Calibrating Diatom Oxygen Isotopes for Paleoceanographic Applications Using a Novel Technique

硅藻测试中硅酸盐的氧同位素组成（δ 18 O）具有提供关键古海洋学信息的潜力，但由于难以将其分离用于地球化学分析而未得到充分利用。这项工作将完善和应用一种新技术（“微生物学”），有可能使硅藻中的d18 O成为一种更常规的测量方法。将进行一系列实验，以提高该技术的效率，减少分析所需的样本量。然后，该技术将被应用到培养的海洋和淡水硅藻，以校准硅藻δ 18 O和温度之间的替代关系。最后，将分析从瓜伊马斯盆地收集的沉积物捕集器和盒式岩芯中的硅藻，以a）限制生物矿化深度，B）比较硅藻和有孔虫之间的氧同位素数据，以及c）评估成岩作用对硅藻δ 18 O数据的影响。发展微生物学技术和硅藻δ 18 O-温度替代关系将使科学家能够利用一个重要的、未充分利用的海洋气候动态信息来源。该项目将支持博士生，并为PI实验室的本科生和未来的博士后研究人员提供最先进技术的培训机会。项目成果将纳入研究生课程。这项研究将通过与英国和德国的研究人员合作加强国际联系。

The oxygen isotopic composition (delta18O) of silicate in diatom tests has the potential to deliver key paleoceanographic information, but is underutilized because of the difficulty associated with isolating it for geochemical analysis. This work will refine and apply a new technique ("microfluorination") that has the potential to make d18O in diatoms a more routine measurement. A suite of experiments will be conducted to improve the efficiency of the technique and reduce the sample size required for analysis. The technique will then be applied to cultured marine and freshwater diatoms in order to calibrate the proxy relationship between diatom delta18O and temperature. Finally, diatoms from a sediment trap and boxcore collected in the Guaymas Basin will be analyzed to a) constrain biomineralization depth, b) compare oxygen isotope data between diatoms and foraminifera, and c) assess diagenetic effects on diatom delta18O data. Developing the microfluorination technique and the diatom delta18O-temperature proxy relationship will enable scientists to tap an important, underexploited source of information about ocean-climate dynamics. The project will support a PhD student and provide training opportunities in a state-of-the-art technique for undergraduate students and future post-doctoral researchers in the PI's lab. Project results will be incorporated into graduate coursework. This research will strengthen international ties via collaboration with investigators in the UK and Germany.