Skip to main content Accessibility help
×
×
Home

Dating of Ross Ice Shelf Cores by Chemical Analysis

  • Michael M. Herron (a1) and Chester C. Langway (a1)
Abstract

Seasonal variations in sodium concentrations have been measured on surface-pit snow samples and on firn and ice core samples from the Ross Ice Shelf, Antarctica. Site locations include J-9 (82° 22’ S., 168° 40’ W.), Roosevelt Island dome (79° 22’ S, 161° 40’ W), C-7-1 (78° 30’ S., 177° 00’ W.), and C-7-3 (78° 20’S., 179° 51’ E.). The predominant source for the Na is sea salt, indicated by greater concentration levels at seaward sites. Al concentrations of the order of only 10–9 g/g show that the input of continental dust is comparable to that at inland Antarctic locations, and that dust contributes only a negligibly small fraction of the Na on the shelf. Maximum Na concentrations occur in the winter or early spring, as is the case for Greenland ice. The annual accumulation-rate at J-9, determined by counting Na concentration peaks with depth, is 90 kg m–2 year–1, in agreement with rates determined radiometrically. Annual cycles in Na concentration are also detectable at depth in the J-9 ice core. It is suggested that Na concentration is a useful diagnostic criterion for distinguishing between East Antarctic ice (10–8 g Na/g), West Antarctic ice (30 × 10–9 g Na/g), and ice that fell as snow on the shelf itself (> 30 × 10–9g Na/g). The transition between snow that is chemically characteristic of the ice-shelf regime to snow of an inland regime is expected to occur near the 500 m elevation contour. This position is up to 200 km inland of the grounding line. A model is presented for the large-scale decrease in Na concentration with distance inland within the ice-shelf regime. Since deeper ice in Ross Ice Shelf cores originated generally further from the ocean, the up-stream origin of shelf ice may be estimated from the chemical profile. The Little America V ice-core chemistry profile shows no discontinuity as would be expected if a recent surge of West Antarctic ice had occurred.

Résumé

Les variations annuelles des concentrations en sodium ont été mesurées sur des échantillons de neige prélevés dans des sondages superficiels et sur des échantillons de glace et de névé issus du Ross Ice Shelf, Antarctique. Les points de prélèvement comprennent J-9 (82° 22’ S., 168° 40’ W.), Roosevelt Island (79° 22’ S., 161° 40’ W.), C-7-1 (78° 30’ S., 177° 00’ W.), et C-7-3 (78° 20’ S., 179° 51’ E.). La source principale de Na est le sel marin, comme l’indique les niveaux de plus grandes concentrations dans les sites face à la mer. Les concentrations en aluminium de l’ordre de seulement 10–9 g/g montrent que l’apport des poussères continentales est comparable à ce qu’il est dans les sites continentaux de l’Antarctique et que ces poussières ne contribuent que pour une fraction négligeable au Na dans la plateforme. Les plus grandes concentrations en Na se produisent en hiver ou au début du printemps comme c’est le cas pour la glace du Groenland. Le taux annuel d’accumulation en J-9 déterminé en comptant les maximums de concentration en Na quand on s’enfonce en profondeur, est de 90 kg/m2/an, résultats en accord avec les taux déterminés par radiométrie. Les cycles annuels de concentration en Na sont aussi détectables en profondeur dans les carottes de glace J-9. On suggère que la concentration en Na est un critère utilisable pour distinguer entre la glace de l’Est Antarctique (10–8 g Na/g), la glace de l’Ouest Antarctique (30 × 10–9 g Na/g) et la glace qui est tombée sous forme de neige sur la plateforme elle-même (>30× 10–9 g Na/g). La transition entre la neige, qui est chimiquement caractéristique du régime de la plateforme, à la neige d’un régime continental s'établie pense-t’on, aux environs de la ligne du niveau 500 m. Elle se situe à plus de 200 km vers l’intérieur à partir de la ligne de décollement. On présente un modèle de la décroissance à une grande échelle de la concentration en Na quand on va vers l’intérieur en restant dans le régime de la plateforme. Comme la glace plus profonde dans les échantillons du Ross Ice Shelf est en général d’origine océanique, on peut déceler les glaces venues du continent à partir du profil chimique. Les profils chimiques de carottes de glace de Little America V ne montrent pas des discontinuités auxquelles on pourrait s’attendre s’il y avait eu une récente crue de l’Ouest Antarctique.

