Date:
Title: Nitrate Test
Aim: A qualitative test to determine the presence of nitrates in water
Apparatus and Materials:
Test tubes, 10ml measuring cylinder
Glass dropper
Concentrated 𝐻2 𝑆𝑂4
Diluted 𝐻2 𝑆𝑂4
Solid iron (II) sulphate
Distilled water
Procedure:
Place 2𝑐𝑚3 of water sample in a test tube.
Acidy the water sample with 1𝑐𝑚3 dilute sulphuric acid.
Add 1𝑐𝑚3 diluted iron sulphate to the acidified water sample and cool.
Carefully add 6 drops concentrated sulphuric acid by allowing it to flow down the side of the test
tube.
5. Allow the mixture to sit undisturbed for 1min.
6. Observe whether a brown ring forms at the surface of the water sample. This indicates the
presence of nitrates in the sample.
1.
2.
3.
4.
Results:
Table: Presence of nitrates in water samples
Sites
1
2
3
4
Presence of nitrates
Yes
No
No
No
Yes
No
Discussion:
The presence of nitrates in none but one of the sites suggests multiple things. First off, nitrates are a
component nutrient for plant growth for most plants, therefore while not definitively we can assume
that site 3 will comparatively have greater aquatic vegetation growth than the other sites. While this
quality would make nitrates a positive substance to contain, it should be noted that excess nitrates can
result in weed growth, algal blooms and toxicity for fish and invertebrates. The affect it could potentially
have on organisms can vary, as nitrate is beneficial in decent amounts as a facilitator of growth in plants
and good bacteria but can be harmful in large quantities as too much growth can result in the ecosystem
becoming unbalanced. What unbalanced would entail is in terms of pH, plants produce oxygen in
daylight hours thereby raising the water pH, yet at the same time the plants respire, removing oxygen
and adding carbon dioxide and lowering the pH throughout the day. This dramatical increase and
decrease in pH can result in deaths of aquatic organisms. In which case, it does not explicitly mean that
sites 1,2 and 4 are worse off than site 3. This rather unusual outlier, that being site 3 possessing nitrates
can be attributed to runoff or leakage from fertilized soil, wastewater, landfills, animal feedlots, septic
systems, or urban drainage. The runoff of fertilized soil is to be the most likely contributory as the
narrow pathway shown below could allow sediments and other minerals to flow into this section of the
river.
Conclusion:
With that being said, the experiment suffered no issues and finding the presence of nitrates in the four
sites of the Coura was successful though the question of whether this was to Coura’s benefit is left in
speculation. The extreme lack or overabundance of nitrates can both be harmful to the ecosystem
therefore with the results shown, it however seems to lean towards the notion that the Coura river is
not suffering an overabundance of nitrates but rather the opposite.