Volume 12, issue 14 | Copyright
Biogeosciences, 12, 4261-4273, 2015
https://doi.org/10.5194/bg-12-4261-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 22 Jul 2015

Research article | 22 Jul 2015

Evidence for biological shaping of hair ice

D. Hofmann1, G. Preuss2, and C. Mätzler3 D. Hofmann et al.
  • 1IBG-3: Agrosphere, Institute of Bio- and Geosciences, Forschungszentrum Jülich, Jülich, Germany
  • 2Birkenweg 7, 57555 Brachbach, Germany
  • 3Institute of Applied Physics, University of Bern, Bern, Switzerland

Abstract. An unusual ice type, called hair ice, grows on the surface of dead wood of broad-leaf trees at temperatures slightly below 0 °C. We describe this phenomenon and present physical, chemical, and biological investigations to gain insight in the properties and processes related to hair ice. Tests revealed that the biological activity of a winter-active fungus is required in the wood for enabling the growth of hair ice. We confirmed the fungus hypothesis originally suggested by Wegener (1918) by reproducing hair ice on wood samples. Treatment by heat and fungicide suppresses the formation of hair ice. Fruiting bodies of Asco- and Basidiomycota are identified on hair-ice-carrying wood. One species, Exidiopsis effusa (Ee), was present on all investigated samples.

Both hair-ice-producing wood samples and those with killed fungus show essentially the same temperature variation, indicating that the heat produced by fungal metabolism is very small, that the freezing rate is not influenced by the fungus activity, and that ice segregation is the common mechanism of ice growth on the wood surface. The fungus plays the role of shaping the ice hairs and preventing them from recrystallisation. Melted hair ice indicates the presence of organic matter. Chemical analyses show a complex mixture of several thousand CHO(N,S) compounds similar to fulvic acids in dissolved organic matter (DOM). The evaluation reveals decomposed lignin as being the main constituent. Further work is needed to clarify its role in hair-ice growth and to identify the recrystallisation inhibitor.

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We investigated an unusual ice type, called hair ice. It grows on the surface of dead wood of broad-leaf trees at temperatures slightly below 0°C. We describe this phenomenon and present our biological, physical, and chemical investigations to gain insight in the properties and processes related to hair ice: we found, that a winter-acive fungus in the wood is required. Ice segregation is the common mechanism. Chemical analyses show a complex mixture of several thousand lignin/tannin compounds.
We investigated an unusual ice type, called hair ice. It grows on the surface of dead wood of...
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