NSF RIDGE 2000 Postdoctoral Fellowship: Development of Raman spectroscopy for in situ quantification and speciation of hydrothermal Fe and Mn particulates and sediments

怀特(0550331)的智慧价值还原的铁和锰的热液通量对全球海水化学和化学合成喷口生物学具有重要的意义。富铁、富锰的热液与海水混合时，多金属硫化物沉淀，海水中的痕量元素被清除到铁、锰氧化物上。这些过程很重要，因为每升喷发的热液都夹带着大约10,000升深海海水。因此，相当于整个海洋体积的物质在时间尺度上与多金属硫化物和铁-锰氧化物发生共沉淀反应，其时间尺度与全球温盐环流相似。除了它们作为化学清除剂的作用外，Fe(II)和Mn(II)的氧化都是水柱和海底化学合成微生物群落的重要能源。这项研究的目的是发展激光拉曼光谱作为一种手段，以测量从海底发出的带电热液喷口流体的原位化学形态。这项工作包括仪器工程努力和地面真实的技术与实验室实验。所有实验都将使用实验室模型激光拉曼光谱仪，带有远程探头和显微镜附件。将使用300摄氏度和400巴的高低温/高压光学元件来模拟深海热液条件。热液沉积物和羽流颗粒将用X射线衍射和X射线荧光光谱进行矿物学表征，然后用作实验室的天然矿物组合。更广泛的影响这项研究为早期职业女性科学家和马萨诸塞州伍兹霍尔海洋研究所的博士后培训提供了研究支持。这项工作将开发用于热液喷口研究的重要金属物种的新的原位化学传感器。由此产生的仪器将是对任何长期大洋中脊观测站的明显补充，并可以进行修改，以向研究人员和公众传播现场化学数据。为了向公众、学生和更广泛的海洋学界传播信息，将扩大一个关于化学传感器工作的网站，增加一个关于拉曼光谱仪器和热液喷口应用的网站。

White (0550331)Intellectual Merit The hydrothermal flux of reduced Fe and Mn has important implications for global seawater chemistry and chemosynthetic vent biology. When Fe and Mn enriched hydrothermal fluid mixes with seawater, polymetallic sulfides precipitate and seawater trace elements are scavenged onto Fe and Mn oxyhydroxides. These processes are important because approximately 10,000 liters of deep-ocean seawater are entrained with every liter of venting hydrothermal fluid. Thus, the equivalent of the entire ocean volume is exposed to co-precipitation reactions with polymetallic sulfides and Fe-Mn oxyhydroxides on timescales that are similar to global thermohaline circulation. In addition to their role as chemical scavengers, the oxidation of both Fe(II) and Mn(II) are important energy sources for chemosynthetic microbial communitiesin the water column as well as at the seafloor. This research aims to develop Laser Raman spectroscopy as a means to measure the in situ chemical speciation of metal-charged hydrothermal vent fluids emanating from the seafloor. The work involves an instrument engineering effort and ground truthing the technique with laboratory experiments. All experiments will use a laboratory model laser Raman spectrometer with a remote probe head and microscope attachment. High and low temperature/ high-pressure optical cells capable of 300 C and 400 bar will be used to simulate deep-sea hydrothermal conditions. Hydrothermal sediments and plume particulates will be mineralogically characterized using X-ray diffraction and X-ray fluorescence spectrometry and then used as natural mineral assemblages for the laboratory. Broader Impacts This research provides research support for a early career female scientist and training of a postdoc at the Woods Hole Oceanographic Institution in Massachusetts. The work will develop new in situ chemical sensors of important metal species for hydrothermal vent studies. The resulting instrument would be an obvious addition to any long-term mid-ocean ridge observatory and could be modified to broadcast in situ chemical data to researchers and the public alike. To disseminate information to the public, students, and the greater oceanographic community, a website on the Chemical Sensor work will be augmented to include one on Raman spectroscopy instrumentation and hydrothermal vent applications.