Oceans, caught between devil and the deep blue sea… (Pun intended!) – XVI

Oil Spills Cleanup…

Hi, friends welcome back almost after a month!  Could not write as the Muse did not show up all these days (or that’s how big writers say!!).  Anyway, back to serious business again!

In various ways, as described in earlier articles, human activities pollute marine ecology.  It is not just harmful to the marine environment, but for the very existence of the human being themselves.  Oils-spills into oceans is one of the major causes of disastrous marine pollution.

Since exploration of oil from marine resources has become a must and oil spills end up occurring accidentally; as a result, it becomes crucial to employ various oil spill cleanup methods.

Cleanup and recovery from an oil spill is complicated and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), the choppiness of seas in the region, and the types of shorelines and beaches involved in the vicinity.  Physical cleanups of oil spills are also incredibly complicated and very expensive. However, microorganisms such as Fusobacteria species demonstrate an innovative potential for future oil spill cleanup because of their ability to colonize and degrade oil slicks on the sea surface.

No two oil spills are the same.  However, some of the primary methods of cleanup response are as follows:

Leave the oil alone so that it breaks down by natural means. If there is no possibility of the oil polluting coastal regions or marine industries, the best method is to leave it to disperse by natural means. A combination of wind, sun, current, and wave action will rapidly disperse and evaporate most oils. Light oils will disperse more quickly than heavy oils.

100505-G-4590R-001 Oak oil skimming responseContain the spill with booms and collect it from the water surface using skimmer equipment. Spilled oil floats on water and initially forms a slick that is a few millimeters thick. There are various types of booms that can be used either to surround and isolate the slick or to block the passage of a slick to vulnerable areas such as the intake of a desalination plant or fish-farm pens or other sensitive locations. Boom types vary from inflatable

neoprene tubes to solid, but light material. Most rise up about a meter above the water line. Some are designed to sit flush on tidal flats while others apply to deeper water and have skirts which hang down about a meter below the waterline. 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 the shore. However, booms and skimmers are less effective when deployed in high winds and high turbulent seas.

They also use dispersants to break up the oil and speed its natural biodegradation. Dispersants act by reducing the surface tension that stops oil and water from mixing. The oil then turns into smaller droplets, which helps promote rapid dilution of the oil by water movements. The formation of droplets also increases the oil surface area, thus increasing the exposure to natural evaporation and bacterial action. Dispersants are most effective when used within an hour or two of the initial spill. However, they 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 seagrass. It can also cause oil to be temporarily accumulated by subtidal seafood. Decisions on whether or not to use dispersants to combat an oil spill must be made in each case. The decision will take into account the time since the spill, the weather conditions, the particular environment involved, and the type of oil that has been spilled.

Introduce biological agents to the spill to hasten biodegradation. Most of the 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. The natural process can be speeded up by the addition of fertilizing nutrients like nitrogen and phosphorous, which stimulate the growth of the microorganisms concerned. However, the effectiveness of this technique depends on factors such as whether the ground treated has sand or pebbles and whether the fertilizer is water soluble or applied in pellet or liquid form.

Controlled burning can effectively reduce the amount of oil in water if done correctly. But it can only be done in low wind and can cause air pollution.

Dispersants and booms and skimmers are the most frequently used methods to clean up ocean oil spills. All means have advantages and disadvantages. The effectiveness depends on the situation – the amount and type of oil, the ocean currents and tides and the weather. Some methods can be harmful to the environment. Oil clean-up agencies have to make decisions about the safety of chemicals used in water and strategies cleanup process taking into account all factors involved as stated above. 

References:

  1. Wikipedia
  2. Marine Insight News Network – January 16, 2018
  3. University of Delaware, Sea Grant program – Oil spill Cleanup

Milind Joshi

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