Question

Biomagnification of DDT in an aquatic food chain starting from water having a concentration of 0.003 ppm may go, in fish eating ...... up to

• A. 2 ppm
• B. 25 ppm
• C. 50 ppm
• D. 100 ppm

Answer 1

The correct option is B 25 ppm

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level.

This phenomenon is well known for mercury and DDT. In this manner, the concentration of DDT is increased at successive trophic levels; e.g., if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification.