Continuous Characterization\nof Insoluble Particles\nin Ice Cores Using the Single-Particle Extinction and Scattering Method

This study presents the integration of the single-particle\nextinction\nand scattering (SPES) method in a continuous flow analysis (CFA) setup.\nContinuous measurements with the instrument allow for the characterization\nof water-insoluble particles in ice cores at high resolution with\na minimized risk of contamination. The SPES method can be used to\ninvestigate particles smaller than 1 μm, which previously could\nnot be detected by instruments typically used in CFA. Moreover, the\nSPES method provides not only the particle concentration and size\ndistribution but also the effective refractive index. We show that\nnonabsorbing mineral particles and absorbing particles from both wildfires\nand fossil fuel burning can be detected with the SPES method in shallow\nice cores from North–East Greenland. The concentration record\nretrieved with SPES correlates well with established methods used\nin continuous measurements of dust content in ice cores. Year-to-year\nvariations in the number distribution of the diameter are only detectable\nby stacking annual layers because of the low nonabsorbing particle\nconcentration of late Holocene ice of approximately 6 × 10<sup>4</sup> mL<sup>–1</sup>. The median diameter in the bottom\n20 m of the EGRIP-S7 core is found to be 0.75 μm (0.72 μm)\nduring the annual maximum (minimum) in dust concentration.