Atlas of Contaminated Sites

Notable case, Wanshan (Tongren), Guizhou, China

Wanshan mercury mining district

万山汞矿

China's "mercury capital", in eastern Guizhou: abandoned mines and smelters that left mercury in the soils and rice paddies. It is where researchers established that in inland China methylmercury reaches people through rice rather than fish.

Phytoremediation

Status
Under assessment
Media
soil, surface water, sediment, air, living organisms
Kind of site
mining, smelter
  1. Area. No official contaminated area was found in the sources read. Wanshan administrative district covers 338 km² (Wikipedia).
  2. People affected. Wanshan district had 47,844 inhabitants at the 2010 census (Wikipedia); this is not an estimate of those exposed.

Contaminants

Metals

Status

Under assessment

The mines are abandoned. Since 2008 the Institute of Geochemistry of the Chinese Academy of Sciences and New Zealand partners have been field-testing ways to lower the mercury available in farm soils; the present state of remediation was not checked for this record.

Story

Wanshan was China's largest centre of mercury mining and smelting. Mining has ceased, but smelting residues and the soils around the abandoned mines keep releasing mercury to the streams and fields below.

In flooded paddies inorganic mercury is converted to methylmercury, which rice accumulates in the grain. Qiu and colleagues (2008) measured more than 100 µg/kg of methylmercury in rice grown at abandoned mercury mines in Guizhou, far more than in other crops. Zhang and colleagues (2010) showed that at four locations in Guizhou rice supplies 94–96% of dietary methylmercury.

Since 2008 the Institute of Geochemistry in Guiyang has worked with New Zealand researchers on plant-based solutions for the farmland of Wanshan, targeting the fraction of mercury available to crops.

Timeline

  1. 2008Phytoremediation trials by the Institute of Geochemistry with New Zealand partners begin; the study on methylmercury in rice is published.
  2. 2010Publication of the study naming rice as the main route of methylmercury exposure.
  3. 2012Field results on phytoextraction with Brassica juncea and thiosulphate are published.

Health

According to Zhang and colleagues (2010), average methylmercury intake for an adult in Wanshan was 0.096 µg per kg body weight per day, and about 34% of inhabitants exceeded the US EPA reference dose (0.1 µg/kg per day).

Plants and fungi at this site

PhytoremediationField scale

Brassica juncea

Field trials by the Institute of Geochemistry (Jianxu Wang, Xinbin Feng) with Christopher Anderson (Massey University) on contaminated farmland at Wanshan: Indian mustard (Brassica juncea, several cultivars) grown with thiosulphate added to the soil, which makes mercury soluble and available to the plant. Mercury appears to be taken up as a thiosulphate complex.

Outcome With thiosulphate, mercury concentrations in roots and shoots rose significantly; 66–94% of the mercury in tissues was in a form similar to the sulphide β-HgS. Mercury in the rhizosphere fell compared with untreated soil, but fractions bound to oxides and organic matter shifted to more available forms. The 2013 paper reports phytoextraction yields of 92, 526, 294 and 129 g of mercury per hectare for four cultivars (figures read from the abstract returned by search; the journal page could not be opened).

From the literature

Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.

Plants

Fungi

Nearby

Notable case, Lengshuijiang (Loudi), China

Xikuangshan antimony mine

225 km

  • Antimony
  • Arsenic
  • Mercury
  • Lead

PhytoremediationMycoremediation

Notable case, Baiyun, Shimen (Changde), China

Shimen realgar mine

300 km

  • Arsenic
  • Antimony

PhytoremediationMycoremediation

Notable case, Huanjiang (Hechi), China

Huanjiang (farmland polluted by mine tailings)

314 km

  • Arsenic
  • Lead
  • Zinc
  • Cadmium

Phytoremediation

Sources

  1. Zhang H., Feng X., Larssen T., Qiu G., Vogt R.D. In inland China, rice, rather than fish, is the major pathway for methylmercury exposure. Environmental Health Perspectives 118(9), Environmental Health Perspectives (abstract via Europe PMC), 2010
  2. Qiu G. et al. Methylmercury accumulation in rice (Oryza sativa L.) grown at abandoned mercury mines in Guizhou, China. Journal of Agricultural and Food Chemistry, ACS (abstract via Europe PMC), 2008
  3. Wang J. et al. Implications of mercury speciation in thiosulfate treated plants. Environmental Science & Technology, ACS (abstract via Europe PMC), 2012
  4. Historic mine waste in rural China (case study), Archimedes NZ / Croesus Projects
  5. Wanshan District, Wikipedia, 2026

Draft compiled from public sources, not yet reviewed.