Seasonal dynamics of phytoand zooplankton of an eutrophicated lake in years with different water content and temperature conditions

2018 ◽  
Vol 53 (3) ◽  
pp. 29 ◽  
Author(s):  
Irina S. Trifonova ◽  
Anna L. Afanas`eva ◽  
Nataliya V. Rodionova ◽  
Keyword(s):  
Water Content ◽  
Seasonal Dynamics ◽  
Temperature Conditions

Aircraft Metallic Materials Under Low Temperature Conditions

1951 ◽  
Vol 55 (482) ◽  
pp. 61-86
Author(s):  
P. L. Teed
Keyword(s):  
Low Temperature ◽  
Water Content ◽  
Metallic Materials ◽  
Atmospheric Conditions ◽  
Ambient Conditions ◽  
Temperature Conditions ◽  
Engineering Problems

The ubiquity of aircraft in being and yet to be, whether civil or military, manned or unmanned, makes them liable to exposure to wide extremes of atmospheric conditions. The range of temperature to which they may be subjected may possibly be from +90° to –90°C. (+194° to –130°F.), that of pressure, from one atmosphere to something approximating to one-tenth of this amount, while the water content (aqueous vapour plus water in suspension; for example, in a very dense tropical cloud), can, on occasion, be as high as 2.5 per cent. by weight and, at stratospheric heights, at least as low as 0.001 per cent. Such variations in ambient conditions are not without chemical and physical repercussions. The engineering problems which arise will be examined, therefore, from both these view points, and attention will be drawn to potential dangers and means suggested for their avoidance.

Hydration Properties of Steel Slag under Different Curing Temperatures

2014 ◽  
Vol 507 ◽  
pp. 295-299 ◽  
Author(s):  
Bo Zhang ◽  
Jin Hu ◽  
Meng Yuan Li
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Water Content ◽  
Cement Paste ◽  
Steel Slag ◽  
Pore Distribution ◽  
Curing Temperature ◽  
Hydration Properties ◽  
Evaporable Water ◽  
Temperature Conditions

The non-evaporable water content, compressive strength, and pore distribution of steel slag paste cured under different curing temperature conditions were investigated in this paper. The non-evaporable water content of steel slag paste at early ages is obviously larger at higher curing temperature. At the age of 28 days, the non-evaporable water content of steel slag paste at normal curing temperature is close to that at high curing temperature, but the compressive strength of steel slag paste at normal curing temperature is much lower than that at high curing temperature. The pore structure of steel slag paste is much coarser than that of cement paste under the same conditions.

Field Validation of DNDC and SWAP Models for Temperature and Water Content of Loamy and Sandy Loam Spodosols

2014 ◽  
Vol 28 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Eugene Balashov ◽  
Natalya Buchkina ◽  
Elena Rizhiya ◽  
Csilla Farkas
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Mean Square ◽  
Seasonal Dynamics ◽  
Mean Square ◽  
Plant Model ◽  
Decomposition Model ◽  
Soil Temperatures

Abstract The objectives of the research were to: fulfil the preliminary assessment of the sensitivity of the soil, water, atmosphere, and plant and denitrification and decomposition models to variations of climate variables based on the existing soil database; validate the soil, water, atmosphere, and plant and denitrification and decomposition modelled outcomes against measured records for soil temperature and water content. The statistical analyses were conducted by the sensitivity analysis, Nash-Sutcliffe efficiency coefficients and root mean square error using measured and modelled variables during three growing seasons. Results of sensitivity analysis demonstrated that: soil temperatures predicted by the soil, water, atmosphere, and plant model showed a more reliable sensitivity to the variations of input air temperatures; soil water content predicted by the denitrification and decomposition model had a better reliability in the sensitivity to daily precipitation changes. The root mean square errors and Nash-Sutcliffe efficiency coefficients demonstrated that: the soil, water, atmosphere, and plant model had a better efficiency in predicting seasonal dynamics of soil temperatures than the denitrification and decomposition model; and among two studied models, the denitrification and decomposition model showed a better capability in predicting the seasonal dynamics of soil water content.

