A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Background Level: 1. The concentration of a substance in an environmental media (air, water, or soil) that occurs naturally or is not the result of human activities. 2. In exposure assessment the concentration of a substance in a defined control area, during a fixed period of time before, during, or after a data-gathering operation.

Bacteria: (Singular: bacterium) Microscopic living organisms that can aid in pollution control by metabolizing organic matter in sewage, oil spills or other pollutants. However, bacteria in soil, water or air can also cause human, animal and plant health problems.

Bailer: A pipe or tube with a valve at the lower end, used to collect groundwater samples from wells or open boreholes.

Bentonite: A colloidal clay, expansible when moist, commonly used to provide a tight seal around a well casing.

Biodegrade: To breakdown organic substances, using microorganisms.

Bioremediation: The process by which living organisms act to degrade oil spills or remove other organic pollutants from soil or water.

Biosurfactant: A surface-active agent produced by microorganisms (see Surfactant).

Borehole: Hole made with drilling equipment.

Breakthrough: The point where contaminants begin to pass through filter media (e.g. granular activated carbon media), due to the media having reached its maximum treatment capacity.

Brownfields: Abandoned, idled, or under used industrial and commercial facilities/sites where expansion or redevelopment is complicated by real or perceived environmental contamination. They can be in urban, suburban, or rural areas. EPA's Brownfields initiative helps communities mitigate potential health risks and restore the economic viability of such areas or properties.

Bulk Sample: A small portion (usually thumbnail size) of a material collected for laboratory analysis to determine asbestos content.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z