17 17 O proxy of anthropogenic O proxy of anthropogenic influences on atmospheric influences on atmospheric reactivity: Towards model reactivity: Towards model interpretation of the ice interpretation of the ice core record core record Becky Alexander, Rokjin J. Park, Daniel J. Jacob Harvard University Justin McCabe and Mark H. Thiemens University of California, San Diego Joël Savarino Laboratoire de Glaciologie et Geophysique de l’Environement American Chemical Society August 25, 2004
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17 O proxy of anthropogenic influences on atmospheric reactivity: Towards model interpretation of the ice core record Becky Alexander, Rokjin J. Park,
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1717O proxy of anthropogenic O proxy of anthropogenic influences on atmospheric influences on atmospheric reactivity: Towards model reactivity: Towards model
interpretation of the ice core recordinterpretation of the ice core recordBecky Alexander, Rokjin J. Park, Daniel J. Jacob
Harvard University
Justin McCabe and Mark H. Thiemens
University of California, San Diego
Joël Savarino
Laboratoire de Glaciologie et Geophysique de l’Environement
American Chemical Society
August 25, 2004
Source: National Ice Core Laboratory
OverviewOverview
Oxidation capacity of the atmosphere
17O sulfate
Greenland ice core record (Milcent and Site A)
GEOS-CHEM Model – What controls 17O variability in Arctic?
– How well does it agree with measurements?
Non-photochemical sulfate production in Arctic
Secondary Species
HNO3, HCHO, CO2, H2SO4, O3, …
Oxidizing Power of the AtmosphereOxidizing Power of the Atmosphere
VolcanoesMarine Biogenics
Biomass burning
Continental Biogenics
Primary Species H2S, SO2, CH4, CO, DMS, CO2, NO, N2O,
particulates
OH
Primary Emissions
NOx, Isoprene, SO2, CH4, …
Industry
hH2O
Current knowledge of the past Current knowledge of the past oxidative capacity of the atmosphereoxidative capacity of the atmosphere
Measurements
Year AD
Year AD
1870 1890 1910 1930 1950 1970 19900
10
20
30
40
50
60
O3 (
ppb)
H2O
2 (M
)
Sigg & Neftel, 1991
Summit
0
2
4
6
1750 20001850 19501800 1900
H2O2 O3
Source ofSource of 1717OO SulfateSulfateSO2 in isotopic equilibrium with H2O :
17O of SO2 = 0 ‰
1) SO32- + O3 (17O=35‰) SO4
2- 17O = 8.75 ‰
17O of SO42- a function relative amounts of OH, H2O2, and O3 oxidation