中文摘要：

云贵川交界区农村流行地氟病且曾以＂土＂拌煤作为生活燃料的现象普遍,煤系地层广泛出露且前人观察指出当地拌煤＂土＂常取自煤系地层风化土.本文以采自该区7个县域的71件煤系地层出露风化土为样本进行研究,结果表明,52%的风化土呈酸性,pH均值为4.62（2.39—5.54,n=37）;硫酸根含量显著偏高,均值达到1778μg·g^-1（295—13086μg·g^-1,n=71）;氟含量总体偏高,均值达到751μg·g^-1（237—1764μg·g^-1,n=71）.酸性风化土的pH与其硫酸根含量的负对数-lg C[SO2-4]成正相关（r=0.75）,表明风化土中酸的存在形式可能为酸性硫酸盐如KHSO4或Na HSO4,而后者可能源自煤系地层中黄铁矿的风化.在一定条件下（燃烧）,风化土内部的酸与氟在燃烧条件下的相互作用可能导致氟化氢释放,且风化土中氟与高硫煤在燃烧条件下相互作用可能加剧氟化氢释放.

英文摘要：

It is an universal phenomenon that clay is used for coal-burning in fluorosis areas in the border of Yunnan,Guizhou and Sichuan,where coal-bearing strata is widely outcropped,and clay for coal-burning is usually considered to be collected from efflorescent clay in coal-bearing strata by some scholars. About 71 samples of efflorescent clay of coal-bearing strata were collected from seven counties in this area and the results confirms that 52% of efflorescent clay was acidic,and the average pH was 4.62（ 2.39—5.54,n = 37）; the content of sulfate was very high,with an average of1778 μg·g^-1（ 295—13068 μg·g^-1,n = 71）; The fluorine content of efflorescent clay was high as a whole,with an average of 751 μg·g^-1（ 237—1764 μg·g^-1,n = 71）. The pH value of the efflorescent clay was positively correlated with the-lg C[SO2-4]（ r = 0.75）,which indicated that the acid may exist in the form of acidic sulfate such as KHSO4 or Na HSO4. Under certain conditions（ combustion）,the interaction between fluorine and acidity in the efflorescent clay may result in the release of hydrogen fluoride under combustion,and the interaction between fluorine and high sulfurcoal may intensify the release of hydrogen fluoride in clay under combustion.