HR: 11:50h
AN: A42B-07    [Abstracts]
TI: Is the Spring Maximum of MSA (Methane Sulfonic Acid) in the Arctic due to Oxidation of DMS (DiMethyl Sulphide) by BrO?
AU: Netcheva, S
EM: Stoyka.Netcheva@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4, Canada
AU: Toom-Sauntry, D
EM: Desiree.Toom-Sauntry@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4, Canada
AU: Li, S
EM: Shao-Meng.Li@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4, Canada
AU: * Bottenheim, J W
EM: Jan.Bottenheim@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4, Canada
AB: Long term measurements of MSA at Alert, NU have revealed a seasonal recurring pattern with two maxima: a first maximum occurs around April/May, while a second maximum is observed in summer (July/August). It has been shown that the origins of these maxima are different. The summer maximum is thought to reflect maximum DMS emission in Northern oceans off the coast of Norway and the northeast Pacific, while the spring maximum could be due to longer range transport of air originating in more Southerly regions of the north Atlantic where DMS emission would be occurring earlier in the season. The explanation for the spring maximum is debatable since by late April the Alert site is usually disconnected from such long range transport, although year-to-year variations in the MSA record appear related to sea surface temperature anomalies in the North Atlantic. It is well known that frequent ozone depletion episodes are observed in the spring at Alert, due to chemistry involving the BrO molecule. Chemical kinetic data show that the BrO molecule is also a very effective oxidant for DMS, and that this oxidation preferentially leads to the formation of MSA, rather than sulphate. In order to investigate whether the spring peak of MSA at Alert could be related to oxidation of DMS by BrO we have collected daily HiVol filters at Alert during the height of the ozone depletion season (late April- mid May 2007). We will report the results of this study and explore correlations with ozone and other chemical parameters, as well as the origin of the air masses sampled using 10-day back trajectories.
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
DE: 4852 Photochemistry
DE: 9315 Arctic region (0718, 4207)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting