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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...
Contexts in source publication
Context 1
... parts of the wood. The hair curvature re- sults from lateral gradients in the growth velocity. The pri- mary direction is radial, the hairs being in the prolongation of wood rays (Fig. 2). Indeed, our observations indicate that the hairs are rooted at the mouths of these rays (Wagner and Mätzler, 2009). Furthermore, the hair-ice thickness (Fig. 3) corresponds to the diameter of the cells (Figs. 8 and 9 in Sect. 2) forming the channels in the wood rays (Schweingruber, ...
Context 2
... get an estimate of d we need the parameters on the right-hand side of Eq. (2). From Fig. 3 and similar obser- vations we find: d h ≈ 0.014 mm, N ≈ 20 mm −2 , and for the hair length we choose l h = 50 mm to get d = 0.15 mm for the crust thickness. The comparison is consistent with the two branches of Fig. ...
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Electrospray ionization (ESI) operating in negative mode coupled to high resolution mass spectrometry is the most popular technique for the characterization of dissolved organic matter (DOM). The vast molecular heterogeneity and the functional group diversity of this complex mixture prevents the efficient ionization of the organic material by a sin...
Citations
... However, there is little experimental evidence to support these ideas in the context of soil. To our knowledge, the most convincing evidence for an accumulation of water in the form of ice was described by Hofmann et al. (2015). Fascinating sculptures of hair ice can form on the surface of dead wood infected by the fungus Exidiopsis effusa through the mechanism of ice segregation. ...
... Although fungal activity is responsible for shaping hair ice, ice segregation proceeds under the same conditions without the fungus but then results in an ice crust. Temperatures recorded by Hofmann et al. (2015) inside and outside of wood samples showed that hair ice formation started when temperatures had decreased to about −0.5 • C in one experiment and to −2.5 • C in another experiment. In both cases, temperature inside the wood increased sharply after the onset of ice formation and stabilized near −0.2 • C through the heat released by ice formation, while temperature outside the wood continued to decrease. ...
... The same process of ice segregation as described by Hofmann et al. (2015) may also take place at the surface or within the porous structure of soil, where larger pores are typically air-filled and water is held in finer capillaries, similar to those supplying water to the hair ice growing on wood. Visible phenomena of water accumulating through ice segregation at or near the soil surface include ice needles and ice lenses (Dash et al., 2006). ...
Soil organic matter carries ice-nucleating particles (INPs) the origin of which is hard to define and that are active at slight supercooling. The discovery and characterization of INPs produced by the widespread soil fungus Mortierella alpina permits a more targeted investigation of the likely origin of INPs in soils. We searched for INPs with characteristics similar to those reported for M. alpina in 20 soil samples from four areas in the northern midlatitudes and one area in the tropics. In the 15 samples where we could detect such INPs, they constituted between 1 and 94 % (median 11 %) of all INPs active at -10 ∘C or warmer (INP-10) associated with soil particles < 5 µm. Their concentration increased overproportionately with the concentration of INP-10 in soil and seems to be greater in colder climates. Large regional differences and prevalently high concentrations allow us to make inferences regarding their potential role in the atmosphere and the soil.
... 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. ...
Hair ice is a rare type of ice formation that resembles thin strands of hair and is found only on rotting wood in specific weather conditions and locations. The peculiar formation of the ice is dependent on the presence of a particular fungus on dead wood from broadleaf woodland, which helps to shape the ice hairs and prevents them from recrystallising. This article details a recent sighting of hair ice at Buckland Abbey in Devon and describes this interesting and unusual phenomenon, as well as outlining the formation process.
... 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. (2010), to cluster the detected molecules within the typical ranges of ...
