Effective diffusivity of sulfuric acid in Antarctic ice cores
<p>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...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-02-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/20/297/2024/cp-20-297-2024.pdf |
| _version_ | 1827355832952553472 |
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| author | T. J. Fudge R. Sauvage L. Vu B. H. Hills B. H. Hills M. Severi E. D. Waddington |
| author_facet | T. J. Fudge R. Sauvage L. Vu B. H. Hills B. H. Hills M. Severi E. D. Waddington |
| author_sort | T. J. Fudge |
| collection | DOAJ |
| description | <p>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 European Project of Ice Coring in Antarctica (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 and age. We find the effective diffusivities for interglacial and glacial maximums to be <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">5</mn><mo>±</mo><mn mathvariant="normal">3</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">9</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="59pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="b145980b1759c18b96e4a542e372bf1f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-20-297-2024-ie00001.svg" width="59pt" height="14pt" src="cp-20-297-2024-ie00001.png"/></svg:svg></span></span> m<span class="inline-formula"><sup>2</sup></span> a<span class="inline-formula"><sup>−1</sup></span>, 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 <span class="inline-formula">−10</span> <span class="inline-formula"><sup>∘</sup></span>C, 3000 m 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.</p> |
| first_indexed | 2024-03-08T04:49:03Z |
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| id | doaj.art-d83bbcaa9c6d47b19ef95591a51fe9c9 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-03-08T04:49:03Z |
| publishDate | 2024-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-d83bbcaa9c6d47b19ef95591a51fe9c92024-02-08T07:38:11ZengCopernicus PublicationsClimate of the Past1814-93241814-93322024-02-012029731210.5194/cp-20-297-2024Effective diffusivity of sulfuric acid in Antarctic ice coresT. J. Fudge0R. Sauvage1L. Vu2B. H. Hills3B. H. Hills4M. Severi5E. D. Waddington6Department of Earth and Space Sciences, University of Washington, Seattle, WA, USADepartment of Earth and Space Sciences, University of Washington, Seattle, WA, USADepartment of Earth and Space Sciences, University of Washington, Seattle, WA, USADepartment of Earth and Space Sciences, University of Washington, Seattle, WA, USADepartment of Geophysics, Colorado School of Mines, Golden, CO, USADepartment of Chemistry “Ugo Schiff”, University of Florence, Florence, ItalyDepartment of Earth and Space Sciences, University of Washington, Seattle, WA, USA<p>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 European Project of Ice Coring in Antarctica (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 and age. We find the effective diffusivities for interglacial and glacial maximums to be <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">5</mn><mo>±</mo><mn mathvariant="normal">3</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">9</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="59pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="b145980b1759c18b96e4a542e372bf1f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-20-297-2024-ie00001.svg" width="59pt" height="14pt" src="cp-20-297-2024-ie00001.png"/></svg:svg></span></span> m<span class="inline-formula"><sup>2</sup></span> a<span class="inline-formula"><sup>−1</sup></span>, 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 <span class="inline-formula">−10</span> <span class="inline-formula"><sup>∘</sup></span>C, 3000 m 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.</p>https://cp.copernicus.org/articles/20/297/2024/cp-20-297-2024.pdf |
| spellingShingle | T. J. Fudge R. Sauvage L. Vu B. H. Hills B. H. Hills M. Severi E. D. Waddington Effective diffusivity of sulfuric acid in Antarctic ice cores Climate of the Past |
| title | Effective diffusivity of sulfuric acid in Antarctic ice cores |
| title_full | Effective diffusivity of sulfuric acid in Antarctic ice cores |
| title_fullStr | Effective diffusivity of sulfuric acid in Antarctic ice cores |
| title_full_unstemmed | Effective diffusivity of sulfuric acid in Antarctic ice cores |
| title_short | Effective diffusivity of sulfuric acid in Antarctic ice cores |
| title_sort | effective diffusivity of sulfuric acid in antarctic ice cores |
| url | https://cp.copernicus.org/articles/20/297/2024/cp-20-297-2024.pdf |
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