Frozen Period Research Articles

Spatial-Temporal Characteristics and Influencing Factors of Lake Water and Groundwater Chemistry in Hulun Lake, Northeast China

Lakes in cold and arid regions are extremely vulnerable to global climate change, and the study of seasonal spatial and temporal fluctuations of lake-groundwater chemistry is of major significance for water resource management and environmental preservation. In this study, we combined hydrogeochemical, multivariate statistical, and spatial interpolation methods to assess spatial and temporal variations of lake and groundwater chemistry in Hulun Lake during the frozen and non-frozen periods. The results show that sodium (Na+) is the most abundant cation in the Hulun Lake area. Bicarbonate (HCO3−) and sulfate (SO42−) are the most predominant anions in the lake, river, and ground water during both seasons. The higher Na+ + K+ concentrations in the frozen season were related to longer circulation time and lower renewable rate. The water chemistry of the lake was of the HCO3-SO4-Cl-Na type and that of groundwater in the east and west regions was of the SO4-Cl-Na and HCO3-Na types, respectively. The chemical compositions of groundwater in the non-frozen season were mainly affected by evaporation and concentration, while rock weathering, evaporation, and human activities jointly controlled groundwater chemical component in the frozen period. Based on hierarchical cluster analysis (HCA) and principal component analysis (PCA) methods, Ca2+, NO3−, and SO42− were identified as the main controlling indicators of the chemical characteristics of groundwater and lake water. The increase of Ca2+ concentration in the center of the lake was related to groundwater discharge along the marginal tectonic fracture zone along the lake shores, which was the potential groundwater discharge area. The unconsolidated aquifer provides recharge channels for groundwater on the eastern side, which has a certain influence on the increase of nutrient concentration (NO3−) in the lake on the eastern shore. This research adds to our rough understanding of the lake-groundwater interaction in Hulun Lake, and provides a scientific foundation for the sustainable use of water resources, as well as the eco-logical integrity preservation in cold and arid regions.

Experimental Study on Creep Characteristics of Unloaded Rock Masses for Excavation of Rock Slopes in Cold Areas

Seasonal freeze–thaw environments are one of the key factors that aggravate the mechanical strength decay of excavated and unloaded rock masses on reservoir banks in cold areas. To study the time-dependent mechanical properties of an excavated and unloaded rock mass on a bank slope under freeze–thaw action, triaxial unloading tests were carried out on sandstone, freeze–thaw tests simulating freezing strength were conducted, and triaxial creep tests were implemented with graded incremental loading on unloaded specimens subjected to freeze–thaw action. The test results showed that the total deformation of the unloaded specimens is significantly increased compared with the conventional specimens, and the lateral direction is more likely to produce creep behaviour than the axial direction. The level of confining pressure determines the level of creep deformation of unloaded specimens and affects the variation law of creep rate. The creep behaviour of the unloaded specimens is aggravated by freeze–thaw action and, the longer the freezing period, the larger the creep strain share, and the creep rate increases significantly. The creep damage pattern of the unloaded specimens subjected to freeze–thaw action is mainly manifested as shear damage, and the creep process intensifies the derivation of tension-type cracks in the specimens. The higher the confining pressure of the unloaded specimen, the more obvious the plastic characteristics and the weaker the brittle characteristics during creep failure. The freeze–thaw action significantly reduces the long-term strength of the unloaded specimen, which is approximately 50~55% of the instantaneous strength. The long-term strength decays significantly with an increasing freezing period, and the research results can provide a theoretical reference for the evaluation of the long-term stability of excavated and unloaded rock masses in cold areas.

