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Seasonality of halogen deposition in polar snow and ice

Citation

Spolaor, A and Vallelonga, P and Gabrieli, J and Martma, T and Bjorkman, MP and Isaksson, E and Cozzi, G and Turetta, C and Kjer, HA and Curran, MAJ and Moy, AD and Schonhardt, A and Blechschmidt, A-M and Burrows, JP and Plane, JMC and Barbante, C, Seasonality of halogen deposition in polar snow and ice, Atmospheric Chemistry and Physics, 14, (18) pp. 9613-9622. ISSN 1680-7316 (2014) [Refereed Article]


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Copyright 2014 The Authors-This article has been distributed under the terms of a Creative Commons 3.0 license. (CC BY 3.0)

DOI: doi:10.5194/acp-14-9613-2014

Abstract

The atmospheric chemistry of iodine and bromine in Polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine emission is attributed to biological communities in the open ocean and hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial–interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine and iodine concentrations and Br enrichment (relative to sea salt content) in polar ice do vary seasonally in Arctic snow and Antarctic ice. Although seasonal variability in halogen emission sources is recorded by satellite-based observations of tropospheric halogen concentrations, seasonal patterns observed in snowpack are likely also influenced by photolysis-driven processes. Peaks of bromine concentration and Br enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. A secondary bromine peak, observed at the end of summer, is attributed to bromine deposition at the end of the polar day. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions. These findings support previous observations of iodine peaks in winter snow strata attributed to the absence of sunlight-driven photolytic re-mobilisation of iodine from surface snow. Further investigation is required to confirm these proposed mechanisms explaining observations of halogens in polar snow and ice, and to evaluate the extent to which halogens may be applied as sea ice proxies.

Item Details

Item Type:Refereed Article
Keywords:polar snow and ice, atmospheric chemistry, atmospheric processes, ozone destruction
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Glaciology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Curran, MAJ (Dr Mark Curran)
Author:Moy, AD (Dr Andrew Moy)
ID Code:95081
Year Published:2014
Web of Science® Times Cited:9
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2014-09-24
Last Modified:2017-10-30
Downloads:259 View Download Statistics

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