Speaker
Description
The location of ice impurities in its microscopic structure, particularly within its grain boundaries, significantly affects the preservation of climatic signals and the deformation behaviour of ice. Ice-impurity interactions also influence the microstructure of ice crystals. Understanding this interplay is highly relevant to interpretations of ice-core records and our understanding of climate change and past Earth conditions. Studying impurities in solid ice presents a significant analytical challenge, and a holistic understanding of ice-impurity interactions requires data acquisition from multiple approaches. Mapping chemical impurities in ice with laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) is one such approach, but it is costly and time-consuming. Here, we combine light, polarised and fluorescence microscopy to provide fast insights into impurity relocation processes in ice, expanding the 2D spatial perspective provided by LA-ICP-MS. Fluorescence microscopy can complement studies of ice formation and metamorphism, particularly by enabling real-time investigation of impurity localisation. To our knowledge, it has not yet been applied specifically to the study of ice impurities. Thus, we built a custom-made epifluorescence setup to follow the behaviour of fluorescent particles simulating ice impurities. We performed image analysis to assess particle behaviour in terms of movement patterns, velocities and allocations relative to grain boundaries in development. We successfully tracked fluorescent particles embedded in artificial ice under laboratory conditions at -15C and -30C, and over time. By enabling fluorescence-based particle tracking during ice ageing, we expand the available approaches for investigating ice-core impurities in terms of their properties and introduce a new methodology with high potential for examining the impacts of impurity allocation on the evolving microscopic structure of ice during ageing.