Saline Ice Research Articles

Effective thermal conductivity of reservoir freshwater ice with attention to high temperature

AbstractA study on effective thermal conductivity (ETC) of natural ice in a reservoir with <3% gas content and ∼300 mg L−1 dissolved matter content in the parent water was conducted in a laboratory. Ice sections were prepared to obtain the ice crystal structure, gas bubble content and ice density. Profiles of horizontal and vertical thermal conductivity of ice samples were determined with attention to relatively high temperature spanning 0 to –10°C. A detailed comparative analysis was conducted of the effects on ETC of direction, ice crystal structure, gas bubbles and temperature. Gas inclusions had little impact on the thermal conductivity of natural reservoir ice due to their quite low content (<3%). At high ice temperature the ETC decreases remarkably as ice temperature approaches the melting point, as the ETC of sea ice does due to its brine volume at ice temperature approaching its melting point. The measured conductivities for temperatures higher than –4°C were less than expected from previous work on saline ice. Whether this was due to the measurement techniques or actual properties of the reservoir ice is not clear. The present findings could lead to better understanding of the thermal processes of ice in natural freshwater bodies.

The consolidation and bond strength of rafted sea ice

The consolidation and bond strength of rafted sea ice were investigated through a series of experiments undertaken in the Ice Physics Laboratory at the UCL. To simulate a section of rafted sea ice, blocks of laboratory grown saline ice were stacked in an insulated tank with spacers between adjacent blocks to allow saline water to flood in. The rate of consolidation was then monitored using a combination of temperature readings recorded in the ice and liquid layer, salinity measurements of the liquid layer, and cores taken at specific times of interest. Two states of consolidation were observed: thermodynamic consolidation where the ice blocks were physically bonded but the bond strength was weak, and mechanical consolidation where the bond had reached full strength. Results showed that the rafted ice had physically bonded in less than a day, however it took many more days (6 to 30 depending on the environmental conditions) for the bond to reach maximum strength. Increasing the thickness of the ice, the salinity of the water and the inter-block gap size all increased the consolidation time. Once consolidated, ice cores were taken and sheared using the asymmetric four-point bending method to measure the strength of the bond between the ice blocks. These were then compared to the shear strength of solid ice blocks simulating level sea ice. Our results show that the shear strength of the bond between the rafted ice blocks is about 30% weaker than that of level ice.

Ultralow elastic stability of salt ice at low temperatures

A model is developed to describe the elastic stability of saline ice with a homogeneous distribution of the components in the volume at high pressures (P > 0.1 GPa) and low temperatures (T < 220 K). This model is based on the basic principles of the theory of elastic percolation and the theory of ion hydration (formation of spherical clusters with water molecule dipoles oriented toward ions) in a liquid solution. This model can be used to find the dependence of the elastic stability of an ice solution on the concentration and temperature for any salts decomposing into ions with various valences and effective radii. Good agreement between the calculated and experimental dependences indicates the existence of hydration spheres in an ice solution, which is characterized by a narrower size distribution of spheres as compared to the liquid state and by a steeper decrease in the sphere size when the salt concentration increases in the range x ∼ 0.001–0.01. The stability of a solid ice solution depends on the temperature and the salt concentration in a complicated manner, having specific features in the form of maxima near phase transitions in a water matrix as a result of competing effects that enhance or weaken the elastic contributions of the frozen spheres. As follows from the model calculations, solid ice solutions can have an ultralow elastic stability (which is lower than that of pure water ice by a factor of 5–30), which was experimentally detected even at low weight fractions of salts at a level of x ∼ 0.0001–0.01 for T < 220 K.

