GLOSSARY - Bioaugmentation for Groundwater Remediation - page 367

In situ chemical reduction (ISCR) ‐ Technology that reduces contaminants in place by

adding chemical reductants such as zero-valent iron, resulting in detoxification or

immobilization of the contaminants.

In situ thermal treatment ‐ Treatment system that generates high temperatures to remove
and destroy contaminants in place. In practice, three types of technologies have been used—
steam injection, electrical resistance heating (generating heat by applying an electrical current)
and thermal conductive heating (using electrical subsurface heaters to radiate heat outwards
through the solid matrix).

Influent ‐ Water, wastewater, or other liquid flowing into a reservoir, basin or in situ target
treatment zone.

Inoculum ‐ 1. Bacteria or fungi injected into compost to start biological action. 2. A medium
containing organisms, usually bacteria or a virus, that is introduced into living organisms or
environmental media.

Interfacial tension ‐ The force at the interface between two immiscible liquids (such as a
chlorinated solvent nonaqueous phase liquid [NAPL] and water) that results from the attractive
forces between the molecules in the different fluids. Generally, the interfacial tension of a
given liquid surface is measured by finding the force across any line on the surface divided by
the length of the line segment (so that interfacial tension is expressed as force per unit length,
equivalent to energy per unit surface area).

Intrinsic bioremediation ‐ A type of in situ bioremediation that uses the innate capabilities of
naturally occurring microbes to degrade contaminants without requiring engineering steps to
enhance the process.

Intrinsic remediation ‐ In situ remediation that uses naturally occurring processes to degrade
or remove contaminants without using engineering steps to enhance the process.

Isotope ‐ Any of two or more species of an element in the periodic table with the same number
of protons. Isotopes have nearly identical chemical properties but different atomic masses and
physical properties. For example, the isotopes chlorine 37 ( 37 Cl) and chlorine 35 ( 35 Cl) both have
17 protons, but 37 Cl has two extra neutrons and thus a greater mass.

Isotope fractionation ‐ Selective degradation of one isotopic form of a compound over

another isotopic form.

Kinetics ‐ The rate at which a reaction occurs.

Lactate ‐ A salt or ester of lactic acid.

Life cycle cost ‐ The overall estimated cost for a particular remedial alternative over the time
period corresponding to the life of the program, including direct and indirect initial costs plus
any periodic or continuing costs of operation and maintenance.

Lipid ‐ Amphiphilic molecule, possessing the ability to separate two different phases or layers
(such as separating water and oil). Often refers to a cell's outer membrane. An amphiphile