激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)法测定底栖有孔虫中的元素/钙比值

Determination of Element/Calcium Ratio in Benthic Foraminifera by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry(LA-ICP-MS)

有孔虫中的微量元素/钙比值是反演古海洋环境和指示现代海洋污染的有效指标。为实现对现代底栖有孔虫进行高效准确的原位分析,建立了基于激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)法测定现代底栖有孔虫元素/钙比值的分析方法。经优化激光能量密度为5 J/cm^(2)、剥蚀斑径为44μm、剥蚀频率为5 Hz、载气流速为0.75 L/min,对每个有孔虫骨架中心部分随机测试7点后取平均值,获得了两种有孔虫样品的元素/钙比值的测试结果,与已发表研究结果吻合良好。对单个有孔虫腔室和隔膜线的元素/钙比值进行了均一性评价与探讨,结果表明,Mg、P、Mn、Na、Sr、B元素可作为单个有孔虫研究的特征元素。对2种典型的现代底栖有孔虫进行了主成分分析,初步实现了基于LA-ICP-MS元素分析的两种种属有孔虫之间的聚类分区,进一步验证了骨架选点法对于有孔虫含量分析比对及聚类分析的可靠性。方法经优化后绿色、高效,可为相关古生物分析研究提供参考。

Trace element/calcium ratio in benthic foraminiferal shells is an effective index for inversion of ancient marine environment and indication of modern marine pollution.To achieve efficient and accurate in-situ analysis of modern benthic foraminifera,an analytical method based on laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)was established to determine the element/calcium ratio of modern benthic foraminifera.After optimization,Under the conditions of laser energy density of 5 J/cm^(2),spot diameter of 44μm,frequency of 5 Hz and He carrier gas flow rate of 0.75 L/min,7 points in the central part of each foraminifera skeleton were randomly tested and then averaged.element/calcium ratios of two foraminifera samples were obtained,which were in good agreement with published research results.The element/calcium ratio in the chamber and diaphragm line of single foraminifera was evaluated and discussed.The results showed that Mg,P,Mn,Na,Sr and B could be used as the characteristic elements for the study of single benthic foraminifera.On this basis,the principal component analysis of two typical modern benthic foraminifera was carried out,and the clustering partition between two genera of foraminifera based on LA-ICP-MS element analysis was preliminarily realized,which further verified the reliability of the skeleton selection method for the comparison of foraminifera content analysis and clustering analysis.The optimized method is green and efficient,which can provide supporting technology for related paleontology analysis and research.