Question

what is the meaning of eutrophication

Answer 1

Here is your answer:
Eutrophication : the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen

Answer 2

the process of too many plants growing on the surface of a river, lake etc. often because chemical that are used to help crops grown have been carried there by train.