Role Of Ice Research Articles

The Role of Ice and Latitude‐Dependent Mantling on Boulder Distributions Across the Martian Northern Lowlands

AbstractBoulders are ubiquitous on rocky planets and provide valuable information about planetary processes. The abundance, size, and distribution of boulders offer insights into the primary processes that form them and the secondary processes that modify their position and size. However, the roles of varying environmental processes, including cryospheric processes, are poorly known. In this study, we analyze over 20 million boulders in the northern lowlands of Mars (50–70°N) to evaluate their distribution and identify environmental factors that might influence their clustering. We used spatial statistics to quantify the degree of boulder clustering across the northern plains. We found two latitudinal trends: overall decreasing clustering with increasing latitude (50–70°N) and a sub‐trend of increased clustering at higher latitudes (65–70°N). Our findings suggest that boulder distribution patterns are linked to the latitude‐dependent mantle (LDM) and subsurface ice. Boulders exhibit higher spatial clustering at higher latitudes, where the ice is thick and continuously present, and the LDM is more pristine. Lower clustering occurs at lower latitudes or regions where the ice loss is likely during interglacial periods, and the LDM degrades, exposing more boulders of varying sizes. We also discovered an anomalous region where boulder clustering is nearly random, located on the edge of the Alba Mons Patera. This area displays distinct geophysical characteristics compared to the rest of the lowlands. Although these characteristics do not indicate a specific process for the variation of boulder distribution in this study, the data suggest a coupling between cryospheric processes and boulder evolution, warranting further research.

Assessment of thermal environment and thermal comfort in a typical composite ice shell building

Composite ice shell buildings are a special type of architecture found in severe cold regions and have played an important role in ice and snow tourism in recent years owing to their ability to offer tourists a romantic and novel experience. We conducted a field study to examine the thermal environment of a typical composite ice shell building in Harbin, China. In the unheated hall and separate small room, the indoor air had an average temperature and relative humidity of −20.64 °C and 76.94%, and −17.71 °C and 79.57%, respectively. Surface heat flux measurement of the north-facing building envelope revealed that the thermal properties of composite and plain ice differed significantly, suggesting that composite ice may have a lower thermal conductivity. The natural ventilation rate of 48,041 m3/h corresponded to an air change rate of 6.86 h−1, making the thermal environment highly susceptible to outdoor meteorological conditions. In addition, we conducted a questionnaire survey to study the thermal sensation and thermal comfort of the tourists. The results showed that the mean thermal sensation for the foot and head were approximately “cold " and “slightly cool”, respectively. The overall and mean thermal sensation for the hand were both between “cool” and “cold”, and the mean thermal comfort was approximately “slightly uncomfortable”. An adaptive thermal sensation prediction model suitable for composite ice shell buildings was developed through the study. These findings can assist in the design and construction of thermal environments that are better suited for short-term stays and specialty tourism.

Tracking cubic ice at molecular resolution.

Ice is present everywhere on Earth and has an essential role in several areas, such as cloud physics, climate change and cryopreservation. The role of ice is determined by its formation behaviour and associated structure. However, these are not fully understood1. In particular, there is a long-standing debate about whether water can freeze to form cubic ice-a currently undescribed phase in the phase space of ordinary hexagonal ice2-6. The mainstream view inferred from a collection of laboratory data attributes this divergence to the inability to discern cubic ice from stacking-disordered ice-a mixture of cubic and hexagonal sequences7-11. Using cryogenic transmission electron microscopy combined with low-dose imaging, we show herethe preferential nucleation of cubic ice at low-temperature interfaces, resulting in two types of separate crystallization of cubic ice and hexagonal ice from water vapour deposition at 102 K. Moreover, we identifya series of cubic-ice defects, including two types of stacking disorder, revealing the structure evolution dynamics supported by molecular dynamics simulations. The realization of direct, real-space imaging of ice formation and its dynamic behaviour at the molecular level provides an opportunity for ice research at the molecular level using transmission electron microscopy, which may be extended to other hydrogen-bonding crystals.

