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How oil spills are controlled across the world?

By Anusha Ravi

Bengaluru, Feb 3: Authorities including Coast guards, volunteers and fishermen are facing a harrowing time attempting to clear the oil spill on the Chennai coastline. For over 6 six days now, the oil spill, that was a result of two cargo ships colliding, has only spread along the coastline even reaching the Marina Beach in Chennai. Environmentalists believe that by Saturday the spill will extend to 45 kms along the coastline if not cleared soon.

Apart from the negligence and failure to acknowledge the seriousness of the oil spill, the Ennore port authorities have come under severe criticism for failing to provide volunteers involved in the clean-up with proper safety gear. Close to thousand people involved in the cleanup process have only been given bare minimal gear in the form of boots and gloves. Armed with buckets and ropes, the volunteers are helping clean up the Chennai shoreline.

How oil spills are controlled?

Worldwide, oil spills are treated as a serious threat to marine life and scientific methods are adopted to clean or contain the spill, the same, however, can not be told of the Chennai oil spill situation.

What is an oil spill

Oil spills occur when crude oil is accidentally released into waterbody by an oil tanker, refinery, storage facility, underwater pipeline or offshore oil-drilling rig. In the case of Chennai, the oil spill was a result of two cargo ships colliding on January 29. Initially, the authorities refused to acknowledge the oil spill and sprung into action only after things went out of hand. Timely intervention could have saved the coastline some damage.

Oil spills are extremely hazardous and environmentally threatening. They need to be contained and cleaned as soon as possible. In most countries, the Coast Guard and the Environmental Protection Agency are the two agencies that are responsible for cleaning up oil spills. From day one, lack of clarity on whose responsibility it is to clean up the oil spill in Chennai allowed spreading of the sludge.

When an oil spill occurs, the oil floats and forms a millimeter-thick layer on the surface of the water. With each passing hour, the sludge spreads due to waves and the wind.

How oil spills are cleaned up worldwide

Four conventional ways of cleaning or containing oil spills are implemented worldwide. Authorities choose the most appropriate method depending on the location of the spill and potential hazards. Weather conditions, waves and currents are also taken into consideration before adopting a method.

  • Using booms and skimmers: Oil from the surface of the water is collected using skimmers. Skimmers are long, buoyant booms, which can be solid or inflatable tubes. They surround and isolate the oil slick. The booms rise about 3 feet above water level. They are then attached to a skirt that hangs underwater. From the surface, skimmers suck or scoop the oil into containment tanks on the shore or on nearby vessels. It is more difficult to use booms and skimmers on the high seas and under conditions of high winds.
  • Usage of dispersants to break down the oil: Chemical dispersants can be used to break down the oil and speed up its natural biodegradation. Dispersants break the slick into droplets of oil, which makes it easier for the oil and water to mix, and for the slick to be absorbed into the aquatic system. This method is not appropriate for all oil spills and locations, though. Dispersants can not be used when it can affect marine organisms. The chemicals and broken-down oil can be absorbed by marine life including sub-tidal seafood that can enter into the food chain.
  • Adding biological agents to the spill: Oil that has washed up along a shoreline can be broken down through a process called biodegradation. Biodegradation occurs when bacteria and other micro-organisms break down the oil into harmless substances, such as fatty acids and carbon dioxide. Clean-up crews can speed up this process of biodegradation by adding fertilising nutrients like nitrogen and phosphorus, which encourage the growth of micro-organisms.
  • Letting the oil break down naturally: If there is no possibility that the oil will pollute coastal regions or marine life, the oil could be left to disperse naturally. The sun, wind, currents and waves can disperse and evaporate most oils, though light oils can disperse quicker than heavier oils. The same, however, cannot be implemented in Chennai given the proximity of the sludge to the coastline and the rapid spread.

While these are the most sought after methods to clear an oil spill, controlled fire is also used as a way to clear oil spills. The oil sludge is allowed to burn out in a controlled manner to get rid of the toxic spill at the earliest. The same, however, cannot be implemented if the spill is very close to human inhabitation.

Despite various methods to contain and clean up an oil spill, the Ennore incident is seeing volunteers make do with buckets and drums, physically scooping the oil even as the toxins have started affecting their health. While the clean up operations are still underway, an inquiry into the collision and cause of the spill has been ordered.

OneIndia News

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