It is certainly one of the most serious oil spills in the world since 1991, when 260,000 tonnes of fuel oil had discharged into the sea off the coast of Angola in southern Africa.
China Sea, the collision between an Iranian tanker Sanchi departing for South Korea and a bulk carrier off Shanghai on 6 January last, causes enormous damage. 32 dead, and a major ecological catastrophe, in clear an immense oil spill of 20 kilometers long. Some 136 000 tonnes of ultralight hydrocarbons are draining into the water and could poison these very long-term fish-rich seabed.
The Iranian tanker was transporting condensate, an ultra-light, hyper-flammable crude. The vessel registered in Panama was operating for the National Iranian Tanker Co (NITC).
The sinking, on Sunday, 14 January 2018, of the Iranian tanker Sanchi, collided on 6 January with a Chinese boat, raised fears of an oil spill comparable to that caused by the Exxon Valdez in Alaska in March 1989, or that of the ABT summer off Angola in 1991.
To this difference, these two vessels carried crude oil while the Sanchi was loaded with condensate, ultralight hydrocarbons whose impact on the ecosystem is more difficult to measure. The fact that the boat sank in any case aggravates the risk of an environmental catastrophe.
The sinking was the worst possible scenario. As long as the tanker was still burning, the 136 000 tons, or 1 million barrels of ultralight crude on board, continued to evaporate. But now that the Mastodon lies at the bottom of the ocean, the hydrocarbons are spreading in the water.
The sea fauna and flora of East China at the front line after the sinking
"The explosion but especially the sinking of the oil tanker Sanchi will have negative consequences for the marine ecosystem. The Sanchi carried a very special kind of oil, condensate composed of toxic elements. And the worst part is that it is a huge amount, observes Ma Jun, Director of the Institute for public and environmental affairs.
This prominent Chinese environmentalist activist is threatening to endanger the richest ecosystem in the East China Sea, already threatened by the overfishing of Chinese, Japanese and Korean boats. These condensates may poison marine mammals such as whales, seabirds, but also mackerel, sea turtles, plankton, shellfish…
"The location of the accident is sensitive, in the natural fishing zone of Zhoushan, the largest (of China). Now, the oil slick is drifting northwards due to the winds and currents, but the waters are also rich in aquatic organisms, "says Ma Jun.
Priority: "evaluate how many tons of condensate and oil have passed"
Surveillance planes have spotted three oil sheets, which the violent winds and currents are drifting to Japan. "I hope that much of the condensate has already evaporated into the air thanks to the fire on board," says the Director of the Institute for public and environmental affairs.
The specialists fear above all the 1 000 tons of fuel oil contained in the vessel's tanks to rotate the turbines. This heavy diesel is the dirtiest oil. It is extremely toxic, for marine organisms, "more viscous". Priority: "evaluate how many tons of condensate and oil have passed through the water".
"It will be difficult to clean them. So they threaten the marine environment in the long run. The Government has already sent the boats to clean the oil sheets. But how to treat condensate under water? It's a tricky problem, "says Ma Jun.
With Heike Schmidt (RFI)