Depletion of Atmospheric Nitrate and Chloride as a Consequence of the Toba Volcanic Eruption

• Published in: Geophysical Research Letters
• Main Authors: Yang, Q., Mayewski, Paul Andrew, Zielinski, G. A., Twickler, M., Taylor, K. C.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 1996
• Subjects: Glaciogeology; Geochemistry; Glaciology; Cryology; Climate Change; Climate; Earth Sciences; Hydrology; Volcanology; ice core
• Online Access: https://digitalcommons.library.umaine.edu/ers_facpub/194; https://doi.org/10.1029/96GL02201; https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1194/viewcontent/depletion_of_atmosphericnitrate.pdf

Continuous measurements of SO42− and electrical conductivity (ECM) along the GISP2 ice core record the Toba megaâ€eruption at a depth 2590.95 to 2091.25 m (71,000±5000 years ago). Major chemical species were analyzed at a resolution of 1 cm per sample for this section. An ∼6â€year long period with extremely high volcanic SO42− coincident with a 94% depletion of nitrate and 63% depletion of chloride is observed at the depth of the Toba horizon. Such a reduction of chloride in a volcanic layer preserved in an ice core has not been observed in any previous studies. The nearly complete depletion of nitrate (to 5 ppb) encountered at the Toba level is the lowest value in the entire ∼250,000 years of the GISP2 ice core record. We propose possible mechanisms to explain the depletion of nitrate and chloride resulting from this megaâ€eruption.