Experimental calibration of stable isotope and REE partitioning in bioapatite

技术说明：生物磷酸钙（生物磷灰石）的地球化学被广泛用于古气候学、古生态学、古海洋学、人类学/考古学、化石法医学、地质年代学和龋齿研究。许多这样的努力是妥协的结构碳酸盐（CO 3）的氧和碳的稳定同位素的分馏，和生物磷灰石和水溶液之间的稀土元素（REE）的分区的认识不足。稳定同位素分馏和稀土元素分配系数将通过在10至60 °C的温度下在同位素和化学特征溶液中合成生物磷灰石来测量。特别强调将被放置在确定的晶体学网站的CO 3替代作为控制同位素分馏，校准牙齿化学的光谱测量，并表征颗粒大小和表面积，以区分晶内与吸附分配系数的REE。将进行时间序列实验，以确保接近平衡，并将复制过去的实验方法，以改进粒度表征，并与新的化学和同位素数据进行比较。非技术/更广泛的影响：该赠款资助生物磷灰石的地球化学行为的全面校准-构成骨骼和牙齿的矿物。这项工作对于验证过去的研究和改进从古气候学和古海洋学到人类学、化石的法医鉴别、地质年代学和可能的牙齿稳定性等众多领域的定量解释非常重要。具体来说，我们将校准方法，以确定生物磷灰石的碳酸盐（CO 3）含量，这强烈控制牙釉质溶解度，并合成具有不同CO 3含量的生物磷灰石。生物磷灰石积累镧系元素以及氧和碳的重同位素的趋势将被校准，并与以前的稀疏测量进行比较。这些数据将为过去对现代牙齿和化石地球化学的解释提供信息，并提高未来涉及现代牙齿和化石牙齿的研究的针对性。教育推广包括为研究生提供研究培训，以及为代表性不足的群体开展本科生研究。其他培训包括为一名年轻的女研究科学家培养指导技能。博伊西州立大学为大部分归国和兼职学生提供服务，本科生平均年龄为27岁。因此，研究和教育活动影响的人口与大多数其他大学不同。

Technical description:The geochemistry of biogenic calcium phosphate (bioapatite) is widely used in studies of paleoclimatology, paleoecology, paleoceanography, anthropology/archeology, fossil forensics, geochronology, and tooth caries. Many such endeavors are compromised by poor understanding of the fractionation of stable isotopes of oxygen and carbon in structural carbonate (CO3), and partitioning of rare-earth elements (REE) between bioapatite and aqueous solutions. Stable isotope fractionations and REE partition coefficients will be measured by synthesizing bioapatite in isotopically- and chemically- characterized solutions at temperatures ranging from 10 to 60 °C. Particular emphasis will be placed on identifying the crystallographic site of CO3 substitution as a control on isotope fractionations, calibrating spectroscopic measurements of tooth chemistry, and characterizing particle sizes and surface areas to distinguish intracrystalline vs. adsorption partition coefficients for REE. Time-series experiments will be conducted to ensure close approach to equilibrium, and past experimental methods will be reproduced for improved particle size characterization and comparison to new chemical and isotopic data. Non-technical/Broader impacts:This grant funds a comprehensive calibration of the geochemical behavior of bioapatite - the mineral that constitutes bones and teeth. This work is important for validating past research and improving quantitative interpretations in numerous fields ranging from paleoclimate and paleoceanography to anthropology, forensic discrimination of fossils, geochronology and possibly dental stability. Specifically, we will calibrate methods to determine the carbonate (CO3) content of bioapatite, which strongly controls tooth enamel solubility, and synthesize bioapatites with different CO3 contents. The tendency for bioapatite to accumulate lanthanide-group elements and the heavy isotopes of oxygen and carbon will be calibrated and compared with sparse previous measurements. These data will inform past interpretations of modern tooth and fossil geochemistry and improve targeting of future studies involving modern and fossil teeth. Educational outreach includes research training for a graduate student, and development of undergraduate research for underrepresented groups. Additional training includes development of mentorship skills for a young female research scientist. Boise State serves a large proportion of returning and part-time students with an average undergraduate age of 27. Thus, research and education activities impact a different demographic than at most other universities.