Zusammenfassung

An Schneeproben aus oberflächlichen Schächten sowie an Firn- und Eiskernen aus dem Ross Ice Shelf, Antarktika, wurden die jahreszeitlichen Schwankungen der Sodium-Konzentration gemessen. Die Proben stammen von folgenden Stellen: J-9 (82° 22’ S., 168° 40’ W.), Roosevelt Island (79° 22’ S., 161° 40’ W.), C-7-1 (78° 30’ S., 177° 00’ W.) und C-7-3 (78° 20’ S., 179° 51’ E.). Die vorwiegende Quelle für das Natrium ist das Meersalz, was sich aus dem höheren Konzentrationsniveau in seewärts gelegenen Stellen ergibt. Aluminium-Konzentrationen in der Grössenordnung von nur 10–9 g/g zeigen, dass der Zustrom kontinentalen Staubes vergleichbar mit dem an innerantarktischen Stellen ist und dass Staub nur einen vernachlässigbaren Bruchteil des Natriums auf dem Schelfeis liefert. Die maximalen Na-Konzentrationen treten im Winter oder frühen Frühling auf, — genau wie im Grönlandeis. Die jährliche Akkumulationsrate in J-9, gewonnen aus Zählungen der Na-Konzentrationsspitzen nach der Tiefe, beträgt 90 kg m–2 pro Jahr, was mit radiometrisch gewonnenen Werten übereinstimmt. Jahreszyklen der Na-Konzentration lassen sich auch in den tiefen Teilen des J-9 Eiskernes feststellen. Die Na-Konzentration erweist sich als brauchbares diagnostisches Kriterium zur Unterscheidung von ostantarktischem Eis (10–8 g Na/g), westantarktischem Eis (30 × 10–9 g Na/g) und Eis, das als Schnee auf dem Schelfeis selbst fiel (>30× 10–9g Na/g). Der Übergang von Schnee, der chemisch charakteristisch für das Schelfeissystem ist, zu Schnee eines landeinwärtigen Systems, dürfte nahe der 500 m Höhenlinie liegen. Diese Position liegt bis zu 200 km landeinwärts der Aufsetzlinie. Es wird ein Modell für die grossräumige Abnahme der Na-Konzentration mit dem Abstand vom Schelfeisrand vorgelegt. Da tieferes Eis in der Ross Ice Shelf im allgemeinen von ozeanfernen Bereichen stammt, kann der Zustromcharakter von Schelfeis aus dem chemischen Profil abgeschätzt werden. Das chemische Profil des Eiskerns von Little America V zeigt keine Diskontinuität, die zu erwarten wäre, falls in jüngster Zeit ein Ausbruch des westantarktischen Eises stattgefunden hätte.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Dating of Ross Ice Shelf Cores by Chemical Analysis
      Available formats
      ×
      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Dating of Ross Ice Shelf Cores by Chemical Analysis
      Available formats
      ×
      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Dating of Ross Ice Shelf Cores by Chemical Analysis
      Available formats
      ×
Copyright
References
Hide All
Boutron, C., and Lorius, C. 1977. Trace element content in East Antarctica snow samples. [Union Géodésique et Géophysique Internationale. Association Internationale des Sciences Hydrologiques. Commission des Neiges et Glaces.] Symposium. Isotopes et impuretés dans les neiges et glaces. Actes du colloque de Grenoble, août/septembre, 1975, p. 164–71. (IAHS-AISH Publication No. 118.)
Boutron, C., and others. In press. Composition of aerosols deposited in snow at the South Pole, time dependency and sources, by Boutron, C. Martin, S. and Lorius, C.. [Paper presented at the ninth International Conference on Atmospheric Aerosols, Condensation and Ice Nuclei, held at Galway, Ireland, 21–27 September 1977.]
Bull, C. B. B. 1971. Snow accumulation in Antarctica. (In Quam, L.O., ed. Research in the Antarctic. A symposium presented at the Dallas meeting of the American Association for the Advancement of ScienceDecember 1968. Washington, D.C., American Association for the Advancement of Science, p. 367421.)
