Q) “Is oil spill an environmental hazard?” Elucidate. Also explain how oil spills can be cleaned.
Answer:
OECD defines an oil spill as oil, discharged accidentally or intentionally, that floats on the surface of water bodies as a discrete mass and is carried by the wind, currents and tides. Oil spills can pollute land, air, or water, though it is mostly used for oceanic oil spills.
Environmental impact of Oil spills
When an oil spill occurs, many elements of the environment may be affected. Depending on the magnitude of the spill and its location, the effects can vary, ranging from minimal to serious ones.
- Ecosystem Destruction: Oil spills can have a major impact on the temporary animal and fish loss of habitat. Heavy oils may affect several organism functions like respiration, feeding, and thermo-regulation. § At the same time, the entire ecosystem can change temporarily because of the chemical components and elements of the spilled oil that are toxic to the environment.
- If an aquatic oil spill is substantial enough (such as in the case of Exxon Valdez 1989 spill or the April 2010 BP spill in the Gulf of Mexico from offshore drilling) then the effects on marine life, birds, humans and ecosystems (including marshes and wetlands, as well as shorelines or gulf coasts) could be serious.
- There are immediate effects on humans, fish, animals, birds and wildlife in general, mainly due to:
- direct contact with the spilled oil including breathing of volatilized oil components (hydrocarbons) from the spill;
- direct contact with the environment polluted with spilled oil components (some of which may persist a long time), such as drinking polluted water or breathing polluted dust particles;
- consumption of polluted food – at any level within the food chain, with a higher risk for food pollution at the higher levels of the food chain, i.e. humans and animals.
If the oil washes into coastal marshes, mangrove forests, or other wetlands, fibrous plants and grasses absorb oil, which can damage plants and make the area unsuitable as wildlife habitat.
- Despite massive clean-up efforts following the 1989 Exxon Valdez oil spill, a 2007 study conducted by the National Oceanic and Atmospheric Administration (NOAA) found that 26,000 gallons of oil were still trapped in the sand along the Alaska shoreline.
Although some organisms may be seriously injured or killed very soon after contact with the oil in a spill, other effects are more subtle and often longer lasting.
- For example, freshwater organisms are at risk of being smothered by oil that is carried by the current, or of being slowly poisoned by long-term exposure to oil trapped in shallow water or stream beds.
On Marine Organisms: Oil spills frequently kill marine mammals such as whales, dolphins, seals, and sea otters.
- Oil can clog blowholes of whales and dolphins, making it impossible for them to breathe properly and disrupting their ability to communicate.
- Oil coats fur of otters and seals, leaving them vulnerable to hypothermia.
- Marine mammals that eat fish or other food exposed to an oil spill may be poisoned by oil and die or experience other problems.
- Oil spills often take a deadly toll on fish, shellfish, and other marine life, particularly if many fish eggs or larvae are exposed to oil.
- Eg: Fisheries impacted by the Exxon Valdez took over three decades to recover.
On Birds: Oil spills also damage nesting grounds, potentially causing serious long-term effects on entire species.
- The 2010 BP Deepwater Horizon offshore oil spill in the Gulf of Mexico, for example, occurred during prime mating and nesting season for many bird and marine species, and long-term environmental consequences of that spill won’t be known for years.
- Oil spills can disrupt migratory patterns by contaminating areas where migrating birds normally stop.
- By coating feathers, oil not only makes flying impossible but also destroys birds’ natural waterproofing and insulation, leaving them vulnerable to hypothermia or overheating.
- As birds frantically preen their feathers to restore their natural protections, they often swallow oil, which can severely damage their internal organs and lead to death.
Methods through which oil spill can be cleaned:
- Oil spills can be partially controlled by chemical dispersion, combustion, mechanical containment and adsorption.
- Containment Booms: Floating barriers, called booms are used to restrict the spread of oil and to allow for its recovery, removal, or dispersal.
- Skimmers: are devices used for physically separating spilled oil from the water’s surface.
- Sorbents: Various sorbents (e.g., straw, volcanic ash, and shavings of polyester-derived plastic) that absorb the oil from the water are used.
- Dispersing agents: These are chemicals that contain surfactants, or compounds that act to break liquid substances such as oil into small droplets. They accelerate its natural dispersion into the sea.
- Bio-agents: Nutrients, enzymes, or microorganisms such as Alcanivorax bacteria or Methylocellasilvestris that increase the rate at which natural biodegradation of oil occurs are added.
Ultimately, the severity of environmental damage caused by an oil spill depends on many factors, including the amount of oil spilled, type and weight of oil, location of the spill, species of wildlife in the area, timing of breeding cycles and seasonal migrations, and even the weather at sea during and after the oil spill.