Environmental Engineering Reference
In-Depth Information
Nonbiodegradable:
Substances that do not break down easily in the
environment.
Non-point source contaminant:
A substance that pollutes or degrades water
that comes from lawn or cropland runoff, the atmosphere, roadways,
and other diffuse sources.
Non-point source water pollution:
Water contamination that cannot be traced
to a discrete source (such as a discharge pipe); instead, it originates
from a broad area (such as leaching of agricultural chemicals from
cropland) and enters the water resource diffusely over a large area.
Nonpolar covalently bonded:
Refers to a molecule composed of atoms that
share their electrons equally, resulting in a molecule that does not
have polarity.
Nutrient:
Any inorganic or organic compound needed to sustain plant life.
o
organic:
Containing carbon, but possibly also containing hydrogen, oxygen,
chlorine, nitrogen, and other elements.
organic chemical:
A chemical substance of animal or vegetable origin hav-
ing carbon in its molecular structure.
organic detritus:
Any loose organic material in streams (such as leaves,
bark, or twigs) removed and transported by mechanical means, such
as disintegration or abrasion.
organic soil:
Soil that contains more than 20% organic matter in the upper
16 inches.
organochlorine compound:
Synthetic organic compounds containing chlo-
rine. As generally used, term refers to compounds containing mostly
or exclusively carbon, hydrogen, and chlorine.
outwash:
Soil material washed down a hillside by rainwater and deposited
upon more gently sloping land.
overland flow:
The flow of rainwater or snowmelt over the land surface
toward stream channels.
oxidation:
A chemical treatment method where a substance either gains
oxygen or loses hydrogen or electrons through a chemical reaction.
oxidizer:
A substance that oxidizes another substance.
P
Parts per million (ppm):
The number of weight or volume units of a con-
stituent present with each 1 million units of a solution or mixture.
Formerly used to express the results of most water and wastewater
analyses, ppm is being replaced by milligrams per liter (mg/L). For
drinking water analyses, concentrations expressed in parts per mil-
lion and milligrams per liter are equivalent. A single ppm can be
compared to a shot glass full of water inside a swimming pool.
