XRF和ICP-MS测定风成沉积铜镍锌等9种重金属元素的对比分析

Comparative study of nine trace elements including copper, niccolum and zinc in eolian deposits analyzed by XRF and ICP-MSZeng Fangming1, Xie Luhua2

中文关键词:  微量元素  XRF  风成沉积  黄土高原  青藏高原东北

英文关键词:trace element  X-ray fluorescence  eolian deposits  Chinese Loess Plateau  northeastern Qinghai-Tibetan Plateau

中文摘要:

      风成沉积的某些微量元素(如Rb、Sr)对过去的气候环境变化具有明确的指示意义,因此需要准确、快速地测定其含量。目前,测定微量元素的含量主要有XRF(X射线荧光光谱)和ICP-MS(电感耦合等离子体质谱)方法。我们对四个风成沉积剖面(黄土高原西峰剖面,青藏高原东北部种羊场剖面、泉吉河剖面、依毛剖面)247件样品进行了XRF和ICP-MS分析,并对其中9种微量元素的含量进行了初步对比分析。结果表明：(1)Cu、Ni、Zn的XRF测试结果和ICP-MS测试结果具有很好的一致性(Pearson相关系数r大于0.84)。(2)Co、Pb的XRF测试结果和ICP-MS测试结果在大多数剖面中具有较好的一致性,但在个别剖面中的一致性较差。(3)在种羊场和泉吉河剖面中,Th的XRF测试结果比ICP-MS的测试结果略低。两种方法测得的As的含量在四个剖面中随深度的变化趋势高度一致；As的XRF测试结果明显比ICP-MS的测试结果低,差值可达11.5 μg/g(变化幅度达214%)。(4)Cr和Tl的XRF测试结果高于ICP-MS的测试结果,两种方法测得的Cr含量的差值达40 μg/g。尽管ICP-MS法具有比XRF法更高的精度,但对于Cu、Ni、Zn,采用高效廉价的XRF法能得到与ICP-MS法相媲美的测试结果。(5)西峰、种羊场剖面采用XRF法测得的Cu、Ni、Zn、As含量与磁化率呈现相似的变化,表明这些元素亦可指示风成沉积记录的气候环境变化。

英文摘要:

      Some trace elements (such as Rb and Sr) in eolian deposits preserve a lot of information about the climatic change and chemical weathering history, which are of great significance for reconstructing the past climatic and environmental changes. Thus, accurate and rapid determination of the trace element contents in eolian deposits is essential for studying the above questions. To date, XRF (X-ray fluorescence spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry) methods are mainly utilized to determine the content of trace elements in eolian deposits. However, the comparative analysis of the trace elements in the same eolian deposit samples analyzed by the above two methods is still scarce. Here we conducted XRF and ICP-MS analyses on 247 samples of four typical eolian-deposit sections on the central Chinese Loess Plateau (XF section) and the northeastern Qinghai-Tibetan Plateau (ZYC section, QJH section, and YM section). The contents of nine trace elements including copper, niccolum and zinc were compared and discussed. The preliminary results show that: (1) Results of Cu, Ni, and Zn analyzed by both XRF and ICP-MS methods are of good consistency, and the variations of Cu, Ni and Zn contents measured by both methods varying with the depth of the section are highly consistent (Pearson’s correlation coefficient r is greater than 0.84). (2) Variations of Co and Pb analyzed by both methods are consistent in most studied sections, but there are inconsistencies in some sections. (3) In the ZYC and QJH sections, Th contents determined by the XRF are slightly lower than those tested by the ICP-MS method. The trend variations of arsenic (As) contents in four studied sections analyzed by both methods are highly consistent. Contents of As tested by the XRF method are significantly lower than those tested by the ICP-MS method, and the difference is up to about 11.5 μg/g, with changing amplitude of about 214%. (4) Cr and Tl contents tested by the XRF method are higher than those determined by the ICP-MS method; the difference of Cr content measured by the two methods can reach about 40 μg/g. According to the above analysis results, and due to the higher precision of the ICP-MS method than the XRF method, the ICP-MS method can be used to obtain more accurate results. However, for Cu, Ni, and Zn, the efficient and cheap XRF method can replace the ICP-MS method to obtain high-quality data. (5) The variations of Cu, Ni, Zn, As tested by the XRF method are similar to those of magnetic susceptibility in the XF section and ZYC section, indicating that concentrations of these elements can also indicate the climatic and environmental changes preserved in eolian deposits.