scholarly journals Migration Law of Atrazine During Freezing of Water

2021 ◽  
Author(s):  
Yan Zhang ◽  
Wanli Zhao ◽  
Aixin Yu ◽  
Yucan Liu ◽  
Fangyun Ren ◽  
...  
Keyword(s):  
Distribution Coefficient ◽  
High Latitude ◽  
Freezing Temperature ◽  
Freezing Process ◽  
Ice Thickness ◽  
Migration Ability ◽  
Initial Concentration ◽  
Atrazine Concentration ◽  
Freezing Period ◽  
Migration Law

Abstract To explore the migration law of atrazine during the freezing process, an indoor simulated freezing experiment was carried out. The distribution coefficient (K) was used to characterize the migration ability of atrazine and explore the effects of freezing thickness, freezing temperature, and initial concentration on the migration of atrazine between ice and water. The research results showed that the concentration relationship between the ice and water phases was: ice < water before freezing < water under the ice. This indicates that atrazine migrated to the water under the ice during the freezing process in our experiment. The K value decreased as the ice thickness, freezing temperature, and initial concentration increased; thus, the greater the ice thickness, the higher the freezing temperature, the greater the initial atrazine concentration, and the greater the ability of atrazine to migrate to the water under the ice. This study provides a reference for managing natural waterbodies in high-latitude and high-altitude environments during the freezing period.

scholarly journals The migration law of magnesium ions during freezing and melting processes

2021 ◽  
Author(s):  
Zhang Yan ◽  
Liu Tongshuai ◽  
Tang Yuanqing ◽  
Zhao Wanli ◽  
Ren Fangyun ◽  
...  
Keyword(s):  
Water Layer ◽  
Melting Process ◽  
Freezing Temperature ◽  
Laboratory Simulation ◽  
Ice Thickness ◽  
Magnesium Ions ◽  
Initial Concentration ◽  
Ice Melt ◽  
Initial Ph ◽  
Migration Law

AbstractTo explore the migration law of magnesium ions (Mg2+) during freezing and melting processes, laboratory simulation experiments involving freezing and melting were carried out to investigate the influence of ice thickness, freezing temperature, initial concentration, and initial pH on the distribution of Mg2+ in the ice-water system. The distribution coefficient “K” (the ratio of the Mg2+ concentration in the ice layer to the Mg2+ concentration in the water layer under ice) was used to characterize the migration ability of Mg2+. The results showed that during the freezing process, the concentration distribution of Mg2+ in the ice and water two-phase system was as follows: ice layer < water before freezing < water layer under ice; in other words, it migrated from ice layer to the water layer under ice. “K” decreased with increasing ice thickness, freezing temperature, initial concentration, and initial pH; the higher the ice thickness, freezing temperature, initial concentration, and initial pH were, the higher the migration efficiency of Mg2+ into the water layer under ice was. During the melting process, Mg2+ was released in large amounts (50–60%) at the initial stage (0–25%) and in small amounts (25–100%) uniformly in the middle and later periods. According to the change of Mg2+ concentration in ice melt water, an exponential model was established to predict Mg2+ concentration in ice melt period. The migration law of Mg2+during the freezing and melting process was explained by using first principles.

scholarly journals Research on the Migration of the Total Manganese during the Process of Water Icing

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1626 ◽  
Author(s):  
Yan Zhang ◽  
Yuanqing Tang ◽  
Aixin Yu ◽  
Wanli Zhao ◽  
Yucan Liu
Keyword(s):  
Lower Layer ◽  
Water System ◽  
Middle Layer ◽  
Freezing Temperature ◽  
Experimental Methods ◽  
Average Concentration ◽  
Laboratory Simulation ◽  
Ice Thickness ◽  
Ice Water ◽  
Migration Law

Our research focused on the migration law of the total manganese (TMn) during the process of water icing. We utilized two experimental methods: (1) natural icing and (2) simulated icing. While using laboratory simulation, we explored the effects of ice thickness, freezing temperature, and initial concentrations on the migration of TMn in the ice-water system. The distribution coefficient “K” (the ratio of the average concentration of TMn in the ice body to the average concentration of TMn in the under-ice water body) was used to characterize it. The results indicated that TMn continuously migrated from ice to under-ice water during the process of water icing. The concentration of TMn in the ice was the upper layer < middle layer < lower layer, and K decreases as the ice thickness, freezing temperature, and initial concentration increased. We explained the migration of TMn during the process of water icing from the perspective of crystallography. Our research can arouse other researcher’s attention towards the change of TMn concentration in lakes in high latitudes during the icebound period.

