Fire and ice : understanding volcanic histories from sulfur isotopes in ice cores ...

• Main Author: Crick, Laura
• Format: Text
• Language: English
• Published: The University of St Andrews 2023
• Subjects: Volcanism; Ice cores; Sulfur isotopes; Mass-independent fractionation; Photochemical model; QE522.C8; Sulfur > Isotopes; ice core
• Online Access: https://dx.doi.org/10.17630/sta/439; https://research-repository.st-andrews.ac.uk/handle/10023/27568

Reconstructing the history of explosive volcanic eruptions is important for understanding the frequency of eruptions and the climatic forcing of these events. Erupted volcanic SO₂ is oxidised to sulfate aerosols which scatter incoming solar radiation. Aerosols are then deposited at the poles resulting in a peak in sulfate above background concentrations. Therefore, polar ice cores provide an important record of volcanism. The mass-independent fractionation of sulfur isotopes (S-MIF) in ice cores is an indicator of sulfur exposure to ultraviolet radiation via eruption into and above the ozone layer in the stratosphere. Sulfate aerosols from large eruptions that reach the stratosphere have a longer residence time and greater climatic impact than tropospheric aerosols from smaller eruptions. In this thesis I measure sulfur isotopes in volcanic ice core sulfate to investigate the ~74ka Toba supereruption and six unidentified volcanic eruptions from 16ka to 32ka. I found large magnitude S-MIF signals (-4.75‰) for ...