Abiotic:
Not caused or produced by living beings.
Accelerated
Bioremediation: Bioremediation accelerated beyond the normal actions
of the naturally occurring microbial community and chemical and geological
conditions, usually by the addition of nutrients or specialized microbes.
Aerobic:
Living, active, or occurring only in the presence of oxygen.
Alluvium:
Any stream-laid sediment deposit.
Anaerobic:
Living, active, or occurring in the absence of free oxygen.
Anisotropy:
The condition of exhibiting properties with different values when
measured in different directions.
Anoxic:
An environment without oxygen.
Aquifer:
Stratum of permeable rock, sand, or gravel that can store and
supply groundwater to wells and springs.
Archaea:
A group of prokaryotic single-celled microorganisms that constitute
the recently recognized Archaea phylogenetic domain. Archaea can be
distinguished from bacteria in that their cell walls do not have murein,
a peptidoglycan-containing muramic acid. Another unique feature of
archaea is the presence of isopranyl ether lipids in their cell membranes.
The Archaea domain includes the methanogens, most extreme halophiles
(needing salt for growth), certain sulfate reducers, hyperthermophiles
(optimum growth temperature of 80C or higher), and the genus Thermoplasma.
Areal:
The measure of a planar region or the surface of a solid.
Bacteria:
A group of prokaryotic single-celled microorganisms that constitute
the Bacteria phylogenetic domain. Unlike archaea, their cell walls
have murein, a peptidoglycan-containing muramic acid. Bacteria may
have spherical (coccus), rod-like (bacillus), or curved (vibrio, spirillum,
or spirochete) bodies. They inhabit virtually all environments, including
soil, water, organic matter, and the bodies of eukaryotes.
Bacteriophage:
A virus that attacks bacteria.
Basalt:
A fine-grained igneous rock dominated by dark-colored minerals.
Bioaccumulation:
Intracellular accumulation of environmental pollutants, such
as heavy metals, by living organisms.
Bioaugmentation:
The addition of microorganisms to the environment.
Biodegradation:
The breakdown of organic materials into simpler components by microorganisms.
Bioremediation:
The use of living organisms to reduce or eliminate environmental hazards
resulting from accumulations of toxic chemicals and other hazardous
wastes.
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Biosequestration:
The conversion of a compound through biological processes to
a form that is chemically or physically isolated or inert.
Biostimulation:
Addition of nutrients, oxygen, or other electron donors and acceptors
to increase microbial activity and biodegradation.
Biotic:
Caused or produced by living beings.
Biotransformation:
Alteration of the structure of a compound by a living organism or
enzyme.
Catalyst:
A substance that activates a chemical reaction and is not itself changed
in the process.
Chelator:
Any of a class of relatively stable coordination compounds consisting
of a central metal atom attached to a large molecule, called a ligand,
in a cyclic or ring structure.
Clastic:
A texture shown by sedimentary rocks from deposits of mineral and
rock fragments.
Complexing
Agent: A dissolved ligand that binds with a simple charged or
uncharged molecular species in a liquid solution to form a complex,
or coordination compound.
Contaminant:
Harmful or hazardous matter introduced into the environment.
Denitrification:
The formation of gaseous nitrogen (N2) or nitrogen oxide
(NO) from nitrate (NO3-) or nitrite (NO2-) by
microorganisms.
Diagenesis:
All of the changes that occur to a fossil (or more generally
any sediment) after initial burial; includes changes that result from
chemical, physical as well as biological processes.
Electromagnetics
: Electromagnetic instruments work by emitting a current into
the ground from a transmitting coil at one end of the instrument.
A secondary magnetic field, which is proportional to the subsurface
conductivity is received at the other end of the instrument and recorded.
Later the operator, using a graphical computer program converts the
readings (expressed in millmho per meter) into a two dimensional map.
Electron:
A stable atomic particle that has a negative charge.
Electron
Acceptor: Small inorganic or organic compound that is reduced
in a metabolic redox reaction.
Electron
Donor: Small inorganic or organic compound that is oxidized in
a metabolic redox reaction.
Enzyme:
A complex protein that acts as a catalyst in living organisms, regulating
the rate at which chemical reactions proceed without itself being
altered in the process.
Eukarya:
The phylogenic domain consisting of one-celled and multicelled organisms
called eukaryotes that maintain their genome within a defined nucleus.
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Evapotranspiration:
The loss of water from the soil, both by evaporation and by transpiration
from the plants growing there.
