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Nanometer |
Abbreviated "nm",
a unit of length equal to one thousandth of a micrometer. Often used to
express the wavelength of ultraviolet light and the colors of visible
light in colorimetric analytical procedures. |
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Negative Charge |
The electrical charge on an
electrode or ion in solution, due to the presence of an excess of
electrons. (See electron, anion.) |
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Negative Head |
A condition of negative
pressure or partial vacuum. |
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Negative Pressure |
A pressure below that of
the surrounding atomspheric pressure at a specific point; a partial
vacuum. |
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Nephelometric Turbidity
Unit |
An arbitrary unit of
measuring the turbidity in water by the light scattering effect of fine
suspended particles in a light beam (contrast to "Jackson Turbidity
Unit"). |
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Neutral |
In electrical systems, the
term used to indicate neither an excess nor a lack of electrons; a
condition of balance between positive and negative charges. In chemistry,
the term used to indicate a balance between acids and bases; the neutral
point on the pH scale is 7.0, indicating the presence of equal numbers of
free hydrogen (acidic) and hydroxide (basic) ions. |
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Neutralization |
The addition of either an
acid or a base to a solution as required to produce a neutral solution.
The use of alkaline or basic materials to neutralize the acidity of some
waters is a common practice in water conditioning. |
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Neutralizer |
A common designation for
alkaline materials such as calcite (calcium carbonate) or magnesia
(magnesium oxide) used in the neutralization of acid waters. |
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Nitrates |
Inorganic compounds that
can enter water supplies from fertilizer runoff and sanitary wastewater
discharges. Nitrates in drinking water are associated with
methemoglobinemia, or blue baby syndrome, which results from interferences
in the bloods ability to carry oxygen. |
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Noncarbonate Hardness |
Water hardness due to the
presence of compounds such as calcium and magnesium chlorides, sulfates or
nitrates; the excess of total hardness over total alkalinity. |
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Non-Transient,
Non-Community Water System |
A water system which
supplies water to 25 or more of the same people at least six months per
year in places other than their residences. Some examples are schools,
factories, office buildings, and hospitals which have their own water
systems. |
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Normal Solution |
A solution containing a
gram equivalent weight of a substance in one liter of solution. (See
equivalent weight.) |
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Ntu |
Abbreviation for "Nephelometric
Turbidity Unit". |