USAP-DC

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EPICA Dome C Sulfate Data 7-3190m Data DOI: https://doi.org/10.15784/601759 Cite as Fudge, T. J., & Severi, M. (2023) "EPICA Dome C Sulfate Data 7-3190m" U.S. Antarctic Program (USAP) Data Center. doi: https://doi.org/10.15784/601759. AMD - DIF Record(s) USAP-1851094_1 Abstract Volcanic deposition of sulfuric acid in ice cores is important both for understanding past volcanic activity and for synchronizing ice core timescales. Sulfuric acid has a low eutectic point, so it can potentially exist in liquid at grain boundaries and veins, accelerating chemical diffusion. A high effective diffusivity would allow post-depositional diffusion to obscure the climate history and the peak matching among older portions of ice cores. Here, we use records of sulfate from the EPICA Dome C (EDC) ice core to estimate the effective diffusivity of sulfuric acid in ice. We focus on EDC because multiple glacial-interglacial cycles are preserved, allowing analysis for long timescales and deposition in similar climates. We calculate the mean concentration gradient and the width of prominent volcanic events, and analyze the evolution of each with depth/age. We find the effective diffusivities for interglacials and glacial maximums to be 5 ± 3 × 10-9 m2 a-1, an order of magnitude lower than a previous estimate derived from the Holocene portion of EDC (Barnes et al., 2003). The effective diffusivity may be even smaller if the bias from artificial smoothing from the sampling is accounted for. Effective diffusivity is not obviously affected by the ice temperature until about -10°C, 3000m depth, which is also where anomalous sulfate peaks begin to be observed (Traversi et al., 2009). Low effective diffusivity suggests that sulfuric acid is not readily diffusing in liquid-like veins in the upper portions of the Antarctic ice sheet and that records may be preserved in deep, old ice if the ice temperature remains well below the pressure melting point. Creator(s): Fudge, T. J.; Severi, Mirko Date Created: 2023-12-22 Repository: USAP-DC (current) License: Creative Commons Attribution Only v4.0 Generic [CC BY 4.0] Spatial Extent(s) West: 123.33, East: 123.33, South: -75.09, North: -75.09 Award(s) NSF 1851022 Version: 1 Related Project(s) Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation Keywords Antarctica