Water-extractable organic matter (WEOM) is the most dynamic and bioavailable fraction of the soil organic matter pool. Although the litter floor is considered the main source of WEOM, roots also release a great amount of labile organic compounds through rhizodeposition processes. This makes the rhizosphere, the small soil volume in proximity to the roots, a soil compartment relatively enriched in WEOM. Since both the rhizosphere and the labile organic C pool are highly sensitive to the environmental conditions we evaluated the characteristics of WEOM from rhizosphere and bulk soil collected from the A horizons of European beech (Fagus sylvatica L.) forest soils of Apennines mountains (central Italy) at two altitudes (800 and 1000 m), using elevation as a proxy for temperature change. Specifically, we tested if i) the rhizosphere contains higher amounts of WEOM with a greater diversity of compounds with respect to the bulk soil, and ii) this effect is more pronounced at higher altitude. At both 800 m and 1000 m above sea level, the main distinction between WEOM from rhizosphere and bulk soil was the larger amounts of sugars in the soil close to the roots. Further, our results indicated an influence of altitude on rhizospheric processes as suggested by the larger concentrations of organic C and soluble phenols, and richness of tannins in the rhizosphere WEOM than in the bulk soil at 1000 m. We attributed this influence to environmental constraints which enhanced the release of labile organics and secondary metabolites by rhizodeposition and humification processes in the rhizosphere. As a whole, our data draw a picture where the roots are able to affect the characteristics of WEOM and environmental constraints enhance the differentiation between rhizosphere and bulk soil. This view confirms the influence of the rhizosphere on the soil C cycle, and the importance of the rhizospheric processes when environmental conditions become harsher.
... 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 5) that resembles images reported for hydrate formation in pipe clogging studies (Makogon, 1997) and hair-ice (Hofmann et al., 2015). However, the most salient characteristic observed in young hydrate lenses is their porous structure made of separate crystals/fibers (Figure 2: test 20; Figure 6: test 15 and also observed in tests 6, 9, 11, 12, and 16-22). ...
Fine-grained sediments limit hydrate nucleation, shift the phase boundary, and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain-scale gas-storage within porous diatoms, ice-to-hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long-term guest molecule transport. Tomographic images and thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine-grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo-pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice-to-hydrate transformation goes through a liquid stage at premelt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time-dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate, and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine-grained sediments within the relatively short time scale available for laboratory experiments.
... This same mechanism produces up to 5 cm long crystals in 3 to 4 hours (Chapter 4, (Hofmann et al. 2015) . ...
Methane hydrates in marine and permafrost sediments are potential energy
resources (Boswell 2009; Collett 2002). The total amount of carbon trapped in gas
hydrate exceeds the sum of all other forms of conventional fossil fuels (Kvenvolden
1988). However, the dissociation of methane hydrates can accelerate climate change
(Archer 2007; Ruppel and Pohlman 2008), cause ground subsidence and trigger seafloor
landslides (Grozic 2010; Hornbach et al. 2007). Over 90% percent of the global hydrate
mass is found in fine-grained sediments (Boswell and Collett 2008). To date, there has
been minimal research in hydrate-bearing fine-grained sediments.
The central themes of this research are the fundamental understanding of hydrate
formation and dissociation in fine-grained sediments, and the associated physical
processes. The discussion ranges from the particle-scale to the macro-scale. This includes
the shift in the phase boundary associated to curvature effects, the particle-displacive
morphology, diffusion induced Leisegang bands and two hydrate formation patterns in
gas-filled openings. We develop laboratory techniques that emulate natural gas hydrate
formations. The experimental results illustrate the hydrate formation process via different
strategies that aim to accelerate the gas supply to the hydrate formation front. In addition,
simulations of physical properties of hydrate-bearing fine-grained sediments address the
segregated morphology of hydrates in fine-grained sediments and the change in physical
properties induced by cryogenic suction. We explore potential methods to produce gas
from hydrate-bearing fine-grained sediments. The analyses on gas production centers on
the technical viability of depressurization, thermal stimulation and chemical stimulation.
... Terrestrial hoar ice forms frost flowers, frost palisades, frost hair, and frost shawls because ice is extruded from liquid reservoirs by supercooled air (Arakawa, 1955;Mason et al., 1963;Lawler, 1993;Matthews, 1999, Wagner andMätzler, 2008). Experiments with fungi in wood show that fungi, such as Exidiopsis effusa (Basidiomycota, Auriculariales), promote frost hair by creating chambers and isolating liquid reservoirs (Hofmann et al., 2015). Uplifted clods and pellets, and sprays of needles radiating from organic objects and from depressions can be seen in some Ediacaran fossil slabs (Fig. 7b). ...
