Hair ice

Diana Hofmann1, Bernhard Steffen2, Ulrich Disko1, Gerhart Wagner3, Christian Mätzler4
1 Institute of Bio- and Geosciences, IBG-3: Agrosphere, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
2 Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
3 em. Professor University of Zurich, Institute for Zoology, Switzerland
4 em. Professor University of Bern, Institute for Applied Physics, Switzerland

P 7.10 in Controls of dissolved organic matter fluxes in ecosystems

Poster Session 1 on Monday, 16:30-18:30

Hair-ice is a rather unknown, natural phenomenon. In contrast to generally known frost needles, originating from atmospheric water, it grows from the basis of wet, rotten hardwood. The hair-like, flexible, linear structures may reach up to 10 cm in length without any ramifications. Hair-ice appears to be related to the biological activity of a fungus mycelium within the wood.

Hair-ice can attract winter-active insects. At the onset of hair-ice melt a very thin fibre becomes apparent, which carries brownish pearl-like water drops. Therefore, it is supposed that organic substances are inherent, which could possibly act as freezing catalyst as well as recrystallization inhibitor. Aim of this work was the chemical characterization of organic substances contained in hair-ice.

First analysis of melted hair-ice shows a total organic carbon value of 235 mg/l. Screened by different methods, no evidence could be found for initially expected proteins, lipids, small volatile substances or carboxylic acids. 

By coupling of Ultra Performance Liquid Chromatography with mass spectrometry (UPLC-MS), a non-resolved chromatogram from a melted hair-ice sample was received. Averaged spectra from different regions are similar among themselves with a broad peak spreading over the mass range 100-650 Da with favored intense, odd-numbered peaks. Such spectra are similar to dissolved organic matter, known e.g. from terrestrial/ marine waters, soil extracts or aerosols. In the next step, samples were desalted and concentrated by solid phase extraction and subsequently analyzed by flow injection analysis in an Electrospray-Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for the analysis of such complex samples due to its outstanding mass resolution and mass accuracy, simultaneously providing molecular level details of thousands of compounds. The characteristics of the FTICR-MS hair-ice spectra with as many as ten or more peaks at each nominal mass are discussed together with spectra from water/ soil samples different sources and guttation droplets of a tree fungus, respectively.

For sample classifying regarding polarity and aromaticity most important is the van Krevelen diagram, usually two-dimensional as atomic ratio H/C versus atomic ratio O/C. By comparison with two references (Hockaday; Sleighter), which arranged various biopolymer substance classes in such plots, lignin could be detected as the main hair-ice component. 

Letzte Änderung 19.06.2014