scholarly journals Soil contribution to CO2 fluxes in Chinampa ecosystems, Mexico

2020 ◽  
Vol 10 ◽  
Author(s):  
Elena Nikolaevna Ikkonen ◽  
Norma Eugenia García-Calderón ◽  
Ervin Stephan-Otto ◽  
Elizabeth Fuentes-Romero ◽  
Abel Ibáñez-Huerta ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Plant Growth ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Seasonal Dynamics ◽  
Plant Biomass ◽  
Vegetation Type ◽  
Ecosystem Carbon ◽  
Dominant Plant Species

Since soil CO<sub>2</sub> flux is a key component of ecosystem carbon balance, quantifying its contribution to the ecosystem carbon flux and understanding the factors that underlie its temporal variation is crucial for a better comprehension of ecosystem carbon dynamics under climate change and for optimal ecosystem use and management. Our objectives were to quantify the contributions of total soil CO<sub>2</sub> efflux (<em>F</em><sub>S</sub>) to ecosystem respiration (<em>R</em><sub>E</sub>) and heterotrophic soil CO<sub>2</sub> efflux (<em>F</em><sub>H</sub>) to <em>F</em><sub>S</sub> in two <em>chinampa</em> ecosystems with different natural grass covers. We also aimed to identify the main environmental drivers of seasonal variability of these contributions. The CO<sub>2</sub> fluxes were measured on each site about every 14 days from September 2008 to August 2009 in the Xochimilco Ecological Park in Mexico City using dark chamber techniques. For two studied sites, <em>R</em><sub>E</sub>,<em> F</em><sub>S</sub> and <em>F</em><sub>H</sub> were estimated on average as 94.1 ± 8.5, 34.7 ± 3.5 and 16.5 ± 1.7 (± S.E.) mg C-CO<sub>2</sub> m<sup>-2</sup> h<sup>-1</sup>, respectively. &nbsp;On average over the study period and sites, the annual cumulative <em>R</em><sub>E</sub>, <em>F</em><sub>S</sub> and <em>F</em><sub>H</sub> fluxes were 824 ± 74, 304 ± 31 and 145 ± 15 g C m<sup>-2</sup> year, respectively. The <em>R</em><sub>E</sub>, <em>F</em><sub>S</sub> and <em>F</em><sub>H</sub> varied between the winter and summer seasons; this variation was explained mostly by seasonal variations of soil temperature, soil water content and shoot plant biomass. Temperature sensitivity of CO<sub>2</sub> fluxes depended on vegetation type and plant growth differences among the sites and decreased in the following order: <em>R</em><sub>E</sub> &gt; <em>R</em><sub>s</sub> &gt; <em>R</em><sub>H</sub>. The contribution of <em>F</em><sub>S</sub> to <em>R</em><sub>E</sub> and <em>F</em><sub>H</sub> to <em>F</em><sub>S</sub> for the two studied sites and period averaged about 38% and 50%, respectively regardless of the site vegetation type, but the degree of <em>F</em><sub>S</sub>/<em>R</em><sub>E</sub> and <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> variability depended on the differences in seasonal dynamics of plant cover. The contribution of <em>F</em><sub>H </sub>to <em>F</em><sub>S</sub> varied from 37% in summer to 73% in winter at the site without a seasonal shift in dominant plant species, but <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> was close to constant during the year at the site with a seasonal change in dominant plant species. During the cold period, the contribution of <em>F</em><sub>H </sub>to <em>F</em><sub>S</sub> increased following plant growth decrease. The linear regression analysis showed that plant biomass was the dominant factor controlling the seasonal variation of <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> ratios, whereas the plant biomass dynamic followed the dynamics of soil water content, water table depth, and soil temperature. Our results suggest that seasonal variation of soil contribution to total fluxes from the <em>chinampa</em> ecosystem is locally differentiated. These differences were related to differences in seasonal dynamics of cover productivity which has been associated with localization of soil water content. This finding has important implications for assessing the contribution of the chinampa ecosystem to the global carbon budget.