A Study of Ice-Formation Phenomena on Freezing of Flowing Water in a Pipe

1987 ◽  
Vol 109 (4) ◽  
pp. 965-970 ◽  
Author(s):  
T. Hirata ◽  
H. Matsuzawa
Keyword(s):  
Freezing Temperature ◽  
Ice Formation ◽  
Freezing Process ◽  
Ice Thickness ◽  
Flow Transition ◽  
Water Pipe ◽  
Temperature Ratio ◽  
Smooth Change ◽  
Ice Water ◽  
Ice Shapes

Ice-formation phenomena in a water pipe whose wall is kept at a uniform temperature lower than the freezing temperature of water are examined under the conditions of an unstable ice-water interface. The onset conditions for a step or smooth change in ice thickness occurring with flow transition from laminar to turbulent are found to be correlated with ice thickness at the contraction region of the ice band and are expressed as a function of a pipe Reynolds number ReD, and a cooling temperature ratio θ. It is shown that the transient freezing process depends strongly on flow as well as temperature conditions and that the typical ice shapes at steady-state conditions can be classified on a θ-ReD coordinate system.

scholarly journals The Migration Law of Iron during the Process of Water Icing

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 441
Author(s):  
Yuanqing Tang ◽  
Yan Zhang ◽  
Wanli Zhao ◽  
Tongshuai Liu ◽  
Yucan Liu
Keyword(s):  
Iron Concentration ◽  
Water System ◽  
Freezing Temperature ◽  
Average Concentration ◽  
Initial Concentration ◽  
Before And After ◽  
Shallow Lakes And Ponds ◽  
Solid Liquid ◽  
Ice Water ◽  
Migration Law

In this study, we utilized simulated icing experiments to investigate the effect of icing thickness, freezing temperature and initial concentration on the migration of iron in the ice–water system during water icing. The distribution coefficient “K” (the ratio of the average concentration of iron in the ice to that in the under-ice water) was used to describe the effect. The results indicated that iron partitioned stronger to under-ice water than to ice during the process of water icing, resulting in the concentration of iron in ice–water system before and after freezing being expressed as: ice < pre-freezing water < under-ice water. K decreased with the increase in icing thickness, freezing temperature and initial concentration. The temperature change in the solution will change the solubility of the solvent, so we explained the migration of iron during the process of water icing from the perspective of solid–liquid equilibrium theory. Too high or too low iron concentration may inhibit the growth of algae, thus affecting the underwater ecological environment. We expect that our study will arouse researcher’s attention to the change in iron concentration in shallow lakes and ponds at high latitudes during the icebound period.

Effect of Particle Size on the Lamellar Pore Microstructure of Porous Al2O3 Ceramics Fabricated by the Unidirectional Freezing

2012 ◽  
Vol 184-185 ◽  
pp. 818-825 ◽  
Author(s):  
Xiao Yong Zhang ◽  
Yan Zhang ◽  
Dou Zhang
Keyword(s):  
Freezing Temperature ◽  
Porous Ceramics ◽  
Solid Loading ◽  
Freezing Process ◽  
Pore Channel ◽  
Nucleation Sites ◽  
Lower Porosity ◽  
Effect Of Particle Size ◽  
Pore Microstructure ◽  
Directional Freezing

Porous Al2O3 ceramics with a lamellar pore microstructure have been fabricated by a directional freezing process using the micro-sized and nano-sized Al2O3 powders. At the same solid loading and freezing temperature, compared with the suspensions of micro-sized Al2O3, the porous ceramics prepared from the suspensions of nano-sized Al2O3 had the narrower lamellar pore channels and thicker channel walls, which were caused by the higher viscosity, stronger inter-particle attraction and more ice nucleation sites in the nano-sized Al2O3 suspensions. For both types of Al2O3 at a specific solid loading, with the increasing of freezing temperature, the wider pore channels and thinner channel walls were observed. These tendencies were weaker by using the nano-sized Al2O3 . The above results show the lower porosity in the ceramics using the nano-sized Al2O3. However, due to the higher sintering activity for the smaller particles, the pore channel walls by using the nano-sized Al2O3 was denser than using the micro-sized Al2O3, leading to the higher mechanical strength of ceramics.

Summer–winter transitions in Antarctic ponds I: The physical environment

2011 ◽  
Vol 23 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Ian Hawes ◽  
Karl Safi ◽  
Brian Sorrell ◽  
Jenny Webster-Brown ◽  
David Arscott
Keyword(s):  
Physical Environment ◽  
Average Rate ◽  
Growth Period ◽  
Ice Formation ◽  
Freezing Process ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Continental Antarctica ◽  
The Antarctic ◽  
Summer Growth

AbstractMeltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to > 80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3–5 to > 60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0–15% of the volume of each pond was still liquid, although this represented 5–35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period.

