Meltwater-induced relocation of chemical species in Alpine firn

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Eichler, Ania ; Schwikowski, Margit ; Gäggeler, Heinz W. (2001)

In order to interpret glaciochemical records with respect to the history of air pollution, an understanding of post-depositional processes taking place in firn and ice is crucial. In a 13-m firn section of an Alpine ice core, we observed a drastic disturbance of the concentration records of certain ionic species which we attribute to the inflow of meltwater. This observation opened up the possibility to investigate the effects of leaching processes on the chemical composition of a natural firn layer. Species were leached with different efficiencies: Whereas the normal seasonal pattern of the concentrations of NH+4, F−, Cl−, and NO−3 and of the δ18O values was preserved, concentrations of K−, Na+, Mg2+, Ca2+, and SO2−4 were significantly decreased. From the patterns of the concentration ratios the elution sequence SO2−4>Ca2+∼Mg2+>K+∼Na+≫NO−3>NH+4∼F−>Cl− was established, which could be explained by ion rearrangement during snow metamorphism. An incorporation of the species Cl−, F−, NH+4, and NO−3 into the ice lattice during grain growth caused their least efficient scavenging by percolating meltwater. In contrast, the predominate exclusion of the ions SO2−4, Ca2+, Mg2+, K+, and Na+ from the ice lattice due to their low solubility in ice and the subsequent segregation at grain surfaces led to the fast removal of these species from the firn layer.DOI: 10.1034/j.1600-0889.2001.d01-15.x
  • References (44)
    44 references, page 1 of 5

    Bales, R. C., Davies, R. E. and Stanley, D. A. 1989. Ion elution through shallow homogeneous snow. Water Resources Research 25, 1869-1877.

    Brimblecombe, P., Tranter, M., Abrahams, P. W., Blackwood, I., Davies, T. D. and Vincent, C. E. 1985. Relocation and preferential elution of acidic solute through the snowpack of a small, remote, high-altitude Scottish catchment. Annals of Glaciology 7, 141-147.

    Brimblecombe, P., Clegg, S. L., Davies, T. D., Shooter, D. and Tranter, M. 1987. Observations of the preferential loss of major ions from melting snow and laboratory ice. Water Research 21, 1279-1286.

    Brimblecombe, P., Clegg, S. L., Davies, T. D., Shooter, D. and Tranter, M. 1988. The loss of halide and sulphate ions from melting ice. Water Res. 22, 693-700.

    BUWAL. 1999. NABEL -L uftbelastung 1998. Messresultate des Nationalen Beobachtungsnetzes f u¨r LuftfremdstoVe, Schriftenreihe Umwelt Nr. 311, Bundesamt f u¨r Umwelt, Wald und Landschaft (BUWAL), Bern, Switzerland, 194 pp.

    Colbeck, S. C. 1987. Snow metamorphism and classification. In: Seasonal snowcovers: physics, chemistry and hydrology (eds. H. G. Jones and W. J. Orville-Thomas). D. Reidel, Dortrecht, pp. 1-35.

    Cragin, J. H., Hewitt, A. D. and Colbeck, S. C. 1996. Grain-scale mechanisms influencing the elution of ions from snow. Atmospheric Environment 30, 119-127.

    Dansgaard, W. 1964. Stable isotopes in precipitation. T ellus 16, 436-468.

    Davis, R. E. 1991. Links between snowpack physics and snowpack chemistry. In: Seasonal snowpacks: processes of compositional change (eds. T. D. Davies, M. Tranter and H. G. Jones). Springer Verlag, Berlin, etc., pp. 115-138. (NATO ASI Series G: Ecological Sciences 28.)

    de Angelis, M. and Legrand, M. 1994. Origins and variations of fluoride in Greenland precipitation. Journal of Geophysical Research 99 (D1), 1157-1172.

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