石笋稀土元素含量的两种溶样方法测试结果对比分析

对于采自川东北诺水河溶洞群的石笋SJ3,采用2%的HNO3和HF+HNO3两种溶样方法分析测试了其稀土元素(REE)含量。结果表明:虽然多数石笋中存在碎屑物质,SJ3的少数样品在采用2%的HNO3溶解后有明显的残留物存在,但采用HF+HNO3全部溶解样品得到的SJ3的REE含量与采用稀HNO3溶样得到的结果并没有显著的差别。这表明SJ3的REE可能主要不是直接来自于地表土壤中难溶的硅酸盐矿物,而可能是土壤风化释放的REE通过吸附在颗粒/胶体态物质的表面,经过岩溶地下水的搬运而沉积到SJ3中。由此认为,采用稀酸溶样基本上可以将石笋SJ3的REE释放出来。 

Rare earth element contents in speleothem determined by two dissolution methods

Rare earth elements (REE) in stalagmite SJ3 collected from NE Sichuan in central China were determined by two dissolving methods, one by 2% HNO3 and the other by a mixture of HF and HNO3. The results indicate that although detrital materials are common in speleothems, a complete dissolution of the calcite powder from SJ3 by HF + HNO3 does not significantly enhance the REE concentrations obtained. This suggests that REEs in SJ3 are not contained in resistant silicate minerals which may not be derived from the overlying soil layer directly. The REEs in SJ3 may be released from the soil under chemical weathering, adsorbed on the surfaces of colloidal and particle materials in karst groundwater and incorporated into SJ3. The results indicated that REE in SJ3 can be released with diluted acids.