Cooling and Freezing of Cashew Apple Using Computational Fluid Dynamics

2020 ◽  
Vol 25 ◽  
pp. 114-132 ◽  
Author(s):  
V.A. Agra Brandão ◽  
R. Araújo de Queiroz ◽  
R. Lima Dantas ◽  
G. Santos de Lima ◽  
N. Lima Tresena ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Nutritional Value ◽  
Fruits And Vegetables ◽  
Numerical Study ◽  
Freezing Process ◽  
Ansys Cfx ◽  
Cashew Apple ◽  
Freezing Period ◽  
Kinetics Of

Freezing is one the most efficient methods for conservation, especially, fruits and vegetables. Cashew is a fruit with high nutritional value and great economic importance in the Northeast region of Brazil, however, due to high moisture content, it is highly perishable. The numerical study of the freezing process is of great importance for the optimization of the process. In this sense, the objective of this work was to study the cooling and freezing processes of cashew apple using computational fluid dynamics technique. Experiments of cooling and freezing of the fruit, with the aid of a refrigerator,data acquisition system and thermocouples, and simulation using Ansys CFX® software for obtain the cooling and freezing kinetics of the product were realized. Results of the cooling and freezing kinetics of the cashew apple and temperature distribution inside the cashew apple are presented, compared and analyzed. The model was able to predict temperaturetransient behavior with good accuracy, except in the post-freezing period.

scholarly journals Study on the Formation Law of the Freezing Temperature Field of Freezing Shaft Sinking under the Action of Large-Flow-Rate Groundwater

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Bin Wang ◽  
Chuan-xin Rong ◽  
Jian Lin ◽  
Hua Cheng ◽  
Hai-bing Cai
Keyword(s):  
Temperature Field ◽  
Groundwater Flow ◽  
Flow Velocity ◽  
Flow Rate ◽  
Freezing Temperature ◽  
Freezing Process ◽  
Flow Rates ◽  
Porosity Reduction ◽  
Shaft Sinking ◽  
Large Flow

Taking into account moisture migration and heat change during the soil freezing process, as well as the influence of absolute porosity reduction on seepage during the freezing process, we construct a numerical model of hydrothermal coupling using laws of conservation of energy and mass. The model is verified by the results of large-scale laboratory tests. By applying the numerical calculation model to the formation of artificial shaft freezing temperature fields under the action of large-flow groundwater, we conclude that groundwater with flow rates of less than 5 m/d will not have a significant impact on the artificial freezing temperature field. The maximum flow rates that can be handled by single-row freezing pipes and double-row freezing pipes are 10 m/d and 20 m/d, respectively, during the process of freezing shaft sinking. By analyzing the variation of groundwater flow rate during freezing process, we find that the groundwater flow velocity can reach 5–7 times the initial flow velocity near the closure moment of the frozen wall. Finally, in light of the action characteristics of groundwater on the freezing temperature field, we make suggestions for optimal pipe and row spacing in freezing pipe arrangement.

THE QUANTITATIVE ESTIMATION OF FROST INJURY AND RESISTANCE IN BLACK LOCUST, ALFALFA, AND WHEAT TISSUES BY DETERMINATION OF AMINO ACIDS AND OTHER NINHYDRIN-REACTING SUBSTANCES RELEASED AFTER THAWING

1964 ◽  
Vol 42 (6) ◽  
pp. 637-649 ◽  
Author(s):  
D. Siminovitch ◽  
H. Therrien ◽  
F. Gfeller ◽  
B. Rheaume
Keyword(s):  
Amino Acids ◽  
Black Locust ◽  
Quantitative Estimation ◽  
Freezing Temperature ◽  
Freezing Injury ◽  
Tree Bark ◽  
Freezing Process ◽  
Frost Injury ◽  
Ninhydrin Reaction

Amino acids and other soluble α-amino compounds are liberated into a leaching medium from tissues of black locust bark, alfalfa, and wheat that are frozen to temperatures which are injurious to the tissues. The amounts liberated increase with lowering in freezing temperature and are proportional to the loss in vital capacity of the tissue. Insignificant amounts of amino acids are released by leaching of non-frozen tissue while a maximum is reached at freezing temperatures which are completely lethal. The amino acids liberated from frozen and thawed tissues must originate from the destruction of living cells by the freezing process. The determination of the concentration of amino acids in the medium in which the plant tissues are leached after freezing can be used therefore as a quantitative method for the estimation of the injury sustained in the freezing.The use of the ninhydrin reaction for the purpose of this determination is described and its application to the estimation of freezing injury and resistance in a variety of hardy and non-hardy tissues of alfalfa, wheat, and black locust tree bark is shown. The extension of this procedure to the determination of injury produced by toxic and other detrimental agents is indicated.

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