Cargo ship sinks near Kerala coast: What can be the impact of oil spills and how are they cleaned up?

How can an oil spill affect the ecosystem? 

Oil spills can severely damage the marine ecosystem as they can result in the death of fish and other organisms, and destroy mangroves and coral reefs. If an oil spill takes place near the coast, it can affect the livelihood of fishermen and disrupt the local economy.

Such spills are dangerous because oil is lighter than water and it keeps floating on the surface of the sea, forming a thin layer called slick. This layer spreads rapidly over the surface as it is carried by wind and ocean currents. Moreover, most of the components of the spilled oil remain suspended in water which can lead to long-term harm. That is the reason why after an oil spill, a quick clean-up with human intervention is necessary.

The MSC ELSA 3 was carrying at least 84.44 metric tonnes of diesel and 367 metric tonnes of furnace oil, according to the Coast Guard. A simulation done by the Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS) showed that if all of this diesel and furnace oil leaked into the sea, there was a high probability that these chemicals would drift towards the coast of Kerala. The entire coastal stretch between Alappuzha and Thiruvananthapuram districts could be affected, the simulation revealed.

Grinson George, director of Central Marine Fisheries Research Institute (CMFRI), told The Indian Express that the oil spill would lead to “short-term impacts, mostly on small scale and artisanal fishermen who work closer to the coast”.

He said that oil smothering — when a coat of oil covers marine organisms — could threaten marine species and impact pelagic fish breeding in the region.

Authorities are also concerned about other hazardous substances that MSC ELSA 3 was carrying. The vessel had at least 12 containers of calcium carbide — a toxic chemical that can form explosive gases when it reacts with water. These gases are a health risk for humans and marine life.

How do oil spills get cleaned up?

Each oil spill has unique aspects as it is influenced by the nature and chemical composition of the oil that gets leaked. Usually, before planning the clean-up, experts try to observe the colour of the oil slick (under sunlight seen as black, rainbow, brown or colourless) which can indicate the possible composition and extent of the spill.

During the clean-up process, pillows made of oleophilic (oil-attracting) materials are first deployed at the site of an oil spill. These materials act like a sponge and absorb oil (not water) from the surface. This helps clean up large portions of undivided oil slicks.

Then, sheets made of cotton, or a material which has properties similar to cotton, are deployed to absorb the leakage.

Another method for removing the oil is to use specialised motors which can pump out water. However, these motors are deployed only when an oil spill has taken place over calm waters such as a lake.

As oil does not mix or dissolve in water, an entire clean-up of this emulsified liquid is not an easy task. The process is very costly and labour-intensive, and can sometimes extend to months.

Also, in water bodies such as rivers and the sea, the perpetual flow of the water can pose a challenge.

Experts suggest that in the case of MSC ELSA 3, if an oil leak takes place, it would be crucial to not let the oil slicks reach near the shores.

Deepak Apte, a leading marine biologist, told The Indian Express, “Monsoon has made an onset and the currents are towards the shore. With the monsoon tides and surges, access to shore areas will be difficult for clean-ups if the oil slicks reach the coast.”