An oil spill occurs when liquid petroleum is released into the ocean or coastal waters. Oil spills include crude oil from tankers, offshore platforms, drilling rigs and wells, as well as refined petroleum from ships. Oil spills have major environmental impacts and cleanup can be difficult.
Sources of Oil Spills
The main sources of oil spills are:
- Tankers and barges – Oil tanker incidents cause the largest spills. Leaks and collisions during transport are major sources.
- Offshore platforms – Drilling rigs and production platforms can spill oil due to accidents, leaks and natural disasters.
- Oil wells – Oil may leak from wells into oceans and coastal waters.
- Ships – Non-tanker vessels can also spill oil and refined fuels like diesel.
Impacts on Marine Life
Oil spills have wide ranging impacts on marine plants and animals:
- Plumage Impairment: Oil causes feathers of seabirds to mat and lose insulation and buoyancy leading to hypothermia and drowning. Over 20,000 birds died after the Exxon Valdez spill.
- Ingestion: Ingested oil causes dehydration, kidney failure and metabolic issues in birds, sea otters and other wildlife. Toxins cause long term population impacts.
- Fur Damage: Fur of otters and other mammals loses insulation capacity when covered in oil resulting in mortality from temperature extremes.
- Photosynthesis Reduction: Oil films the water surface preventing sunlight and oxygen from reaching marine plants and phytoplankton. This impacts the entire food chain.
Recovery Factors
Oil spill cleanup and ecosystem recovery depends on:
- Oil type (light oils evaporate and degrade quicker)
- Water temperature
- Shoreline geology
- Wave action and currents
Largest Oil Spills
The largest oil spills in history are:
- Kuwaiti Oil Fires – 1.4 to 2 billion tons burned
- Lakeview Gusher – Over 1.2 billion tons spilled
- Gulf War Oil Spill – 1 to 1.5 billion barrels released
- Deepwater Horizon – Approximately 500 million gallons
- Ixtoc I – Over 140 million gallons
Oil Spill Bioremediation
Bioremediation utilizes oil-consuming microorganisms to break down and remove oil pollution. There are three main types of oil-degrading bacteria:
- Sulfate-reducing bacteria (anaerobic)
- Acid-producing bacteria (anaerobic)
- General aerobic bacteria (require oxygen)
A 2010 technique named oil-zapping involves spraying oil spills with oil-consuming bacteria to accelerate biodegradation. This bio-remediation method utilizes bacteria that actually feed on hydrocarbons found in crude oil.