LaMotte AM-21 Water Pollution Detection Outfit User Manual
Page 33
Nitrate Test
Nitrogen is essential for plant growth but the presence of excessive amounts
in water supplies presents a major pollution problem. Nitrogen compounds
that may enter water as nitrates, or be converted to nitrates, can originate
from agricultural fertilizers, sewage, industrial and packing house wastes,
drainage from livestock feeding areas, farm manures and legumes. Nitrates in
large amounts can cause “blue babies” (methemoglobinemia) in infants less
than six months of age and is an important factor to be considered in
livestock production, where, in addition to causing methemoglobinemia, it is
responsible for many other symptoms arising from the intake of nitrates in
water supplies. Nitrates, in conjunction with phosphates, stimulate the
growth of algae with all of the related difficulties associated with excessive
algae growth.
US Public Health Service Drinking Water Standards state that 10 ppm
Nitrate Nitrogen is a limit which should not be exceeded. However, to the
sanitary and industrial engineer, the concentration which is of concern is less
than 1 ppm.
In the chemical test for nitrates, a red dye is formed by the coupling of two
chemical intermediates through the action of nitrates derived from the
reduction of the nitrate ion.33
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