Environmental activists are raising the alarm following what the New York Times calls the largest tanker oil spill in nearly 30 years. The Sanchi was carrying 136,000 tons, or more than 1 million barrels, of natural gas condensate when it collided with a freighter in the East China Sea on Jan. 6. While some of the highly toxic oil burned off in a fire before the Iranian ship sank, "it is virtually certain that much of the condensate went into the sea in solution, and that toxic underwater hydrocarbon plume will injure marine life exposed to it," an expert tells Bloomberg. "Even the burned fraction will leave a toxic residue on the water." As Chinese authorities evaluate the environmental impact, water samples are already showing "a dangerously high petroleum concentration around the spill," reports CNN.
But the effects are also spreading. According to China's State Oceanic Administration, two oil slicks resulting from the accident had grown in combined size from 4 square miles on Monday to 52 square miles on Tuesday, when they were in an area 330 miles from Shanghai and roughly 200 miles from Naha, Japan, report the Times and AP. According to Greenpeace, the leaked condensate—likely to be mixed with the fuel that powered the tanker—could "disperse and break down quite quickly, significantly complicating cleanup operations." The group notes the East China Sea is "on the migratory pathway of many marine mammals, such as humpback whale, right whale, and gray whale," and is also "an important spawning ground" for hairtail, chub mackerel, yellow croaker, and blue crab. (Read more oil spill stories.)