GLOSSARY - Bioaugmentation for Groundwater Remediation - page 370

Nanoscale ‐ Generally deals with structures of the size 100 nm or smaller. For example,
reactive iron produced in this size range is referred to as nanoscale iron.

Niche ‐ In ecology, a habitat that supplies the factors necessary for the existence of an
organism or species, or the ecological role of that organism or species within the overall
community of organisms. Derived from the meaning of niche as a place or role that is best
suited for a particular person or thing.

Nonaqueous phase liquid (NAPL) ‐ An organic liquid that is maintained as a separate phase

from water.

Nucleotide ‐ The fundamental building blocks of nucleic acids (RNA and DNA). Composed
of a nucleobase (nitrogenous base), a five-carbon sugar (either ribose or 2 0 -deoxyribose), and
one to three phosphate groups. The order of the nucleotides (A, T, C, or G for DNA) determines
the structure of the genes and their products.

Oligonucleotide ‐ A polynucleotide whose molecules contain a relatively small number of

nucleotides.

Oligotrophic ‐ 1. Any environment, ecosystem, or area that is low in nutrients and/or primary
production. 2. Organisms adapted to low-carbon environments.

Organohalide respiration ‐ Process by which organisms gain energy for maintenance or
growth from reductive dechlorination reactions (i.e., the organisms benefit from contaminant
transformation). Also called chlororespiration, dechlororespiration, halorespiration,
dehalorespiration, chloridogenesis, catabolic reductive dechlorination, metabolic reductive
dechlorination or respiratory reductive dechlorination.

Oxic ‐ Containing oxygen or oxygenated. Often used to describe an environment, a condition,
or a habitat in which oxygen is present.

Oxidation-reduction potential (ORP) ‐ The tendency of a solution to either gain or lose
electrons when it is subject to change by introduction of a new species. A solution with a higher
(more positive) reduction potential than the new species will have a tendency to gain electrons
from the new species (to be reduced by oxidizing the new species); a solution with a lower (more
negative) reduction potential will have a tendency to lose electrons to the new species (to be
oxidized by reducing the new species). A positive ORP indicates the solution is aerobic, while a
negative ORP indicates reducing conditions are dominant.

Oxygenase ‐ An enzyme that introduces oxygen into an organic molecule.

Passive treatment ‐ In situ bioremediation approach in which amendments are added to the
subsurface on a one-time, or infrequent basis. Passive treatment relies on the use of slow-
release electron donors, which can be injected into the subsurface or placed in trenches or wells.

Pathogen ‐ Microorganisms (e.g., bacteria, viruses, or parasites) that can cause disease in
humans, animals, and plants.