Historic mine waste in rural China. Environmental risk must be understood then managed or remediated

Artisanal mercury mining has historically seen mine waste discharged to rivers.

An example of conventional remediation in China. Mercury mine waste covered in concrete.

Use of trees (phytoremediation) to intercept contaminants leaching from mine waste.

Remediation of Trace Element Contaminants at Mining and Industrial Sites: 
Case Study for Heavy Metals in China

Croesus is working with the Institute of Geochemistry of the Chinese Academy of Sciences in Guiyang China to assess the risk of mercury, arsenic and other trace-element pollution of soil due to historic and current mining practices.  Croesus is assisting our Chinese colleagues to design, test and implement risk management solutions, including phytoremediation.  

 

China has a current-day legacy of heavy-metal contamination of soil due to past mining practices.  Guizhou Province has a rich endowment of mineral deposits, and these have been exploited over the centuries for mercury and gold.  Past mining practices were not as environmentally safe or as regulated as they are today. Croesus and the Institute of Geochemistry have been designing and testing phytoremediation solutions for mercury pollution in the Wanshan mercury mining area since 2008. Today a range of larger-scale projects are being implemented to target and recover bioavailable fractions of mercury in soil so that subsequent crops are less likely to accumulate the metal. This work is intended to protect human health through addressing risk related to food safety.

 

Environmental Science and Technology, 46(20), 11013-11020.

Liu, J., Feng, X., Qiu, G., Anderson, C. W. N. and Yao, H (2012).

Prediction of methyl mercury uptake by rice plants (Oryza sativa L.) using the diffusive gradient in thin films technique.

 

Journal of Hazardous Materials, 221-222, 1-18.

Wang, J., Feng, X., Anderson, C. W. N., Xing, Y. and Shang, L. (2012).

Remediation of mercury contaminated sites - A review. 

 

Journal of Hazardous Materials, 186(1), 119-127.

Wang, J., Feng, X., Anderson, C. W. N., Qiu, G., Ping, L. and Bao, Z. (2011).

Ammonium thiosulphate enhanced phytoextraction from mercury contaminated soil - Results from a greenhouse study.

 

Environmental Toxicology and Chemistry, 30(12), 2725-2731.

Wang, J., Feng, X., Anderson, C. W., Zhu, W., Yin, R. and Wang, H. (2011).

Mercury distribution in the soil-plant-air system at the Wanshan mercury mining district in Guizhou, Southwest China.

 

In 2013, collaborative risk assessment of arsenic contamination at a historic gold mine began.  In the aftermath of World War 2, Russian scientists were commissioned to build mineral processing plants in China to process gold and mercury ore by roasting and subsequent hydrometallurgy.  At one location waste material (tailings) was discharged throughout a river valley, downstream of the mining plant. Roasting increased the pH of the tailings to above 10, and at this pH the arsenic content of the rock becomes highly soluble.  There is risk today of diffuse arsenic contamination of water and soil throughout the local area. Key to preventing future risk is the collection and containment of the mining waste.  Croesus is advising on how this can be most efficiently done.

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