Sea ice desalination under the force of gravity in low temperature environments

In winter 2009 and 2010, 9000m3 and 12,000m3 of sea ice, respectively, were collected from Bohai Bay and stored in a desalination pool. In 2009, the experiment lasted 80days, and produced 4500m3 of desalinated water with the salinity of 0.8‰. By contrast, the experiment of 2010 lasted 90days and yielded 6700m3 of water with the salinity of 1.4‰. Experimental results showed that under the force of gravity and low temperature, brine pockets within the sea ice were gradually drained out and sea ice was therefore converted from saline ice to freshwater ice. In this process, ambient temperature significantly affected drainage volume and salinity. When temperature rose, drainage volume increased and salinity decreased. Soluble salts decreased at different magnitudes during the course of gravity-induced desalination, in which chlorides showed the largest magnitude of decrease and sulfates the lowest. pH increased as a result of increasing sodium ion concentration. Insulation measures yielded higher rate of freshwater production by extending the duration of desalination. Shortening the period of desalination while maintaining high yield is worthy of further attention in studying gravity-induced sea ice desalination.

Ice Adhesion Tests on Pliable Polymer Sheets for Protection Against Sea-Water Spray Icing

Heavy sea-water spray icing is a major problem in the maintenance of lighthouses situated in northern harbors facing the Sea of Japan. Moreover, low ice adhesion materials or anti-icing coatings are ineffective over long periods. In this study, we have investigated the characteristics of saline ice adhesion on hydrophilic and hydrophobic pliable polymer sheets that can be used to envelop and thereby protect small lighthouses. We conducted experiments in cold room laboratories, and further, we verified the deicing conditions. Ice adhesion strength tests using fresh water indicated that a highly hydrophobic surface exhibited lower adhesion strength than other test materials. The results of saline ice adhesion tests at −20°C indicated that the adhesion strength decreases very rapidly as the salinity increases for all materials; this trend was particularly remarkable in case of superhydrophilic materials. The water spray icing tests were verified by experiments conducted using an ice model basin. Wet growth of ice occurred on all test specimens including the highly hydrophobic sheets. Furthermore, the initial icing depended significantly on the hydrophobic or hydrophilic surface properties. The icing on the hydrophobic surface was characterized by the formation of vertical streaks of ice; irregular projections could be observed on the ice surface. On the other hand, a thin fluid flow was formed on superhydrophilic surfaces. Exfoliation of pieces of the sheet ice was often observed during the initial growth. Deicing could be easily performed for both pliable polymer sheets. A combination of low ice adhesion property and rapid distortion was effective for the deicing of sea-water spray icing.

Surface structure and biocompatibility of demineralized dentin matrix granules soaked in a simulated body fluid

Demineralized dentin matrix (DDM) granules with excellent biocompatibility were easily prepared using unnecessary human teeth by a new cooling-pulverizing and demineralizing technique. Extracted human teeth were pulverized together with saline ice at 12,000rpm-rotation number of a ZrO2 blade for 30s in a ZrO2 vessel. The pulverized granules exhibited the particle size distribution of 0.5–2mm that was efficient for regeneration of alveolar bone. The (Ca/P) ratios of the granules were 1.60–1.66, which were close to the stoichiometric value of 1.67 for standard hydroxyapatite (HAp). Small amounts of Na+ and Mg2+ ions present at less than 1% were detected. The pulverized granules were dissolved with stirring under 500rpm for 10–60min in 2.0%-HNO3 solutions to obtain partial or complete DDM granules. As the dissolution time increased, crystallinity of HAp phase lowered and asperity on surfaces of the granules became outstanding due to elution of mineral components. At the dissolution of 60min, the pulverizing granules were completely demineralized and the weight decreased to about one-fifth. To improve surface activity of the DDM granules without denaturation of bone growth factors, the DDM granules were soaked at 309.5K and pH 7.40 in a simulated body fluid (SBF). HAp microcrystals were gradually precipitated on surfaces of the DDM granules with increasing the soaking time. Different morphology of the precipitates was observed, depending on the demineralization situation of the pulverized granules. For the DDM with low dissolution efficiency of 42%, porous bone-like apatites at 24h after the soaking and fiber-oriented aggregates at 144h were recognized. The bioactive DDM granules were implanted into the subcutaneous tissues of the back region of rats. At 4 weeks after the implantation, bio-absorption by comparatively small amounts of multi-giant cells was recognized around the surface layers of DDM granules.

