Oil slick from sunken Iranian tanker off China trebles in size

Authorities race to offset environmental disaster from spill of light crude oil

Smoke and flames coming from the burning oil tanker Sanchi off the coast of eastern China on January 14th. The vessel sank, with the loss of all 32 mariners on board. Photograph: AFP/Transport Ministry of China

Smoke and flames coming from the burning oil tanker Sanchi off the coast of eastern China on January 14th. The vessel sank, with the loss of all 32 mariners on board. Photograph: AFP/Transport Ministry of China

 

An oil slick from a sunken Iranian tanker in the East China Sea has more than trebled in size to cover a total surface area of 332sq km from the 101sq km previously reported, authorities said.

Chinese authorities are in a desperate race to avoid a massive environmental catastrophe from the slick, which is the biggest in decades, in waters that are home to heavily fished species such as mackerel, bluefish and crab, as well as migratory pathway for marine animals, including the humpback whale.

Satellite images shows three oil slicks totalling about 332sq km, including one that is 328sq km, the State Oceanic Administration (SOA) said in a statement.

The Sanchi is an Iranian-owned, Panamanian-flagged supertanker and was carrying 113,000 tonnes of light crude oil, or condensate, when it collided with a Hong Kong-registered freighter the CF Crystal on January 6th. It sank on January 14th, with the loss of all 32 mariners on board – 30 Iranians and two Bangladeshis.

The bodies of just three of the crew have been found.

The amount of light crude oil was revised down from the original estimate of 136,000 tonnes, China’s transportation ministry said last week.

Toxic condensate

Condensate is particularly difficult for the authorities to deal with as it does not form an oil slick like traditional crude, but remains invisible under water and highly toxic. It is very difficult to separate from water.

On the surface it can burn off or evaporate. The Sanchi spill is the largest condensate spill on record.

Authorities have now to try to establish how much is below water and how much burned off or evaporated when the Sanchi first sank.

According to the SOA, a 5.4km-long, 1.4km-wide oil slick was seen about 5km northwest of the tanker’s location, while a 4km-long, 400-metre-wide oil slick had been sighted about 5km southeast of the tanker’s location.

Chinese authorities earlier secured the vessel’s black box and have sent three coast guard vessels to the scene to assess the spill, the SOA said.

The ideal solution would be to salvage the vessel but it has already sunk to a depth of 115 metres, making the operation very difficult. The continued presence of condensate in the tanker could trigger another explosion.