Explosive volcanic eruptions emit large amounts of ash and gases into the atmosphere and thereby significantly impact the atmospheric environment. Fallout of substances emitted by a volcanic eruption or produced in the atmosphere under volcanic influence can often be found in polar snow. For example, measurements of volcanic sulfuric acid and sulfate, produced in the atmosphere by the oxidation of sulfur dioxide, in Antarctic and Greenland ice cores have yielded records of past eruptions which are valuable to understanding the role of volcanism in the global climate system.  Study of volcanic fallout preserved in polar snow can also contribute to our knowledge of atmospheric dynamics and chemistry. We found sulfate deposition from the AD 1600 Huaynaputina eruption in Peru, the largest South American eruption in historic times, in the snow layers of 1602 and 1603 in a well-dated central Greenland ice core. It is likely that the Huaynaputina volcanic sulfate in Greenland snow was transported from the equatorial atmosphere to the Arctic via the stratosphere. We also measured perchlorate and found highly elevated perchlorate concentrations in these snow layers. Volcanic eruptions are not known to emit perchlorate. Therefore, volcanic impact on stratospheric chlorine chemistry is probably responsible for the increased perchlorate levels. The temporal variations of sulfate and perchlorate concentrations in the ice core reveal that Huaynaputina perchlorate deposition in snow precedes that of sulfate by a few months. It is possible, but unlikely, that perchlorate generated by the eruption was transported in the atmosphere faster than the volcanic sulfate. We suggest that an alternative and more probable explanation is that transfer of perchlorate from the Arctic stratosphere to the troposphere and eventual deposition with snow is faster than that for volcanic sulfate.

Perchlorate and sulfate in arctic snow from the AD 1600 Huaynaputina (Peru) volcanic eruption

2019 Spring National Meeting

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