To study pH level, clarity and presence of microbes and other living organisms from two different water bodies.
Required Materials and Apparatus
- Test tube.
- pH paper.
- Glass slides.
- Cover slips.
- Filter paper.
- Secchi’s Disk.
- Compound microscope.
- Universal Indicator solution.
To study pH levels:
- Take two clean and dried test tubes.
- Add the collected two different water samples into the two test tubes.
- For a safer side, label the test tubes as A and B.
- Dip the individual pH paper strips into the two different water samples.
- Keep the strips on the tile and wait for the strips to dry.
- Alternatively, pH levels of the water sample can also be found using the universal indicator solution.
- Now, with the help of a dropper, add five drops of universal Indicator solution into both the test tubes.
- Observe the change in colour in both the test tubes and compare the same with the colour chart.
Note the change in colour and associate the same with a broad range indicator paper to get a rough idea of the pH level.
To study the clarity of the water sample:
From a scientific perspective, the number of particles present in a liquid may make it cloudy or hazy. This property is called turbidity. The procedure for finding turbidity of a water body is as follows:
- Reach the centre of a pond in a boat.
- Immerse Secchi’s disc into the water, lowering it eventually until the black and white segments are no longer visible.
- Mark the length on the rope, where the disk is not visible with a pin.
- Name this position as “A”.
- Carefully, bring the disc back up and mark the length of rope where the disc becomes visible again.
- Name this position as “B”.
- Use a meter tape to measure the length of section A to B.
- Next, find the mean length of the rope by using X= (A+B)/2.
The value of X tells us the depth of the photic zone. Below this level, enough light does not penetrate, hence, photosynthesis does not take place.
To study the presence of living organisms
- Take a clean dried test tube.
- Add the collected water sample, preferably from a pond, into the test tube.
- Leave the sample undisturbed, until the sediment settles at the bottom of the test tube.
- Transfer a drop from the test tube on to a glass slide.
- Gently place a coverslip on the slide using a needle.
- Observe the entire slide under a compound microscope.
To study the presence of living organisms:
Pond samples have large numbers of microscopic organisms.
Ensure safety measures are in place when travelling to the centre of the pond.
Learn more in detail about the water, properties of water, other related topics and experiments at BYJU’S Biology