This title appears in the Scientific Report : 2015 
Evidence for biological shaping of hair ice
Hofmann, Diana (Corresponding author)
Preuss, G. / Mätzler, C.
Agrosphäre; IBG-3
Biogeosciences, 12 (2015) 14, S. 4261 - 4273
Katlenburg-Lindau [u.a.] Copernicus 2015
10.5194/bg-12-4261-2015
Journal Article
Terrestrial Systems: From Observation to Prediction
OpenAccess
OpenAccess
Please use the identifier: http://hdl.handle.net/2128/9006 in citations.
Please use the identifier: http://hdl.handle.net/2128/9014 in citations.
Please use the identifier: http://dx.doi.org/10.5194/bg-12-4261-2015 in citations.


Evidence for biological shaping of hair iceD. Hofmann1, G. Preuss2 and C. Mätzler31 Institute of Bio- and Geosciences, Forschungszentrum Jülich, Germany2 57555 Brachbach, Germany3 Institute of Applied Physics, University of Bern, SwitzerlandAn 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, respectively, suppresses the formation of hair ice. Fruiting bodies of Asco- and Basidiomycota are identified on hair-ice carrying wood. One species, Exidiopsis effusa (Ee), has been 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 at the wood surface. The fungus plays the role of shaping the ice hairs and to prevent 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 the main constituent. Further work is needed to clarify its role in hair-ice growth and to identify the recrystallisation inhibitor.