scholarly journals Some physiological parameters of the resistance of woody plants in the arid conditions of the Mangystau desert

2019 ◽  
pp. 13-26
Author(s):  
A. A. Imanbayeva ◽  
I. F. Belozerov
Keyword(s):  
Heat Resistance ◽  
Water Content ◽  
Chlorophyll Content ◽  
Seasonal Dynamics ◽  
Woody Plants ◽  
Chlorophyll Concentration ◽  
Close Correlation ◽  
Physiological Parameters ◽  
Significance Level ◽  
Arid Conditions

The purpose of this study was to identify the possibility of using physiological parameters of growth and development of woody plants as markers of their tolerance to the arid conditions of the Mangistau desert zone. Using the generally accepted representative methods for 21 species of trees and shrubs, we studied the seasonal dynamics of the intensity of transpiration and water content of leaves, chlorophyll concentration and heat resistance. According to the magnitude of transpiration consumption of moisture, three groups of introducents were identified: weakly transpiring (<250 mg/g of raw leaves per hour), mediumtranspiring (250-500) and highly transpiring (> 500). A close correlation was established between the intensity of transpiration (IT) and the water content of the leaves of woody plants (r = 0.79). Soil moisture predetermines from 11.6 to 43.6 % of changes in transpiration flow (r = 0.34-0.66). The close connection between the transpiration intensity and relative humidity (r = -0.59) and air temperature (r = 0.46) is credible at 5 % significance level. With the amount of illumination it is associated statistically incredible (r = 0.19). Seasonal dynamics of IT in most introductions looks like a one-peak curve with a maximum in June. For the daytime course of transpiration changes, three types of rhythms are distinguished: “increasing” (from morning to evening), “falling” (from morning to evening) and “variable” (with a maximum at noon). The intensity of the transpiration process due to significant variability and multifactorial nature cannot be counted among the criteria for resistance of woody plants. However, at the same time, a significant correlation was revealed between the biological resistance of introducents and the coefficient of variation of IT. With an increase in its values, the tolerance of plants to arid habitat conditions usually increases due to their increased ability to self-regulate water exchange. Chlorophyll content is characterized by a double-vertex curve with a maximum in June and September. In the most biologically resistant species (elm elm, spinefly), its concentration is less susceptible to seasonal fluctuations. According to the collected research materials, the chlorophyll content cannot yet be considered a credible parameter of plant resistance, since it strongly depends on the bioecological properties of introduced species, especially in adverse conditions of the Mangistau desert. By heat resistance, plants are ranked in three groups: “low” (50 °С) – 3 species; “medium” (60 °С) – 8 and “high” (70 °С) – 3 taxon. As a genetically fixed bioecological parameter, weakly subject to intraspecific changes, it may well be used as a diagnostic characteristic of the introduction value of plants in arid conditions.

Characterization of frozen hydrated biological specimens by low-loss EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1572-1573
Author(s):  
Songquan Sun ◽  
Richard D. Leapman
Keyword(s):  
Water Content ◽  
Direct Method ◽  
Internal Standard ◽  
Dry Weight ◽  
Dark Field ◽  
Protein Solutions ◽  
Subcellular Compartment ◽  
Differential Shrinkage ◽  
Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

STEM measurement of subcellular water distributions

1993 ◽  
Vol 51 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
S.Q. Sun ◽  
S-L. Shi ◽  
R.A. Buchanan ◽  
S.B. Andrews
Keyword(s):  
Water Content ◽  
Internal Standard ◽  
Dry Weight ◽  
Dry Mass ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Bulk Water ◽  
Inelastic Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

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