Effect of Adding Linseed Oil to The Diet on The Chemical Composition and Some Fatty Acids of Awassi Sheep Meat Chilled and Frozen


 This study was conducted at the experimental farm, Department of Animal Production , College of Agriculture , University of Tikrit for the period from 7/10/2018 to 15/12/2018. Sixteen Awassi lambs with an average body weight of 27kg and aged about 6—7-months were used in this investigation. The lambs were randomly assigned into four groups. Each group has 4 lambs the lambs were placed in individual cages (1 x 1.5 m².) and the aim of this study to investigation the effect of supplementing linseed oil on chemical composition and some fatty acids of Awassi chilled and frozen sheep meat,the results showed high significant differences in frozen period in moisture content of meat compared with chilled period it was ( 70.90 and 66.82)% respectively , and the chilled period conducted high significant differences than the frozen period in fat content ( 9.39 and 8.15)% respectively. About the effect of linseed oil on fatty acids, frozen period conducted high significant differences in Oleic it was 33.59 % while the frozen period conducted a high significant differences in Linoleic and Arachidonic acids it was ( 4.88 and 1.19)% respectively. The interaction between chilled period and treatments, the first and second treatment conducted high significant differences on Oleic acid also first treatment was high in Linoleic Acid percentage. While for the interaction between frozen period and treatments, the fourth treatment was high in Oleic and Linolenic Acid percentage, the first treatment was high in Linoleic Acid percentage it was (5.22)%.

MRNA m6 A methylation in wood frog brain is maintained during freezing and anoxia.

Freeze tolerance is an adaptive strategy that wood frogs (Rana sylvatica) use to survive the subzero temperatures of winter. It is characterized by a variety of metabolic and physiological changes that facilitate successful freezing and anoxia. As both mRNA regulation and posttranslation protein modification have been implicated in freeze tolerance, we hypothesized that posttranslational RNA regulation is also involved in coordinating freeze-thaw cycles and metabolic rate depression. As such, we investigated the most abundant RNA modification, adenosine methylation (N6 -methyladenosine; m6 A) in wood frog brains during 24 h periods of freezing and anoxia. This was followed by an examination of levels of RNA methyltransferases, demethyltransferases, and the readers of RNA methylation. Despite relative levels of methylation on mRNA remaining constant throughout freezing and anoxia, a significant increase in relative abundance of m6 A methyltransferases METTL3 and METTL14 was observed. In addition, we investigated the effect of m6 A RNA methylation on mRNA triaging to stress granules and report a significant increase in stress granule markers TIAR and TIA-1 in both freezing and anoxia. Our findings are the first report of RNA posttranslational regulation during metabolic rate depression in the wood frog brain and suggest that the dynamic RNA methylation observed is not directly linked to mRNA regulation during periods of extreme metabolic reorganization, warranting future investigations.

Dynamics of the freeze–thaw front of active layer on the Qinghai-Tibet Plateau

The seasonal dynamics of the freeze–thaw front during the freezing and thawing period strongly affect the hydrothermal processes in the active layer and the water-energy exchange processes between land and the atmosphere. Therefore, characterizing variation in the freeze–thaw front and its effect on the water and heat transfer mechanisms in the soil layer is important for enhancing our understanding of change in permafrost. In this study, we used data from field observations to analyze the freeze–thaw front dynamics during the freezing and thawing period in permafrost regions of the Qinghai-Tibet Plateau. The zero-curtain duration time was longer during the freezing period than during the thawing period at all sites. Changes in the freeze–thaw front were characterized by three distinct stages: the downward migration of the thaw front, zero curtain process at the bottom of the active layer, and the bidirectional freezing period. In addition, changes in the thaw front and soil moisture thaw period were consistent, but the freezing period of moisture showed large hysteresis compared with ground temperature. There was a power function and exponential relationship between the negative ground temperature and the unfrozen water content during warming and cooling processes, respectively. Linear and power relationships were observed between the net radiation accumulation and thawing front, and there was a power function relationship between the thawing front and soil heat flux. There was a quadratic polynomial relationship between the thawing front and thawing degree-days. The fitted relationships can better represent the dynamics of the freeze–thaw front during the freezing and thawing period. These findings aid our understanding of the hydrothermal characteristics of the active layers and will improve future permafrost simulation models.

Role of Temperature Gradient and Soil Thermal Properties on Frost Heave

In cold regions, the soil temperature gradient and depth of frost penetration can significantly affect roadway performance because of frost heave and thaw settlement of the subgrade soils. The severity of the damage depends on the soil index properties, temperature, and availability of water. While nominal expansion occurs with the phase change from pore water to ice, heaving is derived primarily from a continuous flow of water from the vadose zone to growing ice lenses. The temperature gradient within the soil influences water migration toward the freezing front, where ice nucleates, coalesces into lenses, and grows. This study evaluates the frost heave potential of frost-susceptible soils from Iowa (IA-PC) and North Carolina (NC-BO) under different temperature gradients. One-dimensional frost heave tests were conducted with a free water supply under three different temperature gradients of 0.26°C/cm, 0.52°C/cm, and 0.78°C/cm. Time-dependent measurements of frost penetration, water intake, and frost heave were carried out. Results of the study suggested that frost heave and water intake are functions of the temperature gradient within the soil. A lower temperature gradient of 0.26°C/cm leads to the maximum total heave of 18.28 mm (IA-PC) and 38.27 mm (NC-BO) for extended periods of freezing. The maximum frost penetration rate of 16.47 mm/hour was observed for a higher temperature gradient of 0.78°C/cm and soil with higher thermal diffusivity of 0.684 mm2/s. The results of this study can be used to validate numerical models and develop engineered solutions that prevent frost damage.

Research on Influencing Factors of Freezing and Thawing Process in the regions over 5000 m a.s.l

The freezing and thawing process is a unique feature of the alpine permafrost ecosystem, which controls the growth of microorganisms and alpine meadows, and plays a vital role in animal husbandry development, ecosystem functions and services. Meanwhile, the freezing and thawing process is also affected by external environmental factors, and its spatial differences are very significant, especially in the regions over 5000 m a.s.l. In this study, the freezing and thawing process periods of the Cuoma Township (CM), Xiangmao Township (XM) and Xiaotanggula Mountain (XTGL) sites in the Nagqu River Basin are divided, the effects of altitude, vegetation coverage, air temperature, and organic matter content on the freezing and thawing process are analyzed, the main influencing factors are discussed. The results show that in the regions over 5000 m a.s.l, the thaw initiation period (TIP) starts in early April, the entirely thawed period (ETP) starts in end of May, the freeze initiation period (FIP) starts in end of October, and the entirely frozen period (EFP) starts in early November. Compared with the regions below 5000 m a.s.l, FIP and EFP in the regions over 5000 m a.s.l start earlier, the TIP starts later and the freezing rate is faster. Organic matter content is the main influencing factor during FIP and EFP, and air temperature is the main influencing factor during TIP and ETP. This study is helpful to clarify the changes of freezing and thawing process in the regions over 5000 m a.s.l, and also provides theoretical support for ecological protection and restoration.

Inference of Soil Freezing Front Depth During the Freezing Period From the L-Band Passive Microwave Brightness Temperature

The freezing front depth ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zff</i> ) of annual freeze- thaw cycles is critical for monitoring the dynamics of the cryosphere under climate change because <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zff</i> is a sensitive indicator of the heat balance over the atmosphere-cryosphere interface. Meanwhile, although it is very promising for acquiring global soil moisture distribution, the L-band microwave remote sensing products over seasonal frozen grounds and permafrost is much less than in wet soil. This study develops an algorithm, i.e., the Brightness Temperature inferred Freezing Front (BT-FF) model, for retrieving the interannual freezing front depth ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zff</i> ) with the diurnal amplitude variation (DAV) of L band brightness temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ΔTB</i> ) during the freezing period. The new algorithm assumes 1) the daily-scale solar radiation heating/cooling effect causes the daily surface thawing depth ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztf</i> ) variation, which leads further to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ΔTB</i> ; 2) Δ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TB</i> can be captured by an L-band radiometer; 3) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztf</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zff</i> are negatively linear correlated and their relation can be quantified using the Stefan Equation. In this study, the modeled soil temperature profiles from the land surface model (STEMMUS-FT, i.e., Simultaneous Transfer of Energy, Mass, and Momentum in Unsaturated Soil with Freeze and Thaw) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TB</i> observations from a tower- based L-band radiometer (ELBARA-III) at Maqu are used to validate the BT-FF model. It shows that: 1) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ΔTB</i> can be precisely estimated from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztf</i> during the daytime; 2) the decreasing of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztf</i> is linearly related to the increase of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zff</i> with the Stefan Equation; 3) the accuracy of retrieved freezing front depth is about 5-25 cm; 4) the proposed model is applicable during the freezing period. The study is expected to extend the application of L -band <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TB</i> data in cryosphere/meteorology and construct global freezing depth data set in the future.

A Study on the Train-Induced Vibration Responses of Heavy Haul Railway Subgrade in Seasonally Frozen Regions Using Field Experiments

The dynamic response resulting from heavy haul train leads to the deterioration of the railway subgrade, especially those built in seasonally frozen regions. In this work, a typical heavy haul railway section in a seasonally frozen region is monitored on-site. The time domain and the frequency domain analysis of the subgrade vertical vibration acceleration, dynamic speed, and displacement during the non-frozen period and the frozen period are investigated. The results show that the vibration response of the subgrade is affected by various factors, including the train type, locomotive, traveling speed, train formation, heavy load, and the prevalent season. Further, it is observed that the maximum and average vertical acceleration of the subgrade, the vibration speed, and the dynamic displacement increase during the frozen period. However, the main frequency of the natural vibration remains significantly higher than that before freezing. Moreover, the frozen soil has a significant amplification effect both on the acceleration and the attenuation rate. Similarly, the subgrade’s vibration mode has a low frequency and high amplitude during the freezing period, and the dynamic response characteristics become increasingly apparent as the axle load increases.

New strategy for evaluating the spatiotemporal distribution of groundwater resource quantity under seasonal freeze/thaw in mountainous areas

Mountainous areas that experience seasonal freeze/thaw are distributed worldwide, and the impact of freeze/thaw processes on the groundwater cycle is substantial. For these mountainous areas, the rational division of two key parameters, namely, the groundwater resource quantity calculation unit (GCU) and groundwater resource quantity calculation period (GCP), is a prerequisite for the scientific evaluation of groundwater resource quantity. This is especially important for the Changbai Mountains in Jilin Province, China, which have a distinct geology formed by volcanic processes and have experienced soil seasonal freeze/thaw cycle, implying drastic impacts on the spatiotemporal distribution of groundwater resources. Based on the groundwater flow system theory and considering the influences of freeze/thaw cycles on the groundwater resource quantity, we propose a new strategy to deal with the division of GCUs and GCPs. Three first-level GCUs, eight second-level GCUs, and fifty third-level GCUs were delineated within the Changbai Mountains. Five GCPs were then determined, and the spatiotemporal distribution of groundwater resource quantity was calculated for the different GCUs and GCPs. The groundwater resource quantity in the five GCPs (no freezing, unstable freezing, stable freezing, unstable melting, and stable melting periods) accounted for 62.25%, 11.51%, 11.58%, 5.05%, and 9.61% of the total, respectively. The results provide a scientific basis for the exploitation of groundwater resource in different regions and periods of the study area, and the proposed method offers a new reference strategy for the evaluation of groundwater resource in similar regions.

Seasonal freeze-thaw characteristics of soil carbon pools under different vegetation restoration types on the Longzhong Loess Plateau

