Chemical impurity distribtion (Na, Mg, Sr) in the EPICA Dome C ice core bags 1065 and 3092 and Talos Dome ice core bag 375-B1 obtained from 2D imaging with LA-ICP-MS

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers micron-resolution 2D chemical imaging, which has been adapted recently to ice core analysis. Measurements were performed in 2020 at the Ca'Foscari University of Venice, in order to investigate the localization of impurities in the ice samples. Here images are presented from applying LA-ICP-MS elemental imaging to a samples of the EPICA Dome C ice core and the Talos Dome ice core from Antarctica. Lateral resolution is 35 microns both along and perpendicular to the scan direction. Considered as analytes are Na, Mg and Sr. Background and drift correction as well as image construction were performed using the software HDIP (Teledyne Photon Machines, Bozeman, MT, USA). Impurity images are acquired as a pattern of lines, without overlap in the direction perpendicular to that of the scan, and without any further spatial interpolation. Each pixel in an ice core chemical image has a size of 35 μm x 35 μm. For each chemical element the datasets comprise a numerical matrix which contains rows and columns according to the physical size of the image: an image of 7 mm x 35 mm in size has 200 rows and 1000 columns. The numerical entries in this matrix refer to the recorded intensity (e.g. in counts). Values lower than the detection limit are set to zero. Due to the careful synchronization, the individual pixels of the different chemical channels can be considered to be almost perfectly spatially aligned. In contrast, the mosaic of visual images obtained from the laser camera is not a-priori aligned with the chemical images. The visual images are generally characterized by air bubbles (dark blobs), grain boundaries (dark lines) and occasional sub-grain boundaries (thin dark lines).激光剥蚀-电感耦合等离子体质谱法（Laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS）具备微米级分辨率的二维化学成像能力，近年来该技术已被应用于冰芯分析领域。本数据集的相关测量工作于2020年在威尼斯卡福斯卡里大学（Ca'Foscari University of Venice）开展，旨在探究冰样品中杂质的空间分布特征。本次研究通过LA-ICP-MS元素成像技术，对取自南极洲的EPICA Dome C冰芯与Talos Dome冰芯样品开展分析，并展示对应的成像结果。扫描方向及垂直于扫描方向的横向分辨率均为35微米。本次分析的待测元素包括钠（Na）、镁（Mg）与锶（Sr）。数据的背景校正、漂移校正及成像构建均通过HDIP软件（Teledyne Photon Machines，美国蒙大拿州博兹曼市）完成。杂质成像以线状扫描模式采集，在垂直于扫描方向上无重叠，且未进行任何额外的空间插值处理。冰芯化学成像的每个像素尺寸为35 μm × 35 μm。针对每种待测元素，数据集均包含一组数值矩阵，矩阵的行列数与成像的物理尺寸对应：例如尺寸为7 mm × 35 mm的成像结果，其矩阵包含200行与1000列。矩阵中的数值元素代表记录的信号强度（例如以计数为单位），低于检测限的数值会被置零。由于采用了精准的同步机制，不同待测元素通道的单个像素可视为几乎完全空间对齐。与之相对，通过激光相机获取的可视化图像拼接结果，并未预先与化学成像结果对齐。这类可视化图像通常呈现出以下特征：气泡（暗色团块）、晶界（暗色线条）以及偶尔出现的亚晶界（细暗色线条）。