Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 3 2009 10.5194/acpd-9-12559-2009 http://www.atmos-chem-phys-discuss.net/9/12559/2009/ http://www.atmos-chem-phys-discuss.net/9/12559/2009/acpd-9-12559-2009.html http://www.atmos-chem-phys-discuss.net/9/12559/2009/acpd-9-12559-2009.pdf 12559 12596 2009-05-27 Photolytic control of the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling M. M. Frey maey@bas.ac.uk J. Savarino S. Morin J. Erbland J. M. F. Martins CNRS – Institut National des Sciences de l'Univers (INSU), France Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Joseph Fourier-Grenoble, St Martin d'Hères, France Laboratoire d'Etude de Transferts en Hydrologie et Environnement, Université Joseph Fourier-Grenoble, St Martin d'Hères, France now at: British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom The nitrogen (δ¹⁵N) and triple oxygen (δ^17/18O) isotopic composition of nitrate (NO₃^−) was measured year-round in the atmosphere and snow pits at Dome C (DC, 75.1° S, 123.3° E), and in surface snow on a transect between DC and the coast. Snow pit profiles of δ¹⁵N (δ¹⁸O) in NO₃^− show significant enrichment (depletion) of >200 (<40) ‰ compared to the isotopic signal in atmospheric NO₃^−, whereas post-depositional fractionation in Δ¹⁷O(NO₃^−) is small, allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find in the DC04 (DC07) pit fractionation factors ε of −50±10 (−71±12) ‰, 6±3 (9±2) ‰ and 1±0.2 (2±0.6) ‰, for δ¹⁵N, δ¹⁸O and Δ¹⁷O, respectively. A photolysis model reproduces ε for δ¹⁵N within the range of uncertainty at DC and for lab experiments reported by Blunier et al. (2005), suggesting that the current literature value for photolytic isotopic fractionation in snow is significantly underestimated. Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, ¹⁵N enrichment of the NO₃^− fraction in the snow implies ¹⁵N depletion of emissions. Indeed, δ¹⁵N in atmospheric NO₃^− shows a strong decrease from background levels (4.4±6.8‰) to −35.1‰ in spring followed by recovery during summer, consistent with significant snow pack emissions of reactive nitrogen. Field and lab evidence therefore suggest that photolysis dominates fractionation and associated NO₃^− loss from snow in the low-accumulation regions of the East Antarctic Ice Sheet (EAIS). The Δ¹⁷O signature confirms previous coastal measurements that the peak of atmospheric NO₃^− in spring is of stratospheric origin. After sunrise photolysis drives then redistribution of NO₃^− from the snowpack photic zone to the atmosphere and a snow surface skin layer, thereby concentrating NO₃^− at the surface. Little NO₃^− is exported off the EAIS plateau, still snow emissions from as far as 600 km inland can contribute to the coastal NO₃^− budget. Anastasio, C., Galbavy, E S., Hutterli, M A., Burkhart, J F., and Friel, D K.: Photoformation of hydroxyl radical on snow grains at Summit, Greenland, Atmos. Environ., 41, 5110–5121, 2007. Baertschi, P.: Absolute $^18$O content of the Standard Mean Ocean Water, Earth Planet. Sc. Lett., 31(3), 341–344, 1976. Begun, G M. and Fletcher, W H.: Partion function ratios for molecules containing nitrogen isotopes, J. Chem. Phys., 33, 1083–1085, 1960. Blunier, T., Floch, G L., Jacobi, H W., and Quansah, E.: Isotopic view on nitrate loss in Antarctic surface snow, Geophys. Res. Lett., 32, L13501, \doi10.1029/2005GL023011, 2005. Böhlke, J K., Mroczkowski, S J., and Coplen, T B.: Oxygen isotopes in nitrate: new reference materials for $^18$O:$^17$O:$^16$O measurements and observations on nitrate-water equilibration, Rapid Commun. Mass Sp., 17, 1835–1846, 2003. Boxe, C. S. and Saiz-Lopez, A.: Multiphase modeling of nitrate photochemistry in the quasi-liquid layer (QLL): implications for NO_x release from the Arctic and coastal Antarctic snowpack, Atmos. Chem. Phys., 8, 4855–4864, 2008. Casciotti, K L.: Inverse kinetic isotope fractionation during bacterial nitrite oxidation, Geochim. Cosmochim. Ac., 73, 2061–2076, \doi10.1016/j.gca.2008.12.022, 2009. Casciotti, K L., Sigman, D M., Hastings, M G., Bohlke, J K., and Hilkert, A.: Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method, Anal. Chem., 74, 4905–4912, 2002. Chakraborty, T., Bajpai, P K., and Verma, A L.: Room temperature spectroscopic investigations of K$^14$NO₃, K$^15$NO₃, KNO$_3-x$$^18$O$_x$ and a 1 : 1 mixture of K$^14$NO₃ and K$^15$NO₃: Intermolecular coupling revealed in the vibrational spectra, J. Raman Spectrosc., 30, 189–194, 1999. Chu, L. and Anastasio, C.: Quantum yields of hydroxyl radical and nitrogen dioxide from the photolysis of nitrate on ice, J. Phys. Chem. A, 107, 9594–9602, 2003. Criss, R E.: Principles of stable isotope distribution, Oxford University Press, 1999. Davis, D D., Seelig, J., Huey, G., Crawford, J., Chen, G., Wang, Y H., Buhr, M., Helmig, D., Neff, W., Blake, D., Arimoto, R., and Eisele, F.: A reassessment of Antarctic plateau reactive nitrogen based on ANTCI 2003 airborne and ground based measurements, Atmos. Environ., 42, 2831–2848, \doi10.1016/j.atmosenv.2007.07.039, 2008. Dery, S J. and Yau, M K.: Large-scale mass balance effects of blowing snow and surface sublimation, J. Geophys. Res., 107, 4679, \doi10.1029/2001JD001251, 2002. Dibb, J E. and Fahnestock, M.: Snow accumulation, surface height change, and firn densification at Summit, Greenland: Insights from 2 years of in situ observation, J. Geophys. Res., 109, D24113, \doi10.1029/2003JD004300, 2004. Dibb, J E., Whitlow, S I., and Arsenault, M.: Seasonal variations in the soluble ion content of snow at Summit. Greenland: Constraints from three years of daily surface snow samples, Atmos. Environ., 41, 5007–5019, \doi10.1016/j.atmosenv.2006.12.010, 2007. Frey, M M., Stewart, R W., McConnell, J R., and Bales, R C.: Atmospheric hydroperoxides in West Antarctica: links to stratospheric ozone and atmospheric oxidation capacity, J. Geophys. Res., 110, D23301, \doi10.1029/2005JD006110, 2005. Frey, M M., Bales, R C., and McConnell, J R.: Climate sensitivity of the century-scale hydrogen peroxide (H₂O₂) record preserved in 23 ice cores from West Antarctica, J. Geophys. Res., 111, D21301, \doi10.1029/2005JD006816, 2006. Frey, M. M., Savarino, J., Erbland, J., and Morin S., in preparation, 2009. Freyer, H D., Kobel, K., Delmas, R J., Kley, D., and Legrand, M R.: First results of $^15$N/$^14$N ratios in nitrate from alpine and polar ice cores, Tellus B, 48, 93–105, 1996. Frezzotti, M., Pourchet, M., Flora, O., Gandolfi, S., Gay, M., Urbini, S., Vincent, C., Becagli, S., Gragnani, R., Proposito, M., Severi, M., Traversi, R., Udisti, R., and