A laboratory study of soil conditions affecting emissions of nitrous oxide from packed cores subjected to freezing and thawing

2011 ◽  
Vol 91 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Mario Tenuta ◽  
Brad Sparling
Keyword(s):  
Nitrous Oxide ◽  
Laboratory Study ◽  
Surface Soil ◽  
Microbial Biomass C ◽  
Soil Conditions ◽  
Freezing And Thawing ◽  
Treated Soil ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Tenuta, M. and Sparling, B. 2011. A laboratory study of soil conditions affecting emissions of nitrous oxide from packed cores subjected to freezing and thawing. Can. J. Soil Sci. 91: 223–233. A series of laboratory experiments using a packed core soil assay was carried out to test several soil conditions affecting the emission of N2O (nitrous oxide) during thawing of soil. The assay consisted of a sandy loam soil packed to 1.1 Mg m−3, moistened to 80% water-filled pore space, and temperature treated to 4 or −20°C for 2.5 d; the emissions from thawing soil were then determined as the differences in N2O release rates of the temperature-treated soils when placed at 15°C. Nitrate addition to surface soil (0–10 cm) enhanced thaw emission. Thaw emissions, averaged for deeper collected soil (10–30 and 30–60 cm), was 0.3% with NO3− treatment and 1.2% without NO3− treatment of that for surface soil treated similarly. Higher thaw emission for surface soil was related to greater organic matter and microbial biomass C contents and denitrifying enzyme activity than deeper collections of soil. Increasing the bulk density of soil from 1.1, 1.2, and 1.25 Mg m−3 decreased thaw emission. A second freeze-thaw cycle of the highest compaction treatment resulted in an emission of 2.3% of the first freeze-thaw cycle. Acetylene increased thaw emission of N2O and more so for NO3− untreated than treated soil. Using the acetylene inhibition method, the N2O:N2 ratio of gas produced was higher for frozen (0.17) than cold (0.07) treated soil, respectively, without the addition of NO3−. The addition of NO3− increased the N2O:N2 ratio of gas produced with the ratio being 2.45 and 0.53 for frozen and cold-treated soil. The results are consistent with biological denitrification being a source of N2O with conditions promoting N2O production rather than consumption enhancing thaw emissions.

Mechanisms leading to enhanced soil nitrous oxide fluxes induced by freeze–thaw cycles

2013 ◽  
Vol 93 (4) ◽  
pp. 401-414 ◽  
Author(s):  
Neil Risk ◽  
David Snider ◽  
Claudia Wagner-Riddle
Keyword(s):  
Nitrous Oxide ◽  
De Novo ◽  
Greenhouse Gas Emission ◽  
Soil Aggregates ◽  
Soil Conditions ◽  
Natural Environments ◽  
Freezing And Thawing ◽  
Surface Layers ◽  
Freeze Thaw ◽  
Thaw Cycle

Risk, N., Snider, D. and Wagner-Riddle, C. 2013. Mechanisms leading to enhanced soil nitrous oxide fluxes induced by freeze–thaw cycles. Can. J. Soil Sci. 93: 401–414. The freezing and thawing of soil in cold climates often produces large emissions of nitrous oxide (N2O) that may contribute significantly to a soil's annual greenhouse gas emission budget. This review summarizes the state of knowledge of the physical and biological mechanisms that drive heightened N2O emissions at spring melt. Most studies of freeze–thaw N2O emissions have concluded that denitrification is the dominant process responsible for the large thaw fluxes. Soil moisture, availability of carbon and nitrogen substrates, and freeze temperature and duration are the major factors identified as controlling freeze–thaw cycle (FTC) N2O emissions. Two mechanisms are proposed to lead to enhanced N2O emissions at thaw: (1) the physical release of N2O that is produced throughout the winter and trapped under frozen surface layers and/or within nutrient-rich water films in the frozen layers, and (2) the emission of newly produced (de novo) N2O at the onset of thaw, which is stimulated by increased biological activity and changes in physical and chemical soil conditions. Early studies implicated the physical release of N2O from subsurface soil layers as the main mechanism contributing to spring thaw emissions, but most current studies do not support this hypothesis. Mounting evidence suggests that most of the emitted N2O is produced de novo. This may be fueled by newly available denitrification substrates that are liberated from dead microbes, fine roots, and/or the disintegration of soil aggregates. The release of N2O trapped in shallow surface layers may represent a small, but important contribution of the total emissions. Application of new techniques to study microbial communities in their natural environments, such as metagenomics and stable isotope studies, have the potential to enhance our understanding of the soil N cycle and its linkages to FTC N2O emissions. Future field studies of N2O emissions ought to quantify both overwinter accumulation/release and the de novo production of N2O so that the contribution of each mechanism to the annual emission budget is known.

