In a polluted environment, the concentration of pollutant would be maximum in the tertiary consumers.

Explanation:
Pollutants are harmful substances that contaminate the environment, often released by human activities such as industrial processes, transportation, and waste disposal. These pollutants can enter the ecosystem through various pathways such as air, water, and soil, and can accumulate in organisms as they move up the food chain.

1. Introduction to the food chain:
The food chain represents the transfer of energy and nutrients from one organism to another in an ecosystem. It consists of different trophic levels, including producers, primary consumers, secondary consumers, and tertiary consumers.

2. Producers:
Producers, such as plants and algae, are the first trophic level in the food chain. They convert sunlight energy into chemical energy through the process of photosynthesis. However, since they are at the bottom of the food chain, they are less likely to accumulate high concentrations of pollutants compared to other trophic levels.

3. Primary consumers:
Primary consumers are herbivores that feed on producers. They obtain energy and nutrients by consuming plants or algae. Although they are one step higher in the food chain compared to producers, their concentration of pollutants is still relatively low. This is because the pollutants present in plants or algae are often diluted and metabolized to some extent by primary consumers.

4. Secondary consumers:
Secondary consumers are carnivores that feed on primary consumers. They obtain energy and nutrients by consuming herbivores. As they are at a higher trophic level, they can accumulate a higher concentration of pollutants compared to primary consumers. However, their concentration of pollutants is still lower than that of tertiary consumers.

5. Tertiary consumers:
Tertiary consumers are top-level carnivores that feed on other carnivores. They obtain energy and nutrients by consuming secondary consumers. Since they are at the highest trophic level, they have the potential to accumulate the highest concentration of pollutants. This is known as biomagnification or bioaccumulation, where the concentration of pollutants increases as they move up the food chain.

In conclusion, in a polluted environment, the concentration of pollutants would be maximum in tertiary consumers. This is because they are at the highest trophic level and can accumulate the pollutants present in lower trophic levels through the process of biomagnification.