Fily, M.: New estimations of precipitation and surface sublimation in East Antarctica from snow accumulation measurements, Clim. Dynam., 23, 803–813, \doi10.1007/s00382-004-0462-5, 2004. Gallet, J C., Arnaud, L., and Domine, F.: Specific surface area of snow at Dome C, Antarctica. Rates of change for timescales from 1 day to 60 years, Geophys. Res. Abstr., EGU2009-4270, 2009. Grannas, A. M., Jones, A. E., Dibb, J., Ammann, M., Anastasio, C., Beine, H. J., Bergin, M., Bottenheim, J., Boxe, C. S., Carver, G., Chen, G., Crawford, J. H., Dominé, F., Frey, M. M., Guzmán, M. I., Heard, D. E., Helmig, D., Hoffmann, M. R., Honrath, R. E., Huey, L. G., Hutterli, M., Jacobi, H. W., Klán, P., Lefer, B., McConnell, J., Plane, J., Sander, R., Savarino, J., Shepson, P. B., Simpson, W. R., Sodeau, J. R., von Glasow, R., Weller, R., Wolff, E. W., and Zhu, T.: An overview of snow photochemistry: evidence, mechanisms and impacts, Atmos. Chem. Phys., 7, 4329–4373, 2007. Guillory, W A. and Bernstein, M L.: Infrared-Spectrum of matrix-isolated nitric acid, J. Chem. Phys., 62, 1058–1060, 1975. Hastings, M G., Steig, E J., and Sigman, D M.: Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores, J. Geophys. Res., 109, D20306, \doi10.1029/2004JD004991, 2004. Hastings, M G., Sigman, D M., and Steig, E J.: Glacial/interglacial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core, Global Biogeochem. Cy., 19, GB4024, \doi10.1029/2005GB002502, 2005. Heaton, T. H E., Wynn, P., and Tye, A M.: Low $^15$N/$^14$N ratios for nitrate in snow in the High Arctic (79°N), Atmos. Environ., 38, 5611–5621, \doi10.1016/j.atmosenv.2004.06.028, 2004. Huber, J R.: Photochemistry of molecules relevant to the atmosphere: Photodissociation of nitric acid in the gas phase, ChemPhysChem, 5, 1663–1669, \doi10.1002/cphc.200400071, 2004. Hudson, P K., Shilling, J E., Tolbert, M A., and Toon, O B.: Uptake of nitric acid on ice at tropospheric temperatures: Implications for cirrus clouds, J. Phys. Chem. A, 106, 9874–9882, \doi10.1021/jp020508j, 2002. Jacobi, H W., Annor, T., and Quansah, E.: Investigation of the photochemical decomposition of nitrate, hydrogen peroxide, and formaldehyde in artificial snow, J. Photoch. Photobio. A, 179, 330–338, 2006. Jarvis, J C., Steig, E J., Hastings, M G., and Kunasek, S A.: Influence of local photochemistry on isotopes of nitrate in Greenland snow, Geophys. Res. Lett., 35, L21804, \doi10.1029/2008GL035551, 2008. Kaiser, J., Hastings, M G., Houlton, B Z., Röckmann, T., and Sigman, D M.: Triple Oxygen Isotope Analysis of Nitrate Using the Denitrifier Method and Thermal Decomposition of N₂O, Anal. Chem., 79, 599–607, \doi10.1021/ac061022s, 2007. Kunasek, S A., Alexander, B., Steig, E J., Hastings, M G., Gleason, D J., and Jarvis, J C.: Measurements and modeling of $\Delta^17$O of nitrate in snowpits from Summit, Greenland, J. Geophys. Res., 113, D24302, \doi10.1029/2008JD010103, 2008. Legrand, M R. and Delmas, R J.: Soluble impurities in four Antarctic ice cores over the last 30 000 years, Ann. Glaciol., 10, 116–120, 1988. Legrand, M R., Wolff, E W., and Wagenbach, D.: Antarctic aerosol and snow fall chemistry: Implications for deep Antarctic ice core chemistry, Ann. Glaciol., 29, 66–72, 1999. Li, W J., Ni, B L., Jin, D Q., and