On Monday, workers in Australia rushed to contain an oil spill from a grounded ship in the Great Barrier Reef. The Chinese-registered Shen Neng 1 ship was carrying 72,000 tons (65,000 metric tons) of coal, and was loaded with 1,000 tons (950 metric tons) of fuel when it collided into the Douglas Shoals region of the coral reef late Saturday.
Immediate efforts are being made to stabilize the damaged vessel, isolate the oil, and prevent further damage to the fragile coral. A boom will be placed around the ship to contain the oil leaking from its hull.
According to Marine Safety Queensland, about two tons of oil has already spilled into the water. The oil slick is approximately 300 feet (91 meters) wide and stretches close to two miles (3.2 km), according to news reports.
Oil spills occur when crude oil is accidentally released into a body of water by an oil tanker, refinery, storage facility, underwater pipeline or offshore oil-drilling rig.
Oil spills can be extremely hazardous and environmentally threatening, and need to be contained and cleaned as soon as possible. In the United States, the Coast Guard and the Environmental Protection Agency are two agencies that are responsible for cleaning up oil spills.
When an oil spill occurs, the oil floats and forms a millimeter-thick layer on the surface of the water. Timing is crucial to prevent the slick's spread.
There are four basic ways to clean or contain an oil spill, and workers determine the most appropriate method depending on the location of the spill, potential hazards, weather conditions, waves and currents.
- Contain the spill using booms, and collect the oil from the surface of the water using skimmers: Long, buoyant booms, which can be solid or inflatable tubes, surround and isolate the oil slick. The booms rise about 3 feet (1 meter) above water level, and are 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.
- Use 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 especially not in all locations. Dispersants should not be used when it can affect marine organisms, as the chemicals and broken-down oil can be absorbed by marine life including sub-tidal seafood that can enter into the food chain.
- Add 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 fertilizing nutrients like nitrogen and phosphorous, which encourage the growth of micro-organisms.
- Let 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 heavy oils.
The most notorious oil spill in history was the Exxon Valdez catastrophe in 1989. This disastrous oil spill released 11 million gallons (more than 41 millio liters) of crude oil into the Prince William Sound in Alaska, and largely served as a wake-up call to the detrimental effects of oil spills on the ecosystem.
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