Bioremediation: Glossary
ABIOTIC: Not biotic or living
ANOXIC: Habitat devoid of oxygen
ANTHROPOGENIC: Derived from human activities
AQUIFER: Water-bearing stratum of permeable rock, sand, or gravel
BIOAUGMENTATION: The addition of microorganisms that can metabolize and grow on
specific organic compounds.
BIOAVAlLABILITY: The availability of chemicals to be potentially degraded by
microorganisms
BIODEGRADATION: compound undergoes biological transformation; does not imply extent
nor whether endproducts are innocuous.
BIOSTIMULATION: A process that increases microbial degradation of contaminants via
addition of nutrients, oxygen, or other electron donors and acceptors.
BIOTRANSFORMATION: Alteration of the structure of a compound by a living organism or
enzyme
BIOVENTING: Process of supplying oxygen in situ to soil microbes by forcing air through
unsaturated contaminated soil at low flow rates. This stimulates biodegradation and minimizes
stripping volatiles into the atmosphere. Frequently used to remediate soil under structures since it
is relatively non-invasive.
BROWNFIELD: An abandoned, idled, or under-used industrial or commercial facility where
expansion or redevelopment is complicated by a real or perceived environmental contamination
BTEX: Benzene, toluene, ethylbenzene, and xylenes components of gasoline
COMETABOLISM: The biodegradation of a pollutant by an organism while using some other
compound(s) for growth and energy. There is little or no benefit to the biodegrading organism,
the pollutant just happens to be affected by the enzymes of the cometabolizing organism growing
on a primary substrate.
DENITRIFICATION: The formation of gaseous nitrogen and/or oxides of nitrogen from nitrate
or nitrite by some bacteria during ANAEROBIC RESPIRATION. Denitrification only occurs
under ANAEROBIC or MICROAEROPHILIC conditions. It can sometimes be used to remove
nitrate or nitrite from liquid wastes.
EX SITU: Out of the original place (Excavated).
IN SITU: In place, without excavation.
INTRINSIC BIOREMEDlATION (NATURAL ATTENUATION): Bioremediation by the
naturally occurring microbial population and naturally occurring chemical, biological, and
geological conditions.
MINERALIZATION: The breakdown of organic matter to inorganic materials of lowest energy
(such as carbon dioxide and water) by bacteria and fungi.
NAPL: Non-aqueous phase liquid. This can be lighter than water (LNAPL), or more dense than
water (DNAPL).
NITRATE RESPIRATION: (dissimilatory nitrate reduction) The use of nitrate as a terminal
electron acceptor for ANAEROBIC RESPIRATION. This process occurs under ANAEROBIC
or MICROAEROPHILIC conditions. Not all bacteria are capable of this form of metabolism and
the nitrate may not be reduced completely to nitrogen gas (may stop at nitrite, for example).
When the nitrate is reduced to gaseous forms the process is called DENITRIFICATION. This
can sometimes be used to remove nitrate or nitrite from liquid wastes.
NITRIFICATION: The oxidation of ammonia to nitrite and then nitrate by bacterial species such
as Nitrosomonas and Nitrobacter, respectively. This process is strictly aerobic.
PERSISTENT: compound does not undergo biodegradation in certain environments.
RECALCITRANT: compound resists biodegradation in wide variety of environments.
REDOX POTENTIAL: The oxidation-reduction potential of an environment. Measures the
tendency of the environment to be reducing (donate electrons) or oxidizing (accept electrons).
REDUCTIVE DECHLORINATION: Removal of CI as chloride ion from an organic compound
by reducing the carbon atom from C-Cl to C-H. The chlorinated compound acts as the terminal
electron acceptor and microbe may gain energy.
RHIZOSPHERE: Soil surrounding plant roots that is influenced by the root. Typically a few
millimeters or at most centimeters from the plant root. Important because this area is higher in
nutrients and thus has a higher and more active microbial population.
VADOSE ZONE: Unsaturated zone of soil above the groundwater, extending from the bottom of
the capillary fringe all the way to the soil surface.
WEATHERING: All physical and chemical changes produced by atmospheric agents.
XENOBIOTIC: Compound foreign to biological systems. Often refers to human-made
compounds that are resistant or recalcitrant to biodegradation and decomposition.