Microparticles and crystal microstructure in polar ice sheets

• Main Authors: Eichler, Jan, Weikusat, Christian, Wegner, Anna, Twarloh, Birthe, Behrens, Melanie, Hörhold, Maria, Jansen, Daniela, Kipfstuhl, Sepp, Wilhelms, Frank, Weikusat, Ilka
• Format: Conference Object
• Language: unknown
• Published: Alexander von Humboldt Foundation 2019
• Subjects: Antarc*; Antarctica; Greenland; ice core; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/50501/; https://epic.awi.de/id/eprint/50501/1/20190912-JAGFoS2019-Raman_.pdf; https://www.jsps.go.jp/j-bilat/fos_jag/jishi_02.html; https://hdl.handle.net/10013/epic.69c69cc1-4f2e-490b-81ca-52877bd5b19f

The pollution input in polar ice sheets in Greenland and Antarctica is of atmospheric aeolian origin, just as all natural non-ice impurities as well. They thus provide potential information on the evolution of the atmospheric share of pollutants in the ocean. Aerosols found in ice are transported with atmospheric circulation and wind patterns and are deposited e.g. with precipitating snow. The impurity content in this so-called meteoric ice is relatively low compared to many other natural materials such as rocks (ppb to ppm range). The reason is that most aerosols in the atmosphere have been removed by fall-out or precipitation during transport from the impurities’ sources to the remote ice sheet. Non-ice constituents in polar ice cores have been studied in the last decades mainly for reconstructions of past atmospheric aerosol concentrations, with respect to questions conceding the global climate change. The fastest and easiest analytical way is chemical analysis of the melted water from ice cores. However despite the tiny concentrations, the interactions with and effects of impurities in the solid ice influence the physical properties of the material as a whole: e.g. electric as well as dielectric response and, in particular, mechanical behaviour thus “softness” of the material seems to be strongly controlled by impurities. Smaller concentrations of impurities (up to a few ‰) do soften the material as a whole, while larger concentrations of particles harden it, depending on the type of impurities of course. The underlying processes are partly hypothesised for decades, but not yet proven or understood satisfactorily as the quest for ppb to ppm concentrations in solid matrix material is a search for a “needle in a haystack”. To improve the data basis regarding the in-situ form of incorporation and spatial distribution of impurities in ice we used micro-cryo-Raman spectroscopy to identify the location, phase and composition of micrometer-sized inclusions in natural ice samples (NEEM ice core from Greenland and ...