Environmental Engineering Reference
In-Depth Information
Phreatic surface:
the top of the zone of saturation. Also referred to as water table.
Phreatic zone:
the region within the subsurface where all available pore space is saturated
with water. Also termed zone of saturation.
Phthalate:
a group of approximately 25 organic compounds consisting of esters of phthalic
acid.
Phytoremediation:
removal of contaminants using plants.
Piezometer:
a device inserted into the subsurface that penetrates the groundwater surface
for purposes of collecting hydrologic, chemical, or other information with respect
to groundwater. Also referred to as monitoring well.
Piezometric surface:
an imaginary surface representing the static level groundwater
would rise. Also referred to as potentiometric surface, isopotential level, and pres-
sure level.
Plate tectonics:
scientific theory describing the large scale motion of Earth's lithospheric
plates.
Plasticity:
a property of soil or rock allowing it to be deformed beyond the point of recov-
ery without cracking or exhibiting appreciable change in volume.
Point source pollution:
pollution originating from an identifiable source such as an
exhaust pipe or smokestack.
Polarity:
directional charge.
Pollution:
the human introduction into the environment of substances harmful to human
health or ecosystems. Also referred to as contamination.
Pollution prevention:
preventing contaminants from entering the environment by reduc-
ing or eliminating waste at the source. Methods include modifying production
processes, promoting the use of nontoxic or less toxic substances, implementing
conservation techniques, and reusing materials rather than putting them into a
waste stream.
Polychlorinated biphenyl:
a group of synthetically produced chemicals with 1-10 chlo-
rine atoms attached to a biphenyl.
Polycyclic aromatic hydrocarbons:
a group of more than 100 organic compounds with
multiple benzene rings. Also referred to as polynuclear aromatic hydrocarbons.
Polynuclear aromatic hydrocarbons:
a group of more than 100 organic compounds with
multiple benzene rings. Also referred to as polycyclic aromatic hydrocarbons.
Porosity:
the volume of open space within sediment, usually expressed as a percent.
Positive feedback:
when the outcome of a process within a system speeds up or magnifies
the system's activity or work output.
Potable water:
water used for any human purpose.
Potency:
the degree to which a substance or agent can cause harm to an organism when
exposed. Also referred to as toxicity.
Potentiometric surface:
an imaginary surface representing the static level groundwater
would rise to. Also referred to as piezometric surface, isopotential level, and pres-
sure level.
Precambrian:
referring to the earliest period of geological time, between about 4600 and
543 million years ago, from when Earth was formed until the first simple forms of
life appeared.
Pressure level:
an imaginary surface representing the static level groundwater would
rise. Also referred to as potentiometric surface, isopotential level, and piezometric
surface.
Prevention:
minimizing the potential of contaminants entering the environment, usually
through engineering controls.
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