中国煤中汞的环境地球化学研究

在测试分析中国7个省62个煤样品中汞的含量基础上,结合已有1 637个中国煤样品中汞的数据,全面探讨了中国煤中汞的环境地球化学特征.并采用逐级化学提取实验和相关分析方法,分析和研究了中国煤中汞的化学赋存状态.分析结果表明:中国煤中汞的含量一般为0.1~0.3mg/kg,平均0.19 mg/kg,接近于美国的平均值(0.17 mg/kg),高于世界的平均值(0.10 mg/kg);汞在不同地区、不同成煤时代以及不同煤类中分布极不均匀;其赋存状态也多种多样,高硫煤中汞与硫化物关系密切,主要赋存在黄铁矿中;低硫煤中,硫化物结合态和有机结合态汞常共同占支配地位;影响汞分布和赋存状态的主要原因是地质因素.实验结果表明,在岩浆侵入的煤层中,汞大多以硅酸盐结合态存在.煤中汞的赋存状态与煤中汞的释放、毒性有着重要的关系.同时燃煤释放的汞已对中国部分地区的环境造成了污染,控制燃煤过程中汞的排放是今后研究的重要内容之一.

Study on environmental geochemistry of mercury in Chinese coals

62 coal samples were collected from coal fields in 7 provinces.The contents of Hg from 1 699 coal samples were analyzed,and the sequential extraction tests were carried out for 29 coal samples.The concentration,distribution,mode of occurrences and impact factors of Hg in Chinese coals were studied.The environmental impacts and typical features of Hg were also discussed.It is concluded that most Hg values in Chinese coals range from 0.1 to 0.3 mg/kg,averaging 0.19 mg/kg,which is slightly higher than the average value of the world coals(0.10 mg/kg) and close to that in the U.S.coals(0.17 mg/kg).In coals from Southwestern China,the content of Hg is the highest and many people may have been affected due to coal combustion.Most likely modes of occurrences of Hg in high-sulfur and high-Hg coals are in solid solution in pyrite.But in low-sulfur coals,the modes of occurrences of Hg are more variable,and organic-bound Hg may dominate.Geological factors may influence Hg forms in some coals and the silicate-bound Hg may be the main form in some coals because of magmatic intrusion.Hg emissions during coal combustion have resulted in serious environmental contamination in China,particularly in the Northeast and Southwest,where high concentrations of Hg occur in the atmosphere.