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

scholarly journals USING SMOS PASSIVE MICROWAVE DATA TO DEVELOP SMAP FREEZE/THAW ALGORITHMS ADAPTED FOR THE CANADIAN SUBARCTIC

2015 ◽  
Vol XL-1-W5 ◽  
pp. 365-368 ◽  
Author(s):  
P. Kalantari ◽  
M. Bernier ◽  
K. C. McDonal ◽  
J. Poulin
Keyword(s):  
Land Cover ◽  
Time Series Data ◽  
Passive Microwave ◽  
Soil Freezing ◽  
Series Data ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Impact

Seasonal terrestrial Freeze/Thaw cycle in Northern Quebec Tundra (Nunavik) was determined and evaluated with passive microwave observations. SMOS time series data were analyzed to examine seasonal variations of soil freezing, and to assess the impact of land cover on the Freeze/Thaw cycle. Furthermore, the soil freezing maps derived from SMOS observations were compared to field survey data in the region near Umiujaq. The objective is to develop algorithms to follow the seasonal cycle of freezing and thawing of the soil adapted to Canadian subarctic, a territory with a high complexity of land cover (vegetation, soil, and water bodies). Field data shows that soil freezing and thawing dates vary much spatially at the local scale in the Boreal Forest and the Tundra. The results showed a satisfactory pixel by pixel mapping for the daily soil state monitoring with a > 80% success rate with in situ data for the HH and VV polarizations, and for different land cover. The average accuracies are 80% and 84% for the soil freeze period, and soil thaw period respectively. The comparison is limited because of the small number of validation pixels.

scholarly journals Mechanical Properties of Sandstone Cement-Stabilized Macadam

2019 ◽  
Vol 9 (17) ◽  
pp. 3460 ◽  
Author(s):  
Qiang Du ◽  
Ting Pan ◽  
Jing Lv ◽  
Jie Zhou ◽  
Qingwei Ma ◽  
...  
Keyword(s):  
Cement Content ◽  
Influence Factors ◽  
Road Construction ◽  
Experimental Investigations ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Test Pieces ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Brazilian Splitting

Application of sandstone in cement-stabilized macadam (CSM) is an effective way to utilize sandstone. To determine the feasibility of using sandstone as a CSM aggregate, a series of experimental investigations, such as unconfined compressive strength (UCS) tests, Brazilian splitting tests and freeze-thaw cycle tests, were conducted on sandstone cement-stabilized macadam (SCSM). Three mixed variables, covering the cement content, aggregate type and curing period, were set as influence factors. The testing results indicated that the UCS, indirect tensile strength (ITS) and frost resistance property of the test-pieces increased with cement content and curing age. Considering the asphalt pavement design specifications for China, the UCS and ITS values of the SCSM complied with the requirements of light traffic road construction before freeze-thaw cycles. However, the SCSM subjected to freezing and thawing meets the requirements only when the cement content is 4.5%. Therefore, it is noteworthy that CSM containing sandstone aggregates should be applied with caution in cold region because of insufficient freeze resistance.

scholarly journals PSXIII-2 Cryopreservation effect on biological parameters of poultry semen

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 372-373
Author(s):  
Mikhail A Zhilinsky ◽  
Evgeniya K Tomgorova ◽  
Baylar S Iolchiev ◽  
Anastasia N Vetokh ◽  
Hanum V Ashraf ◽  
...  
Keyword(s):  
Germ Cells ◽  
Genetic Material ◽  
Middle Section ◽  
Sperm Cryopreservation ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Negative Effect ◽  
Live Sperm

