Nitrates. The root of all evil, or a bare necessity? In
order to answer this question, one needs to understand what Nitrates are, and
what they are used for. Hopefully, this should help with understanding this
concept in the simplest of terms.
What are Nitrates?
Basically, a nitrate is a molecular ion that are the
consequence of the chemical bondage of one positively charged Nitrogen ion with
three negatively charged Oxygen ions. This therefore creates the overall chemical
formula of NO3-. Nitrates are only naturally formed. This
can occur in the atmosphere where there is an abundant source of Nitrogen and
some Oxygen, due to such events lightning strikes. This Nitrate can be
transferred to the Earth’s surface via precipitation (rainfall). This is by far
not the greatest contributor of the Earth’s nitrate, instead this occurs
biologically. Nitrification is the natural process most commonly associated
with the production of Nitrates in the Earth’s natural environment. This
process is represented through the following chemical reaction:
Nitrification:
NH3 (aqueous) + 2O2 (aqueous) => NO3-
(aqueous) + H20 (liquid) + H+ (aqueous).
 |
| Figure one: Diagram graphically showing the Nitrogen Cycle, inclusive of the Nitrification process. Source: Wikipedia.org |
As expressed in figure one, nitrification is a biological process that ultimately
produces Nitrate from Ammonia. This occurs due to the oxidation of Ammonia into Nitrite, which further oxidises into Nitrate. Biological processes such as
the decomposition of flora and fauna cause such a process. The key component of
the process is autotrophic bacteria within soils, and organisms which fixate
nitrate out of organic material. Nitrification is an important process in the development
of productive soils.
Nitrates physically appear in the form of salts. These ‘salts’ are
highly soluble when in contact with water. This means that in the advent of nitrates interacting with water bodies, the overall chemical
composition of the water body changes, resulting in increased levels of nitrate
within the water body.
Importance of Nitrates
Essentially, Nitrate supports life. This is because Nitrates
are a readily available source of Nitrogen which is required to sustain life
both within flora and fauna. In the context of dairy farming, ammonia is
applied to pastures in the form of fertilizers From this base, autotrophic
bacterium then fixates nitrate from the ammonia, providing the soils with a
nitrogen source, generating a greater source of nutrients for flora. This leads to
more fertile pasture, resulting in greater grass growth, which theoretically
should increase production.
However, in saying this, there needs to be caution in terms
of how much Nitrate is within the ecological system. This is because a system
can only handle so much nitrogen within it before it gets to a point of
saturation, such as waterways. Detrimental effects of high amounts of nitrates
within systems such as water bodies include eutrophication due to the increase
in nutrients and decrease in oxygen. Eutrophication can lead to the mortality
of the marine ecology, and also have hazardous effects to humans if nitrate
levels within drinking water exceed recommendations.
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Sources:
Nitrogen Cycle - http://commons.wikimedia.org/wiki/File:Nitrogen_Cycle.svg
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