How can pollution be found in greater amounts at higher trophic levels compared to lower trophic levels

Pollution can be found in greater amounts at higher trophic levels compared to lower trophic levels by Biomagnification. It indicates the presence or increase in the concentration of toxic materials or pollutants in the tissues of living organisms in a trophic level of an eco system.

Through the process of biomagnification. An example is what happens with mercury in marine species.

Explanation:

Mercury is a pollutant known as a problem for the environment and the oceans, which affects the marine fauna to varying degrees and therefore the health of human beings. Methylmercury is the most toxic form of mercury and accumulates in the tissues of organisms. It is capable of bioaccumulating up to about one million times along the marine trophic chain, from microorganisms to predatory fish and mammals. In view of the ability to accumulate in organisms through trophic levels, higher concentrations are expected to be found in predatory fish and marine mammals (higher trophic levels), through the process known as biomagnification.

when it is at an intermediate population density