Science of Water : Concepts and Applications

Glossary 411
Monitoring well A well designed for measuring water levels and testing groundwater quality.
Multiple-tube fermentation method A laboratory method used for coliform testing, which
uses a nutrient broth placed in a culture tubes. Gas production indicates the presence of
coliform bacteria.
N
National Primary Drinking Water Regulations (NPDWRs) Regulations developed under
the Safe Drinking Water Act, which establish maximum contaminant levels, monitoring
requirements, and reporting procedures for contaminants in drinking water that endanger
human health.
National Pollutant Discharge Elimination System (NPDES) A requirement of the CWA that
discharges meet certain requirements prior to discharging waste to any water body. It sets
the highest permissible effl uent limits, by permit, prior to making any discharge.
Near Coastal Water Initiative This initiative was developed in 1985 to provide for the management
of specifi c problems in waters near coastlines that are not dealt with in other
programs.
Nitrate An ion consisting of nitrogen and oxygen (NO 3 ). Nitrate is a plant nutrient and is very
mobile in soils.
Nonbiodegradable Substances that do not break down easily in the environment.
Nonpoint source A source (of any water-carried material) from a broad area, rather than from
discrete points.
Nonpoint-source contaminant A substance that pollutes or degrades water that comes from
lawn or cropland runoff, the atmosphere, roadways, and other diffuse sources.
Nonpoint-source water pollution Water contamination that originates from a broad area (such
as leaching of agricultural chemicals from crop lad) and enters the water resource diffusely
over a large area.
Nonpolar covalently bonded 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 having 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 in.
Organochlorine compound Synthetic organic compounds containing chlorine. As generally
used, this 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 fl ow The fl ow of rainwater or snowbelt over the land surface toward stream channels.
Oxidation When a substance either gains oxygen or loses hydrogen or electrons in a chemical
reaction. One of the chemical treatment methods.
Oxidizer A substance that oxidizes another substance.