Chemicals used in the cleanup of fuel oil leaking from a wrecked Russian tanker in the Sea of Japan are not a panacea, and overuse will destroy the region’s ecosystem, experts say.According to the Maritime Safety Agency, the government authorizes two types of chemicals to combat sea pollution. A chemical mostly made from surfactant — much like a dish-washing detergent — breaks oil down into smaller molecules, which float about 1 meter below the surface for several months. Once the molecules get small enough, they are ingested by marine bacteria. Five prefectures where oil washed ashore in the current spill have consulted with the agency and are spraying the chemical along the coast from MSA helicopters and Maritime Self-Defense Force ships.Another way to clean the ocean is to use a liquid or powdery chemical that solidifies the fuel oil into gel, said Takashi Onda, the MSA’s maritime disaster prevention specialist. But to do this, oil must first be fenced in and prevented from escaping until the slime solidifies, at which time the oil is contained in nets. This idea has yet to be tried on the current spill, Onda said. The gelling method will not work in rough seas, where high waves would probably carry oil slicks over the fences toward shore.Experts agree that scooping fuel oil without using chemicals is the best way to protect the ecosystem. But bucket brigades and oil vacuum machines on the beaches cannot prevent the huge spills from washing ashore.