Clausen, H. B., and Dansgaard, W. 1977. Less surface accumulation on the Ross Ice Shelf than hitherto assumed. [Union Géodésique et Géophysique Internationale. Association Internationale des Sciences Hydrologiqnes. Commission des Neiges et Glaces.] Symposium. Isotopes et impuretés dans les neiges et glaces. Actes du colloque de Grenoble, août/septembre 1975, P. 172–76. (IAHS-AISH Publication No. 118.)
Cragin, J. H., and others. [c 1977.] Interhemispheric comparison of changes in the composition of atmospheric precipitation during the Late Cenozoic Era, [by] Cragin, J. H. Herron, M. M. Langway, C. C. Jr, and Klouda, G. [A.]. (In Dunbar, M. J., ed. Polar Oceans. Calgary, Alberta, Arctic Institute of North America, p. 617–31.)
Crary, A. P., and others. 1962. Glaciological studies of the Ross Ice Shelf, 1957–1960, by Crary, A. P. Robinson, E. S. Bennett, H. F. and Boyd, W. W. Jr, IGY Glaciological Report Series (New York), No. 6.
Dansgaard, W., and others. 1977. Stable isotope profile through the Ross Ice Shelf at Little America V, Antarctica, [by] Dansgaard, W. Johnsen, S. J. Clausen, H. B. Hammer, C. U. and Langway, C. C. Jr. [Union Géodésique et Géophysique Internationale. Association Internationale des Sciences Hydrologiques. Commission des Neiges et Glaces.] Symposium. Isotopes et impuretés dans les neiges et glaces. Actes du colloque de Grenoble, août/septembre 1975, p. 322–25. (IAHS-AISH Publication No. 118.)
Giovinetto, M. B., and Zumberge, J. H. 1967. The ice regime of the eastern part of the Ross Ice Shelf drainage system. Union de Géodésie et Géophysique Internationale. Association Internationale d’Hydrologie Scientijique. Assemblée générale de Berne, 25 sept.–7 oct. 1967 [Commission de Neiges et Glaces.] Rapports et discussions, p. 255–66. (Publication No. 79 de l’Association Internationale d’Hydrologie Scientifique.)
Gow, A. J. 1970, Deep core studies of the crystal structure and fabric of Antarctic glacier ice. U.S. Cold Regions Research and Engineering Laboratory. Research Report 282.
Haefeli, R. 1961. Contribution to the movement and form of ice sheets in the Arctic and Antarctic. Journal of Glaciology, Vol. 3, No. 30, p. 1133–50.
Heap, J. A., and Rundle, A. S. 1964. Snow accumulation on the Ross Ice Shelf, Antarctica. (In Mellor, M., ed. Antarctic snow and ice studies II. Washington, D.C., American Geophysical Union, p. 119–25. (Antarctic Research Series, Vol. 2.))
Herron, M. M., and Langway, C. C. jr., 1978. Seasonal variations in Ross Ice Shelf precipitation chemistry, Eos. Transactions, American Geophysical Union, Vol. 59, No. 4, p. 308. [Abstract.]
Herron, M. M., and Langway, C. C. jr., Unpublished. Glaciological regimes of the Ross Ice Shelf, Antarctica. [Presented to the SCAR Working Group on Glaciology, Mendoza, Argentina, 19 October 1976.]
Herron, M. M., and others. 1977. Atmospheric trace metals and sulfate in the Greenland ice sheet, [by] Herron, M. M. Langway, C. C. Jr, Weiss, H. V. and Cragin, J. H.. Geochimica et Cosmochimica Acta, Vol. 41, No. 7, p. 915–20
Hughes, T. J. 1973. Is the West Antarctic ice sheet disintegrating? Journal of Geophysical Research, Vol. 78, No. 33, p. 7884910.
Johnsen, S. J., and others. 1972. Oxygen isotope profiles through the Antarctic and Greenland ice sheets, [by] Johnsen, S. J. Dansgaard, W. Clausen, H. B. Langway, C. C. Jr. Nature, Vol. 235, No. 5339, p. 429–34.
Johnsen, S. J., and others. 1977. Microparticles in “Byrd” Station ice core: further comments on the paper by Thompson, L. G. Hamilton, W. L. and Bull, C. [B. B.] [by] Johnsen, S. J. Hammer, C. U. Reeh, N. Dansgaard, W.. Journal of Glaciology, Vol. 18, No. 78, p. 164. [Letter.]
Junge, C. E. 1963. Air chemistry and radioactivity. New York, Academic Press.
