Study of the structure and chemical composition of a shallow ice core from Ushkovsky volcano

The chemical composition (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₃⁻ and SO₄²⁻) of an ice core from the Ushkovsky volcano was studied. A shallow (13.85 m) core was drilled in the fall of 2022 in the Gorshkov crater. The majority of the core (56%) consists of infiltration ice, formed by the penetration and subsequent freezing of liquid water in the firn layer. Melting, induced by an increase in the radiation balance in the region, is forced by volcanic eruption products deposited on the glacier’s surface. Part of the chemical record is disrupted by meltwater. Frequent large stochastic events (volcanic eruptions and Siberian wildfires) add further complexity to the interpretation of the paleosignal. Based on the nature of the obtained concentration records, we identified three groups of ions with different primary sources and assessed the role of leaching in their distribution within the glacier. The source of ions subject to migration due to leaching (SO₄²⁻, F⁻, Ca²⁺ and Mg²⁺) is volcanic activity; this process has a minimal impact on chemical markers of forest vegetation and biomass burning (NH₄⁺ and NO₃⁻), and the impact of leaching on the group of marine aerosols (Cl⁻, Na⁺ and K⁺) could not be assessed within this study. Thus, despite the contribution of various processes to the formation of the chemical record in the Ushkovsky glacier, the concentration profiles of the main ions can be used to reconstruct the environmental conditions in the region.