Water and salt distribution in coastal saline soil after infiltration of melt-water of saline water ice with different sodium adsorption ratio

在室内利用相同矿化度(10 g·L^-1)、不同钠吸附比(5、10 和30)的咸水进行咸水结冰融水模拟试验、结冰融水入渗和咸水直接入渗的土柱试验, 以淡水处理为对照, 分析不同钠吸附比咸水结冰融水入渗下滨海盐土水盐分布特征。结果表明: 咸水冰融化过程中, 融出水的矿化度和钠吸附比均呈由高到低的变化趋势。咸水结冰融水入渗速度和入渗深度均快于和深于淡水。咸水钠吸附比越小, 结冰融水入渗速率越快、深度越深。水盐分布也表现为低钠吸附比咸水结冰处理的表层土壤含水量较低, 水分向深层迁移, 这种水分分布也使盐分向深层运移, 表现为表层土壤含盐量低, 深层土壤含盐量大。土层含水量低钠吸附比咸水处理高于高钠吸附比处理, 10~45 cm 土层则表现出相反的趋势; 表层土含盐量低钠吸附比处理高于高钠吸附比处理, 且咸水处理下土壤脱盐的深度大于淡水处理。钠吸附比5 的咸水结冰处理, 0~10 cm 土壤平均含水量和含盐量分别为30.3%和1.1 g·kg^-1, 显著低于其他处理。为比较咸水结冰灌溉和咸水直接灌溉的效果, 室内利用含盐量为10 g·L^-1、钠吸附比10 的咸水进行直接入渗的土柱(土壤含盐量为21.3 g·kg^-1)模拟试验, 结果表明: 与咸水直接入渗处理相比, 咸水结冰融水处理盐分淋洗效果更好, 该处理0~25 cm土层平均土壤含盐量为2.9 g·kg^-1, 显著低于咸水直接入渗的10.6 g·kg^-1。

A rate and state friction law for saline ice

Sea ice friction models are necessary to predict the nature of interactions between sea ice floes. These interactions are of interest on a range of scales, for example, to predict loads on engineering structures in icy waters or to understand the basin-scale motion of sea ice. Many models use Amonton's friction law due to its simplicity. More advanced models allow for hydrodynamic lubrication and refreezing of asperities; however, modeling these processes leads to greatly increased complexity. In this paper we propose, by analogy with rock physics, that a rate- and state-dependent friction law allows us to incorporate memory (and thus the effects of lubrication and bonding) into ice friction models without a great increase in complexity. We support this proposal with experimental data on both the laboratory (∼0.1 m) and ice tank (∼1 m) scale. These experiments show that the effects of static contact under normal load can be incorporated into a friction model. We find the parameters for a first-order rate and state model to be A = 0.310, B = 0.382, and μ0 = 0.872. Such a model then allows us to make predictions about the nature of memory effects in moving ice-ice contacts.

Selective retention in saline ice of extracellular polysaccharides produced by the cold-adapted marine bacterium Colwellia psychrerythraea strain 34H

AbstractThe retention of salts in laboratory-grown ice was compared to the retention of extracellular polysaccharide substances (EPS) produced by the cold-adapted marine gammaproteobacterium, Colwellia psychrerythraea strain 34H. Saline ice was formed, by means of a cold-finger apparatus, from artificial sea-water solutions containing either native dissolved EPS from strain 34H, the same EPS but heat-treated, or dissolved EPS from the uninoculated growth medium. Results indicated that only the native (unheated) EPS of strain 34H was retained preferentially in the ice. Temperature and volumetric measurements of the ice further suggested a link between the heat-labile fraction of this EPS of marine bacterial origin and potential habitat alteration. Bacterial EPS may join algal EPS in our understanding of how extracellular polymers help to establish and sustain the microbial community that inhabits sea ice.