Not a single paleosol had been described from rocks of Ediacaran age until 2011, but 354 Ediacaran paleosols have been described by 20 different authors since then. Some of these newly recognized paleosols have proven controversial, so this paper reviews 20 distinct tests to determine whether a particular Ediacaran bed could be a paleosol, or not. One problem has been that Ediacaran paleosols are not precisely like modern soils because they lack root traces, a diagnostic feature of Silurian and geologically younger paleosols. The principal problem for recognition of some Ediacaran paleosols is the occurrence in them of megafossils assumed to have been marine, although most of these fossils remain problematic for both biological and ecological affinities. Not all the tests discussed here are diagnostic of paleosols, some are ranked permissive or persuasive. Permissive conditions for paleosols include ripple marks, hummocky bedding, pyritic limestones, acritarchs or thalloid fossils, low strontium isotopic ratios, high δ26Mg ratios, and red color. Persuasive tests include loessites, tsunamites, desert playa minerals, low boron content, high δ10B isotopic ratios, high carbon/sulfur ratios, and very low total/reactive iron ratios. Diagnostic tests include matrix-supported lapilli or crystal tuff parent materials, ice wedges and other cryoturbation, sepic birefringence fabrics, evaporitic sand crystals, and negative geochemical strain and mass transfer, and highly correlated δ13C and δ18O. Like other geological periods, the Ediacaran is known from a variety of marine and non-marine paleoenvironments
... More recently our understanding of the process has changed, thanks largely to the patient work of Wagner, Mätzler and others (Hofmann et al., 2015). It now seems that rather than being pushed up from below by the fungus the water is drawn to the surface by purely physical forces. ...
To study the source and content change of oridonin in the ice ribbons, the contents of oridonin in the ice ribbons and bleeding sap of Isodon rubescens at different times were determined with RP-HPLC. The paraffin sectioning and electron microscopy imaging were performed to study the transport channel of oridonin in the stem. The results showed that there were abundant xylem rays and perfect pit pairs in the secondary xylem of I. rubescens stems. The oridonin content in the ice ribbons of I. rubescens stems was lower than that in the stem of I. rubescens and even decreased over time. The contents of oridonin in the bleeding sap of I. rubescens stems was equal to that in second-day ice ribbons and was lower than that in first-day ice ribbons. The water in the ice ribbons of I. rubescens stems originated from water absorbed by the roots from soil. This water was transported from the roots of I. rubescens to the stem and then transferred through efficient lateral conducting tissues to the surface of the stem. The oridonin in the phloem and cortex of I. rubescens stems dissolves in water originating from the soil and freezes in the form of ice ribbons below 0 °C.
Owing to its unique structure, morphology, and crystal quality, low-dimensional (L-D) ice has attracted increasing attention in recent years. With a size (at least in one dimension) between that of a single water molecule and a snowflake, L-D ice does not only appear as an intermediate state during the dimensional change but can also manifest extraordinary characteristics, from its molecular structures to its physical properties, which offer exciting opportunities for a better understanding and utilization of ice. In this article, we start with a brief introduction to the crystal growth, structure, and typical characterization techniques of ice and then review recent progress in the study of crystal growth, molecular structures, phase morphologies, and physical properties of zero-, one-, and two-dimensional (0-, 1-, and 2D) ice. Extraordinary behaviors of ice in low dimensions and extreme conditions are highlighted. Finally, the future outlook for the physical study and technological applications of L-D ice is briefly discussed.
Expected final online publication date for the Annual Review of Materials Research, Volume 53 is July 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Mit ca. 50.400 Arten in ungefähr 2300 Gattungen sind die Basidiomyceten (wissenschaftlich Basidiomycota) nach den Ascomycota die zweitgrößte Abteilung der Fungi (◘ Abb. 2.1). Zu dieser Gruppe gehören die meisten Großpilze, darunter viele Speise- und Giftpilze. Das Schlüsselmerkmal der Arten der Basidiomycota ist die Basidie, eine Zelle, die als kleiner Ständer (lat. basidium = kleine Basis mit Füßen) meist jeweils vier Basidiosporen trägt.
