通过野外系统采样和室内分析,研究了湖南凤凰县茶田汞矿区耕层土壤及水稻中Hg的含量分布以及土壤-水稻系统中Hg的传输和分配。结果表明:由于地质成因和人为采选矿活动导致矿区土壤及作物中Hg大量富集,与对照区相比,矿区耕作土壤、稻根、稻秆、稻米中Hg平均含量分别增加了267.6倍、8.6倍、5.8倍和2.3倍。土壤中的有机-硫化态Hg同稻根、稻秆、稻米中Hg含量间均呈现显著正相关性,但整体而言,Hg由土壤→稻根以及稻根→稻米的富集/迁移系数较低,移动性弱。矿区稻米Hg平均含量为0.09±0.04μg/g,与国家粮食卫生标准(GB2762–2005)的限值(0.02μg/g)相比,超标达4.5倍。当地居民终生平均每天摄入的Hg量为0.75μg/(kg.d),超过WHO推荐的可耐受剂量[0.71μg/(kg.d)],面临较大的健康风险。对矿区中多种元素研究发现,稻米中Hg、Pb、Se共同富集,其复合污染机制的研究亟待开展。
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.
[1] Horvat M,Nolde N,Fajon V.Total mercury,methylmercury and selenium in mercury polluted areas in the province Guizhou,China.Science of the Total Environment,2003,304:231～256.
[2] 杨林生,王五一,谭见安,等。环境地理与人类健康研究成果与展望。地理研究,2010,29(9):1571～1583.
[3] 邹晓锦,仇荣亮,周小勇,等。蔬菜重金属暴露接触对大宝山矿区及周边居民的健康风险。地理研究,2008,27 (4):855～862.
[4] 李晓燕,陈同斌,谭勇壁,等。北京市小麦籽粒的重金属含量及其健康风险分析。地理研究,2008,27(6):1340～1346.
[5] Cui Y L,ZhuY G,Zhai R H,et al.Transfer of metals from soil to vegetables in an area near a smelter in Nanning, China.Environment International,2004,30:785～791.
[6] 郑娜,王启超,郑冬梅。锌冶炼厂周围重金属在土壤-蔬菜系统中的迁移特征。环境科学,2007,28(6):1349～1354.
[7] Wang G,Su M,Chen Y,et al.Transfer characteristics of cadmium and lead from soil to the edible parts of six vegetable species in southeastem China.Environmental Pollution,2006,144:127～135.
[8] 谭红,何绵林,梁琏。中国贵州大气汞的沉降。贵州科学,2002,18(1):34～42.
[9] 李永华,王丽珍,王五一,等。HG-ICP-AES法测定多金属矿区人发中的汞和砷。光谱学与光谱分析,2007,27 (4):789～791.
[10] 仇广乐。贵州典型汞矿区汞的地球化学研究。北京:中国科学院研究生院博士学位论文,2005.96～99.
[11] Rauret G,López-Sánchez J F,Sahuquillo A,et al.Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials.Journal of Environmental Monitor, 1999,1:57～61.
[12] 李永华,杨林生,李海蓉,等。湘黔汞矿区土壤汞的化学形态及污染特征。环境科学,2007,28(3):645～648.
[13] Li Y H,Wang W Y,Luo K L,et al.Environmenta behaviors of selenium in soil of typical selenosis area,China. Journal of Environmental Sciences,2008,20:859～864.
[14] 王丽珍。高频感耦等离子体发射光谱法测定毛发、粮食中多种元素。分析化学,1989,17(9):847～850.
[15] USEPA.Risk assessment guidance for superfund:Volume I,Human health evaluation manual.EPA/540/1-89/ 002.Washington DC,1989.
[16] Sun H F,Li Y H,Ji Y F,et al.Environmental contamination and health hazard of lead/cadmium around the Chatain mercury mining area,western Hunan Province,China.Transactions of Nonferrous Metals Society of China, 2010,20(2):308～314.
[17] WHO(World Health Organization).Inorganic mercury.Environmental health criteria 118.IPCS,International Programme on Chemical Safety.Geneva,1991.
[18] 潘佑尼,杨园治。湖南省土壤背景值及研究方法。北京:中国环境科学出版社,1988.238～268.
[19] 李永华。湘西多金属矿区汞铅的环境行为及健康效应。北京:中国科学院地理科学与资源研究所博士后研究工 作报告,2004.48～71.
[20] 余贵芬,吴泓涛,蒋新,等。腐殖酸结合汞对多年生植物(Citrus Sinensis L.Osbeck)的生物有效性初探。土壤,2006,38(4):435～440.
[21] Zheng N,Wang Q,Zheng D,et al.Mercury contamination and health risk to crops around the zinc smelting plant in Huludao City,northeastern China.Environmental Geochemistry and Health,2007,29:357～455.
[22] 李永华,王五一,杨林生,等。湘西多金属矿区汞铅污染土壤的环境质量。环境科学,2005,26(5):187～191.
[23] 鲍振襄,鲍珏敏。湘西-黔东汞矿带硒的赋存特征。有色金属矿产与勘查,1995,4(1):30～34.
[24] 杜式华,于志洁。汞与硒在植物中的相互作用。环境科学,1987,8(6):43～46.
[25] Shanker K,Mishra S,Srivastava S,et al.Study of mercury-selenium(Hg-Se)interactions and their impact on Hg uptake by the radish(Raphanus sativus)plant.Food and Chemical Toxicology,1996,34:883～886.