Experimental studies on shear failure of freeze-bonds in saline ice:

Abstract This paper is the second of two papers that present and discusses the results from experiments where artificially created freeze-bonds made from saline ice were tested on direct shear with the freeze-bond oriented horizontally. It discusses the friction forces after freeze-bond failure and the failure energy. The friction force showed increasing linear trends with a non-zero intercept when plotted against the normal force. It shows that for low confinements Amonton's law is insufficient. For larger confinements the values of friction coefficient were in the range of previously reported measurements in ice–ice friction. A slightly decreasing trend of the frictional forces was found when the initial ice temperature increased. A Mohr–Coulomb type of model was proposed to model the ice–ice frictional stresses as function of the normal stresses. An empirical model was obtained to describe freeze-bond failure and subsequent deformation by introducing softening of the cohesion and angle of internal friction. The failure energy had similar trends to those observed for the freeze-bond shear strength when plotted against normal confinement, initial ice temperature and submersion time. Quadratic fitting to the data of failure energy as a function of freeze-bond shear strength allowed the estimation of the elastic shear modulus of the freeze-bond by applying a simple rheological model. The values found were between 2 kPa and 6 kPa which are very low compared with the shear elastic modulus for the ice blocks.

Experimental studies on shear failure of freeze-bonds in saline ice: Part I. Set-up, failure mode and freeze-bond strength

Abstract The strength of freeze-bonds in thin saline ice has been investigated through two series (in 2008 and 2009) of experiments in the Hamburg Ship Model Basin (HSVA) as a function of the normal confinement ( σ ), the submersion time (Δ t ) and the initial ice temperature ( T i ). The freeze-bonds were mostly formed in a submerged state, but some were also formed in air. The experimental set-up was improved in the 2009 experiments. In 2008 a ductile-like failure mode dominated (78%), whereas in 2009 the brittle-like dominated (93%). We suggest that this is a combined ice and test set-up effect. The 2009 experimental procedures allowed for careful sample handling giving higher strength and it was softer. Both these things should provoke a more brittle-like force–time response. The average freeze-bond strength in brittle-like samples was around 9 kPa while in ductile-like samples was around 2 kPa. The maximum freeze-bonds strength were measured for short submersion times, from 1 to 20 min, and reached a maximum value of 30 kPa. A Mohr–Coulomb like failure model was found appropriate to represent the freeze-bond shear strength as function of the normal confinement. Saline freeze-bonds in saline water had cohesion/friction angle around 4 and 1.4 kPa/25° for the brittle- and ductile-like samples respectively, which fitted well with previously published data. A bell-shape dependence for τ c vs. Δ t was found, which agreed with the predictions by Shafrova and Hoyland (2007). We suggest that this is essentially a freeze-bond porosity effect and propose three phases in time with subsequent cooling, heating and equilibrium to account for this trend. Qualitative experiments showed that the submersion time and the initial ice temperature were strongly coupled. To account for the connection between contact time, block dimensions and ice properties and the freeze-bond strength, dimensionless number were used. Fourier scaling was more appropriate than Froude scaling to scale freeze-bonds. The freeze-bonding made in air developed fast (in less than 30 s) when the ice was cold and dry, but no freeze-bonding occurred for the same contact times when the ice was warm and wet.

Low-Frequency Electrical Properties of Ice−Silicate Mixtures

The low-frequency electrical properties of mixtures of silicates and saline H(2)O were measured over broad ranges of temperature and frequency to assess the subfreezing interactions between these materials synoptically, particularly the effects of adsorbed, unfrozen water. Adsorbed water content was determined using nuclear magnetic resonance. Materials were chosen to control effects of grain size and mineralogical complexity, and the initial salt content was also specified. The temperature-dependent DC conductivity of a sand-salt-H(2)O mixture was found to be described well by Archie's law, with either brine or salt hydrate (above and below the eutectic, respectively) as the conductive and partially saturating phase. For materials with pore sizes less than a few micrometers, the brine/hydrate channels become disconnected, and the DC conductivity is controlled by the surrounding ice. High DC conductivity in a montmorillonite-H(2)O mixture is attributed to proton mobility in interlayer adsorbed water. The ice content of the sand mixture was recovered from the static dielectric permittivity using a power-law mixing model. Ice relaxation frequencies were higher than those observed in defect-saturated saline ice, indicating that additional defects are able to form in proximity to silicate surfaces. Five dielectric relaxations related to H(2)O were identified: two orientation polarizations (ice and adsorbed water), two Maxwell-Wagner interfacial polarizations (because of the conductivity differences between hydrate and silicate and adsorbed water and ice, respectively), and a low-frequency dispersion, probably caused by charge hopping. Thicknesses of a few H(2)O monolayers and the preference of hydronium for surface sites, making adsorbed water slightly acidic, favor protons as the mobile charges responsible for these adsorbed-water interfacial polarizations.

