A series of oil-pipeline explosions have China National Petroleum Corp (CNPC) scrambling to clean up an estimated 1,500 tons of crude oil covering about 50 square kilometers of ocean near Dalian in north China’s Liaoning province, the Wall Street Journal reported. The unexplained explosions occurred late Friday and took 15 hours to extinguish. No casualties were reported, but pressure has been laid on CNPC, the parent company of PetroChina (PTR.NYSE), to minimize the environmental, business and political impact of the spill. The incident follows closely news about the closure of Zijin Mining’s Shanghang copper plant after wastewater leaked into a nearby waterway.