Oil spill is the accidental or non-accidental release of refined (diesel, gasoline, kerosene, etc.) or unrefined (crude oil) petroleum into the sea (usually) or onto landmasses. The oil that floats is referred to as oil slick – a thick film (around a millimeter), which is thickest in the middle and thinner on the edges. The layer of oil is created because water and oil don’t mix, thanks to the density differences between the two. As the thick film spreads courtesy waves, water currents, wind, etc., it loses its density and becomes thinner.

Skimming oil in the Gulf of Mexico. Image credit Flickr
Skimming oil in the Gulf of Mexico. Image credit: Flickr

Oil usually floats in both salt and fresh water; however, there are instances when crude oil could sink in fresh water. The oil that sinks in mixes with water and sand and other particulate matter to form tar balls or solidified crude oil lumps. These tar balls have a hard exterior and soft core and are usually scattered and isolated, which means they do not pose the same threat as oil slicks. Like earthquakes, oil spills happen regularly (such as ships discharging fuel), but only the most catastrophic and large-scale spills grab media and public attention.

Oil Spill Cause and Progression

As aforementioned, an oil spill could be accidental or man-made, and even natural (sea floor seepage). The accidents usually involve tankers and pipelines. Oil refineries, oil storage facilities and broken equipment could accidentally emit crude oil. Oil spills can also happen while transferring oil to a vessel or ship. Various drilling (into the earth’s crust) activities and repair operations gone wrong can cause the spill too. Some primary non-accidental reasons are natural calamities or human acts such as war and terrorism.

Oil washed ashore. Image credit: Flickr
Oil washed ashore. Image credit: Flickr

The increase in demand of petroleum products over the years has warranted massive oil transportation, thereby causing more oil spills or augmenting the risks associated with it (at least). Aging oil tankers and increasing oil tanker sizes also account for the spills. Improper and irresponsible oil waste disposal activities such as not disposing motor oil properly is a reason too.

An oil slick can spread, migrate, thicken or thin out. It could spread further across the sea or move towards land if no action is being taken to control or address it. Ocean currents, relationship between water and air temperature, the refined or crude oil’s chemical composition, presence of icebergs, wind direction, etc. determine what oil slicks lead to.

Potential Damage

It is rare for a major oil spill to go unnoticed or not affect its surroundings. These spills are usually quite hazardous and environment-threatening. Generally, the level of environmental damage caused by an oil spill hinges on several factors, such as the amount of spill, oil’s weight and type, spill location, wildlife species in the area, oil spill timing (seasonal migrations and breeding cycles), and weather before and after the spill.

The oil hurts birds' flying abilities, often drowning them in the process. Image credit: Flickr.
The oil hurts birds’ flying abilities, often drowning them in the process. Image credit: Flickr

Spills could hit the shorelines and unrestricted flows can affect wildlife and also cause soil erosion. For instance, if the oil hits mangrove forests, coastal marshes or other wetlands, the grasses and fibrous plants would absorb the oil, damaging the plants and rendering the entire area unfit for wildlife habitation.

The spilled oil harms algae, fishes, sea mammals, seaweed, birds and also beach soil and rocks. The oil’s sticky nature can hinder breathing abilities of fishes, drown birds and prevent them from flying away, and intoxicate animals and fishes that consume the contaminated water.

If birds aren’t dry and clean, they’ll lose their buoyancy or abilities to float. The oil also hurts furry animals’ insulating traits or their ability to stay warm. Some birds and fishes may swallow the oil, getting poisoned in the process and fatally damaging their internal organs. Human health is also affected when people eat fishes exposed to or contaminated by oil spills.

Depending on the amount of spill, it may take a few weeks, months and even years to clear the spill and the associated impact. For instance, the Exxon Valdez oil spill that happened in Prince William Sound, Alaska on March 24, 1989, still had a negative impact on the region’s ecological environment two decades later.

Clearing Oil Spills

The duration and tools needed primarily depend on the oil type, water state (currents and waves), and weather. Also, the cleaning method employed depends on how quickly the cleanup activity is initiated. Usually, the farther the spill from human habitats, the easier and quicker it is to control and clear the spill.  

Measures to address an oil spill. Image credit: Flickr
Measures to address an oil spill. Image credit: Flickr

If the cleaning team reaches the spot within an hour or two of an oil spill, it would usually look to contain and skim the slick. Strategically positioned floating booms can be used to capture or divert oil flow or spread. Once the slick is directed to a designated spot, sorbent or oil-absorbing booms can be used to manually absorb the oil. Also, boats that can scoop or suck the oil into contaminant tanks could be employed.

Detergents, called dispersants, are also used to clean oil slicks by breaking down the oil and speeding up the natural biodegradation process. In other words, dispersants break into the oil’s slickness, letting small oil drops blend with and get  absorbed by the water. However, this technique is the most hazardous of them all as the absorbed oil can affect marine life and also enter the human food chain.

At times, the oil is set on fire and burned. This process is referred to as in situ burning. Though effective, the method leads to toxic smoke creation and is therefore not a feasible method, especially when the spillage is close to the coast.

Fertilizers such as nitrogen and phosphorus are evenly applied to the shoreline affected by the oil spill. These fertilizers encourage growth of microorganisms. These biological agents then break the oil down into natural components such as carbon dioxide and fatty acids.

The sun and the ocean’s waves help break down oil in water, with the oil evaporating eventually. This is why certain cases of oil spills are not looked at with concern, especially if the spill is located far away from the coast or doesn’t pose any imminent threat to human civilization or wildlife.

To minimize damage to birds and aquatic species, cleanup agencies use balloons and floating dummies to scare the animals away from the oil slicks. Sensing danger, some shore birds could relocate and escape. However, sea birds that have to dive and swim for their food are likely to stay back and, as a result, do not escape the impact of the spill.

Oil Spill Prevention

Preventing oil spills is more important than clearing a spill, and it should therefore be given the highest priority. Since oil spills are more due to human carelessness and less courtesy accidents, it’s important related industries incorporate preventive measures every time. Piping systems and machinery should always be inspected for tightness and any sign of leaking gaskets and seals. Any country or tourist spot located nearby shipping or oil drilling lanes should always be ready to tackle oil spills as the oil spill risks are higher.

As aforementioned, minor spills are common, meaning even individuals could contribute to oil spills. Therefore, people who head to the sea on their private boats or run a ferry should check their boats and related equipment at least once every year for leaks and deterioration. The boat’s hoses and fuel lines should always be in good condition. And pumps and funnels must be used to handle and transfer boat fuel, to mitigate oil leaking into water.