Superlow elastic stability of NaCl-H2O ice at 100–215 K

A superlow elastic stability of low-saline NaCl-H2O ice in a broad range of low temperatures (100–215 K) has been observed under the conditions of strong uniaxial compression. The level of elastic stability of the saline ice (containing a low mass fraction of NaCl within p = 0.0001–0.01) was 15–30 times smaller than in pure freshwater ice. This phenomenon can be used for the controlled production of steam, hydrogen, and oxygen using explosive fragmentation and in other low-temperature processes involving ice.

Therapeutic Hypothermia After Cardiac Arrest: A Simpler Approach

Guidelines recommend initiating therapeutic hypothermia as soon as possible after return of spontaneous circulation (ROSC) in patients with witnessed cardiac arrest, especially when the initial rhythm is ventricular tachycardia/ventricular fibrillation (VT/VF). Various instruments, such as surface-cooling suits, endovascular catheters, and cooling caps, have been used for this purpose. In a prospective observational study, researchers evaluated the effectiveness of cold saline infusion and ice packs for inducing and maintaining therapeutic hypothermia in 38 adult patients (mean age, 60) …

Low-Frequency Electrical Properties of Polycrystalline Saline Ice and Salt Hydrates

We measured the 1 mHz-1 MHz electrical properties of ice-hydrate binary systems formed from solutions of NaCl, CaCl(2), and MgSO(4), with supplementary measurements of HCl. Below the eutectic temperature, electrical parameters are well described by mixing models in which hydrate is always the connected phase. Above the eutectic temperature, a salt concentration threshold of approximately 3 mM in the initial solution is required for the unfrozen brine fraction to form interconnected, electrically conductive networks. The dielectric relaxation frequency for saline ice increases with increasing impurity content until Cl(-) reaches saturation. Because there is insufficient H(3)O(+) for charge balance, salt cations must be accommodated interstitially in the ice. Dielectric relaxations near the ice signature were identified for CaCl(2).6H(2)O and MgSO(4).11H(2)O but not for NaCl.2H(2)O. Ionic and L-defect concentrations in salt hydrates up to approximately 10(-4) and 10(-3) per H(2)O molecule, respectively, follow from the electrical properties, Jaccard theory, and the assumption that protonic-defect mobilities are similar to ice. These high defect concentrations-up to a few orders of magnitude greater than saturation values in ice-indicate that intrinsic disruption of hydrogen bonding in salt hydrates is common.

Infiltration of melting saline ice water in soil columns: Consequences on soil moisture and salt content

A soil column experiment was conducted to study the water and salt redistribution in a coastal saline soil under infiltration of saline ice meltwater. Four salinity levels (0, 5000, 10,000, and 15,000 mg l −1 diluted seawater) and three volumes (1800, 2700, and 3600 ml) of source water were used. The results indicated that the soil water content increased with the volume of applied ice. In the top soil layers, water content was higher under salt-free ice treatment than under saline ice treatments. In the deeper soil layers, however, the saline ice treatments showed higher water content than the salt-free ice treatment. While infiltration of meltwater reduced the salt content of the surface layer of all the treatments, the desalting depths of the saline ice treatments were greater than the desalting depth of the salt-free ice treatment. The results demonstrated that in the monsoon regions, saline soils could be improved through infiltration with meltwater of saline ice.

Effects of sample size, centrifugal acceleration and brine inclusions on the elastic modulus of sea ice

AbstractWe present a re-analysis of the results obtained from a series of measurements on freshwater and saline ice beams under various centrifugal accelerations. The data show a strong influence of beam size, brine volume and centrifugal acceleration on the elastic modulus of ice. The data suggest a transition brine volume at around 9%, which might occur close to the melting point, at which the elastic modulus of ice drops rapidly due to a possible change of brine-pocket structure. Furthermore, for brine volumes less than 9%, there is a negligible increase in the elastic modulus measured under high centrifugal acceleration, but for brine volumes more than 9% the increase is considerable, approaching that measured with freshwater ice. This may be due to necking of brine drainage channels just above the ice/water interface at high centrifugal acceleration. A model of sea ice was constructed based on existing theories of brine inclusions in sea ice, which satisfactorily predicts the observed trends.

