Question

How can a robin have a ddt concentration of 444 ppm even though the soil contains only 10 ppm of ddt

Answer 1

Robin can have a ddt concentration of 444ppm while the ddt concentration of soil is 10 ppm. This happens due to biological magnification.

Explanation:

In biological magnification the concentration of toxic substances at successive trophic levels keeps increasing. Due to biomagnification, what starts out as a small concentration grows  while moving to successive trophic levels. DDT is a pesticide which is used to kill pests that affect crops.

DDT used in farms gets deposited in the soil. From the soil it can reach various trophic levels. At each trophic level its concentration keeps increasing.

Robin is a bird that is a secondary consumer and thus belongs to the higher trophic level. Thus even if the DDT concentration is as low as 10ppm in the soil its concentration will keep increasing and can become a high value like 444ppm.