Ammonia Nitrogen (NH3)
Ammonia (NH3) is an inorganic, nitrogen containing compound which in small
amounts can be useful as a source of nitrogen for plant growth. In large quantities,
it can be a bad pollutant. Ammonia typically comes from the decay (usually under
low concentrations of dissolved oxygen) of organic material such as dead plants
& animals, and excrement from feedlots or sewage.
The amount of ammonia found in slow-moving streans is usually higher than
in fast streams as more decaying materials have a chance to settle out, and
the lack of current lessens the amount of oxygen diffusing into the stream from
the air.
Typically in fast moving streams the ammonia concentration should be much
lower, partly because less decaying material is able to settle out, and partly
because more oxygen is available. If a faster stream has a high oxygen content,
then one should suspect that sewage from septic tanks, or sewage from storm
runoff (In Portland, sewage and storm water travel down the storm drains. During
dry weather, the sewage gets diverted to the sewage treatment plant. When it
rains alot, some of the sewage gets washed out to local streams! Yuck!!!), recent
application of fertilizer on neighborhood lawns or golf courses, or farm runoff.
The amount of ammonia nitrogen in a stream may also rise as the water becomes
more alkaline (pH is greater than 7.0).
Over time, ammonia gets broken down by bacteria in the stream to form nitrates
(NO3).
Slichter