The oil coast in Tuapse on the Black Sea: in late May, an oil slick appeared in the water of the popular Russian resort, covering over a million square meters. According to the authorities, the cause was a leak from a deepwater header. The city was put in high alert, with over a ton of adsorbent dropped from vessels, and environment specialists examining the water and the coastline.
This is one of the many accidents that are talked about and covered in the news, like the one that happened in Norilsk for example. However, even more local accidents never make get any news coverage: according to RosPrirodNadzor (the Federal Service for Supervision of Natural Resources), 819 oil spill incidents were registered in the country in 2019, the total area affected being 93.6 hectares, while in 2018 there were 3,053 such instances. Scientific Russia on the biggest oil spills and cleanup methods.
Leaky pipes and ecoterrorism
Pipeline and reservoir failures may cause greater damage than the accident in Tuapse did. An example of that in Russia is loss of containment in Nornickel’s tank of diesel fuel. Around 21,000 tons of flammable material spilled into the rivers Ambarnaya, Daldykan and their tributaries in May 2020. Greenpeace calls the environmental disaster in Siberia the biggest in the high Arctic area, but history remembers even greater damage caused by faulty fuel storage and transportation systems.
January, 2000, Rio de Janeiro – an offshore pipeline burst. The resulting oil slick spread over 40 square kilometers after 1.3 million liters of fuel were released. The authorities banned fishing in the Guanabara Bay for 45 days, and after that the fishing business there shrank by half. Local residents back then remembered a black tide and waves that were coming to the shore not with the usual rumbling but with squelching of a thick paste.
And the biggest oil spill in history was not caused by negligence, but by malicious intent and an act of ecoterrorism. During the war in the Persian Gulf, Iraqi troops released up to 1.5 million tons of oil into the water in order to impede landing on the coast. No-one could calculate exactly how much fuel was spilled during the war, different sources providing different data: some estimates say that 8 million barrels had gone into the gulf before the war was over. American troops bombed several oil wells and pipelines to stop further oil dumping. No cleanup was done for awhile due to continuing military action and smoke from fires at oil wells. Fuel spread, covering about 1,000 square kilometers of water in the gulf and 600 km of the coastline. The cleanup cost up to five billion US Dollars.
Stop, absorb, remove
After an oil spill, it is important to contain the oil slick to a certain area to prevent the spread of the pollution through water. Booms are used for that – floating barriers made with a fabric resistant to the impact of acids, alkali and oil products. They are designed to be rapidly deployed and contain the oil spill area. When the oil slick is contained, it is time to clean up. There are mechanical, thermal, physico-chemical and biological methods.
The most dangerous method for the environment and first responders is in-situ burning. The fuel is set on fire when it has not mixed with the water yet and the film is at least 3 mm thick. Safety measures are important in this process – the windspeed should not exceed 9 m a second, the slick should not be close to a coast with trees, houses and dry grass on it. Burning oil releases carcinogens into the air.
One of the safe cleanup methods is recovering oil by skimmers. This is equipment that can collect up to 99 percent of oil products from the water. Different types of skimmers are used depending on the type and quantity of the substance: there are belt, tube and disk skimmers. Oil products recovered by a skimmer can be reused.
The physico-chemical method involves sorbents. Sawdust, graphite or peat is spilled onto the oil slick; the sorbent absorbs the fuel, forming oil saturated lumps. The lumps are then removed from the water surface. Some substances used as sorbents, e.g. sphagnum peat moss sorbents, can degrade oil, so they do not have be collected afterwards.
The biological method is used after mechanical or physico-chemical cleanup, when the film is at least 0.1 mm thick. To further clean up the affected area, bacteria or fungi are inserted, which degrade the hydrocarbon mass. Few microorganisms are capable of absorbing and digesting oil, mostly Pseudomonas bacteria. The biological method is safe for the environment.
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