Development of a Laser Spectroscopy System for Analysis of 17Oexcess on Ice Cores

该奖项支持一个为期两年的项目，该项目旨在开发一种快速精确测量水中18O/16O和17O/16O同位素比值差异的方法，称为17O过量。17o过量测量是地球化学领域的最新创新，是对传统氢（D/H）和氧（18O/16O）比值测量的补充。17O/16O的常规测量数量有限，因为分析耗时费力，其中涉及通过氟化将水转化为氧，然后进行高精度质谱分析。该项目将使用一种新的空腔衰荡光谱（CRDS）系统，该系统是由华盛顿大学和Picarro公司（加利福尼亚州圣克Clara）以及冰与气候中心（哥本哈根尼尔斯玻尔研究所）共同开发的。本研究的主要知识价值是改进了CRDS方法，用于测量170个额外的离散水样品，以获得与使用质谱的传统方法相竞争的精度和准确性。这将通过量化水蒸气浓度变异性和仪器记忆的影响，根据标准水对仪器进行精确校准，以及改进光谱分析来实现。与科罗拉多大学博尔德分校合作，CRDS系统还将与用于冰芯分析的连续流系统相结合。目标是在2015-2017年，为美国主导的下一个南极冰芯项目提供一个可用于冰芯处理的操作系统。这项研究更广泛的影响包括能够测量大气中过量的17o水蒸气，这可以用来提高对对流、水分输送和冷凝的理解。这里提出的仪器开发工作与几个NSF-GEO项目支持的研究相关，包括水文学、气候和大尺度动力学、古气候、大气化学以及北极和南极项目。本提案将资助一名博士后研究员。

Steig/1341360This award supports a two-year project to develop a method for rapid and precise measurements of the difference in 18O/16O and 17O/16O isotope ratios in water, referred to as the 17O-excess. Measurement of 17O-excess is a recent innovation in geochemistry, complementing traditional measurements of the ratios of hydrogen (D/H) and oxygen (18O/16O). Conventional measurements of 17O/16O are limited in number because of the time-consuming and laborious nature of the analyses, which involves the conversion of water to oxygen via fluorination, followed by high-precision mass spectrometry. This project will use a novel cavity ring-down spectroscopy (CRDS) system developed by a joint effort of the University of Washington and Picarro, Inc. (Santa Clara, CA), along with the Centre for Ice and Climate (Neils Bohr Institute, Copenhagen). The primary intellectual merit of the research is the improvement of the CRDS method for measurements of 17Oexcess of discrete samples of water, to obtain precision and accuracy competitive with conventional methods using mass spectrometry. This will be achieved by quantification of the effects of water vapor concentration variability and instrument memory, precise calibration of the instrument against standard waters, and improvements to the spectroscopic analyses. The CRDS system will also be coupled to continuous-flow systems for ice core analysis, in collaboration with the University of Colorado, Boulder. The goal is to have an operational system available for ice core processing associated with the next major U.S.-led ice core project at South Pole, in 2015-2017. The broader impacts of the research include the ability to measure 17O-excess in ambient atmospheric water vapor, which can be used to improve understanding of convection, moisture transport, and condensation. The instrument development work proposed here is relevant to research supported by several NSF-GEO programs, including Hydrology, Climate and Large Scale Dynamics, Paleoclimate, Atmosphere Chemistry, and both the Arctic and Antarctic Programs. This proposal will support a postdoctoral researcher.