Question

Measurement of water pollution is made by
(a)Coliform count
(b)Biological oxygen demand
(c)pH
(d)All of the above

Answer 1

Hint The contamination of water bodies, usually as a result of human activities is termed as water pollution. Water bodies include lakes, rivers, oceans, aquifers, groundwater, and water pollution results when contaminants are introduced into them.

Complete answer:
The quality of water in water bodies significantly affects the underwater flora and fauna and the overall health of the environment. It is known that numerous physical, chemical, and biological factors affect the quality of water in the ponds, lakes, streams, rivers, oceans, and groundwater.
Biochemical oxygen demand(BOD) is the most extensively used parameter to measure the organic pollution in sewage as well as surface water. It basically involves the measurement of dissolved oxygen (DO) utilized by the microorganisms for the biochemical oxidation of organic matter.
The intestinal tract of humans is very rich in coliform bacteria and is estimated that each person discharges about 100-400 billions of coliform organisms per day. Therefore, its detection is a clear indication of fecal contamination and thus the presence of pathogenic organisms. On the other hand, the absence of these organisms shows that the water is free from disease-causing organisms.
pH is also a great tool to measure water pollution. Water with a very low or high degree of pH can indicate a sign of chemical or heavy metal toxicity.

Additional information:
The various limitations of BOD:
-BOD measures only biodegradable organic matter.
-A high concentration of bacterial concentration is required.
-For measuring the BOD of toxic wastewater, pre-treatment is required.
-Requires a long period of incubation i.e. 5 days.
Despite all drawbacks, BOD is very widely used all over the world for practical and economic reasons.
Polluted water bodies mainly contain toxic heavy metals and organic and inorganic compounds and lack dissolved oxygen. In addition to the release of substances, such as chemicals or microorganisms, water pollution may also include the release of energy, in the form of radioactivity or heat, into bodies of water.

So, the correct answer is All of the above

Notes: Scientists use many different instruments to determine the quality of water including Secchi disks, probes, nets, gauges, and meters. Nowadays water quality is not just measured by direct sampling. Information related to the physical and chemical aspects of water can also be derived from aerial and satellite.