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Supplementary Material
Nitrate post-depositional processes in Svalbard surface snow
Mats P. Björkman 1,2,3*
, Carmen P. Vega
4 , Rafael Kühnel 1,2
, Francesca Spataro
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, Antonietta
Ianniello 5 , Giulio Esposito 5 , Jan Kaiser 6 , Alina Marca 6 , Andy Hodson 7 , Elisabeth Isaksson 1 and
Tjarda J. Roberts
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1 Norwegian Polar Institute, Norway. 2 University of Oslo, Norway. 3 Now at: University of
Gothenburg, Sweden.
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Uppsala University, Sweden.
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C.N.R.-Istituto sull’Inquinamento
Atmosferico (IIA), Italy.
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University of East Anglia, U.K.
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University of Sheffield, U.K.
8 Université d’Orléans, France.
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Figure S1: The nitrate photolytic rate ( J
NO3-
) estimated by France et al., (2010) as a function of the solar zenith angle (
θ
SZA
) during clear sky condition for Ny-Ålesund fresh surface snow.
Included as a line is the polynomial function (Eq. 7) used to calculate J
NO3-
for the top 5 cm of the snowpack during the spring 2010.
Figure S2: Box model results, using the photolytic rate function ( J
NO3-
, Eq. 7) and the dry deposition rate ( F model
(LND)). Given in a) is the modeled
δ t
for
18
O (Eq. 13) for the three isotopic deposition scenarios (
δ atm
) where; + 40 ‰ resembles the OH signal found in Greenland (Jarvis et al., 2009); + 75 ‰ resembles a mid-latitude signal (Morin et al., 2009); and + 100 ‰ resembles the influence of BrO chemistry (Morin et al., 2009). Also included in a) is the actual measured
δ ( 18 O) and co-occurring linear regression models ( lm, Table 1). Similarly b) gives the modeled δ t for
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N (Eq. 13) for the three isotopic deposition scenarios (
δ atm
) where; – 20 ‰ represents Polar basin air (Morin et al., 2009); – 13 ‰ represent ambient air (Amoroso et al., 2010); and + 5 ‰ represents a local biogeochemical signal (Amoroso et al.,2010). Also included in b) is the measured
δ
(
15
N) and developed lm
’s. Given in c) is the modeled c t
(Eq. 11 & 12) along with the measured c
NO3
and lm ’s. Furthermore, the fractionation sensitivity test is included as shaded areas around the box model results in a) and b).
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Figure S3: Atmospheric column content of BrO as given by GOME-2 satellite data (available at: http://www.iup.uni-bremen.de/doas/scia_data_browser.htm) here reproduced with the courtesy of Andreas Richter (University of Bremen). Further information on GOME-2 BrO data can be found in Begoin et al. (2010).
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References:
Amoroso, A., Domine, F., Esposito, G., Morin, S., Savarino, J., Nardino, M., Montagnoli, M., Bonneville,
J. M., Clement, J. C., Ianniello, A., and Beine, H. J., 2010: Microorganisms in Dry Polar Snow
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Are Involved in the Exchanges of Reactive Nitrogen Species with the Atmosphere.
Environmental Science & Technology, 44: 714-719.
Begoin, M., Richter, A., Weber, M., Kaleschke, L., Tian-Kunze, X., Stohl, A., Theys, N., and
Burrows, J. P., 2010: Satellite observations of long range transport of a large BrO plume in the
Arctic, Atmospheric Chemistry and Physics , 10: 6515-6526.
France, J. L., King, M. D., and Lee-Taylor, J., 2010: The importance of considering depth-resolved photochemistry in snow: a radiative-transfer study of NO
2
and OH production in Ny-Alesund
(Svalbard) snowpacks. Journal of Glaciology, 56: 655-663.
Frey, M. M., Savarino, J., Morin, S., Erbland, J., and Martins, J. M. F., 2009: Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling. Atmospheric Chemistry and Physics, 9: 8681-8696.
Jarvis, J. C., Hastings, M. G., Steig, E. J., and Kunasek, S. A., 2009: Isotopic ratios in gas-phase HNO
3 and snow nitrate at Summit, Greenland. Journal of Geophysical Research-Atmospheres, 114: -.
McCabe, J. R., Boxe, C. S., Colussi, A. J., Hoffmann, M. R., and Thiemens, M. H., 2005: Oxygen isotopic fractionation in the photochemistry of nitrate in water and ice. Journal of Geophysical
Research-Atmospheres, 110: D15310.
Morin, S., Savarino, J., Frey, M. M., Domine, F., Jacobi, H. W., Kaleschke, L., and Martins, J. M. F.,
2009: Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65 degrees S to 79 degrees N. Journal of Geophysical Research-Atmospheres, 114:
D05303.
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