【作者】 闫丽娜；

【导师】 李胜荣；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2009， 硕士

【摘要】 鱼耳石因为具有生物惰性而成为环境信息的良好载体,可以客观记录水体环境的历史变迁及低浓度污染物的富集。目前,国内外开展利用鱼耳石进行湖泊的水质评价及动态监测研究主要基于对水体及耳石进行微化学分析,另外,寻找各类简洁灵敏的标型特征证实鱼耳石与水体水质存在一定的耦合关系也非常必要。本文将水质环境差异较大的白洋淀和密云水库两个研究区的鲤鱼耳石作为研究对象,首次将X射线断层扫描技术(CT)及Micro-CT技术运用到鲤鱼耳石对水环境中重金属元素的响应关系研究中,同时利用XRD、SEM、LA-ICP-MS等技术对鲤鱼耳石进行了物相、结构、形貌及富集元素的研究,扫描电镜下作者清楚地观察到了矢耳石日轮以及年轮界线;微区XRD实验显示两地鲤鱼耳石矿物种和晶体结构未见整体性差异,但晶胞参数略有差异,白洋淀水域晶胞参数出现明显畸变倾向,微耳石的晶胞参数a普遍比标准晶胞参数a小,矢耳石的晶胞参数a也普遍比标准晶胞参数a小,而晶胞参数b、c普遍比标准晶胞参数大,密云水库耳石晶胞参数在标准晶胞参数附近波动,无明显规律;LA-ICP-MS分析结果显示白洋淀水域耳石中的Cu和Pb含量大于密云水库相应元素的含量,密云水库耳石中的常量元素Mg含量高于白洋淀水域耳石中Mg的含量; Micro-CT实验数据统计表明白洋淀水域鲤鱼耳石的Micro-CT值高于密云水库鲤鱼耳石的Micro-CT值。对以上实验结果与数据综合分析表明:研究区水质状况基本不会影响耳石中碳酸钙晶型的选择,但对晶胞参数略有影响,常量元素Mg、Ba及重金属元素Cu和Pb等共同导致了碳酸钙晶胞参数畸变。重金属元素Cu和Pb的富集程度是导致两研究区水域Micro-CT值差异的主要原因。原子序数大的Cu和Pb元素在白洋淀水域鲤鱼耳石中含量较高,直接导致了高密度体素的产生,当X射线入射过程中与Cu和Pb元素碰撞,由于Cu和Pb的原子系数大,其电子结合能高,密度高,原子结构最紧密,X射线可以被大量吸收,即对X射线的吸收系数大,进而导致Micro-CT值高。综上,利用Micro-CT实验数据统计对比可以反映出鲤鱼耳石中原子序数大的重金属元素信息。耳石中的元素与水体元素具有相似的分布趋势,且对水体中相应元素有明显的富集作用。因此,鲤鱼耳石Micro-CT特征与水环境中重金属元素存在一定的耦合关系,可作为标型特征指示水体中重金属元素信息。更多还原

【Abstract】 Otolith becomes a good environmental information carrier because of the biological inertia, and can objectively record the historical changes in the water environment and the enrichment of low concentrations of pollutants. At present, the research which otolith is used for the water quality evaluation and dynamic monitoring of lakes is mainly based on the micro-chemical analysis of the water body and otolith at home and abroad. It is necessary to find out some simple and sensitive typomorphic characters which can confirm there are some coupling relationship between otolith and the water quality.This paper studies carp otolith from the Baiyangdian and the Miyun Reservoir whose water quality are different. X-ray tomography (CT) and Micro-CT technology are first applied to the study of the response relationship between carp otolith and the heavy metals in the water, while XRD, SEM, LA-ICP-MS techniques have been used to the study of otolith phase, structure, morphology and elemental enrichment. The author clearly observe daily growth rings and the growth ring boundary of sagittae under SEM; Micro-area XRD showed there is no overall difference in mineral species and crystal structure of otolith from the different waters, but there is a slightly different about lattice parameters, lattice parameters a of the lapillus is smaller than the standard lattice parameters in the Baiyangdian, while lattice parameters c of the sagittae is bigger than the standard lattice parameters; LA-ICP-MS analysis revealed that the contents of Cu and Pb of otoliths in Baiyangdian are higher than the contents of corresponding elements of otoliths in Miyun reservoir, the content of Mg of otoliths in Miyun reservoir is higher than the content of otoliths in the Baiyangdian; Micro-CT experimental data shows that the Micro-CT value of otolith from the Baiyangdian is higher than that r from the Miyun Reservoir.Comprehensive analysis shows that: the water quality will not affect polymorph of calcium carbonate in otolith basically, but a slight impact on lattice parameters, Mg and the heavy metals Cu and Pb led to aberration of lattice parameters of calcium carbonate. The contents of Cu and Pb is the main factor to the the difference of Micro-CT value of otolith from different waters. The contents of Cu and Pb which have a high atomic number are higher in otolith from the Baiyangdian waters, resulting of the high density voxels. Cu and Pb have the characters: high atomic number, high electronic binding energy ,high density and the atomic structure is tightness .The X-ray collides with Cu and Pb and can be absorbed largely when the X-ray irradiate the otolith, which led to large absorption coefficient and the high value of Micro-CT. To sum up, information on heavy metals with high atomic number in the carp otolith can be reflected by statistical comparison of Micro-CT data. Elements in otoliths have the similar distribution trend with elements of the waters and can be obviously enriched. Therefore, there is the coupling relationship between Micro-CT character of carp otolith and the heavy metals in waters, which can be used to direct the information of the heavy metals in waters as typomorphic character.更多还原