9:15 AM - 9:30 AM
[ACC29-02] Sulfur isotope ratio of sulfate aerosols in an Antarctic Dome Fuji ice core during the last glacial period: a potential contribution from the Atacama Desert
Keywords:ice core, isotope, Antarctica, desert
The flux of sulfate onto the ice in Antarctica has remained relatively stable over glacial-interglacial cycles. However, the mechanism behind the stable flux is controversial because of a lack of evidence for changes in multiple source emissions. To provide a new constraint on the interpretation of sulfate aerosols, we measured a new sulfur isotopic (34S) record in the Antarctic Dome Fuji ice core (Uemura et al., 2022).
During the Last Glacial Maximum (LGM), the sulfur isotope ratio was depleted compared to that during the Holocene and was negatively correlated with terrestrial contributions. This result supports the hypothesis of increased terrestrial sulfate during the LGM but does not favor the constant marine biogenic sulfate hypothesis.
Further, we complied sulfur isotope values in potential gypsum sources to explore potential source areas (PSAs). The sulfur isotope value of the terrestrial endmember suggests that the PSAs for the DF sulfate during the LGM is characterized by low sulfur isotope value and a high SO42-/Ca2+ ratio. A potential source area for such DF ice core data is the high-altitude region of the Atacama Desert, which is consistent with such unique sulfur isotope value and a high SO42-/Ca2+ ratio. We cannot rule out contributions from other areas because of the limited geochemical data in source regions. For example, geochemical data suggest that the Puna-Altiplano Plateau is another important PSA for dust.
These results demonstrate that the estimation of changes in sources of sulfate significantly affects the interpretation of the relationship between climate and sulfate flux records in ice cores. Therefore, the contribution of soluble salts in deserts should be considered when interpreting ion data in Antarctic cores during the LGM.
Reference: Uemura et al. (2022), Soluble salts in deserts as a source of sulfate aerosols in an Antarctic ice core during the last glacial period, Earth and Planetary Science Letters, 578, 117299, https://doi.org/10.1016/j.epsl.2021.117299
During the Last Glacial Maximum (LGM), the sulfur isotope ratio was depleted compared to that during the Holocene and was negatively correlated with terrestrial contributions. This result supports the hypothesis of increased terrestrial sulfate during the LGM but does not favor the constant marine biogenic sulfate hypothesis.
Further, we complied sulfur isotope values in potential gypsum sources to explore potential source areas (PSAs). The sulfur isotope value of the terrestrial endmember suggests that the PSAs for the DF sulfate during the LGM is characterized by low sulfur isotope value and a high SO42-/Ca2+ ratio. A potential source area for such DF ice core data is the high-altitude region of the Atacama Desert, which is consistent with such unique sulfur isotope value and a high SO42-/Ca2+ ratio. We cannot rule out contributions from other areas because of the limited geochemical data in source regions. For example, geochemical data suggest that the Puna-Altiplano Plateau is another important PSA for dust.
These results demonstrate that the estimation of changes in sources of sulfate significantly affects the interpretation of the relationship between climate and sulfate flux records in ice cores. Therefore, the contribution of soluble salts in deserts should be considered when interpreting ion data in Antarctic cores during the LGM.
Reference: Uemura et al. (2022), Soluble salts in deserts as a source of sulfate aerosols in an Antarctic ice core during the last glacial period, Earth and Planetary Science Letters, 578, 117299, https://doi.org/10.1016/j.epsl.2021.117299