Soil carbon pools are important for maintaining the stability of the carbon cycle in terrestrial ecosystems and regulating climate change. However, it is not clear how soil carbon pools change under different vegetation restoration types at high altitudes during frequent seasonal freeze-thaws (FTs). Therefore, we studied the seasonal FT variability (before freezing, early stages of freezing, stable freeze stage, thawing stage) of soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and easily oxidized organic carbon (EOC) under three vegetation restoration types (Grassland, GL; Caragana korshinskii, CK; Xanthoceras sorbifolia, XS) on the Longzhong Loess Plateau region. We found that during the seasonal FT, the 0–40 cm SOC, MBC, DOC, and EOC contents were higher in XS vegetation than in GL and CK vegetation, but the sensitivity index of SOC was lower in XS vegetation (sensitivity index = 2.79 to 9.91). In the 0–40 cm soil layer, the seasonal FT process reduced the MBC content and increased the DOC content in the three vegetation soils. Meanwhile, DOC and EOC contents accumulated obviously in the stable freezing period and decreased significantly in the thawing period. We also found that the SOC, MBC, DOC, and EOC contents were higher in the surface soils (0–10 cm) than in the underlying soils (10–20 and 20–40 cm), while the sensitivity of the soil carbon pool fractions to seasonal FT processes differed considerably between soil depths. Redundancy analysis (RDA) showed that soil total nitrogen, temperature, total phosphorus, and soil water content were important environmental factors influencing soil carbon pool fractions during seasonal FT. This study suggested that in the Longzhong Loess Plateau region, soil MBC and DOC were more susceptible to seasonal FT phenomena and that the soil system of the Xanthoceras sorbifolia vegetation had a stronger soil C sequestration function during the seasonal FT process.

Hydrothermal Changes and Physicochemical Characteristics of Subtropical Subalpine Soils under Freezing and Thawing

The soil column samples were collected for indoor simulated freeze-thaw experiments to monitor the soil hydrothermal dynamics and measure the basic physicochemical properties to research the effects of freeze-thaw on the hydrothermal process of peat bog soil and its relationship with physicochemical properties. The results indicate that in the initial phase of freezing-thawing, soil water content decreases and soil temperature changes, respectively. Unfrozen water content in soil in the stable freezing period decreases sharply. Compared with the freezing period, the fluctuation of soil moisture rate during thawing is more moderate with the temperature change. Soil ammonium nitrogen content decreases with decreasing soil temperature and is significantly positively correlated with soil water content after freeze-thaw, while total phosphorus, fast-acting phosphorus, total nitrogen and nitrate have no significant correlation with soil temperature and soil moisture content after freeze-thaw.

Mechanism for the subglacial formation of cryogenic brines

AbstractCryogenic brines are under-studied, despite the fact that they may contain information about past ice-sheet behavior. Cryogenic brines form through cryoconcentration of seawater, although the specific setting and mechanism of formation have been debated. Previous conceptual models of brine formation require seawater isolation from the ocean in a closed basin experiencing freezing. We propose instead that they may form in pore spaces of marine sediments subjected to repeat cycles of ice-sheet advance and retreat. During periods of basal freezing, cryoconcentration produces hypersaline brines which experience downward flow driven by unstable density stratification. Our advection-diffusion model of porewater chemistry evolution successfully recreates the porewater chemistry of two deep Antarctic cores containing cryogenic brines (AND-1B and AND-2A), suggesting that cryogenic brines can be formed through the repeated isolation and cryoconcentration of marine waters within subglacial sediment pore spaces of modern and past ice sheets.

EFFECT OF FREEZING PRESERVATION PERIOD ON SOME SENSORY CHARACTERISTICS OF THREE IRAQI LOCAL FISH SPECIES

The current study was conducted to determine the ideal period for freezing of three fish species of in the Iraqi local markets which are common carp Cyprinus carpio ,catfish Silurus triostegus and mullet Planiliza abu through sensory evaluation and the effect of freezing time on the flavor, juiciness and general acceptability of fish .A total of20 samples, were taken for each species of fresh local fish and were frozen at 18°C for different freezing periods : 1 day (T2), 15 days (T3), 30 days (T4) and 45 days (T5) , in addition to the fresh treatment T1 that has not been subjected to freezing. Results of common carp showed that the best freezing time was recorded for treatments T2, T3 and T4 which attained 6.8, 6.6 and 6.2, respectively, for the flavor. The treatment T2, T3 and T4 were recorded 6.4, 6.8 and 6.6 respectively, for tenderness .The treatments T2, T3 and T4 were amounted 7.4, 6.6 and 6.6 respectively, for the Juiciness. Results of the general acceptance of treatments T2, T3 and T4 were 7.6, 7.2, 6.6 respectively. Results of the catfish and the mullet for flavor showed that the best freezing period was for the two treatments T2 and T3, which were 7.4, 6.4 in the catfish and 6.6 and 5.4 in the mullet respectively. T2 and T3 continued to be significantly superior to the freshness of the catfish and the mullet over T4 and T5 and it was 7.0, 6.4 for the catfish and 5.8, 5.6 for the mullet, respectively. T2 and T3 were superior for the juiciness of catfish by 7.0 and 6.6 and for mullet, 5.8 and 5.6 respectively. As for the trait of general acceptance, it was superior in the two treatments T2 and T3 for catfish and mullet and they were 7.4, 6.8 for catfish 6.8 and 6.4 for mullet respectively.