Genomic analysis reveals the role of integrative and conjugative elements in plant pathogenic bacteria

BackgroundICEs are mobile genetic elements found integrated into bacterial chromosomes that can excise and be transferred to a new cell. They play an important role in horizontal gene transmission and carry accessory genes that may provide interesting phenotypes for the bacteria. Here, we seek to research the presence and the role of ICEs in 300 genomes of phytopathogenic bacteria with the greatest scientific and economic impact.ResultsSeventy-eight ICEs (45 distinct elements) were identified and characterized in chromosomes of Agrobacterium tumefaciens, Dickeya dadantii, and D. solani, Pectobacterium carotovorum and P. atrosepticum, Pseudomonas syringae, Ralstonia solanacearum Species Complex, and Xanthomonas campestris. Intriguingly, the co-occurrence of four ICEs was observed in some P. syringae strains. Moreover, we identified 31 novel elements, carrying 396 accessory genes with potential influence on virulence and fitness, such as genes coding for functions related to T3SS, cell wall degradation and resistance to heavy metals. We also present the analysis of previously reported data on the expression of cargo genes related to the virulence of P. atrosepticum ICEs, which evidences the role of these genes in the infection process of tobacco plants.ConclusionsAltogether, this paper has highlighted the potential of ICEs to affect the pathogenicity and lifestyle of these phytopathogens and direct the spread of significant putative virulence genes in phytopathogenic bacteria.

Polar Amplification in Idealized Climates: The Role of Ice, Moisture, and Seasons

AbstractThe drivers of polar amplification are investigated by isolating the role of sea‐ice processes, moist energy transport, and the seasonal cycle of insolation in two models, an energy balance model and an idealized general circulation model. Compared to a simple ice‐albedo feedback (temperature‐dependent surface albedo), the addition of thermodynamic‐ice processes and the seasonal cycle of insolation profoundly affects seasonal polar warming. Climatologically limited‐extent ice in the warm season permits only small increases in absorbed solar radiation, producing weak warming, while thick, cold ice in the cold season enables a large radiatively forced response. Despite this enhanced winter warming, the annual‐mean polar amplification is modestly reduced by thermodynamic‐ice processes. When latent heat transport is disabled, polar amplification is further reduced by a factor of 1.8 across the range of ice representations, suggestive of a nearly additive warming by ice and moist‐transport processes.

Controls on Wintertime Nonbrightband Rain Rate and Frequency in California’s Northern Coast Ranges

AbstractNon-brightband (NBB) rain is a shallow, orographic precipitation that does not produce a radar brightband as a result of melting ice crystals. However, NBB rain is not the same as warm rain, which excludes ice from being involved in the microphysical growth of precipitation. Despite this difference, NBB rain is often treated as warm rain in the literature, and past studies have mostly ignored the role of ice. Here, we use two wet-seasons (2015-16 and 2016-17) at four precipitation observing sites in the Northern Coast Ranges of California to show the role of echo top height and ice in determining NBB rain intensity. It was found that NBB rain was only absent of brightbands 32-46% of the time depending on location of the site. Additionally, all NBB rain rates that exceeded 10 mm hr−1 exhibited observable brightbands during the hour period. We also define Growth Efficiency (GE) as the ability of shallow rain clouds to produce raindrops larger than drizzle size (D > 0.5 mm). High-GE rain drop size distributions were composed of fewer small drops and more large drops than low-GE rain, which was mostly drizzle. High-GE rain occurred with echo top heights above the freezing level where rapid growth of precipitation was observed by radar. Echo tops that only extended 1 km or less above the freezing level suggested hydrometeor growth from mixed-phase processes, indicating that ice may be present in coastal precipitation at warmer temperatures than previously considered.

Freeze-up, Break-up, and Colonial Circulation

This paper examines the place of ice and snow in the process of Euro-Canadian colonisation of what are today the Yukon and Northwest Territories. Using oral histories and accounts of Indigenous life experiences from the late nineteenth and early twentieth centuries, the paper opens with an examination of the ways in which ice and snow, freeze-up and break-up, were inextricable from wider social and cultural relationships between Indigenous northerners and otherthan-human nature. Intensified trade and missionary activity after the mid-nineteenth-century along the Mackenzie and Yukon rivers and their tributaries created new colonial geographies, rhythms, and knowledge. These paid close attention to the character of ice, the timing of freeze-up and break-up, and the transportation possibilities of the open water season especially. By examining the histories of a scarlet fever epidemic in 1865 and an influenza epidemic in 1928, this paper uses the role of ice and its transformations in shaping the movements of pathogens to trace emerging northern colonial ecologies between 1860 and 1930.

Mechanical Response of Nanocrystalline Ice-Contained Methane Hydrates: Key Role of Water Ice.

