Which of the following causes degradation of $RBCs$?

$...............$ is any undesirable change in the physical,chemical,or biological characteristics of air,land,water,or soil.

The addition of elements like nitrogen and phosphorus to a lake through streams leads to:

Which one of the following pesticides is banned nowadays?

In a pond,if there is too much wastage,then the $BOD$ of the pond will:

Biochemical Oxygen Demand $(BOD)$ is not a good index for pollution in water bodies receiving effluents from which of the following?