocarbons; formed from weathered oil.
Related flyer: NOAA on understanding tarballs (pdf)

Total Petrolium Hydrocarbons (TPH): A termused to describe a broad family of serveral hunderd chemical compounds that originally come from crude oil. TPH is really a mixture of chemicals. They are called hydrocarbons because almost all of them are made entirely from hydrogen and carbon. Crude oil can vary in how much of each chemical they contain. (ATSDR)

Toxicity: The degree to which a substance can harm humans or animals.