Impact of oil pollution Revision Notes

Oil pollution occurs when petroleum or its products are accidentally released into the environment, especially marine areas. The main sources include offshore oil drilling platforms, pipelines transporting oil, and shipping activities such as oil tankers. Offshore drilling rigs extract oil from beneath the seabed, and leaks or accidents can release oil directly into the sea. Pipelines, often buried under the seabed or on land near coasts, may rupture due to corrosion or damage, causing spills. Shipping accidents, including collisions or groundings of oil tankers, can release large quantities of oil rapidly. For example, the 1989 Exxon Valdez tanker spill released millions of litres of crude oil into Alaskan waters.

• Offshore drilling platforms can leak or spill oil during extraction.
• Pipelines may rupture or leak due to damage or corrosion.
• Shipping accidents involving oil tankers cause sudden large spills.

Once oil enters the marine environment, it spreads over the water surface because oil is less dense than water. The oil forms a thin layer called an oil slick, which can be carried by wind, waves, and currents. This spreading increases the area affected and can transport oil to distant shorelines. Weather conditions influence the rate of spread and evaporation of lighter oil components. For example, after a spill, oil may reach beaches hundreds of kilometres away, contaminating coastal habitats and human recreational areas.

• Oil floats on water, forming a slick that spreads over large areas.
• Wind, waves, and currents transport oil to shorelines.
• Weather affects evaporation and breakdown of oil components.

Oil pollution severely affects seabirds by coating their feathers. Feathers provide insulation and waterproofing; when covered in oil, birds lose these properties, leading to hypothermia and drowning. Oiled birds also ingest toxic substances while preening, causing internal damage. For instance, after oil spills, large numbers of birds such as gulls and penguins have been found dead or weakened. The loss of bird populations disrupts local food chains and biodiversity.

• Oil coats feathers, destroying insulation and waterproofing.
• Birds may die from hypothermia or drowning.
• Ingested oil causes internal poisoning.
• Bird population declines affect ecosystem balance.

Marine mammals like seals, dolphins, and whales are vulnerable to oil pollution. They can inhale toxic fumes from oil on the water surface or ingest oil-contaminated prey. Oil exposure can cause skin irritation, respiratory problems, and damage to internal organs. For example, seals exposed to oil spills may suffer from reduced reproduction and increased mortality. These effects reduce population sizes and disrupt marine food webs.

• Inhalation of toxic fumes causes respiratory issues.
• Ingestion of oil-contaminated food leads to poisoning.
• Skin contact causes irritation and infections.
• Population declines disrupt marine ecosystems.

Coral reefs are sensitive to oil pollution because oil blocks sunlight essential for photosynthesis by symbiotic algae living in corals. Toxic compounds in oil poison coral polyps and other reef organisms, leading to coral bleaching and death. Beaches contaminated by oil suffer from habitat degradation, affecting organisms like crabs and shorebirds. Oil on beaches also reduces their recreational value for humans. For example, after spills, cleanup is difficult and may involve removing contaminated sand, which disturbs the natural environment.

• Oil blocks sunlight, harming coral photosynthesis.
• Toxicity causes coral bleaching and death.
• Beaches become polluted, harming wildlife habitats.
• Human use of beaches is negatively affected.