Changes in oxidative stress and ultrastructure of the sperm of silver barb, Barbonymus gonionotus , related to cryopreservation using a dry shipper

An investigation was conducted to clarify the role of oxidative stress and ultrastructural changes on the sperm of the silver barb, Barbonymus gonionotus caused by the cryopreservation. The sperm was cryopreserved using a dry shipper and 500-μl straws loaded with 160 μl extended semen and 10% DMSO, frozen for 2 min within the upper chamber of the dry shipper, and immediately transferred into the lower chamber for cryostorage. Lipid peroxidation (LPO) levels of silver barb sperm were affected by the freezing and cryostorage period, progressively increasing (p < 0.01) throughout the 14-day cryostorage. The ultrastructural defects, apoptotic, and necrotic cells were higher (p < 0.01) in the post-thawed sperm. There were inverse correlations between ultrastructural damage and the sperm qualities (motility; r = −0.84, p < 0.0001 and viability; r = −0.72, p < 0.001). In conclusion, this cryopreservation procedure had the effect on the oxidative and ultrastructural damage in the sperm cells. There is a need for antioxidants supplement to avoid the oxidative damage and ultrastructural alteration during freezing–thawing process.

Machine Learning Model-Based Ice Cover Forecasting for a Vital Waterway in Large Lakes

The St. Marys River is a key waterway that supports the navigation activities in the Laurentian Great Lakes. However, high year-to-year fluctuations in ice conditions pose a challenge to decision making with respect to safe and effective navigation, lock operations, and ice breaking operations. The capability to forecast the ice conditions for the river system can greatly aid such decision making. Small-scale features and complex physics in the river system are difficult to capture by process-based numerical models that are often used for lake-wide applications. In this study, two supervised machine learning methods, the Long Short-Term Memory (LSTM) model and the Extreme Gradient Boost (XGBoost) algorithm are applied to predict the ice coverage on the St. Marys River for short-term (7-day) and sub-seasonal (30-day) time scales. Both models are trained using 25 years of meteorological data and select climate indices. Both models outperform the baseline forecast in the short-term applications, but the models underperform the baseline forecast in the sub-seasonal applications. The model accuracies are high in the stable season, while they are lower in the freezing and melting periods when ice conditions can change rapidly. The errors of the predicted ice-on/ice-off date lie within 2–5 days.

Lycium barbarum Polysaccharide Inhibits Lipid Oxidation and Protein Degradation in Tan Sheep Meatballs during Frozen Storage.

The aim of the present study was to evaluate the effectiveness of Lycium barbarum polysaccharide (LBP) on lipid oxidation and protein degradation in Tan sheep meatballs during the frozen period. The meatballs were treated with LBP at 0.01%, 0.02%, and 0.03% and stored at –18±1°C for 0, 3, 6, 9, and 12 weeks. The effects of LBP treatment were investigated using the contents of total volatile basic nitrogen (TVB-N), texture profile (TP), thiobarbituric acid reactive substances (TBARS), colour, and pH values, compared with 0.02% butylated hydroxytoluene treatment and the blank control. The results showed that LBP treatment significantly decreased TBARS content compared with the control, which confirmed LBP to be a highly effective component in preventing lipid oxidation of Tan sheep meatballs during frozen storage, and protein degradation in Tan sheep meatballs had a significant inhibition effect because of TVB-N value reduction. In addition, the colour, TP and pH values of meatballs treated with LBP were improved dramatically. To further determine the quality changes of the blank control and all treated groups during storage, the comprehensive score evaluation equation based on principal component analysis was obtained: Y=0.51632Y1+0.29589Y2 (cumulative contribution rate=81.221%), and the 0.02% LBP-treated group had a higher comprehensive score than the other groups, and the quality of LBP-treated meatballs was better as well. In summary, LBP may reduce or inhibit lipid oxidation and protein degradation, and enhance overall quality and shelf-life in prepared meat products.

