Shape, Size, and Elemental Composition of Individual Aeolian Nano- and Micro-particles Within the Horizontal Ice Core from Taylor Glacier, East Antarctica, During the Last Climatic Cycle

Abstract:

Throughout Earth’s most recent climate cycle, aeolian dust concentrations, size distributions, and chemical composition have changed significantly due to differences in sources of emission and atmospheric circulation. In the atmosphere, dust particles serve as direct and indirect climate forcings due to their optical scattering and absorption properties, and because they serve as cloud/ice nuclei, respectively. These forcings influence Earth’s albedo and depend on a particle’s physicochemical properties such as shape, size, and chemical composition. Glacial ice serves as a time-capsule of Earth’s past atmosphere and stratigraphically captures deposited atmospheric dust through time. Using Scanning Transmission Electron Microscopy (STEM) and Energy Dispersive X-ray Spectrometry (EDXS) we have measured individual nano- and micro-particles that were entrapped in ice sections from the horizontal ice core of Taylor Glacier, East Antarctica. These sections cover Earth’s most recent glacial period, the last glacial-interglacial transition, and the current interglacial period, the Holocene (~45 ky – 8.5 ky BP). In particular, we report measurements of particles smaller than 200 nanometers in glacial ice. Particle dimension, aspect ratio (AR), circularity (CIRC), and chemical-elemental composition have been assessed to understand how these physicochemical properties have changed throughout Earth’s most recent climate cycle and the role they played in changing climate conditions.