Water ice and gas hydrates can coexist in the permafrost and polar regions on Earth and in the universe. However, the role of ice in the mechanical response of ice-contained methane hydrates is still unclear. Here, we conduct direct million-atom molecular simulations of ice-contained polycrystalline methane hydrates and identify a crossover in the tensile strength and average compressive flow stress due to the presence of ice. The average mechanical shear strengths of hydrate-hydrate bicrystals are about three times as large as those of hydrate-ice bicrystals. The ice content, especially below 70%, shows a significant effect on the mechanical strengths of the polycrystals, which is mainly governed by the proportions of the hydrate-hydrate grain boundaries (HHGBs), the hydrate-ice grain boundaries (HIGBs), and the ice-ice grain boundaries (IIGBs). Quantitative analysis of the microstructure of the water cages in the polycrystals reveals the dissociation and reformation of various water cages due to mechanical deformation. These findings provide molecular insights into the mechanical behavior and microscopic deformation mechanisms of ice-contained methane hydrate systems on Earth and in the universe.

High yield, single crystal ice via the Bridgman method.

The surface chemistry of ice and of water is an important topic of study, especially given the role of ice and water in shaping the environment. Although snow, granular, and polycrystalline ice are often used in research, there are applications where large surface areas of a known crystallographic plane are required. For example, fundamental spectroscopy or scattering studies rely on large area samples of known crystalline orientation. In addition, due to its slower dynamics and decreased number of molecular configurations, ice can be viewed as a reduced complexity model for the complex hydrogen bonding environment found at the surface and within the bulk of liquid water. In our studies using Sum Frequency Generation (SFG) vibrational spectroscopy, we have shown that each crystalline face has a unique spectral signature and therefore a unique chemistry and chemical activity. A reliable, reproducible, high performance method of producing large single crystal samples is needed to support this surface chemistry research. The design, construction, and use of a computer-controlled, ice-growth machine based on the Stockbarger modified Bridgeman technique is described. The instrument reliably produces relatively large single crystals that are optically flawless (that is, no visible flaws when viewed in a crossed polarizer), and in very high yield. Success rates of 95% are typical. Such performance has not been observed in the literature.

New insights on the roles of ice, water and climate change in recent landscape development on Mars

ABSTRACTGround-ice exists widely on Mars and has been observed directly – the Phoenix Mars Lander revealed it in trenches only centimeters deep. The landscape surrounding Phoenix would not look out of place in the antarctic or in ice-age Europe – a stony plain patterned by a regular network of polygons. However, the generation of liquid water from ground-ice thaw on Mars is hotly debated. Models tell us that ground-ice on Mars cannot melt under current conditions, instead subliming directly to vapour without becoming liquid, and geomorphological evidence of sublimation is abundant. However, recent very high resolution images of Mars from HiRISE (High Resolution Imaging Science Experiment) now reveal suites of landforms consistent with ground-ice thaw and resulting liquid flows. These landforms first remind us of the importance of testing our models by observation, but might instead hint that the chemistry of Martian ground-ice allows it to thaw at unexpectedly low temperatures.

The role of ices in star-forming clouds

Ices play a critical role during the evolution of interstellar clouds. Their presence is ubiquitous in the dense molecular medium and their impact is not only limited to chemistry. Species adsorbed onto dust grains also affect cloud thermodynamics. It all depends on the interstellar conditions, the chemical parameters, and the composition of ice layers. In this work, I study the formation of ices by focusing on the interplay between gas and solid phase to determine their role on cloud evolution and star formation. I show that while the formation of ices greatly impacts the cloud chemistry, their role on the thermodynamics is more conservative, and their influence on star formation is only marginal.

Halogen activation via interactions with environmental ice and snow in the polar lower troposphere and other regions

Abstract. The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the regional atmospheric oxidizing capacity in specific situations. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media upon which marine algae live. This paper reviews the nature of environmental ice substrates that participate in halogen chemistry, describes the reactions that occur on such substrates, presents the field evidence for ice-mediated halogen activation, summarizes our best understanding of ice-halogen activation mechanisms, and describes the current state of modeling these processes at different scales. Given the rapid pace of developments in the field, this paper largely addresses advances made in the past five years, with emphasis given to the polar boundary layer. The integrative nature of this field is highlighted in the presentation of work from the molecular to the regional scale, with a focus on understanding fundamental processes. This is essential for developing realistic parameterizations and descriptions of these processes for inclusion in larger scale models that are used to determine their regional and global impacts.

Freezing Effect on Chirality Generation of DL-Alanine-N-Carboxy-Anhydride Oligomerization in Aqueous Solution

This article is concerned with a study of the role of ice in the synthesis of oligopeptides containing L- or D-enantiomeric excess (ee) from racemic alanine. With this aim, the oligomerization of DL-alanine-N-carboxyanhydride was investigated by keeping this activated derivative in liquid (+22 degrees C) or frozen (-20 degrees C) aqueous solutions for 30 days. The aqueous solution of the peptide mixtures were gel-filtered and the aliquots of the fractions were completely hydrolyzed to alanine monomers. These monomers were then derivatized with 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide (Marfey's reagent) and analyzed by RP-HPLC to reveal the occasional enantiomeric excess of L- or D-Ala. The mass spectrometry of the gel-filtered fractions pointed to open-chain peptide mixtures together with a slight amount of cyclic ones, where the residue numbers ranged between 5-8. Our studies indicated that an enantiomeric excess of L- or D-Ala appeared in some oligopeptide fractions. Their excesses were significantly larger in the frozen than liquid solution. Speculations are made as concerns the implications of our findings in the events of prebiotic chemistry.

