Sanchi oil spill contamination

23 January 2018

Article: 52/307

An emergency ocean model simulation shows that waters polluted by the sinking Sanchi oil tanker could reach Japan within a month. The new simulation also shows that although pollution is most likely to reach the Japanese coast, it is also likely to affect Jeju Island, with a population of 600,000. However, the fate of the leaking oil is highly uncertain, as it may burn, evaporate, or mix into the surface ocean and contaminate the environment for an extended duration.

These latest predictions have been made possible by new information about where the Sanchi oil tanker finally sank. Based on this update, the team of scientists from the National Oceanography Centre (NOC) and the University of Southampton have run new ocean model simulations to assess the potential impact of local ocean circulation on the spread of pollutants. These simulations were run on the global ocean circulation model, NEMO.

The Sanchi tanker collision originally occurred on the border between the Yellow and East China seas, an area with complex, strong and highly variable surface currents. However, in the following week, the stricken tanker drifted before sinking much closer to the edge of the East China Sea, and to the major western boundary current known as the Kuroshio Current. The predictions of these new simulations differ significantly from those released last week, which suggested that contaminated waters would largely remain offshore, but could reach the Korean coast within three months. Using the same methods, but this new spill location, the revised simulations find that pollution may now be entrained within the Kuroshio and Tsushima currents.

These currents run adjacent to the northern and southern coasts of southwestern Japan. In the case of contaminated waters reaching the Kuroshio, the simulations suggest these will be transported quickly along the southern coasts of Kyushu, Shikoku and Honshu islands, potentially reaching the Greater Tokyo Area within two months. Pollution within the Kuroshio may then be swept into deeper oceanic waters of the North Pacific.

The revised simulations suggest that pollution from the spill may be distributed much further and faster than previously thought, and that larger areas of the coast may be impacted. The new simulations also shift the focus of possible impacts from South Korea to the Japanese mainland, where many more people and activities, including fisheries, may be affected.

Source: NOC News Release, 16 January 2018