Development of High-Resolution, Multi-Century Records of Trace Element Deposition in West-Central Greenland Using ICP-MS

首席调查员将以前所未有的时间分辨率(约50至100个样品)开发三个空间分布的、连续的、多世纪以来的20多种化学物种、微量元素和同位素的冰化学记录。这些独特的记录将极大地扩大冰化学数据在一系列环境和全球变化问题研究中的可能应用。这项工作建立在美国国家科学基金资助的沙漠研究所(DRI)最近开发的一种新的连续、高分辨率冰芯分析方法--痕量连续流动分析(CFA-TE)的基础上。CFA-TE是一种将连续冰芯熔融器与电感耦合等离子体质谱(ICPMS)和传统的连续流动分析(CFA)系统直接耦合的新型分析方法。该仪器使得对广泛的化学物种、微量元素和同位素进行连续、高分辨率和精确共同登记的冰化学测量成为可能。对格陵兰岛顶峰约137米岩心的测量表明了这种新方法的潜力。利用为成功进行顶峰分析而开发的样品处理和分析方案，CFA-TE将用于测量格陵兰中西部干燥雪区高积雪区的一个存档冰芯和两个新的约140米长的冰芯上的20多种化学物质、微量元素和同位素。该地区受到来自北美的大气环流和人为污染的大范围变化的强烈影响。这些新的冰化学记录将从公元1750年左右延伸到现在，将是格陵兰冰芯产生的最高分辨率的、长达数个世纪的元素和同位素冰化学记录。冰芯化学数据在环境、生物地球化学和全球变化研究中的应用受到以下因素的限制：1)即使是高分辨率的研究，样品的分辨率也相对较低；2)不同的化学测量在深度上不准确的联合记录；以及3)在冰芯中常规测量的化学物种、元素和同位素的数量有限。最近开发的用于冰芯分析的CFA-TE方法消除了其中许多问题，并为以相对较低的成本开发非常高分辨率、广谱的冰化学记录提供了新的机会。结合Summit最近完成的类似测量，这些丰富的数据集将为利用冰化学数据调查环境和全球变化问题开辟新的途径，从与人为、火山和生物质燃烧有关的微量元素尘埃到半球尺度环流的变化。

McConnell0221515The Principal Investigator will develop three spatially distributed, continuous, multi-century glaciochemical records of more than 20 chemical species, trace elements, and isotopes with unprecedented temporal resolution (~50 to 100 samples). These unique records will significantly expand possible applications of glaciochemical data to the study of a range of environmental and global change issues. This work builds on recent NSF-funded development at the Desert Research Institute (DRI) of a new method for continuous, high-resolution ice-core analyses called Continuous Flow Analysis with Trace Elements (CFA-TE). CFA-TE is a novel analytical approach in which a continuous ice-core melter is coupled directly with an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and traditional Continuous Flow Analysis (CFA) system. The apparatus makes possible continuous, high-resolution and exactly co-registered glaciochemical measurements of a broad spectrum of chemical species, trace elements, and isotopes. Measurements on an approximately 137meter core from Summit, Greenland demonstrate the potential of this new approach. Using sample handling and analytical protocols developed for the successful Summit analyses, CFA-TE will be used to measure more than 20 chemical species, trace elements, and isotopes on one archived and two new approximately140-m ice cores from high accumulation regions of the dry snow zone in west-central Greenland. This area is strongly influenced by large-scale changes in atmospheric circulation and anthropogenic pollution from North America. These new glaciochemical records will extend from around 1750 A.D. to the present and will be the highest resolution, multi-century elemental and isotopic glaciochemical records ever produced from Greenland ice cores.The application of ice-core chemical data in environmental, biogeochemical,and global change studies has been limited by 1) relatively coarse sample resolution in time even for high resolution studies, 2) inexact co-registration in depth for different chemical measurements, and 3) the limited number of chemical species, elements, and isotopes routinely measured in ice cores. The recent development of the CFA-TE method for ice-core analysis eliminates many of these issues and presents a new opportunity to develop very high-resolution, broad-spectrum glaciochemical records at relatively modest cost. Together with similar, recently completed measurements from Summit, these rich data sets will open new avenues for using glaciochemical data to investigate environmental and global changes issues ranging from anthropogenic, volcanic and biomass-burning-related trace element fallout to changes in hemispheric-scale circulation.