The July 16 oil spill on Dalian's coast, while smaller and more controllable than the infamous Gulf of Mexico spill, is nonetheless a major environmental disaster that will pose a hazard to the area's ecosystem for the next 10 years, despite all the cleanup efforts, researchers say.

Workers in Dalian, Liaoning province, start on Sunday to clean up the crude oil that gushed into the sea after an oil pipe exploded at the coastal city's Xingang Harbor. [China Daily]

Even after the estimated 15-day cleanup, all the pollutants will not be gone, said Zhao Zhangyuan, a researcher with the Chinese Research Academy of Environmental Sciences.

"They will decompose and then spread," he said. "It will affect our ecosystems in the same way the Mexico Gulf accident will affect that area. Ours is different only in its degree and scale."

The decomposed oil could cause a cancer risk, Zhao said. "Fish, algae and other creatures in the contaminated water will not survive and birds will fly away," he said. Many of the birds will die, researchers agreed.

Oil spill cleanups are a challenge for any country. If not handled properly, destruction could follow, said Ma Yong'an, a researcher with the National Marine Environment Monitory Center (NMEMC).

Xu Guochen, secretary-general of Dalian's city government, said at a press conference on Monday morning that all the 1,500 tons of spilled oil is expected to be removed within five to seven days. But Wu Guogong, deputy director of the local environmental protection bureau, said the contaminated water will be removed in five to 10 days.

By Sunday, 180 tons of oil had been recollected and on Monday, 160 tons of oil removed.

Wu dispelled Zhao's claims, saying the impact would not be that severe. "The amount of the spilled oil is not large and 10 years is an improper estimate," he said. The investigation on the environmental damage will start soon, he said.

The Dalian incident has aroused widespread public attention as a comparison to the recent Gulf of Mexico oil spill, the largest offshore spill in United States history. The struggle to clean up is ongoing. The Dalian accident happened at a time when China is accelerating offshore oil drilling, and the sea water quality in some regions is worsening.

At 6:10 pm July 16, a petroleum port on China's northeast coastline was rocked when two pipelines exploded and an oil spill followed.

The crude oil gushed into the Yellow Sea and is spreading at a fast speed though an oil fence put in place to try to stop it. Clean-up vessels are trying to stop the flow.

On Saturday evening, local authorities announced that some 50 square kilometers of water has been affected. One day later, its impact was expanded to an area of 183 sq km.

On Sunday morning, the coastline was covered with thick, black oil. The water farther away was stained as well, glittering with the iridescent colors of petroleum. In some areas, the layer of oil is one meter deep.

A China Daily reporter who managed to enter the port area on Sunday immediately smelled the intense, pungent odor of petroleum.

A netizen named "Dalian old folk" blogged on sina.com that evening that he could smell petroleum while walking on a Jinzhou district street, some 20 km away from the port.

The fumes' gases contain sulphur and aromatic hydrocarbon that are not fatally toxic, Xu said.

Wu Jianjun, 21, who runs an Internet caf near the site, said on Monday afternoon that the smell had dissipated. But a China Daily reporter that day still smelled a slight smell of petroleum in the area.

Wu and other residents said they felt a bit dizzy but they are not sure whether it is from the oil.