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Difficulty: Very hardConservation of Natural Resources and Environmental Management

An agricultural wetland ecosystem bordering a freshwater body has suffered severe ecological degradation due to continuous runoff containing high concentrations of nitrate fertilizers and persistent synthetic pesticides. Environmental managers aim to implement an integrated biological restoration strategy that reduces excess nutrient enrichment (eutrophication) while preventing the bioaccumulation of toxic residues across trophic levels. Which of the following integrated management approaches provides the most ecologically sustainable solution to restore the ecosystem?

  1. Establishing vegetative riparian buffer zones to intercept surface runoff and applying denitrifying bacteria to convert excess aquatic nitrates into inert nitrogen gas.Answer
  2. B
    Inoculating the aquatic body with Rhizobium bacteria to convert dissolved nitrates into organic amino acids and introducing top-level predatory fish to consume pesticide-exposed plankton.
  3. C
    Dredging the wetland basin to expose bare bed rock so that primary succession can re-establish vegetation, while applying chemical neutralizers to break down organochlorines.
  4. D
    Introducing high-density carnivorous fish to consume saprophytic fungi, thereby reversing the pyramid of energy to oxygenate anaerobic bottom sediments.

Answer

Establishing vegetative riparian buffer zones to intercept surface runoff and applying denitrifying bacteria to convert excess aquatic nitrates into inert nitrogen gas.
Establishing vegetative riparian buffer zones physically traps agricultural runoff carrying synthetic pesticides and excess fertilizers before it enters the water body. Simultaneously, biological denitrification by specialized bacteria converts dissolved aquatic nitrates into harmless atmospheric nitrogen gas (N2N_2), directly resolving eutrophication without secondary toxic chemical inputs.

Step-by-Step Solution

1
Analyze the cause of ecosystem degradation
Identify that excess nitrate runoff causes eutrophication (algal blooms and oxygen depletion), while persistent pesticides lead to biomagnification in food chains.
Effective environmental management requires targeting both physical runoff containment and biochemical pollutant reduction.
2
Evaluate biological mechanisms for nutrient reduction
Denitrifying bacteria (such as Pseudomonas species) convert excess dissolved nitrates into gaseous nitrogen gas (N2N_2), reducing nutrient loading in water bodies.
Denitrification removes excess bioavailable nitrogen from aquatic systems, addressing the root cause of eutrophication.
3
Assess land-water boundary management practices
Riparian buffer zones (strips of native vegetation along waterways) filter sediment, absorb agrochemicals, and stabilize soil banks.
Vegetative buffers physically impede runoff carrying pesticides and nitrates before reaching aquatic habitats.
4
Synthesize the correct integrated conservation strategy
Combining riparian buffers with bacterial denitrification provides a dual-action, chemical-free restoration approach.
This strategy prevents incoming pollution while actively remediating existing nitrate accumulation.

Key Concept

Biological remediation, nutrient cycling, and physical conservation techniques in environmental management
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Topics

Conservation of Natural Resources and Environmental Management

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