Junge, C. E., and Gustafson, P. E. 1957. On the distribution of sea salt over the United States and its removal by precipitation. Tellus, Vol. 9, No. 2, p. 164–73.
Koide, M., and Goldberg, E. D. 1971. Atmospheric sulfur and fossil fuel combustion. Journal of Geophysical Research, Vol. 76, No. 27, p. 7689–96.
Koide, M., and others. 1979. Depositional history of artificial radionuclides in the Ross Ice Shelf, Antarctica, [by] Koide, M. Michel, R. Goldberg, E. D. Herron, M. M. and Langway, C. C. Jr. Earth and Planetary Science Letters, Vol. 44, No. 2, p. 205–33.
Langway, C. C. jr, and Herron, M. M. 1977. Polar ice core analysis. Antarctic Journal of the United States, Vol. 12, No. 4, p. 152–54.
Langway, C. C. Jr, and others. 1974. Chemical profile of the Ross Ice Shelf at Little America V, Antarctica, by Langway, C. C. Jr, Herron, M. M. and Cragin, J. H.. Journal of Glaciology, Vol. 13, No. 69, p. 431–35.
Langway, C. C. Jr, and others. 1977. Seasonal variations of chemical constituents in annual layers of Greenland deep ice deposits, [by] Langway, C. C. Jr, Klouda, G. A. Herron, M. M. and Cragin, J. H.. [Union Gédoésique et Géophysique Internationale. Association Internationale des Sciences Hydrologiques. Commission des Neiges et Glaces.] Symposium. Isotopes et impuretés dans les neiges et glaces. Actes du colloque de Grenoble, août/septembre 1975, p. 302–06. (IAHS-AISH Publication No. 118.)
Murozumi, M., and Shimizu, H. 1972. Chemical constituents in the surface snow cover on the Mizuho Plateau—west Enderby Land area, East Antarctica, 1970–1971. (In Ishida, T., ed. Glaciological research program in Mizuho Plateau—west Enderby Land. Part 1, 1969–1971. Tokyo, Polar Research Center, National Science Museum, p. 132–34. (Japanese Antarctic Research Expedition. JARE Data Reports, No. 17 (Glaciology).))
Murozumi, M., and others. 1969. Chemical concentrations of pollutant lead aerosols, terrestrial dusts, and sea salts in Greenland and Antarctic snow strata, [by] Murozumi, M. Chow, T. J. and Patterson, C. Geochimica et Cosmochimica Acta, Vol. 33, No. 10, p. 1247–94.
Rand, J. H. 1975. 100-meter cores from the South Pole and the Ross Ice Shelf. Antarctic Journal of the United States, Vol. 10, No. 4, p. 150–51.
Rand, J. H. 1977. Ross Ice Shelf Project drilling, October–December 1976. Antarctic Journal of the United States, Vol. 12, No. 4, p. 150–51.
Stauffer, B., and Moell, M. 1977. Geochemical and isotope studies, Ross Ice Shelf Project. Antarctic Journal of the United States, Vol. 12, No. 4, p. 145–46.
Thomas, R. H. 1976. Thickening of the Ross Ice Shelf and equilibrium state of the West Antarctic ice sheet. Nature, Vol. 259, No. 5540, p. 180–83.
Toba, Y. 1965. On the giant sea-salt particles in the atmosphere. I. General features of the distribution. Tellus, Vol. 17, No. 1, p. 131–45.
Tsunogoi, S. 1975. Sea salt particles transported to the land. Tellus, Vol. 27, No. 1, p. 5158.
U.S. Geological Survey. 1972. Map of the Ross Ice Shelf. Washington, D.C., U.S. Geological Survey and National Science Foundation. [Scale 1 : 1000 000, also 1 : 2188 800.]
Warburton, J. A., and Linkletter, G, O. 1977. Precipitation-forming mechanisms and the chemistry of precipitation on the Ross Ice Shelf, Antarctica. [Union Géodésique et Géophysique Internationale. Association Internationale des Sciences Hydrologiques. Commission des Neiges et Glaces.] Symposium. Isotopes et impuretés dans les neiges et glaces. Actes du colloque de Grenoble, août/septembre 1975, p. 8894. (IAHS-AISH Publication No. 118.)
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Glaciology
  • ISSN: 0022-1430
  • EISSN: 1727-5652
  • URL: /core/journals/journal-of-glaciology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed