Located in Guangdong province near the Hengshui River, the Daobaoshan mine is property of the state-owned Guangdong Daobaoshan Mining Co. Ltd. At Daobaoshan, roughly 6,000 tons of copper ore and 850,000 tons of iron ore are mined each year, and the mine was once the largest zinc mine in China.
Wastewater and sludge from the mine’s activities have polluted the lower section of the Hengshui, and mounds of tailings are discarded along rice paddy fields. Locally used waters and soils have become contaminated with cadmium, lead, arsenic, as well as other heavy metals, thereby affecting the health of the various villages and towns located nearby.
One of the primary regions impacted by the pollution from Daobaoshan mine is Shangba Village. With a population of roughly 3,300, Shangba is an agricultural village where rice and sugar are the main crops. Environmental testing in the region has demonstrated that both the irrigation water and agricultural soils of Shangba Village contain concentrations of cadmium that exceed the national average, and health surveys show a very high local incidence of cancer. The source of Shangba’s high cadmium levels is a nearby dam that stores tailings from the Daobaoshan mine.
In July of 2009, Blacksmith Institute identified the Guangdong Institute of Eco-Environment and Soil Sciences to be its local partner for the remediation of Shangba Village. Blacksmith provided financial support and technical assistance.
The ultimate aims of the project were to 1) Remediate the contaminated soils with cadmium-accumulating rice plants, 2) Reduce the presence of heavy metals in the food chain through the application of silicate fertilizer, and 3) Develop a method for purifying water sources used by villagers for irrigation.
To assist in this process, from 2009 to 2010, Blacksmith Institute helped the Guangdong Institute formulate a stakeholder group, which consisted of members from the Shaoguan Environmental Protection Bureau, city government, and Center for Disease Control and Prevention. With assistance from Blacksmith’s TAB, this group met at least monthly throughout the year to design the remediation, collect baseline data, and plan intervention projects. Local citizens were also recruited to participate in the process.
By November of 2010, Guangdong Institute’s pilot experiment with cadmium-accumulating rice plants and silicon fertilizer showed a 5 to 8 percent yield increase when compared to contaminated soils without this treatment. Likewise, after water purification methods—including physical precipitation of suspended substance and heavy metals with polymer, chemical adjustment of pH with limestone and slag, and biological treatment with wetlands—the concentration of cadmium was found to be within national standards, and water can now safely be discharged into surface bodies or used in irrigation.
In the last stages of the remediation project, Blacksmith will continue to advise and fund the Guangdong Institute and stakeholder group to refine the design of their water purification technique and to finalize heavy metal analysis of the remediation experiment. Lastly, the group will prepare a booklet with the main results of this project to distribute the knowledge and countermeasures gained to the residents of Shangba Village.