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Glossary of Terms

Selected words or terms critical to the understanding of the Hudson River PCBs Reassessment are defined below.

Administrative Order On Consent - A legal agreement signed by EPA and an individual, business, or other entity through which the entity agrees to take an action, refrain from an activity, or pay certain costs. It describes the actions to be taken, applies to civil actions, and can be enforced in court. In limited instances it may be subject to a public comment period.

Administrative Record - The body of documents that "forms the basis" for the selection of a particular response at a site. For example, the Administrative Record for remedy selection includes all documents that were "considered or relied upon" to select the remedy through the record of decision.

Bioaccumulation - refers to the process by which contaminants such as PCBs accumulate or become magnified as they move up the food chain. PCBs concentrate in tissue and internal organs, and as big fish eat little fish, they accumulate all the PCBs that have been eaten by everyone below them in the food chain. Another term for this is Biological Magnification.

BIOLOGICAL MAGNIFICATION - see Bioaccumulation (above).

BIOTRANSFORMATION - Biotransformation refers to the process by which compounds are biologically changed. One example is dechlorination (see below).

CONGENER - A congener is one of the 209 different PCB compounds. A congener may have between 1 and 10 chlorine atoms, which may be located at various positions on the PCB molecule.

CONGENER SPECIFIC ANALYSIS (“PCB Fingerprinting”) - A form of chemical analysis that distinctly identifies and quantifies individual PCB congeners. It allows scientists to see distinct PCB patterns or signatures in the environment. These can identify the PCB source material, the likely source areas and the degree and type of subsequent alteration.

CORE SAMPLING - Sediment samples are taken by pushing a hollow tube into the river bottom and removing a core. The cylindrical core sample is then sliced and the various slices analyzed. High-Resolution Sampling sliced the core into many thin slices (approximately one to 1.5-inches thick). Low-Resolution Sampling sliced the core into fewer slices (approximately 9-inches thick).

DECHLORINATION - The process of removing chlorine atoms from a PCB molecule while leaving the main molecular structure intact. In the Hudson, this only affects the outer chlorine atoms. In most instances, dechlorination of a PCB molecule simply yields a different PCB molecule.

DEGRADATION - The sum of natural processes which cause a decrease in PCB mass (weight, not quantity) by either dechlorination or outright destruction of PCB molecules.

WATER COLUMN STUDY - Investigation of water-borne PCBs to characterize their sources, movement, and distribution.

Two additional, more comprehensive glossaries are available as links:
Terms of Environment (Master EPA glossary of acronyms and environmental terms )
Glossary of Risk Assessment terms


For information about this page, contact: kluesner.dave@epa.gov


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