Bacterial incorporation of leucine into protein down to −20 °C with evidence for potential activity in sub-eutectic saline ice formations

Direct evidence for metabolism in a variety of frozen environments has pushed temperature limits for bacterial activity to increasingly lower temperatures, so far to −20 °C. To date, the metabolic activities of marine psychrophilic bacteria, important components of sea-ice communities, have not been studied in laboratory culture, not in ice and not below −12 °C. We measured [ 3H]-leucine incorporation into macromolecules (further fractionated biochemically) by the marine psychrophilic bacterium Colwellia psychrerythraea strain 34H over a range of anticipated activity-permissive temperatures, from +13 to −20 °C, including expected negative controls at −80 and −196 °C. For incubation temperatures below −1 °C, the cell suspensions [all in artificial seawater (ASW)] were first quick-frozen in liquid nitrogen. We also examined the effect of added extracellular polymeric substances (EPS) on [ 3H]-leucine incorporation. Results showed that live cells of strain 34H incorporated substantial amounts of [ 3H]-leucine into TCA-precipitable material (primarily protein) down to −20 °C. At temperatures from −1 to −20 °C, rates were enhanced by EPS. No activity was detected in the killed controls for strain 34H (or in Escherichia coli controls), which included TCA-killed, heat-killed, and sodium azide- and chloramphenicol-treated samples. Surprisingly, evidence for low but significant rates of intracellular incorporation of [3H]-leucine into protein was observed for both ASW-only and EPS-amended (and live only) samples incubated at −80 and −196 °C. Mechanisms that could explain the latter results require further study, but the process of vitrification promoted by rapid freezing and the presence of salts and organic polymers may be relevant. Overall, distinguishing between intracellular and extracellular aspects of bacterial activity appears important to understanding behavior at sub-freezing temperatures.

A research about the cooling effect of using 10% saline ice bags in fever patients who have accepted the extracorporeal circulation operation

目的 探讨采用10%的盐水冰袋冰敷在体外循环术后高热患者物理降温中的效果.方法对124例体外循环术后高热患者的物理降温效果进行比较,研究组60例,应用10%的盐水冰袋作为物理降温的用具;对照组64例,使用传统的橡胶冰袋冰敷作为物理降温用具.记录降温后不同时间患者体温下降的情况.结果2组病例冰枕冰敷后0.5,1.5 h降温效果差异无显著性(P＞0.05);冰枕冰敷后2.5,4.0 h降温效果差异有显著性(P＜0.05).结论10%的盐水冰袋冰敷具有降温效果好、持续时间长,冰袋内为霜水,患者感觉舒适,值得临床推广应用。

Laparoscopic renal parenchymal hypothermia with novel ice-slush deployment mechanism

Objectives To report the development of a novel, simple-to-use method for laparoscopic deployment of fine-quality saline ice slush by way of a 10-mm end-effector for laparoscopic parenchymal hypothermia. Methods A mechanism for making fine ice slush was created, and a 10-mm laparoscopic end-effector was designed and constructed for deployment of the ice slush. The novel ice slush deployment system was tested in a porcine model and compared with that of standard open ice slush cooling. After atraumatic hilar clamping, the cortical and medullary temperatures in the upper, middle, and lower poles were measured with thermocouples. Results Six pigs were evaluated in each group. In all cases, the kidneys were successfully cooled to our goal temperature of 15° to 25°C within 10 minutes and were maintained at the target temperature for 1 hour. The core body temperature for the slush group was decreased by 3°C but did not change in the open group. The renal temperatures quickly returned to normal on unclamping of the renal hilum. One pig in the open group died of acidosis and another in the same group experienced thrombosis of the renal artery. No complications occurred in the laparoscopic group. Conclusions We describe a novel, simple-to-use mechanism for producing and delivering fine ice slush in a laparoscopic setting. The technique achieves optimal parenchymal hypothermia expeditiously.