Transmission and health risks of mercury in soil-paddy system in Chatian mercury mining area,Fenghuang County,Hunan Province
湖南凤凰茶田汞矿区土壤-水稻系统中汞的传输及其健康风险

Mercury(Hg) in paddy soils and rice as well as its translocation and accumulation in Chatian Hg mining area of Fenghuang County,Hunan Province were studied based on field systematic sampling and laboratory analysis.The results showed that Hg concentrations in the paddy soils and rice were significantly enriched,which were primarily due to the high natural geologic background levels and anthropogenic mining activities.The average concentration of Hg in paddy soils,rice root,rice shoots and rice grain in mercury deposit area were,in average,276.6,8.6,5.8 and 2.3 folds of the corresponding parts in the control area,respectively.The concentration of Hg in paddy soils in organic-sulfide form was significant positively correlated with Hg contents in rice roots,rice shoots and rice grain.However,the transfer coefficients of Hg of paddy soils-rice roots and rice roots-rice grain were quite low.The content of Hg in rice grain in Chatian mercury mining area was 0.09±0.04 μg/g,4.5 times of the limited value(0.02 μg/g) of the National Food Sanitary Standard(GB2762-2005).Average daily intake dose(ADD) of Hg of local population ranged from 0.408 to 1.225 μg/(kg·d),mean 0.75 μg/kg body weight per day,exceeding 0.71 μg/(kg·d) of provisional tolerable daily intake(PTDI) recommended by WHO.The local inhabitants faced huge health risk due to high Hg exposure via rice consumption.In addition,Se and Pb were also found to be co-enriched in the rice grain in Chatian mining area,indicating that co-contamination of Hg and Pb may result in great risks to human health in this area.