Chemical defense soldiers monitor elements on a metal container in the core area of the blast site in New Binhai Area, Tianjin, on Sunday. (Photo: chinadaily.com.cn/Zhu Xingxin)
Sodium cyanide at the periphery of the Tianjin blast area will mostly be collected and cleared by Monday evening, He Shushan, deputy mayor of Tianjin, said at a press conference Monday morning.[Special coverage]
Some of the highly toxic chemicals were scattered at the periphery, but mostly within a 100,000-square-meter core area, He said, adding that sand and earth barriers were built around the core area to prevent any leakage.
A "very complicated and difficult" clean-up, partially due to the presence of 16,500 empty shipping containers within the core area, is under way, he said.
Workers are now searching empty shipping containers for chemicals dispersed by the blast.
Cofferdams will also be reinforced to prevent the outflow of contaminated water after it rains, He said.
Monitoring has shown air quality in the area and water in the nearby river are within safe standards.
Bao Jingling, chief engineer of the city's bureau of environmental protection, said about 700 tonnes of sodium cyanide were stored at the blast site and they remain intact.
Sodium cyanide is a highly toxic white, water-soluble powder that prevents the body from using oxygen. It is fatal if inhaled or ingested.
It is mainly used in chemical manufacturing and to extract gold and other metals in mining.
When treated with acid, it releases the highly poisonous gas hydrogen cyanide.
