烟煤和无烟煤中碘的赋存形态及其环境效应分析

采用逐级化学提取和电感耦合等离子体质谱(ICP-MS)研究烟煤和无烟煤中碘的赋存形态。结果表明,烟煤和无烟煤中各种形态的碘含量由高到低依次都是有机态、铁锰氧化物结合态、水溶态、残留态、离子交换态和碳酸盐结合态。烟煤和无烟煤中有机结合态碘平均含量分别为47.4%±3.28%和43.3%±2.42%,Fe-Mn氧化物结合态碘分别为36.8%±3.70%和34.6%±4.77%,水溶态和离子交换态碘平均含量之和分别为10.3%±3.00%和14.3%±3.37%,碘的平均潜在淋失率分别10.9%和16.0%,平均潜在可淋失浓度分别为0.9μg/g和1.2μg/g。这说明无烟煤中生物有效态碘含量高于烟煤,在表生条件下烟煤和无烟煤中淋出的碘都能导致地表水中碘的浓度升高;无烟煤中碘的有利环境效应大于烟煤,而不良环境效应小于烟煤。

Modes of iodine occurrence in bituminous coal and anthracite and their environmental effects

Modes of iodine occurrence in bituminous coal and anthracite were investigated by using inductively coupled plasma mass spectrometry(ICP-MS) and sequential chemical extraction.The results showed that iodine in both these coals occurs in a descending order of organic,bound with Fe-Mn oxide,water-soluble,residue,ion exchangeable,and the fraction bound to carbonate.In bituminous coal and anthracite,the mean relative content values are 47.4%±3.28% and 43.3%±2.42% for iodine bound to organic matter,36.8%±3.70% and 34.6%±4.77% for the iodine bound to Fe-Mn oxides,respectively;the amounts of water soluble and ion exchangeable iodine are 10.3%±3.00% and 14.3%±3.37%,respectively;the potential leachable rates of iodine are 10.9% and 16.0%,and potential leachable iodine contents 0.9 μg/g and 1.2 μg/g,respectively.These results suggested that iodine leaching from both these coals can lead to an increase of iodine concentration in surface water at the supergene conditions;the effect of iodine in anthracite is more environmentally favorable than that in bituminous coal.