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Difficulty: HardEnvironmental Pollution: Types, Causes and Control Measures

Which of the following statements regarding pollutant dynamics, biological indicators, and soil remediation technologies for environmental pollution are correct?

  1. Bioaccumulation refers to the accumulation of a toxic chemical inside a single organism over its lifespan, whereas biomagnification describes the progressive increase in contaminant concentration across successive trophic levels of a food web.Answer
  2. B
    Lichens serve as sensitive bioindicators primarily for monitoring water turbidity and heavy metal runoff in aquatic benthic ecosystems.
  3. Phytoextraction is a phytoremediation mechanism where hyperaccumulator plant species absorb heavy metals from contaminated soils through their roots and translocate them into harvestable shoot tissues.Answer
  4. D
    High concentrations of dissolved nitrate (NO3−NO_3^-) in drinking water cause Skeletal Fluorosis by substituting hydroxyl ions in hydroxyapatite bone mineral structures.

Answer

The correct statements are: (1) Bioaccumulation refers to toxin accumulation within a single organism while biomagnification is the increase across trophic levels, and (2) Phytoextraction uses hyperaccumulator plants to absorb heavy metals into harvestable shoots.
Bioaccumulation describes contaminant accumulation within an individual organism over time, while biomagnification describes the escalation of lipid-soluble toxin concentrations across sequential trophic levels. Additionally, phytoextraction is an established biological soil remediation process where hyperaccumulator plants draw heavy metals up through root systems into shoots for removal.

Step-by-Step Solution

1
Analyze ecotoxicological definitions of bioaccumulation versus biomagnification.
Bioaccumulation occurs at the organism level as lipophilic compounds (e.g., DDT, methylmercury) accumulate faster than they are metabolized. Biomagnification transfers these contaminants up food chains to top predators.
Differentiates population and trophic dynamic terms accurately.
2
Evaluate the ecological role of lichens as environmental bioindicators.
Lichens depend directly on atmospheric precipitation and air quality. Their fungal-algal symbiosis is highly susceptible to atmospheric sulfur dioxide (SO2SO_2), making them terrestrial air quality indicators, not aquatic indicators.
Identifies the correct medium and pollutant indicator pairing.
3
Assess soil phytoremediation mechanisms.
Phytoextraction relies on hyperaccumulators (such as *Brassica juncea* or *Indian mustard*) to extract metals like lead, cadmium, and nickel from soil matrix into shoot systems for harvesting.
Validates sustainable technological control measures for land pollution.
4
Examine water pollution toxicology and human health impacts.
Excessive nitrate (NO3−NO_3^-) oxidizes iron in hemoglobin to methemoglobin, impairing oxygen transport in infants (Methemoglobinemia/Blue Baby Syndrome). Fluorosis is caused by excess fluoride (F−F^-) ions.
Exposes the chemical-pathology mismatch.

Key Concept

Pollutant Dynamics, Ecotoxicology, and Environmental Control Technologies
Estimated Time:2m 0s
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Topics

Environmental Pollution: Types, Causes and Control Measures