Atmospheric chemistry of an Antarctic volcanic plume
We report measurements of the atmospheric plume emitted by Erebus volcano, Antarctica, renowned for its persistent lava lake. The observations were made in December 2005 both at source, with an infrared spectrometer sited on the crater rim, and up to 56 km downwind, using a Twin Otter aircraft; with the two different measurement platforms, plume ages were sampled ranging from <1 min to as long as 9 h. Three species (CO, carbonyl sulfide (OCS), and SOâ) were measured from both air and ground. While CO and OCS were conserved in the plume, consistent with their long atmospheric lifetimes, the downwind measurements indicate a SOâ/CO ratio about 20% of that observed at the crater rim, suggesting rapid chemical conversion of SOâ. The aircraft measurements also identify volcanogenic HâSOâ, HNOâ and, recognized for the first time in a volcanic plume, HOâNOâ. We did not find NOx in the downwind plume despite previous detection of NOâ above the crater. This suggests that near-source NOx was quickly oxidized to HNOâ and HOâNOâ, and probably NO32 (aq), possibly in tandem with the conversion of SOâ to sulfate. These fast processes may have been facilitated by "cloud processing" in the dense plume immediately downwind from the crater. A further striking observation was Oâ depletion of up to ~35% in parts of the downwind plume. This is likely to be due to the presence of reactive halogens (BrO and ClO) formed through heterogeneous processes in the young plume. Our analysis adds to the growing evidence for the tropospheric reactivity of volcanic plumes and shows that Erebus volcano has a significant impact on Antarctic atmospheric chemistry, at least locally in the Southern Ross Sea area.
document
https://n2t.org/ark:/85065/d7z60q9m
eng
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publication
2016-01-01T00:00:00Z
publication
2010-02-27T00:00:00Z
An edited version of this paper was published by AGU. Copyright 2010 American Geophysical Union.
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