Geographical Investigation of Water Quality

How to use the water test kit to check for turbidity, PH value and dissolved oxygen.

Turbidity

Definition:

Turbidity is the measure of the relative clarity of water. 

Importance:

Murkiness can give some clues to what may be in the water. There may be dissolved pollutants or bacteria. However, murky water does NOT necessarily mean there is pollution.

Steps for measuring turbidity:

1.Pour the collected sample water into the white container.

2.Compare the appearance of Secchi disk icon in the container to the chart.

Precautions taken to ensure accuracy of readings:

•Fill up the container to the turbidity line located on the label. Record the result as turbidity in JTU.

Dissolved Oxygen

Definition:

The dissolved oxygen is the amount of oxygen dissolved in a given volume of water, at a given temperature and atmospheric pressure.

This can be measured in milligrams per litre (mg/l) or parts per million (ppm).

Importance:

The amount of dissolved oxygen needed

     to sustain fish life is about 4 mg/l or 4 ppm.   

Steps for measuring dissolved oxygen:

1. Fill the vial with the water collected.

2. Ensure no bubbles visible

3. Insert 2 tablets for dissolved oxygen testing

4. Close the cover

5. shake continuously for 10 mins

6. Observe colour change and compare colour against the dissolved oxygen chart.

Precautions taken to ensure accuracy of readings for dissolved oxygen:

•Vial must be submerged into the white container while filling the vial with collected water. This is to avoid introducing bubbles in the vial.

•Always place the vial or test tube against the white background when comparing collected water with the given chart. 

PH value

Definition:

It is a measurement of acidity or alkalinity of an aqueous solution.

Importance:

Most aquatic animals prefer a range of pH 6.5 to 8.0.

pH can be affected by acid rain or wastewater discharges

If the living conditions have a pH value away from this range, these aquatic animals will either flee or die.

Steps for measuring PH value:

1. Fill the test tube up to the 10 ml mark 

2. Insert a PH tablet into the test tube.

3. Observe colour change and compare colour against the PH chart.

Precautions taken to ensure accuracy of readings:

•Always place the test tube against the white background when comparing collected water with the given chart.