Particles in the great Pinatubo volcanic cloud of June 1991: The role of ice

Pinatubo's 15 June 1991 eruption was Earth's largest of the last 25 years, and it formed a substantial volcanic cloud. We present results of analysis of satellite‐based infrared remote sensing using Advanced Very High Resolution Radiometer (AVHRR) and TIROS Operational Vertical Sounder/High Resolution Infrared Radiation Sounder/2 (TOVS/HIRS/2) sensors, during the first few days of atmospheric residence of the Pinatubo volcanic cloud, as it drifted from the Philippines toward Africa. An SO2‐rich upper (25 km) portion drifted westward slightly faster than an ash‐rich lower (22 km) part, though uncertainty exists due to difficulty in precisely locating the ash cloud. The Pinatubo clouds contained particles of ice, ash, and sulfate which could be sensed with infrared satellite data. Multispectral IR data from HIRS/2 were most useful for sensing the Pinatubo clouds because substantial amounts of both ice and ash were present. Ice and ash particles had peak masses of about 80 and 50 Mt, respectively, within the first day of atmospheric residence and declined very rapidly to values that were <10 Mt within 3 days. Ice and ash declined at a similar rate, and it seems likely that ice and ash formed mixed aggregates which enhanced fallout. Sulfate particles were detected in the volcanic cloud by IR satellites very soon after eruption, and their masses increased systematically at a rate consistent with their formation from SO2, which was slowly decreasing in mass during the same period. The initially detected sulfate mass was 4 Mt (equivalent to 3 Mt SO2) and after 5 days was 12–16 Mt (equivalent to 9–12 Mt SO2).

Ice–silicate fractionation among icy bodies due to the difference of impact strength between ice and ice–silicate mixture

Laboratory experiments on the impact disruption of ice–silicate mixtures were conducted to clarify the accretion process of small icy bodies. Since the icy bodies are composed of ice and silicates with various porosities, we investigated the effect of porosity on the impact disruption of mixtures. We tested the mixture target with the mass ratio of ice to silicate, 0.5 and with 5 different porosities (0, 12.5, 25, 32, 37%) at the impact velocities of 150 to 670 m/s. The silicate mass ratio was changed from 0 to 0.5 in steps of 0.1 at a porosity of 12.5% and a constant impact velocity of about 300 m/s. The impact strength of the mixture was found to decrease with increasing porosity and the silicate mass ratio between 0.1 and 0.5 could enhance the strength of the icy target. The observed dependence of the impact strength on the porosity is opposite to that observed for pure ice. This difference could play an important role in ice–silicate fractionation during the accretion process. Because, ice rich bodies are easily broken as the porosity decreases in their evolution, the collisional growth could be prohibited. On the other hand, among the silicate rich bodies the collisional growth could be enhanced.

River-Ice Ecology. II: Biological Aspects

River ice is an integral and important component of the flow regime in cold-regions environments. As demonstrated in a companion paper, it can significantly affect many of the hydrologic, geomorphic, and chemical characteristics of a river. Building on such a physical template, this paper reviews the related biological effects at all stages of winter ice cover, including the period of autumn cooling, initial freeze-up, main winter, and breakup. Special focus is placed on the role of ice in seasonal movements and avoidance behavior of fish and benthic organisms, the creation of unique in-channel and riparian habitats, the modification of aquatic and floodplain vegetation, and some river-ecology theories, including disturbance ecology and flood-pulse theory. Included is a comprehensive reference list, the most complete ever assembled on this subject.

Cryo-bioorganic chemistry: freezing effect on stereoselection of L- and DL-leucine cooligomerization in aqueous solution.

