Where do nitrates come from?
All aquatic organisms excrete wastes and aquatic
plants and organisms eventually die. These activities create
ammonia. Some bacteria in the water change this ammonia
to produce nitrite which is then converted by other bacteria
to nitrate. Nitrates (NO3-) are an oxidized
form of nitrogen and are formed by combining oxygen and nitrogen.
Nitrates also come from the earth. Soil contains
organic matter, which contains nitrogen compounds.
Just like the ammonia in water, these nitrogen compounds in the soil are converted
by bacteria into nitrates.
Although nitrates occur naturally in soil and
water, an excess levels of nitrates can be considered to be a contaminant of ground and surface waters.
Most sources of excess nitrates come from human activity. The
source of excess nitrates can usually be traced to agricultural
activities, human wastes, or industrial pollution.
Nitrogen fertilizers have been applied to fields,
yards, and golf courses to promote the growth of plants. Rainwater
can wash nitrates in the fertilizers into streams and rivers or the
nitrates can seep into the ground water.
This runoff problem tends to be most serious when the fertilizer is
animal waste or manure.
In addition to animal waste, untreated human sewage
can contribute to nitrate levels in surface and ground water.
Leaking or poorly functioning septic systems are a source of such
nitrates. City sewage treatment plants treat sewage to make it non-hazardous,
but treatment plants still release nitrates into waterways.
In addition, industrial plants that produce
paper or munitions are potential sources of nitrate pollution.
Although having excess nitrates is usually associated
with some type of human activity, excess nitrates can come from
natural sources. A good example of this is the presence of large
numbers of birds that might live in or around a body of water.
Bird excretions that get into the water can create large amounts
2 | 3
| Objectives | Pre-Test
| Presentation | Activity
Quality Modules |
Pages | Standards