Environmental Management (0680) | Management of oil pollution

Study Notes: Management of Oil Pollution

Welcome to Section 2.5 & 2.6: Managing Oil Pollution!

We rely heavily on oil for energy, but transporting and extracting it can lead to devastating spills. In this section, we will explore where these spills come from, how they harm the environment, and the crucial strategies we use to prevent them and clean them up. This knowledge is vital for protecting our precious marine and coastal ecosystems!

2.5 The Causes and Impacts of Oil Pollution

Understanding Oil Spills: Where Does the Oil Come From?

Oil pollution in marine and coastal areas results mainly from human activities related to finding, moving, and using oil. The syllabus highlights three main causes:

1. Off-Shore Oil Extraction

This refers to drilling for oil deep under the seabed.

• Drilling Accidents: Blowouts or equipment failures on oil rigs (platforms) can cause massive, uncontrolled releases of crude oil into the ocean.
• Did you know? The deeper the extraction, the harder the spill is to control, as shown by major incidents in the Gulf of Mexico.

2. Pipelines

Pipelines transport oil both underwater and along coastal areas.

• Leakage or Ruptures: Corrosion (rust), natural disasters (like earthquakes), or accidental damage (like being hit by a ship's anchor) can cause pipelines to break, releasing oil slowly or rapidly.

3. Shipping (Oil Tankers)

Tankers carry huge amounts of crude oil across the world’s oceans. This is perhaps the most famous cause of massive spills.

• Collisions and Groundings: If a large tanker collides with another vessel or runs aground (hits the seabed or rocks near the shore), its cargo tanks can rupture, leading to a catastrophic spill.

Quick Review: The three main sources of massive oil spills are extraction (drilling), pipelines (transportation infrastructure), and shipping (tankers).

The Environmental Impacts of Oil Pollution

Oil is lighter than water, so it floats on the surface, forming a slick. Crude oil is toxic and viscous (thick), leading to severe damage across marine and coastal ecosystems.

Impacts on Ecosystems: Birds

Birds are often the most visible victims of an oil spill.

• Loss of Insulation: Oil coats the feathers, causing them to mat together. This destroys the bird's ability to keep warm (insulation) and stay waterproof.
• Hypothermia: Without insulation, the birds quickly lose body heat and die from the cold (hypothermia).
• Reduced Buoyancy: Oiled feathers make it hard for the bird to float or fly, leading to drowning or starvation.
• Poisoning: Birds try to clean their feathers by preening and end up swallowing the toxic oil, which poisons their internal organs.

Impacts on Ecosystems: Marine Mammals

Creatures like seals, dolphins, and whales are also severely affected.

• Loss of Insulation: For mammals with fur (like sea otters or seals), oil coats their fur, destroying its insulating properties, leading to hypothermia.
• Poisoning: Mammals inhale oil vapours or ingest oil when feeding in polluted waters, damaging their lungs, livers, and kidneys.

Impacts on Ecosystems: Coral Reefs and Beaches

Coastal habitats suffer long-term damage.

• Coral Reefs: Oil slicks block sunlight needed by the symbiotic algae living within the corals, causing the corals to bleach and die. The toxic components of the oil also directly kill or inhibit the growth of coral polyps.
• Beaches and Coastlines: Oil washes ashore, coating sand, rocks, and mudflats. It is extremely difficult and expensive to remove. The oil penetrates the sand, poisoning organisms (crabs, shellfish, burrowing worms) that live there, disrupting the entire food web.

Key Takeaway: Oil is devastating because it is toxic, sticky, and destroys the natural insulating properties of animal coverings (fur and feathers).

2.6 Management of Oil Pollution

Managing oil pollution involves two key areas: reducing the frequency of spills (prevention) and minimising the damage when a spill occurs (cleanup).

Strategy 1: Reducing Oil Spills (Prevention)

The best way to manage oil pollution is to stop it from happening in the first place! Prevention strategies often focus on regulating the shipping industry.

International Convention for the Prevention of Pollution from Ships (MARPOL)

This is a vital international agreement (convention) designed to prevent pollution from ships, including oil.

• Goal: MARPOL sets international standards regarding the design, construction, equipment, and operation of ships to minimize marine pollution.
• Legislation: It makes it illegal for ships to deliberately dump oil or oily waste into the sea.
• Enforcement: Countries that sign MARPOL agree to enforce these rules on their ships and within their waters.

Memory Tip: MARPOL sounds like MARine POLlution—it’s all about preventing it!

Double-Hulled Oil Tankers

This is one of the most effective technological strategies implemented globally, often required under MARPOL rules.

• Design: A double-hulled tanker has two complete layers of hull (shell) surrounding the cargo area, separated by a gap (usually several feet).
• Protection: If the outer hull is damaged (e.g., in a minor collision or running aground), the inner hull remains intact, preventing the oil from leaking into the sea.
• Single vs. Double: Older tankers often had single hulls, meaning a breach instantly led to a spill. Double hulls provide a critical protective layer.

Strategy 2: Minimising the Impacts (Cleanup)

When a spill happens, we need strategies to quickly contain the oil and remove it before it causes long-lasting damage.

1. Oil Booms (Containment)

Booms are the first line of defense used immediately after a spill is detected.

• What they are: Floating barriers made of plastic, rubber, or metal. They sit on the water surface, with a skirt extending beneath.
• How they work: They act like a fence to contain the floating oil slick, stopping it from spreading further, especially protecting sensitive areas like beaches or coral reefs.
• Analogy: Think of a floating barrier used to keep swimmers in a certain area—the boom does the same for the oil.

2. Skimmers (Removal)

Once the oil is contained by booms, skimmers are used to physically take the oil off the water surface.

• What they are: Special vessels or devices that scoop, vacuum, or absorb the floating oil.
• How they work: They mechanically separate the oil from the water, allowing the recovered oil to be pumped into storage containers for later disposal or recycling.

3. Detergent Sprays (Dispersants)

Detergents are chemicals sprayed onto the oil slick.

• How they work: Detergents act like dish soap on grease. They break the large oil slick into tiny droplets.
• Effect: These small droplets disperse (spread out) throughout the water column, making them less visible and allowing them to be broken down faster by natural processes (bacteria).
• Warning: Detergents must be used carefully! They can be toxic to marine life themselves, so their use is often controversial and restricted to spills far away from coastal habitats.

Case Study Requirement

To fully prepare for the exam, you must study a specific Case Study of a named oil pollution event. You should know:
1. The cause of the spill.
2. The impacts it had on the local ecosystem.
3. The management strategies (booms, skimmers, MARPOL rules, etc.) used afterwards.