Flow
Cells: Containers that are a few meters in size and serve as tools
for examining blocks of soils and subsurface cores that are larger
than the laboratory-scale core samples. They provide "controlled
environments" that simulate the natural subsurface environment
in a laboratory setting without field releases.
Fungi:
Spore-producing eukaryotic organisms that lack chlorophyll; examples
of fungi include molds, rusts, mildews, smuts, mushrooms, and yeasts.
Ground
Penetrating Radar (GPR): Emit short pulses of radio-frequency
electromagnetic energy into the subsurface from a transmitting antenna.
The energy passes through the ground and some is reflected back to
the receiving antenna. A computer processes the reflected signal,
measures the strength and time between emission and reception and
produces a visual representation of the subsurface.
Groundwater:
Water found beneath the earth’s surface that fills pores between
materials, such as sand, soil, or gravel; supplies wells and springs.
Heavy
Metals: Metallic elements with high molecular weights. Such metals
are often residual in the environment, exhibit biological accumulation,
and are generally toxic in low concentrations. Examples include chromium,
mercury, and lead.
Heterogeneity:
Consisting of dissimilar constituents.
Hydraulic
Conductivity: The rate at which water will move through soil in
response to a given potential gradient.
Hydrology:
The study of the occurrence, distribution, and circulation of natural
waters of the earth.
Infrastructure:
Utilities and other physical support systems needed to operate a laboratory
or test facility. Included are electric distribution systems, water
supply systems, sewage disposal systems, and roads.
Inorganic
Compounds: Chemicals that do not contain carbon, which is usually
associated with life processes; for example, metals are inorganic.
In
situ: In the original position or place.
Intrinsic
Bioremediation: Bioremediation at a given site as a function
of the naturally occurring microbial population and naturally occurring
chemical, biological, and geological conditions. Also known as natural
attenuation when dominated by biological processes, or natural bioremediation.
Isotope:
Any of two or more species of atoms of a chemical element with
the same atomic number (number of protons) and nearly identical chemical
behavior but with a different number of neutrons, hence a different
atomic weight.
Karst:
A barren limestone region characterized by fissures, caves, and underground
channels.
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Lysimeters/Caissons:
Large (holding tons of soil) open-ended canisters that can be
closed with a lid, creating a closed system. Soil and sediment can
be placed in the lysimeter to simulate the natural environment.
Magnetometer:
Uses a sealed vessel containing a coiled copper wire surrounded by
oil. The instrument generates a small current that causes the protons
within the oil to spin in the direction of magnetic north. The protons
then generate a small signal, which is sent to the collection part
of the device via the coiled wire. By measuring the signal intensity
and comparing it to a known atomic constant–the gyromagnetic
ration of the proton–the magnetic field intensity at a discrete
location can be obtained.
Methanogen:
Microorganism that produces methane.
Microbe
(microorganism): any living organism invisible or barely visible
to the naked eye and generally observable only through a microscope.
Multi-level
Well Sampler: A device, up to six feet long with separators
every five centimeters, that can be lowered into a well. The separators
form vertical barriers to prevent water from flowing between sampling
intervals. Researchers can collect samples from any depth within the
well to study the water constituents, homogeneity or heterogeneity.
The sampler can be left in the well for an extended period or removed
after samples are collected daily.
Natural
Attenuation: Degradation or transformation of contaminants in
an environment via naturally occurring physical, chemical, and biological
processes. May include intrinsic bioremediation.
Non-reactive
Tracer: An inert substance, such as helium gas, perfluorocarbons,
or bromide, that can be used to obtain a greater understanding of
groundwater flow paths and movement. When extracted from a downgradient
well, an inert tracer is the same chemical or compound as that injected.
See "Reactive Tracer."
Operable
Unit: A regulatory term meaning the division of cleanup of a release
site into discrete action units that eliminate or mitigate a release,
a threat of a release, or an exposure pathway.
Organic
Compounds: Chemical compounds that contain carbon and hydrogen,
elements usually associated with life processes.
Oxidation-Reduction
Reaction: Coupled reactions in which one compound becomes oxidized,
releasing electrons, while another becomes reduced, gaining the electrons
released.
Pathogen:
A specific causative agent (such as a bacterium or virus) of disease.
pH:
A measure of acidity and alkalinity of a solution that is a number
on a scale from 0 to 14. A value of 7 represents neutrality, lower
numbers indicate increasing acidity, and higher numbers increasing
alkalinity. Each unit of change represents a tenfold change in acidity
or alkalinity. This change in acidity or alkalinity is the negative
logarithm of the effective hydrogen-ion concentration or hydrogen-ion
activity in gram equivalents per liter of the solution.