Zhang, Q G.: Measurement of the absolute abundance of oxygen-17 in V-SMOW, Kexue Tongbao – Chinese Sci. Bull., 33, 1610–1613, 1988. Madronich, S. and Flocke, S.: The role of solar radiation in atmospheric chemistry, in: Handbook of Environmental Chemistry, edited by: Boule, P., Springer Verlag, Heidelberg, 1–26, 1998. Majoube, M.: Fractionation factor of $^18$O between water vapour and ice, Nature, 226, 1242–1242, \doi10.1038/2261242a0, 1970. Mariotti, A.: Atmospheric nitrogen is a reliable standard for natural $^15$N abundance measurements, Nature, 303, 685–687, 1983. Masson-Delmotte, V., Hou, S., Ekaykin, A., Jouzel, J., Aristarain, A., Bernardo, R T., Bromwich, D., Cattani, O., Delmotte, M., Falourd, S., Frezzotti, M., Gallee, H., Genoni, L., Isaksson, E., Landais, A., Helsen, M M., Hoffmann, G., Lopez, J., Morgan, V., Motoyama, H., Noone, D., Oerter, H., Petit, J R., Royer, A., Uemura, R., Schmidt, G A., Schlosser, E., Simoes, J C., Steig, E J., Stenni, B., Stievenard, M., van~den Broeke, M R., de~Wal, R. S. W V., de~Berg, W. J V., Vimeux, F., and White, J. W C.: A review of Antarctic surface snow isotopic composition: Observations, atmospheric circulation, and isotopic modeling, J. Climate, 21, 3359–3387, \doi10.1175/2007JCLI2139.1, 2008. McCabe, J R., Boxe, C S., Colussi, A J., Hoffmann, M R., and Thiemens, M H.: Oxygen isotopic fractionation in the photochemistry of nitrate in water and ice, J. Geophys. Res., 110, D15310, \doi10.1029/2004JD005484, 2005. McCabe, J R., Thiemens, M H., and Savarino, J.: A record of ozone variability in South Pole Antarctic snow: Role of nitrate oxygen isotopes, J. Geophys. Res., 112, D12303, \doi10.1029/2006JD007822, 2007. Meijer, H. A J. and Li, W J.: The use of electrolysis for accurate delta O-17 and delta O-18 isotope measurements in water, Isot. Environ. Healt. S., 34, 349–369, 1998. Miller, C E. and Yung, Y L.: Photo-induced isotopic fractionation, J. Geophys. Res., 105(D23), 29039–29051, 2000. Morin, S., Savarino, J., Frey, M M., Yan, N., Bekki, S., Bottenheim, J W., and Martins, J. M F.: Tracing the Origin and Fate of NO_x in the Arctic Atmosphere Using Stable Isotopes in Nitrate, Science, 322, 730–732, \doi10.1126/science.1161910, 2008. Morin, S., Savarino, J., Frey, M M., Domine, F., Jacobi, H.-W., Kaleschke, L., and Martins, J. M F.: Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65 S to 79 N, J. Geophys. Res., 114, D05303, \doi10.1029/2008JD010696, 2009. Mulvaney, R. and Wolff, E W.: Evidence for Winter Spring Denitrification of the Stratosphere in the Nitrate Record of Antarctic Firn Cores, J. Geophys. Res., 98(D3), 5213–5220, 1993. Mulvaney, R., Wagenbach, D., and Wolff, E W.: Postdepositional change in snowpack nitrate from observation of year-round near-surface snow in coastal Antarctica, J. Geophys. Res., 103, 11021–11031, 1998. Neumann, T A., Albert, M R., Lomonaco, R., Engel, C., Courville, Z., and Perron, F.: Experimental determination of snow sublimation rate and stable-isotopic exchange, Ann. Glaciol., 49, 1–6, 2008. Pettre, P., Pinglot, J F., Pourchet, M., and Reynaud, L.: Accumulation distribution in Terre Adelie, Antarctica – Effect of meteorological parameters, J. Glaciol., 32, 486–500, 1986. Pursell, C J., Everest, M A., Falgout, M E., and Sanchez, D D.: Ionization