by: Institute of Geochemistry, Chinese Academy of Sciences
Due to the long-term mining and smelting of mercury ore, the mercury pollution of farmland soil in China's mercury mining areas is serious. Local residents eat agricultural products grown on contaminated soil for a long time, so they are exposed to varying degrees of mercury exposure.
At present, the existing mercury-contaminated soil remediation technology is generally too high, the remediation time is long, the effect is unstable, and the farmers' income is not guaranteed. Therefore, it cannot be applied in large-scale mercury-contaminated farmland remediation. In response to the problem of remediation of mercury-contaminated farmland in mining areas, Feng Xinbin, a researcher at the Institute of Geochemistry, Chinese Academy of Sciences, took a different approach. By screening native crops with low accumulated mercury, and for the first time based on the geographical characteristics of the contaminated area, the agricultural plant structure adjustment plan was constructed for the first time.
The research team systematically collected 679 samples from Wanshan mercury mining area (a total of 4566 hectares of farmland) including 43 crops, analyzed the mercury content of the edible part of the crop and evaluated its ability to enrich mercury. The study found that the mercury content in the edible part of crops was in the range of 2.4-1075 μg kg-1, while the mercury content in the corresponding soil was in the range of 0.6-789.6 mg kg-1. Four crops with low accumulated mercury were found, including radish (2.03-10.71 μg kg-1), strawberry (2.80-10.43 μg kg-1), corn (1.23-21.32 μg kg-1) and potato (0.84-13.39 μg kg-1), the mercury content of the edible parts of these crops is lower than the limit (10-20 μg kg-1) specified in the national food safety standards (Figure 1). Further field trials were conducted to verify the ability of the above four crops to accumulate mercury. Based on these findings, the agricultural planting structure adjustment plan for the polluted area of the Wanshan mercury mining area was constructed. After evaluation, the implementation of this strategy will reduce the accumulation of mercury in agricultural products in the region by up to 92%, and increase the economic output of crops in the region by 3.6 times, to reduce the population's exposure to mercury and enable farmers to obtain economic benefits.
Related research results "Mercury accumulation in crops at a mercury-polluted mining site: agricultural planning to manage mercury risk in farming communities" were published in the Journal of Cleaner Production in the field of environmental science.
Figure: Mercury content in vegetables, fruits, food crops and Rhizosphere Soil in mercury mining area
Editor in charge: Ye Ruiyou