Phytoremediation:
Remediation using plants to remove contaminants from soils.
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Piezometers:
Used to measure fluctuating groundwater levels. Piezometers
are installed in monitoring wells and operate by converting pressure
exerted on a submersed diaphragm into a frequency signal that is transmitted
up the well to a data recorded via a wire. For each pressure, there
is a corresponding frequency signal. The signal generated by each
piezometer is collected in a central data recorder. The depth of groundwater
is calculated factoring varying weather conditions, such as temperature
and barometric pressure. Measurements of the water table can be collected
at any specified time interval, depending on the researchers’
needs.
Plume:
An elongated body of fluid, usually mobile and varying in shape.
Used to define the contaminated areas of an environment.
Precipitate:
The process whereby a solid settles out of a solution.
Prokaryote:
One-celled microorganism whose genome is not contained within
a nucleus. Comprising the two domains Bacteria and Archaea.
Protozoan:
Any of a phylum or subkingdom (Protozoa) of chiefly motile and heterotrophic
unicellular protists (as amoebas, trypanosomes, sporozoans, and paramecia)
that are represented in almost every kind of habitat.
Radioactivity:
Spontaneous emission by radionuclides of energetic particles
through the disintegration of their atomic nuclei; the rays emitted.
Radionuclide:
A radioactive species of an atom. Tritium, strontium-90, and uranium
—235 are radionuclides.
Reactive
Tracer: A substance, such as sulfate or ammonium that may interact
with groundwater, minerals in sediments, or microorganisms. When extracted
from a downgradient well, a reactive tracer is not the same chemical
or compound as that injected. See "Non-reactive Tracer."
Receptors:
Plants, animals, and people that may be exposed to contamination.
A receptor can be exposed via the air and soil pathways (e.g., inhalation,
ingestion, and contact), and the surface and groundwater pathways
(e.g., contact and ingestion).
Redox
Reaction: Oxidation-reduction reaction, involving transfer of
electrons.
Resistivity:
A technique using electrodes in contact with the ground to measure
electrical resistivity. The depth of investigation is a function of
the electrode spacing and geometry.
Saturated
Zone: An underground geologic layer in which all pores and fractures
are filled with water.
Sediment:
Material in suspension in water or deposited from suspension or
precipitation.
Seismic
Refraction: Works by inducing a sound wave into the ground by
means of a percussive device and measuring the return signal at predetermined
distances from the source. By measuring the time it takes for the
sound wave to arrive at the receivers, the researcher is able to infer
the nature of the subsurface material.
Siliceous:
Of, relating to, or containing silica or a silicate.
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Stratified
Sedimentary Rock: Formed, deposited, or arranged sedimentary
rock in a sheetlike mass of one kind lying between beds of other kinds.
Stratigraphy:
A branch of geology that deals with the origin, composition, distribution,
and succession of strata.
Substrate:
The substance acted upon by an enzyme.
Subsurface:
The geologic zone below the surface of the earth; includes rock and
sediment materials lying near but not exposed to the earth’s
surface.
Subsurface
Geophysical Tomography: Subsurface geophysical (cross
hole) tomography allows the researcher to create a horizontal profile
of the subsurface using a method similar to that used from the surface
to generate a vertical profile. This method first requires that bore
holes be installed. The depth and diameter of the bore holes used
are limited only by the size of the instruments to be lowered into
them and the depth to which researchers are concerned. Instruments
are lowered into at least two bore holes and a current is induced
on one end. On the other end, a receiver measures the current. That
reading is sent to a computer where the researchers can map the subsurface
profile in the horizontal plane. By repeating this process at varying
depths throughout the bore holes, they are able to generate a three
dimensional profile of the subsurface. The bore holes can be backfilled
when researchers have collected the data desired.
Surfactant:
A natural or synthetic chemical that promotes the wetting, solubilization,
and emulsification of various types of organic chemicals.
Tracer
Elements: See reactive and nonreactive tracers.
Transmissivity:
The rate at which water is passed through a unit width of rock
under a unit hydraulic gradient.
Unsaturated
Zone: An underground geologic layer in which pores and fractures
are filled with a combination of air and water.
Vadose
Zone: The unsaturated zone above the water table. Also known as
the zone of aeration.
Volatile
Organic Compounds (VOCs): Organic compounds that evaporate at
room temperature.
Water
Table: The upper limit of a geologic layer wholly saturated with
water.
Zone
of Root Influence: Soils or sediments in which roots from surface
plants may be found or that may have an altered geochemistry due to
nearby root/fungal associations.