Postplanting Microclimate, Germination, and Emergence of Perennial Grasses in Wyoming Big Sagebrush Steppe

Several recent studies have hypothesized that postgermination/preemergence soil freezing can have a major negative impact on spring emergence of seeded perennial grasses in the Intermountain western United States. In this experiment, we measured germination and emergence of 4 fall-seeded perennial grasses at 15 sites in southeastern Oregon, north-central Nevada, and southwestern Idaho in 2 different yr. We used hydrothermal germination and seedbed microclimatic models to estimate planting date effects on germination and preemergence mortality and evaluated these simulations relative to measured germination and seedling emergence in the field. There were clear indications that both germination and emergence were responsive to site-year effects, but premature fall germination before winter freezing events was not a factor in emergence rates. In all cases, planting was sufficiently late in the fall to avoid significant postgermination/preemergence freezing injury for the sites and years tested. Emergence was weakly correlated to seedbed favorability in the late winter and spring after the principal period of soil freezing. Our data show that for the 2 yr of this study, we can only account for a relatively small portion of any abiotic effects on spring emergence. General inferences about planting date effects, however, may have been limited by arid conditions during the 2-yr field study relative to long-term climate normals.

Studying the effect of adding aqueous extracts of lemongrass and bay leaf on the microbial and sensory properties of frozen camel burger

The current study aimed to study the effect of adding aqueous extracts of lemongrass and bay leaves at concentrations (1-0.5%) on the microbial and sensory characteristics of camel burgers preserved in freezing at a temperature of (-18°C) and for periods of preservation (0-2-4-6) weeks. The results showed a significant decrease at the level (p&lt;0.05) for the numbers of total bacteria, cold-loving bacteria, and colonic bacteria for camel burgers preserved in freezing (-18°C) and for storage periods of (0-2-4-6) a week, in addition to that when studying the sensory tests. For camel burger preserved in freezing (-18°C) and preservation periods (0-2-4-6) a week, a significant increase was observed at the level (p&lt;0.05) of the studied traits during the preservation period, except for the color trait, as a significant decrease was observed with the increase in the preservation period.

A floating remote observation system (FROS) for full seasonal lake ice evolution studies

A floating remote observation system (FROS) was designed to investigate the full seasonal evolution of lake ice. FROS operates effectively in open water and ice. It can automatically measure meteorological data, such as the air temperature and solar radiation, as well as ice/snow data, including ice thickness and snow depth. These observations help to fill the current knowledge gap of lake ice observations during the early freezing and late melting periods because of the limited bearing capacity of ice cover. A mid-latitude lake was selected for field experiments to verify the effectiveness of FROS, where the duration of the survey was 101 days, of which 97 were during an ice-covered period. The results reveal that the lake ice went through a fast freezing period, equilibrium period, and a melting period, with a maximum ice thickness of 35.5 cm. The ice melting rate was 1.7 cm/day, which was approximately double the ice growth rate of 0.7 cm/day during the fast freezing period. FROS was able to record the complete evolution of lake ice and of different meteorological elements, with good stability in both open water and frozen conditions, and can accommodate wind speeds up to 6.4 m/s. Meanwhile, FROS has good versatility, and other measurement instruments such as chlorophyll and dissolved oxygen sensors, longwave radiometers, and conductivity sensors can be added to it. The application of FROS will be important for calculations of the thermal balance of snow and ice, and studies of the annual and seasonal evolution of ecological characteristics in frozen lakes.