Abstract Sperm cryopreservation is one of the most important elements for the creation of genetic material cryobanks in order to preserve the gene pool of poultry. Cryopreservation methods and parameters directly affect the viability of germ cells after thawing. The effect of freeze-thaw cycles on biological usefulness of bird sperm was studied. Semen was frozen in paillettes. Thawing sperm was carried out at a temperature of 38 °С. Sperm activity was assessed using CASA technology “ARGUSSOFT”. Sperm motility after cryopreservation decreased in roosters, quails and guinea fowls by 62 ± 3 %, 66 ± 1 % and 60 ± 1 %, respectively. The proportion of live sperm also decreased: in roosters - from 89 ± 4 % to 48 ± 2 %, in quails - from 93 ± 3 % to 49 ± 3 %, in the guinea fowls - from 92 ± 2 % to 45 ± 4 %. As a result of freezing and thawing, the proportion of spermatozoa with abnormal morphology increased. A change in the frequency of anomalies occurrence in individual segments was observed. The number of spermatozoa with flagella pathology was increased. The proportion of sperm with pathology of the head, middle section and flagellum increased by 0.4 %, 0.4 % and 1.3 % (P ≤ 0.001) respectively, in the frozen-thawed samples of roosters, compared with the indicators established for a freshly obtained ejaculate. A similar trend was observed in other poultry types. Thus, the freeze-thaw cycle had a negative effect on the activity and viability of poultry spermatozoa. Supported by RSF No 16-16-04104.

Laboratory Test of Uniaxial Compressive Strength of Shanghai Frozen Soils under Freeze-Thaw Cycle

2013 ◽  
Vol 716 ◽  
pp. 688-692 ◽  
Author(s):  
Xiang Dong Hu ◽  
Jin Tai Wang ◽  
Xing Fu Yu
Keyword(s):  
Soft Soil ◽  
Underground Space ◽  
Freezing And Thawing ◽  
Frozen Soils ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Ground Freezing ◽  
Freeze Thaw Cycle ◽  
Artificial Ground Freezing ◽  
Mechanical Characters

The artificial ground freezing (AGF) is now widely employed in constructions with the expanding underground space exploitation in Shanghai. In order to avoid geological disasters which might appear in the AGF practice, it is urgently needed to do laboratory tests on the physical and mechanical characters of Shanghai soft soil under freezing and thawing action. This paper tests three kinds of soils from the location ofShanghai Metro line 4 constructions in different state, i.e. original state, freeze-thaw state and secondary freeze-thaw state, and obtains the changing rules of soil characters under secondary freeze-thaw action.

scholarly journals Numerical Simulation of the Effect of Freeze–Thaw Cycles on the Durability of Concrete in a Salt Frost Environment

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1198
Author(s):  
Hao Li ◽  
Yuan Zhang ◽  
Haolong Guo
Keyword(s):  
Numerical Simulation ◽  
Bending Moment ◽  
Temperature Curve ◽  
Concrete Durability ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Impact ◽  
Erosion Environment

In order to improve the accuracy of the analysis of the impact of freeze–thaw cycle on concrete durability in a salt freezing environment, the numerical simulation of the impact of the freeze–thaw cycle on concrete durability in a salt freezing erosion environment is studied in this paper. Firstly, considering the influence of axial force and bending moment on the relationship between bending moment and curvature, a concrete fiber beam column model is established. Then, according to the joint influence of temperature field, stress field and seepage field on concrete in the process of freezing and thawing, the control differential equation of the freezing and thawing cycle is established. The freeze–thaw damage section is divided, the non-uniform distribution of freeze–thaw damage is determined, and the division of the freeze–thaw damage section is completed. According to the linear relationship between freeze–thaw damage degree, relative dynamic elastic modulus, freeze–thaw cycle times and position variables, the durability of concrete is numerically simulated, and the attenuation law of bond strength at different section depths after freeze–thaw is determined. The results show that the temperature curve simulated by the design method is consistent with the actually measured temperature curve, which can better reduce the temperature change of the inner core of the test block during freezing and thawing, and the relative dynamic elastic modulus is in good agreement with the actual value, which can prove that the method in this paper has certain practical application value. It is expected to provide some reference for solving the durability problem of concrete in a salt frost erosion environment and the optimal design of concrete structures.

