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Mercury pollution in rice and related risk of human methylmercury exposure in Wanshan mercury mining area.

WANG Ya1, LI Ping2**, WU Yong-gui1   

  1. (1College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; 2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China)
  • Online:2015-05-10 Published:2015-05-10

Abstract:

To evaluate the risk of methylmercury (MeHg) exposure through rice consumption for local residents, 168 rice samples were collected at seven sites of two catchments in Wanshan mercury (Hg) mining area to analyze the total mercury (THg) and MHg concentrations. THg concentrations in rice ranged from 2.4 to 401.0 ng·g-1, with an average of 42.4 ng·g-1, and THg concentrations in 51% of samples exceeded the national food standard for Hg (20 ng·kg-1). MeHg concentrations varied from 1.1 to 45.1 ng·g-1, with an average of 11.7 ng·g-1, and it accounted for 44.8% of THg in rice on average. A significant positive correlation (r=0.44, P<0.01) was observed between THg and MeHg concentrations in rice, while a negative correlation relationship (r=-0.59, P<0.01) was found between rice THg and the percentage of THg as MeHg. Heavy mercury pollutions were found at sites in the upstream region which are close to the mine wastes and THg concentrations in rice samples of the different sites demonstrated a gradient of decrease with increasing the distance from the pollution source in the two catchments. The risk assessment indicated that, local residents in Hg highly polluted areas (such as Dashuixi, Meizixi, and Baiguoshu) had a high risk of MeHg exposure through rice consumption and residents in other areas were also at potential risk of MeHg exposure.

 

Key words: trade-off, Saussurea przewalskii, reproductive characteristics, altitude, individual size