Dead fish, toxic drinking water ... Now for the human toll

Take a look at Hechi city, a booming mining town in the northwest of Guangxi, and the jarring dissonance immediately hits you.

Misty limestone peaks stretch away from a crystalline river, all set in a lush green expanse. It would be one of the most mesmerising landscapes in the mainland, except for the dozens of smokestacks, short, tall, all grimy, lining both sides of the river.

The chimneys mostly belong to metal smelters, one of which was responsible for January's poisoning of the Longjiang, an upstream tributary of the Pearl River. The authorities are not naming the culprit, however.

In the daytime, the chimneys appear to be idle. However, locals living along the river tell of the smelters' dirty secrets. At night, they say, those chimneys churn out a vast cloud of black smoke that enters their homes and stirs them from sleep, gasping for breath.

'The filthy smoke billowing through those chimneys often chokes us awake, and we could also see flames light up the night sky,' said one resident of a city suburb, who refused to be named for fear it would bring trouble.

On January 15, the rest of the country woke up to the pollution horror gripping the city. Pictures of a river of dead fish shocked the nation and led to the discovery that 21 tonnes of cadmium, a life-threatening toxic metal had been leaked into the Longjiang.

The scale of the spill is equal to about two-thirds of the total amount of cadmium discharged nationwide in 2010. Experts warned of an immediate health and environmental challenge as well as serious long-term implications.