Evidence for biological shaping of hair ice

Abstract

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, 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.

Laboratory Strategies for Hydrate Formation in Fine‐Grained Sediments

“…In addition to variables explored with THF hydrate, gas transport plays a critical role on the evolving hydrate morphology when hydrate formation is gas limited. Some tomograms show a striped‐fibrous hydrate structure (Figure ) that resembles images reported for hydrate formation in pipe clogging studies (Makogon, ) and hair‐ice (Hofmann et al, ). However, the most salient characteristic observed in young hydrate lenses is their porous structure made of separate crystals/fibers (Figure : test 20; Figure : test 15 and also observed in tests 6, 9, 11, 12, and 16–22).…”

A hair ice observation in Devon

“…The earliest records of this phenomenon go back to the early twentieth century, when a paper was published on the suspected interaction between ice and fungus on wood on which hair ice was sighted (Wegener, ). This has recently been confirmed in detailed studies carried out in German forests (Hofmann et al, ), in which hair‐ice‐producing wood was treated with fungicides and hot water to prove that this would subsequently prevent the formation of hair ice.…”

“…There have been two recent sightings of this phenomenon at Buckland Abbey, the second of which was observed at 0830 gmt (0830 utc) on 12 January 2018. The weather conditions were damp and calm, and temperatures at the time of the observations were around 0°C, with noticeably lower temperatures in the valley where confirmed in detailed studies carried out in German forests (Hofmann et al, 2015), in which hair-ice-producing wood was treated with fungicides and hot water to prove that this would subsequently prevent the formation of hair ice.…”

Altitude affects the quality of the water-extractable organic matter (WEOM) from rhizosphere and bulk soil in European beech forests

“…The formula assignment was performed by an in-house developed calculation program using Scilab routines. The results obtained from the ESI FT-ICR MS were presented by plotting van Krevelen diagrams (Kim et al, 2003) of H/C versus O/C molar ratios of the CHO compounds (Hofmann et al, 2015). To estimate the proportion of WEOM components four regions were delineated within the diagrams according to Sleighter and Hatcher (2007) and Ohno et al…”