Question

A lake near a village suffered heavy mortality of fishes within a few days. Which of the following statements could be the correct explanation for this?
(i) Lots of urea and phosphate fertilizers were used in the crops in the nearby fields.
(ii) The croplands of the village were sprayed with DDT.
(iii) The lake water turned green and stinky.
(iv) Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis.

• A. (i) and (iii)
• B. (i) and (ii)
• C. (ii) and (iii)
• D. (iii) and (iv)

Answer 1

The correct option is A (i) and (iii)

Option 'B' correct

A lake near a village suffered heavy mortality of fishes

within a few days, because Lots of urea and phosphate

fertilizers were used in the crops in the ricinty and

the area was sprayed with DDT by an aircraft,

Inorganic Phosphrous and pollutes water these

increase due to which algae increase gently at the

surface of water forming water bloom Due to death

of these algae their organic malter gets decomposed

due to which oxygen gets depleted & aquatic animals

die.