Question

Define
d.o. and
b.o.d with respect to water pollution

Answer 1

the amount of oxygen required to break down a certain organic matter is called biological oxygen demand. thus if more amount of organic waste is added to water aerobic bacteria uses the oxygen to break down the waste , thus aquatic organisms are left with meager oxygen. BOD is the indicator of level of pollution in water bodies.
anaerobic bacteria which does not use oxygen on breaking down creates foul smell and bad odour.
addition of inorganic waste leads to assimilation of soluble nitrates and phosphates which leads to growth of algae and microorganisms that causes eutropication.

Answer 2

Answer:

Water pollution is the contamination of water bodies, usually as a result of human activities. Water bodies include for example lakes, rivers, oceans, aquifers and groundwater. Water pollution results when contaminants are introduced into the natural environment.