The oil industry contributes greatly to the global GDP, but sometimes accidents happen! We’ve all heard about catastrophic oil spills that can cause huge losses to the economy while severely damaging the environment. Here’s a primer on what it is and how it happens.
What are oil spills?
An oil spill refers to the accidental release of petroleum into the environment. When oil spills on land, the effect is usually localized, and thus, it can be cleaned up rather easily. In contrast, marine oil spills may result in oil pollution over large areas and present serious environmental hazards. In addition, oil spills can sometime occur on ice (e.g. in the Arctic regions). Oil spills often trigger images of gigantic oil tankers malfunctioning and releasing their dense, black contents into the sea! While it is true that majority of marine oil spills occur during transportation by tankers and faulty pipelines (about 70 percent), neglect during offshore drilling and production activities also contribute significantly. Oil spills in the water can also be caused by natural seepage. As tectonic plates shift, oil can be released from reserves trapped deep beneath the ocean floor. Natural seepage is sometimes accelerated through human activity such as drilling.
Land-based oil spills may not be as visually dramatic as those of a marine accident, but can be just as harmful to land and coastal areas! Most engines, such as those used in automobiles, run on petroleum-based fuel and lubricants. These substances are slowly released during operation, accumulating on roads or in the ground, where they can poison the surrounding soil. After it rains, these pollutants can end up in local wells and reservoirs, streams and rivers, and ultimately in the ocean. On land, storage tanks and pipes may be damaged by natural disasters such as hurricanes, earthquakes, or tornadoes, or simple wear caused by time. The damage can result in leaks of different sizes. Such oil spills can be especially disastrous if a pipeline is damaged, often due to structural failure or excessive pressure, because of the high volume of oil these lines can release.
Why are oil spills dangerous?
We’ve all heard stories about the ‘dangers of the sea’, like sharks, whales, squids, etc. But, have we considered the threats we pose to them?
Large and catastrophic oil spills which release over 30,000 tons of oil are relatively rare events, and their frequency has decreased considerably in recent times, thanks to technology. But, when such episodes occur, they cause irreparable ecological damage primarily for sea birds and mammals, and result in long-term environmental disturbances, which adversely affect fisheries and marine culture.
The improper disposal of used motor oil can worsen runoff and pollution. Dumping used oil in a drain is illegal in many places because drains often run directly to nearby rivers, lakes, or other bodies of water, and eventually into the sea. These waterways can quickly become polluted, killing fish and other wildlife.
Ecosystems have high natural variability and are subject to ever-changing environmental phenomena such as storms, climatic anomalies (e.g. El Niño) as well as anthropogenic pressures. Organisms have varying degrees of natural resilience to these pressures on their habitats. This natural variability means it is unlikely that exact pre-spill conditions will be reached. It makes determining the point of recovery following an oil spill, and the time it will take, difficult to predict. Marshes and sediments in Prince William Sound in Alaska retained oil from the massive oil spill of the Exxon Valdez in 1989 for many years, affecting the development of fish embryos on the bottom. After ten years, pockets of oil remained in these marshes, and mussels, clams, ducks and sea otters showed evidence of harm in some localized areas.
Needless to say, oil spills must be cleaned up as quickly as possible to prevent further damage to the environment!
However, remedial actions after oil spills are sometimes controversial. Some of the possible ‘solutions’ such as aggressive cleaning with large, heavy equipment may cause more harm than good.
How do we know if the oil spill has been completely cleaned up?
It is generally accepted that recovery is reached when a community of plants and animals characteristic of that habitat are established and functioning normally.
How are oceans decontaminated after an oil spill?
Efforts to clean up an oil spill at sea are difficult and taxing.
The only readily available solution is physically gathering the oil, and removing it from an area using vacuums and skimmers (a hovercraft, or other vessel that has little or no displacement at speed. Skimmers float across the top of the slick contained within the boom and suck or scoop the oil into storage tanks on nearby vessels or on the shore)
Wildlife is cleaned and moved as soon as possible.
Sometimes, dispersants are used to break up the oil and speed up its natural biodegradation.
Dispersants reduce the surface tension that prevents the oil and water from mixing ( since they are immiscible liquids). Small droplets of oil are formed, which promote rapid dilution of the oil by water movements. This also increases the surface area of the oil, thus, increasing the exposure to natural evaporation and bacterial action.
However, dispersants are not appropriate for all oils and all locations. Successful dispersion of oil through the water column can affect marine organisms like deep-water corals and sea grass. It can also cause oil to be temporarily accumulated by sub-tidal seafood.
Why not let nature look after itself?
If the oil is left alone, it will eventually begin to break down by natural means. This may be a little time consuming, but, by not interfering, the region has more chances of full recovery.
If there is no possibility of the oil reaching, and consequently polluting, coastal areas or marine industries, it is best to allow it to disperse by natural means. The combination of wind, sunlight, current, and wave action will rapidly disperse and evaporate most oils.
To speed up the process, biological agents can be introduced to hasten biodegradation. Most components of oil washed up along a shoreline can be broken down by bacteria and other microorganisms into harmless substances such as fatty acids and carbon dioxide. This action is called biodegradation.
To make it even faster, fertilizing nutrients, like nitrogen and phosphorus, which stimulate growth of the microorganisms are introduced.
Need help cleaning up an oil spill at sea?
Why not look up the ‘ Little Black Book of Oil Spill Clean up Contractors’?
There’s even an international directory of oil spill clean-up contractors!
The little black book spans 140 pages, and lists contract details of over 1,000 contractors in 50 countries!
We’ve all heard that ‘Prevention is better than cure’. So, how do we prevent an oil spill?
Companies like shell have developed technology that can help avert an oil spill, especially in regions like Alaska and the arctic.
A stitch in time save nine. Equipment must be periodically inspected for deterioration and leaks. On boat, all fuel lines and hoses must be in good condition and seals and connections – tight. All the damaged parts must be replaced with new fittings.