In Situ / Laboratory Testing

· Colour
In Situ:
Unit of measurement: “HAZEN”
Colour is determined measured visually with the use of a Colour Comparator.

· Nitrate
In situ:
1) Nitraver 5 Nitrate reagent powder added to 10ml of sample.
2) Shake vigorously for a minute.
3) Allow reaction to occur for another five minutes.
4) If nitrate is present, amber colour develops.
5) Determine concentration of nitrite via colorimetry by comparing against a blank sample using a turntable colour comparator

In lab: Titration - Kjeldahl method titrate (sulphuric acid) indictor (Indicating Boric Acid)

· Nitrite
In situ:
1) Nitraver 5 Nitrate reagent powder added to 10ml of sample.
2) Shake vigorously a minute.
3) Allow reaction to occur for another five minutes.
4) If nitrate is present, amber colour develops.
5) Determine concentration of nitrite via colorimetry by comparing against a blank sample using a turntable colour comparator

Nitrate/Nitrite In Situ Testing: Using a turntable Colour Comparator

Nitrate

The nitrate levels for all the sites are relatively constant and lie within the acceptable range of below 50mg/L (following WHO's guidelines).

Nitrate concentration is low as the source, water that flows into the grease trap, contains a low concentration of nitrate as well. This is probably because the detergents or soaps used had a low concentration of nitrate in them.

There were prevalent nitrate content in the next 4 sites. However, having Tank b4 Pond as a control, we know that the concentrations are normal and probably a natural-occurring concentration in the environment.

Nitrate vs Nitrite

The graph shows that there is a strong relation between the nitrates and nitrites concentration in the waters of the sites, Tank before Pond not included. This was mainly caused by the similar values of the nitrate and nitrites concentrations that remained mostly in the same range as shown by the table. Thus, the relation between these ions are insignificant.

The maximum acceptable concentration (MAC) for nitrate & nitrite in drinking water is 45 mg/L & 3.2mg/L respectively. Given that our average values for nitrate & nitrite is 0.0838mg/L & 0.0186mg/L respectively, this shows that the water is usable as potable water & for domestic purposes.

The nitrate value increases as its sources in water includes breeding of tadpoles and fishes, especially in the ponds. Their wastes (that contained organic-nitrogen) would have contributed to the increase in nitrate. The nitrite value is low as it is only formed by drinking water distribution systems that use chloramines, such as tap water. Only under anaerobic conditions, nitrate may be degraded to nitrite.

http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/nitrate_nitrite/index-eng.php