of nitric acid on ice, J. Phys. Chem. A, 106, 7764–7768, \doi10.1021/jp025697k, 2002. Rattigan, O., Lutman, E., Jones, R L., Cox, R A., Clemitshaw, K., and Williams, J.: Temperature-dependent absorption cross-sections of gaseous nitric acid and methyl nitrate, J. Photoch. Photobio. A, 66, 313–326, \doi10.1016/1010-6030(92)80003-E, 1992. Röthlisberger, R., Hutterli, M A., Sommer, S., Wolff, E W., and Mulvaney, R.: Factors controlling nitrate in ice cores: Evidence from the Dome C deep ice core, J. Geophys. Res., 105, 20565–20572, 2000. Röthlisberger, R., Hutterli, M A., Wolff, E W., Mulvaney, R., Fischer, H., Bigler, M., Goto-Azuma, K., Hansson, M E., Ruth, U., Siggaard-Andersen, M L., and Steffensen, J P.: Nitrate in Greenland and Antarctic ice cores: a detailed description of post-depositional processes, Ann. Glaciol., 35, 209–216, 2002. Sato, K., Takenaka, N., Bandow, H., and Maeda, Y.: Evaporation loss of dissolved volatile substances from ice surfaces, J. Phys. Chem. A, 112, 7600–7607, 2008. Savarino, J., Kaiser, J., Morin, S., Sigman, D. M., and Thiemens, M. H.: Nitrogen and oxygen isotopic constraints on the origin of atmospheric nitrate in coastal Antarctica, Atmos. Chem. Phys., 7, 1925–1945, 2007. Sigman, D M., Casciotti, K L., Andreani, M., Barford, C., Galanter, M., and Bohlke, J K.: A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater, Anal. Chem., 73, 4145–4153, 2001. Silva, S R., Kendall, C., Wilkison, D H., Ziegler, A C., Chang, C. C Y., and Avanzino, R J.: A new method for collection of nitrate from fresh water and the analysis of nitrogen and oxygen isotope ratios, J. Hydrol., 228, 22–36, 2000. Taylor, J R.: An Introduction to Error Analysis: The study of uncertainties in physical measurements, University Science Books, 2nd edn., 1997. Thibert, E. and Domine, F.: Thermodynamics and kinetics of the solid solution of HNO₃ in ice, J. Phys. Chem. B, 102, 4432–4439, 1998. Thomas, J L., Roeselova, M., Dang, L X., and Tobias, D J.: Molecular dynamics simulations of the solution-air interface of aqueous sodium nitrate, J. Phys. Chem. A, 111, 3091–3098, \doi10.1021/jpl0683972, 2007. Wagenbach, D., Legrand, M., Fischer, H., Pichlmayer, F., and Wolff, E W.: Atmospheric near-surface nitrate at coastal Antarctic sites, J. Geophys. Res., 103, 11007–11020, 1998. Wang, S Z., Bianco, R., and Hynes, J T.: Depth-dependent dissociation of nitric acid at an aqueous surface: Car-Parrinello molecular dynamics, J. Phys. Chem. A, 113, 1295–1307, \doi10.1021/jp808533y, 2009. Wolff, E W. and Delmas, R J.: Nitrate in Polar Ice, in: Ice Core Studies of Global Biogeochemical Cycles, edited by: Delmas, R J., Springer Verlag, NATO ASI Series I, 30, 195–224, 1995. Wolff, E W., Jones, A E., Martin, T J., and Grenfell, T C.: Modelling photochemical NO_x production and nitrate loss in the upper snowpack of Antarctica, Geophys. Res. Lett., 29(20), 1944, \doi10.1029/2002GL015823, 2002. Wolff, E. W., Jones, A. E., Bauguitte, S. J.-B., and Salmon, R. A.: The interpretation of spikes and trends in concentration of nitrate in polar ice cores, based on evidence from snow and atmospheric measurements, Atmos. Chem. Phys., 8, 5627–5634, 2008. Yung, Y L. and Miller, C E.: Isotopic fractionation of stratospheric nitrous oxide, Science, 278, 1778–1780, 1997.