Investigating the preservation of rapid climate signals in the ice matrix using 2D LA-ICP-MS

In recent years, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been further developed to obtain aerosol-derived impurity records from ice core samples at sub-mm to µm resolution (Müller et al., 2011; Bohleber et al., 2020).

For thinned ice from the lower parts of ice cores, the high spatial resolution of the method in principle promises to resolve climate variability at temporal scales that are unresolvable by other methods such as continuous flow analysis. However, spatially resolved, two-dimensional maps of the impurity distribution in the ice from LA-ICP-MS have revealed the complex interplay between the impurities and the ice’s polycrystalline structure (Della Lunga et al., 2014; Bohleber et al., 2020; Stoll et al., 2023). Some impurities such as sodium, predominantly from sea salt aerosols, show very high localisation along grain boundaries. Other elements that are typically associated with water-insoluble dust aerosols such as iron, aluminium, and calcium, however, often do not show such a strong localisation but are dispersed as particles in the ice matrix.

This localisation poses the question: At what spatial and thus temporal scale the LA-ICP-MS records are interpretable as climate records? And at which scale the post-depositional processes in the ice masks the climate signal by e.g. by dynamic or static recrystallization. This is especially relevant in the context of the evolution of the ice towards generally larger crystal sizes with increasing depth within the ice sheet accompanied by the thinning of the annual layers.

To investigate the preservation of high-frequency climate variability, we applied our newly developed 157 nm cryo-LA-ICP-MS/MS setup (Erhardt et al., 2025) to ice covering the warming transition into Greenland Interstadial 1 in the EGRIP ice core at 1375 m depth. Here, we present spatially resolved impurity maps at the ~100-µm scale spanning the rapid warming transition. Bulk concentration data from continuous flow analysis of the same ice indicates that this warming transition is exceptionally fast at EGRIP, happening within only a few years. Ice-fabric data shows grain diameters increasing from 1.5 to 1.8 mm across this transition from dustier stadial to cleaner interstadial ice (Stoll et al., 2025). This makes it a good candidate to investigate the imprint of the ice matrix onto rapid climate signals in the ice-core impurity record.

 

Bohleber, P. et al. (2020) Imaging the impurity distribution in glacier ice cores with LA-ICP-MS. Journal of Analytical Atomic Spectrometry

Della Lunga, D. et al. (2014) Location of cation impurities in NGRIP deep ice revealed by cryo-cell UV-laser-ablation ICPMS. Journal of Glaciology

Erhardt, T. et al. (2025) Rationale, design and initial performance of a dual-wavelength (157 & 193 nm) cryo-LA-ICP-MS/MS system. Journal of Analytical Atomic Spectrometry

Müller, W., Shelley, J.M.G. & Rasmussen, S.O. (2011) Direct chemical analysis of frozen ice cores by UV-laser ablation ICPMS. Journal of Analytical Atomic Spectrometry

Stoll, N. et al. (2023) Chemical and visual characterisation of EGRIP glacial ice and cloudy bands within. The Cryosphere

Stoll, N. et al. (2025) Linking crystallographic orientation and ice stream dynamics: evidence from the EastGRIP ice core. The Cryosphere