The chirality of L-/DL-leucine (50-50%) cooligomerization was investigated in liquid and frozen aqueous solutions. Cooligomerization was carried out by carbonyldiimidazole activation without initiator at an ambient (+ 22 degrees C) and frozen (- 18 degrees C) temperature, respectively. The separated samples obtained after different time intervals of treatment were completely hydrolyzed (HCl) and the diastereomeric L- and D-leucine derivates of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-L-alanine amide) were then traced and evaluated by RP-HPLC analysis. After 9 days of oligomerization, the L-Leu content was slightly enhanced in the liquid (57%) and somewhat more enhanced in the frozen (64%) samples. After 17 days, however, the L-Leu content had decreased in the liquid (53%) and frozen (56%) conditions. These L-enantiomer amplifications indicate that an L-antipode is preferentially incorporated into the alpha-helical turn of the oligomer in the earlier stage of cooligomerization, while, later, the D-antipode is also incorporated. The role of ice in the improved stereoselection is discussed. This is the first recorded example of the effect of freezing on stereoselection.

The role of ice in determining mixing intensity in Ellis Fjord, Vestfold Hills, East Antarctica

Mixing in Ellis Fjord, Vestfold Hills, East Antarctica, is controlled by processes which are influenced by the extent of ice formation. A study of water temperature and salinity at a site near the middle of the fjord was undertaken from May 1994 to February 1995 after a summer (1993–94) in which the ice cover of the fjord was largely retained. Vertical mixing resulting from the exclusion of salt during the limited winter formation of ice was insufficient to mix completely the non-meromictic basins of the fjord. In contrast, a previous study during a winter with far more ice production recorded much stronger vertical mixing throughout the fjord. Warming and freshening of the fjord during the 1994–95 summer, when the ice again did not melt significantly, was attributable to the flow of warmer, less saline water along the fjord. This process was probably related to the formation of tidal jets at the narrow and shallow entrance to the fjord, and was thus influenced by the ice conditions around the entrance. These jets would also have introduced significant amounts of extra-fjord water (along with any resident biota) into the fjord.

IL-12-induced IFN-gamma is dependent on caspase-1 processing of the IL-18 precursor.

IL-12 and IL-18 are IFN-gamma-inducing cytokines. In the present study, the role of endogenous IL-18 in the induction of IFN-gamma by IL-12 was investigated in mice. In the presence of a specific inhibitor of caspase-1 (also known as IL-1beta-converting enzyme, or ICE) IL-12-induced IFN-gamma from splenocytes was reduced by 85%. Using splenocytes from ICE-deficient mice, IL-12-induced IFN-gamma was reduced by 80%. However, the role of ICE was not through processing and release of IL-1beta. Neutralizing anti-IL-18 IgG reduced IL-12-induced IFN-gamma in splenocytes by 85%. Splenocytes cultured in vitro spontaneously released IL-18 into the extracellular compartment over time. Extracellular levels of IL-18 significantly correlated with IL-12-induced IFN-gamma and were reduced in cells obtained from ICE-deficient mice. In vivo, IL-12 administration increased circulating levels of IL-18 in wild-type mice but not in ICE-deficient mice. Both neutralization of IL-18 and ICE deficiency significantly reduced induction of circulating IFN-gamma in mice receiving IL-12. The IL-18 precursor was constitutively expressed in the livers and spleens of untreated mice. Furthermore, administration of IL-12 significantly increased liver-associated IL-18 levels. These data demonstrate that endogenous, ICE-cleaved IL-18 significantly contributes to induction of IFN-gamma by IL-12.

The Role of Debris-Rich Ice in Flow Near the Margins of Glaciers (Abstract)

The margins of many ice sheets and ice caps are marked by the presence of alternating layers of debris-laden and clean ice. The role of this ice in flow and sediment transport near the margins of glaciers has been the subject of considerable controversy between glacial geologists and glaciologists for over three decades.Glacial geologists (Goldthwait, 1951, 1960, 1971, 1975; Bishop, 1957; Souchez, 1967, Boulton, 1970, 1972; Hambrey, 1976) commonly refer to the debris-bearing ice bands as “thrust planes” or “shear planes”, apparently seeing them as reverse faults which transport rock debris from the glacier bed to the surface in a “conveyor-belt-like” manner (Goldthwait, 1975, p. 192). As supporting evidence for the shear-plane mechanism, glacial geologists have offered only qualitative observations and none seem to have actually observed it in action. Glaciologists on the other hand, particularly Weertman (1961), Hooke (1968; 1973), and Hooke and Hudleston (1978), have objected to this concept on physical grounds and have presented convincing arguments for doubting that it is mechanically sound. In spite of the controversy surrounding it, the shear-plane mechanism has gained wide acceptance among geologists and physical geographers and has been perpetuated in recent years through a number of popular introductory geology and physical geography textbooks (e.g. Embleton and King, 1975; Judson, Deffeyes, and Hargraves, 1976; Leet, Judson, and Kauffman, 1978; Press and Siever, 1982; Hamblin; 1982).