Environmental workers pour water treatment material into the Zhanghe river to purify the water in Yuecheng reservoir in the downstream city Handan, North China's Hebei province on Jan 8, 2013. Nearly nine tons of aniline, a toxic chemical widely used to manufacture pigments, leaked from a chemical plant in North China's Shanxi province, affecting the city's water supply in neighboring Hebei province. The treatment involves pouring activated carbon - charcoal that has been treated with oxygen to open up millions of tiny pores between the carbon atoms – into the water system. [Photo/Xinhua]