LaMotte Nitrate-Nitrogen Enzyme Reduction Test Kit - Manual (Page 2)

run-off and erosion from farms contribute to excessive nutrient levels in surface
and groundwater. In suburbs, septic systems and lawn fertilizer run-off from
millions of homes are an example of nonpoint source pollution. After a rain
storm in urban areas, run-off from highways and parking lots washes nutrients
into storm water systems.
Ni trate Con tam i na tion
In slow-moving, shallow bodies of water, excess nutrients encourage the growth
of algae and aquatic vegetation. In a short amount of time, vegetation may cover
the entire area and swimming and boating may become impossible. Dense mats
of algae on the surface will block sunlight needed by submerged aquatic
vegetation (SAV). As the habitat changes, the water quality becomes poor and
only pollution tolerant species will remain. If sediment from erosion and run-off
is trapped in the sunken roots and rotting vegetation the entire waterway may fill
in completely in a process called eutrophication.
In fast moving streams, nutrient levels may be high but the flow of water will
prevent the establishment of floating aquatic plants and algae. During seasonal
fluctuations the water flow may become reduced and streams will then become
choked with algae.
Industrial processes that use natural water for cooling, like power plants, can be
damaged when the source water is thick with algae. Bathers and boaters using
recreational waters will experience clumps of floating algae in the water and
rotting algae on the shoreline after an algae bloom.
Drinking water containing high nitrate levels can affect the ability of blood to
carry oxygen. This condition, called methemoglobinemia, is especially harmful to
infants and anyone with a compromised immune system.
Test ing for Ni trate
The impact of nutrient overload on the environment is becoming better
understood and nitrate testing is becoming more widespread. The demands of the
monitoring community are for less hazardous reagent systems and kits with an
increasingly lower detection limit.
Nitrate can not be measured directly. It can be reduced to nitrite and then
measured colorimetrically. Nitrite forms a reddish-purple color under acidic
conditions with the addition of sulfanilamide and
N-(1-naphthyl)-ethylenediamine-dihydrochloride indicator. This color is then
matched to a color standard to determine the nitrate level.
Widely used test methods utilize heavy metals to reduce the nitrate to nitrite.
The most commonly used metals are cadmium and zinc. Cadmium, which is
more hazardous than zinc, gives better sensitivity at low concentrations so it is
used in kits with lower ranges. Recently, a reagent system was developed that has
the sensitivity of cadmium reduction at low concentrations and uses