Water quality in the Chinese town of Sanbao has plummeted after heavy metal waster was dumped in the Nanpan river basin.
Authorities were alerted to the problem after 38 of a farmer's 51 sheep were found dead after drinking from a water source nearby.
Further investigation showed that as well as being dumped in Sanbao, more than 5,000 tonnes of chromium slag heaps were dotted around the region.
The toxic waste was dumped by two workers at an unlicensed waste disposal firm, which was contracted to process the waste.
Chromium slag has also been discovered in the mountains of Zhangjiaying village and heavy rainfall has washed dangerous levels of hexavalent chromium into water supplies - like the one that killed the Sanbao farmer's sheep.
Hexavalent chromium is a well-known carcinogen when inhaled and its use in Europe is severely limited by the Restriction of Hazardous Substances Directive.
Recently, sea mammal expert Dr Ingrid Visser told the BBC that heavy metal build-up in ocean food chains could be the reason behind falling killer whale numbers.
Posted by Lauren Steadman