Development of a new method for the analysis of individual biological history of the aquatic creatures using synchrotron radiation X-ray fluorescence imaging

经过三年的研究，取得了以下成果：1.样品制备：建立了同步辐射X射线荧光微探针分析的样品制备方法。对于鱼耳石标本，采用矢状面和30 μ m厚的耳石芯进行分析比较合适。2.指纹图谱元素的研究：ICP-AES分析了不同来源的鱼类耳石，发现其含有Sr、Zn、Fe、Mg、Mn和Al等微量元素，其中Sr最适合作为环境水体盐度变化的指示剂。3.同步辐射的应用：利用同步辐射X射线荧光微探针研究了Ca、Sr和Fe的二维分布。测量是在高能加速器研究组织光子工厂进行的。样品由Si（111）双晶单色器产生的17 keV X射线激发。在束径约100 × 100 μ m ~ 2、计数时间10秒/步的条件下，用X射线微束成功地进行了微量元素如铁（平均约100 ppm）的二维分析。因此，我们建立了X射线荧光成像技术作为一个新的重要工具，表征微量元素的耳石。4.仪器：我们已经开发了一种新的X射线荧光成像系统，用于常规分析的微量元素在硬组织中使用常规的实验室X射线源。该系统利用由弯曲石墨单色仪获得的单色Mo Ka X射线，这使我们能够进行高灵敏度的分析。5.方法的验证：为了验证本文开发的方法，分析了淡水鳗鱼，马苏鲑鱼和灯笼鱼的耳石。结果表明，该方法能够很好地反映个体的迁徙历史，从而充分验证了该方法的有效性。

After the investigation for three years, the following results have been obtained.1.Sample Preparation : Methods of sample preparation for synchrotron radiation X-ray fluorescence microprobe analysis was developed. For the fish otolith preparation, sagaital plane with otolith core of 30mum thick was revealed to be suitable for the analysis.2.Investigation of finger-print elements : ICP-AES analysis of otoliths of various fishes of different origin disclosed that they contain Sr, Zn, Fe, Mg, Mn and Al as trace components, among which Sr is found to be most suitable for the indicator of the salinity change of their environmental water.3.Application of Synchrotron Radiation : Two-dimensional distributions of Ca, Sr and Fe were clarified by synchrotron radiation X-ray fluorescence microprobe. Measurements were made at Photon Factory, High Energy Accelerator Research Organization. Samples were excited by an X-ray of 17 keV generated by a Si (111) double-crystal monochromator. Two dimensional analysis of trace elemenls such as iron (average : around 100 ppm) was successfully carried out by using X-ray microbeam under the following condition : beam size, ca 100x1OO um2 and counting time of 10sec/step. Thus we have established the XRF imaging technique as a new important tool for characterization of the trace elements in the otoliths.4.Instrumentation : We have developed a new X-ray fluorescence imaging system for routine analysis of the trace elements in the hard tissues by using conventional laboratory X-ray source. This system utilizes monochromatic Mo Ka X-ray obtained by a curved Graphite monochoromator, which enables us to carry out high sensitivity analysis.5.Validation of the methods : To verify the method developed here, otoliths of the freshwater eel, masu salmon and lantern fish were analyzed. As the results, the individual migratory history was well demonstrated and thus, we conclude this method was sufficiently verified.