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Water Analysis
Much of what is called water chemistry is the chemistry of substances
suspended or dissolved in water. It involves the determination of these substances and
materials. The amounts of dissolved and suspended matter in water are generally
measured in terms of parts per million parts of water or ppm.
Chemical examination of water rarely requires the determination of minor
constituents amounting to mere traces. Instead, the usual water analysis report
includes: suspended matter; total dissolved solids; hydrous silica, alumina, and iron;
the cations, sodium, potassium, calcium and magnesium; and the anions, carbonate,
chloride, and sulphate. In recent years, the fluoride ion has become more important.
Waters with fluoride of the order of 10ppm. or thereabouts can be very injurious to
the teeth of growing children but on the other hand, 1ppm. is regarded by some to be
highly beneficial.
A sanitary water analysis is primarily dependent on the detection of bacteria.
Presence of Bacterium coli is indicative of contamination by sewage, and pathogenic
bacteria such as Bacterium typhosum may be present. Such analyses are
supplemented by chemical examination, which is generally limited to biochemical
oxygen demand, chlorides in excess of those in uncontaminated supply, and the
determination of various forms of combined nitrogen ranging from proteins and
ammonium compounds to nitrites and nitrates. More or less completely oxidized
nitrogen compounds indicate less recent contamination, but are danger signals. The
quantity and nature of toxic metals must be determined where industrial wastes are a
factor.
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