HR: 0800h
AN: A21C-0869 [Abstracts]
TI: Transformations of Model Organic Compounds on Snow Grains at Summit, Greenland
AU: * Galbavy, E S
EM: esgalbavy@ucdavis.edu
AF: University of California at Davis, Department of Land, Air, and Water Resources, University of
California at Davis, One Shields AVE, Davis, CA 95616
United States
AU: Ram, K
EM: kerram@ucdavis.edu
AF: University of California at Davis, Department of Land, Air, and Water Resources, University of
California at Davis, One Shields AVE, Davis, CA 95616
United States
AU: Anastasio, C
EM: canastasio@ucdavis.edu
AF: University of California at Davis, Department of Land, Air, and Water Resources, University of
California at Davis, One Shields AVE, Davis, CA 95616
United States
AB:
Photochemical reactions in snowpacks produce a number of chemicals species that can significantly impact the overlying
atmosphere and transform many organic pollutants. During this past summer's field season at Summit we examined the kinetics
for the disappearance of a suite of model organic compounds in surface snowpack. Our compounds (2-nitrobenzaldehyde, sodium
benzoate, syringol, 4-chlorophenol, 2-oxo-butanoic acid, and phenanthrene) were chosen because they represent markers from
several different emission sources and because they have a range of expected fates, i.e., their lifetimes will be determined
by different processes. These processes include direct photolysis and reactions with oxidants such as hydroxyl radical (OH)
and singlet molecular oxygen (1O2*)
In addition to measuring the rates of loss of the model organics, we also measured concentrations of OH and
1O2* in the snow samples, as well as rates of direct photolysis of the organics in frozen, purified water.
Our goal was to compare the measured lifetimes of the organic compounds with calculated lifetimes based on reactions with OH
and 1O2* and direct photolysis. While certain compounds behaved as expected, others decayed more slowly, or
more rapidly, than expected, indicating that other, unidentified, snow grain reactions and/or mechanisms are significant.
The rates of organic compound loss, the potential reasons for the observed differences, and the implications for lifetimes of
trace organic pollutants in polar regions will be discussed.
DE: 0736 Snow (1827, 1863)
DE: 3300 ATMOSPHERIC PROCESSES
DE: 9315 Arctic region (0718, 4207)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005