नमस्कार विद्यार्थी मित्रांनो Study of water samples collected from different water bodies for their pH, clarity and presence of living organisms (microscopic/planktonic) हे प्रॅक्टिकल Experiments to be performed - PART A मधील आहे. याचाच अर्थ तुम्हाला हे प्रॅक्टिकल Exam मध्ये Examiner ला Performe करून दाखवायचे आहे. म्हणूनच प्रॅक्टिकल Exam च्या दृष्टीने हे Experiment अतिशय महत्त्वाचे आहे. या ब्लॉग मध्ये आपण Practical Book मधील या Experiment Number - 7 ची उत्तरे पाहणारं आहोत. ही उत्तरे काळजीपूर्वक वाचून आपल्या Practical Book मध्ये लिहा किंवा तुमच्या कॉलेजमधील संबंधित विषय शिक्षकांची मदत घ्या.
7. Study of water samples collected from different water bodies for their pH, clarity and presence of living organisms (microscopic/ planktonic).
Aim :- To study water samples for measuring pH, clarity (turbidity) and presence of living organisms.
1. pH test of water sample with Litmus paper :
Introduction :-
pH is a measure of acidity or alkalinity of water. The pH of water is primarily decided by the salts present in soil from where the water sample is collected. But pH also changes due to organic matter, fertilizers, sewage and other pollutants.
Requirements :- Different water samples, sample bottle with cap, pH papers of different ranges etc.
Procedure :- Collection and preparation of sample:
1. Collect water samples in a clean, dry plastic jar.
2. Cap the jar tightly and shake vigorously a few times.
3. Allow the sample to stand for 5 to 10 minutes.
4. Remove the cap of the jar.
5. Dip the litmus paper in it for a second, holding it with a clean dry for foreceps (avoid touching with your fingers).
Observation :- 1. Observe the colour change.
2. Match the resultant colour with colour code on the pH colour stripe. Identify the pH and note it.
Result :-
1. PH value of 6.5 to 7.5, is referred to as more or less 'neutral'.
2. If pH is less than 6.5 then the water is acidic.
3. If the pH is more than 7.5 it is alkaline.
| Sr. No. | Water Sample | pH | Clarity |
|---|---|---|---|
| 1. | Water Sample - 1 | 7.0 (Neutral) | Water is clear & transparent. |
| 2. | Water Sample - 2 | 7.5 (Neutral) | Water is less turbid & not clear. |
2. Clarity of Water :
Test of water for clarity (Turbidity) :-
Measuring water clarity is an important part of environmental science. Often lakes or streams contain pollutants or sediments that make water cloudy. This often has a bad effect on the organisms that live in such waters. Typical source of turbidity in drinking water include the water discharges, algae or aquatic weeds, humic acid and other organic compounds resulting from decay of plants, leaf litter, small animals, etc. in water sources and high iron and phosphorus concentrations which give water a rust-red coloration.
Units of measuring Turbidity :-
In the late 1800's Tyndall and Rayleigh started the scientific study of light scattering. This phenomenon is used to understand the clarity of water. Most of the early study considered the absorption and transmittance. Many units such as JTU (Jackson "Candle" Turbidity Units), TE/F (of formazin) European units, Kieselguhr \((SiO_{2})\) units, Nephelometric Turbidity Units (NTU), were and are being used.
Requirements :- Four 1000 ml beakers, distilled water, Cardboard box or some other suitable box, torch/lamp or bulb and different water samples.
Procedure :-
Collection and preparation of sample:
1. Collect water samples in a clean, dry plastic jar.
2. Avoid touching to prevent contaminating the sample.
3. Prepare Tyndall set up from a cardboard box as shown in the diagram. This set-up can be made by making a hole in a cardboard box and fixing a bulb or torch on the other side of the box.
4. Pour distilled water in a clean beaker and use this as a standard.
5. Pour different water samples in a clean dry beakers and place the samples one by one and compare the turbidity.
6. Place each beaker in the Tyndall set up and observe the beaker through hole for clarity/turbidity.
Observation :-
1. Observe the clarity of distilled water.
2. Compare and note the turbidity of samples.
3. Record your observation as clear, less turbid, moderately turbid and highly turbid.
Result :-
1. The light is scattered because of the particles present in water.
2. More particles make water more turbid and reduce the clarity.
Conclusion :- The water is turbid hence not suitable for consumption without treatment.
3. Presence of living organisms :
Requirements :-
Water samples, microscope, slides, dropper, methylene blue, spirit lamps, etc.
Procedure :-
1. Put the drop of water sample on a slide and spread it evenly to make a thin film.
2. Allow it to dry and then heat it gently to fix it.
3. Put a drop of methylene blue on the smear and keep the slide for staining for 2 minutes.
4. Observe under microscope.
5. Different types of microorganisms can be observed such as paramoecium diatoms, algae and some planktons, copepod, daphnia, rotifer, etc.
6. Make a record of the same for all the samples separately.
1. Amphipod 2. Mosquito larva 3. Isopods 4. Dytiscus larva 5. Adult Dytiscus 6. Water scorpion 7. First instar may fly nymph 8. Second instar may fly nymph 9. Nymph of dragon fly.
Observation :- Tap water did not contain any observable organisms, indicating it is suitable for consumption. In contrast, pond water was found to contain a variety of organisms, including algae, Spirogyra, Oscillatoria, and microscopic animals such as Daphnia, rotifers, and dragonfly nymphs, making it unsuitable for consumption.
Inference :- Tap water is suitable for consumption, whereas pond water is not.
Questions
1. Why is turbid water not suitable for consumption?
Ans :- Turbid water may cause gastrointestinal disorders, nausea, and headaches. The particles causing turbidity can shield microorganisms from disinfectants, making the water difficult to purify.
2. What is Biochemical Oxygen Demand (BOD)?
Ans :- Biochemical oxygen demand (BOD) is the amount of dissolved oxygen required by aerobic microorganisms to break down organic material in water.
3. What is water pollution?
Ans :- Water pollution refers to the introduction of harmful substances, such as chemicals or microorganisms, that degrade water quality and make it unsuitable or toxic for living organisms.
4. What are the causes of water pollution?
Ans :- Common causes of water pollution include domestic sewage, industrial effluents, and the excessive use of fertilizers and pesticides.
5. What are planktons? Is there any difference in the planktons occurring in fresh water and sea water?
Ans :- Plankton are microscopic organisms found in both seawater and freshwater.
Multiple Choice Questions
1. ...arthropods found in fresh water bodies.
a. Daphnia
b. Hermit crab
c. Amphipod
d. Padina
Ans :- a. Daphnia
2. BOD of water means...
a. Biological oxygen demand
b. Biochemical oxygen demand
c. Biologically observed diatoms
d. Biologically observed daphnia
Ans :- b. Biochemical oxygen demand
3. Methylene blue stain is used to observe...
a. Planktons
b. Bacteria
c. Algae
d. Viruses
Ans :- b. Bacteria
4. Experimental set up deviced by...is used to observe water clarity.
a. Wingbarg
b. Tyndall
c. Strassburger
d. Waldeyer
Ans :- b. Tyndall
5. If pH is less than...then water is acidic.
a. 6.5
b. 10.5
c. 4.5
d. 12.5
Ans :- a. 6.5
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