Phenylketonuria can be used by an enzymatic deficiency or it can be presetn due to:

Phenylketonuria results from the deficiency of the enzyme phenylalanine hydroxylase

Explanation:

Phenylalanine hydroxylase converts phenylalanine to tyrosine. Deficiency of this enzyme leads to accumulation of phenylalanine leading to the disorder known as phenylketonuria

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.