The oil slick started spreading five days ago when a pipeline at a busy northeastern port exploded, sparking a massive fire that took more than 15 hours to contain. Hundreds of boats have been deployed to help with the cleanup.
At least one person has been killed in those efforts, a 25-year-old firefighter, Zhang Liang, who drowned Tuesday after a wave threw him from a vessel and pushed him out to sea, the state-run Xinhua News Agency reported. Another man who also fell in was rescued.
Beaches near Dalian, once named China's most livable city, were closing as oil started reaching their shores, Xinhua reported.
"The oil spill will pose a severe threat to marine animals, and water quality, and the sea birds," Huang Yong, deputy bureau chief for Dalian, China Maritime Safety Administration, told Dragon TV.
The environmental group Greenpeace China released several photographs this week showing oil-slicked rocky beaches, a man covered in thick black sludge up to his cheekbones. One worker, covered in oil, was being carried away by a colleague, but he was not identified.
The amount of oil spilled in the explosion was still not clear Wednesday, though China Central Television earlier reported an estimate of 1,500 tons. That would amount roughly to 400,000 gallons (1,500,000 liters) — as compared with 94 million to 184 million gallons in the BP oil spill off the U.S. coast.
State Oceanic Administration released the latest size of the contaminated area in a statement Tuesday.