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Difficulty: MediumEnvironmental Hazards and Resource Management in Nigeria

Crude oil spillage is a severe environmental hazard in the riverine and coastal areas of the Niger Delta region in Nigeria. Which of the following represents the primary immediate ecological impact of an oil slick on aquatic ecosystems in this region?

  1. It forms a barrier on the water surface that inhibits atmospheric oxygen dissolution and reduces sunlight penetration necessary for photosynthesis.Answer
  2. B
    It causes rapid chemical weathering of riverbed rocks, transforming them directly into metamorphic slate deposits.
  3. C
    It reverses the natural flow direction of major Niger Delta tributaries, forcing river discharge northward into the Chad Basin.
  4. D
    It instantly converts non-renewable petroleum hydrocarbons into renewable organic agricultural nutrients across savanna soils.

Answer

The primary immediate ecological impact of an oil slick on aquatic ecosystems is the formation of a surface barrier that inhibits atmospheric oxygen dissolution and restricts sunlight penetration.
Floating crude oil creates an impermeable layer over water bodies. This slick limits dissolved oxygen exchange with the atmosphere and blocks sunlight from reaching aquatic plants and phytoplankton, leading to widespread hypoxia and biological death in the Niger Delta.

Step-by-Step Solution

1
Identify the environmental hazard and affected zone
The hazard is crude oil spillage located in the Niger Delta aquatic and wetland ecosystem.
Understanding the physical properties of crude oil in water body environments is essential to evaluating its ecological consequences.
2
Analyze the physical behavior of crude oil when released onto water
Crude oil is less dense than water and floats on the surface, spreading rapidly into an oil slick.
The surface floating behavior creates a continuous physical barrier between the water body and the atmosphere.
3
Evaluate the biological and ecological consequences of this barrier
The slick prevents dissolved oxygen replenishment from the air and blocks sunlight penetration, suffocating fish and killing photosynthetic plankton.
Solar radiation and dissolved oxygen are vital prerequisites for primary biological productivity and aquatic life survival.

Key Concept

Impact of Crude Oil Spillage on Marine and Freshwater Ecosystems
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Topics

Environmental Hazards and Resource Management in Nigeria

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