Effets de cycles de gel–dégel sur les propriétés d'une argile sensible

1995 ◽  
Vol 32 (4) ◽  
pp. 725-740 ◽  
Author(s):  
M. Roy ◽  
P. La Rochelle ◽  
S. Leroueil ◽  
J.M. Konrad ◽  
G. Bergeron
Keyword(s):  
Laboratory Study ◽  
Structure Change ◽  
Triaxial Tests ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Mercury Porosimeter ◽  
Sensitive Clay ◽  
High Suction ◽  
Scanning Electron

A laboratory study of the evolution of the behaviour of a sensitive clay under many freeze–thaw cycles is presented; it follows the laboratory study of Leroueil et al. (1991) and the field study of Roy et al. (1992). The physical properties of the clay have been followed by means of consistency and permeability tests after each freeze–thaw cycle, and the mechanical behaviour has been assessed by means of falling cone, oedometer, and consolidated isotropically undrained triaxial tests. The changes in internal structure have been observed by means of the scanning electron microscope and the mercury porosimeter. The results show that the changes in properties are significant during the first three freeze–thaw cycles and hardly significant during the following cycles. The structure change can be explained by the high suction that develops during the generation of ice lenses behind the frost front. Key words : clay, freeze–thaw, shear strength, permeability, heaving, settlements. [Journal translation]

scholarly journals PSIV-25 Effect of Various Handling Methods of Plasma and Serum Samples on Pregnancy Associated Glycoprotein Concentrations

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 289-290
Author(s):  
Grace M Wesson ◽  
Lohana Fernandez ◽  
Rebecca K Poole ◽  
Gessica A Franco ◽  
Sydney T Reese ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Plasma Samples ◽  
Freezing And Thawing ◽  
Serum Samples ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Repeated Freezing ◽  
Pregnancy Status ◽  
Handling Methods

Abstract Pregnancy associated glycoproteins (PAG) can be used as a biomarker for early pregnancy diagnosis, so accurate and consistent PAG detection is critical. The objective of this study was to determine if plasma and serum PAG concentrations were altered when centrifugation occurred at different times post-collection, when subjected to repeated freezing and thawing, and when monoclonal antibodies were kept in frequently or infrequently opened containers. Plasma (n = 4) and serum (n = 4) samples were collected from two open cows and two pregnant cows 28 days after artificial insemination. Pregnancy status was determined via transrectal ultrasonography. Plasma and serum samples were evenly separated and either centrifuged on the day of collection, or placed at 4°C and centrifuged the next day. An in-house PAG ELISA was performed on all samples before freezing (NOTHAW), after being frozen for one week (INTACT), after one freeze/thaw cycle (THAW1), two freeze/thaw cycles (THAW2), and three freeze/thaw cycles (THAW3). Data were analyzed using one-way ANOVA (GLM procedure, SAS 9.4). All samples from open cows were below the baseline of the assay. For pregnant cows, plasma samples had greater PAG concentrations than serum samples (11.84 vs 3.30 ± 0.66 ng/mL, respectively, P < 0.05). No differences were observed for day of centrifugation in both plasma and serum samples (P = 0.50 and P = 0.60, respectively) and in handling of monoclonal antibodies (P = 0.90). Freezing and thawing did not impact PAG concentrations in plasma samples (P = 0.19), but did alter serum concentrations (P = 0.01). Specifically, THAW1 (1.98 ng/mL) and THAW2 (1.42 ng/mL) serum PAG concentrations were lower compared to NOTHAW, THAW3, and INTACT samples (4.66, 4.85, and 3.57 ng/mL, respectively). Based on these data, plasma yields more consistent results than serum, even after several freeze-thaw cycles, and handling of monoclonal antibodies or time of centrifugation has no significant effect on measured PAG.

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