How the Sanchi’s oil could spread
On Jan. 14, the Iranian tanker Sanchi sank in the worst oil shipping disaster in decades, killing all 32 crew onboard. Water contaminated by the cargo of toxic condensate oil and the ship’s fuel oil could reach as far as Japan or South Korea.
Risk of impact
The ultra-light, toxic cargo of condensate would probably dissolve, forming a poisonous plume under the sea surface. However, it remains unclear how long condensate would stay in the water, with South Korean officials believing it would most likely evaporate.
The ship was powered by heavy fuel oil, which is more stubborn in the environment and could wash up on shores.
Data from Britain’s National Oceanography Centre and the University of Southampton simulates where oil may drift within three months.
It remains unclear how long condensate would stay in the water before evaporating. The ship’s engine fuel is more persistent and could wash up on shores.
Data from Britain’s National Oceanography Centre and the University of Southampton shows where oil may drift within three months.
Currents
The spill site sits among several ocean currents, including the powerful Kuroshio Current, which runs along the coast of Japan and out to the north Pacific Ocean. There are some weaker currents moving slowly north from the spill site toward South Korea.
“Strong ocean currents mean that, once released into the ocean, an oil spill can relatively rapidly spread over large distances,” Dr. Katya Popova of the National Oceanography Centre, said on the centre’s website.
The spill site sits among several ocean currents, including the powerful Kuroshio Current. Some weaker currents move slowly north from the spill site toward South Korea.
Simulating the spread
The following animation shows the trajectories of 6,000 virtual oil particles across a number of ocean current scenarios in January. This gives an indication how fast polluted water would travel and where it might go.
Day 1
In the first two weeks after the sinking, pollutants would likely remain in open water close to the Sanchi wreck site.
Day 15
Particles can be seen reaching smaller islands off southern Japan. The Kuroshio Current runs directly through this area, which is rich in marine life and has numerous coral reefs.
Day 26
The particles spread further, and a large group continues to drift north towards South Korea. More are present around the waters of Kyushu island, Japan, and some reach even further along the Japanese coast.
Day 41
Pollutants could now have drifted to the southern coast of Jeju island in South Korea, home to protected marine areas. In some scenarios, pollutants can also be seen reaching as far as the Greater Tokyo area of Japan.
Day 61
Particles are mostly concentrated in the East China Sea and in the waters between South Korea and Japan. Those to the south of Japan are rapidly transported northeast along the coastline and into the north Pacific Ocean.
Reefs and protected areas
The East China Sea is known for its diverse, although already polluted, marine ecosystem. Japan’s Osumi Islands and Tokara Archipelago lie in the potential drift areas and are rich in marine life and coral. Many waters in the area are protected.
The East China Sea is known for its diverse, although already polluted, marine ecosystem. Japan’s Osumi Islands and Tokara Archipelago lie close to the potential drift areas and are rich in marine life and coral.
The island of Yakushima in particular, boasts one of the richest and most abundant varieties of fish in Japan. Its sandy beaches are also important spawning grounds for loggerhead turtles.
Fishing grounds
Another major concern is damage to the region’s rich fish reserves. The Zhoushan fishing ground is known as one of the biggest in the area. If edible fish are contaminated, traces of pollution could eventually be consumed by humans.
Another concern is damage to fish reserves. If edible fish are contaminated, traces of pollution could be consumed by humans.
This map shows areas fished last year in the same three months following the date of sinking, according to Global Fishing Watch, an independent non-profit organisation.
The immediate or long-term damage to fisheries and marine life in the area remains to be seen. An official at Japan’s Fisheries Agency said the agency is closely monitoring the situation and studying it could do to assess or prevent the potential damage, although there had been no direct impact so far on the Japanese fishing industry.
Fishing data: Global Fishing Watch