Levels of the heavy metal thallium were found to exceed safe limits in a major river in Hunan province, threatening the safety of drinking water in nearby cities, Caixin magazine reported this week.
Citing an unpublished government notice circulating online, Caixin said the thallium concentration in the section of Leishui River between the cities of Chenzhou and Hengyang was considered “abnormal”. Yongxing County, an area under Chenzhou’s administration, initiated a Level 4 emergency response – indicating a “sudden environmental event” – on March 16.
On March 25, a notice issued by the Hunan Provincial Department of Ecology and Environment confirmed this. It stated that the concentration of thallium was found to be 0.13 micrograms per litre, above the national 0.1-microgram limit for drinking water. The source of the pollution was a cement production company in Chenzhou, where thallium dust was dislodged during the dismantling of a kiln and washed into the river by rainwater, the department said.
Thallium is a toxic heavy metal that, when inhaled or consumed, can cause health problems, with symptoms such as abdominal pain, numbness and hair loss. The main source of thallium pollution is industrial production, primarily generated during the smelting of non-ferrous metals such as lead, zinc, and copper, and ferrous metals such as steel, noted Peng Yingdeng, a researcher at the Industrial Wastewater Pollution Control Engineering Technology Center of China’s Ministry of Ecology and Environment.
Demand for bottled water has increased in areas such as Leiyang, a city downstream of Chenzhou which gets some of its tap water from Leishui, reported China National Radio.
Leishui is the largest tributary of the Xiangjiang River, and many sulphur mines, pyrite mines and smelters exist along the latter, said Peng. In recent years, the Xiangjiang River basin has faced multiple instances of excess discharge and abnormal concentrations of thallium. In 2023, Caixin reported that since 2020, abnormal concentrations of thallium have been recorded in 17 of the 22 drinking water sources along the Xiangjiang.
After a cleanup effort in 2022, however, the average thallium concentration of the Xiangjiang River basin has decreased by more than 50% from 2020 levels, said Huang Yu, deputy director of the Hunan ecology and environment department.
Read Dialogue Earth’s previous analysis on China’s policy on pollution.