Dear aneesh

When ammonia is dissolved in water, it is partially ionized depending upon the pH and temperature. The ionized ammonia is called Ammonium and is not toxic to the fish. As the pH drops and the temperature decreases, the ionization and ammonium increases which decreases the toxicity .Ammonia tends to block oxygen transfer from the gills to the blood and can cause both immediate and long term gill damage. The mucous producing membranes can be destroyed, reducing both the external slime coat and damaging the internal intestinal surfaces. Fish suffering from Ammonia poisoning usually appear sluggish, often at the surface as if gasping for air .

PHYSICO-CHEMICAL ANALYSIS

 pH, Temperature, conductivity, TDS and dissolved oxygen

These chemical properties were determined electrometrically with a multi- parameter data logger.

Chloride and salinity as chloride

 These were determined titrimetrically . About 25ml of the sample was measured in a beaker and a drop of potassium chromate indicator added. The solution was titrated with AgNO3 solution until the appearance of brick red colour as the end point.

 Calculations:

Cl- (mg/l) = Volume of AgNO3 titrated × 0.3 × 1000/ Volume of sample

Salinity as chloride = Cl- × 1.65

 Ammonia

About 50ml of the sample was measured into distillation flask. 0.4g of magnesium oxide was added and distilled into a beaker containing 10ml of 2% boric acid and combined indicator. This was titrated back with 0.1M HCl and the titre value was recorded.

Calculation: NH3 (mg/l) = Titre value × 100/ Sample volume use