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Difficulty: HardPollution Types, Causes, Effects, and Control

In ecological studies of environmental degradation, chemical pollutants disrupt ecosystem stability through distinct biochemical, aquatic, and atmospheric mechanisms. Match each environmental pollutant listed on the left with its corresponding primary ecological impact on the right.

  • Agricultural runoff containing excess nitrates and phosphatesInduces rapid algal bloom, followed by microbial decomposition that severely elevates biochemical oxygen demand (BOD) and causes hypoxic aquatic dead zones.
  • Persistent organochlorines such as dichlorodiphenyltrichloroethane (DDT)Undergoes progressive trophic concentration (biomagnification), attaining toxic thresholds in apex predators such as piscivorous birds.
  • Industrial atmospheric emissions of sulphur dioxide (SO2\text{SO}_2) and nitrogen oxides (NOx\text{NO}_x)Forms low-pH precipitation that leaches essential mineral cations from soils and mobilizes toxic phytotoxic aluminum ions into freshwater systems.
  • Stratospheric release of synthetic chlorofluorocarbons (CFCs)Undergoes photolytic cleavage to yield chlorine radicals that catalytically decompose protective stratospheric ozone (O3\text{O}_3), increasing surface exposure to harmful UV-B radiation.

Answer

Agricultural runoff matches eutrophication and high BOD; Persistent organochlorines (DDT) match trophic biomagnification; Industrial sulphur dioxide and nitrogen oxides match acid rain precipitation and soil nutrient leaching; Stratospheric CFCs match catalytic ozone depletion and increased surface UV-B exposure.
Each pollutant matches its precise ecological degradation mechanism: agricultural nutrient runoff drives aquatic eutrophication and elevated BOD; organochlorine pesticides like DDT undergo trophic biomagnification; industrial sulphur and nitrogen oxides form acid precipitation; and stratospheric CFCs catalyze the breakdown of the ozone layer.

Step-by-Step Solution

1
Analyze the biochemical impact of inorganic agricultural fertilizer runoff in aquatic environments.
Excess nitrates and phosphates cause eutrophication, leading to algal bloom, high microbial oxygen consumption during decay, and elevated biochemical oxygen demand (BOD).
Identify the primary mechanism of water pollution caused by nutrient enrichment.
2
Examine the bioaccumulative trajectory of lipophilic pesticides like DDT through food chains.
Because DDT is persistent and non-biodegradable, its concentration amplifies at higher trophic levels (biomagnification).
Trace the movement of non-metabolized organochlorine toxic compounds across trophic layers.
3
Evaluate the atmospheric interactions of gaseous sulphur dioxide (SO2\text{SO}_2) and nitrogen oxides (NOx\text{NO}_x).
These gases form weak acids in rainwater, yielding acid rain which acidifies aquatic systems and leaches soil cations (Ca2+\text{Ca}^{2+}, Mg2+\text{Mg}^{2+}).
Relate atmospheric gaseous effluents to precipitation acidity and soil chemistry alterations.
4
Determine the photochemical reaction of chlorofluorocarbons (CFCs) in the upper atmosphere.
UV photolysis releases chlorine atoms that catalytically destroy ozone (O3\text{O}_3) molecules, depleting the stratospheric ozone layer.
Connect synthetic halogenated hydrocarbons to stratospheric ozone degradation.

Key Concept

Pollution Mechanisms and Ecological Degradation Pathways
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Topics

Pollution Types, Causes, Effects, and Control

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