Solute movement through undisturbed soil columns under pasture during unsaturated flow

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1153 ◽  
Author(s):  
I. Vogeler ◽  
D. R. Scotter ◽  
S. R. Green ◽  
B. E. Clothier
Keyword(s):  
Water Content ◽  
Unsaturated Flow ◽  
Sandy Loam ◽  
Richards Equation ◽  
Initial Water Content ◽  
Soil Columns ◽  
Initial Water ◽  
Undisturbed Soil ◽  
Significant Difference ◽  
Solute Movement

Previous studies of solute movement concerning the influence of initial soil water content have led to apparently contradictory results. Here we describe some experiments which aimed to determine the effect of both pasture and initial water content on solute movement. Solid SrCl2, CaCl2, and Ca(NO3)2 were surface-applied to undisturbed columns of a fine sandy loam under short pasture. The soil columns were 300 mm in both diameter and length. A rotating rainfall simulator delivered steady-state rainfall at about 10 mm/h. The leachate at the base was collected under suction and analysed, and one column was analysed for resident concentrations of strontium. Solute transport could be accurately described by coupling Richards’ equation with the convection dispersion equation, when ion exclusion or exchange were taken into account. The dispersivity was about 70 mm, only slightly higher than found previously for the same soil without vegetation. There was no significant difference in intrinsic behaviour when solute was applied to either an initially wet or a dry topsoil. The contrasting results from earlier published studies were probably due to incipient ponding and macropore flow. This will not usually occur in New Zealand pasture soils under typical rainfall intensities, but might under irrigation or when the soil structure is degraded. It is suggested that soil cores need to have dimensions at least as large as the dispersivity if they are to encompass most of the local variation in solute concentration.

Measurement of SWCC of Xiamen Residual Soil by Filter Paper

2012 ◽  
Vol 256-259 ◽  
pp. 1046-1051
Author(s):  
Dong Xia Chen ◽  
Ma Xiu Zhang ◽  
You Qiang Lin ◽  
Jian Ni
Keyword(s):  
Hysteresis Loop ◽  
Water Content ◽  
Filter Paper ◽  
Unsaturated Soils ◽  
Experimental Program ◽  
Initial Water Content ◽  
Residual Soil ◽  
Soil Specimen ◽  
Initial Water ◽  
Significant Difference

Soil suction is one of the most important parameters for unsaturated soils. An experimental program was carried out to measure the maric suction of soil specimens of a residual soil in Xiamen by filter paper method. Initial water content, soil structure, and stress state were taken into account to investigate the hysteresis loop of SWCC. The air-entry value of test soil is about 140kPa and residual saturation is about 18%. The soil specimen at wet of optimum has the largest hysteresis loop for a relatively uniform pore-size distribution. However, the soil specimen at dry of optimum has the smallest hysteresis loop. The soil specimen at optimum lies between them. For specimens subjected to different stress states under various applied loads, the higher the applied load on the specimen, the smaller the size of hysteresis loop. In drying or wetting process, there is a significant difference in matric suction though soil specimens are at same water content. Therefore, for this kind of soil, it should be attention that the shear strength may be greatly reduced during rainstorms.

Simulation of the rainfall runoff process using a hysteretic infiltration redistribution model

Soil Research ◽  
1975 ◽  
Vol 13 (2) ◽  
pp. 133 ◽  
Author(s):  
KK Watson ◽  
SJ Lees
Keyword(s):  
Water Content ◽  
Soil Profile ◽  
Sandy Loam ◽  
Water Status ◽  
Surface Flux ◽  
Numerical Approach ◽  
Initial Water Content ◽  
Initial Water ◽  
Rainfall Events

The significance of the soil profile and its accompanying water status in deterministic catchment models is discussed in relation to the current use of the soil-store concept. An alternative numerical approach is described in which the movement of water into and through the soil profile (together with the determination of runoff volumes) is continuously monitored during any pattern of rainfall and non-rainfall events. A significant component in the approach is the use of a comprehensive domain-type hysteresis model for the analysis of infiltration-redistribution sequences. The simulation is illustrated by using a rainfall hyetograph of 7 h duration (including one non-rainfall period of 1 h) as the flux input into a homogeneous profile of a sandy loam of uniform initial water content. The time-dependent relationships of rate of surface flux, depression storage and runoff volume are calculated for the duration of the hyetograph period. Profiles of water content are also presented.

Influence of initial water content and strain rate on remolded yield stress in marine clay

2021 ◽  
pp. 1-8
Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Yield Stress ◽  
Initial Water Content ◽  
Marine Clay ◽  
Initial Water

scholarly journals Application of the Calorimetric Methods to the Characteristics of Seeds from Olives

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 90
Author(s):  
Andrzej Bryś ◽  
Joanna Bryś ◽  
Marko Obranović ◽  
Dubravka Škevin ◽  
Szymon Głowacki ◽  
...  
Keyword(s):  
Olive Oil ◽  
Water Content ◽  
Cooling System ◽  
Waste Product ◽  
Normal Pressure ◽  
Ash Content ◽  
Initial Water Content ◽  
Scanning Calorimetry ◽  
Initial Water

The olive oil industry represents an important productive sector in the Mediterranean basin countries. Olive stone is an essential by-product generated in the olive oil extraction industries and it represents roughly 10% by weight of the olive fruit. The seeds of pickled olives are also a significant waste product. In the present study, we have investigated the possibility of the use of differential scanning calorimetry for the thermal characterization of seeds from green and black pickled olives from Croatia. The differential scanning calorimeter (DSC) with a normal pressure cell equipped with a cooling system was used to determine the thermal properties of seeds from olives. The following analyses were also performed: the determination of calorific values in a pressure bomb calorimeter, the determination of initial water content, the determination of changes of water content during drying at the temperatures of 30 °C, 50 °C and 80 °C, the determination of a percentage content of seeds mass to the mass of the whole olives, and the determination of ash content. Seeds from olives are characterized by very good parameters as a biomass. The analyzed olive seeds were characterized by low water content, low ash content, and a relatively high caloric value.

scholarly journals Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1933 ◽  
Author(s):  
Chenglong Yin ◽  
Wei Zhang ◽  
Xunli Jiang ◽  
Zhiyi Huang
Keyword(s):  
Water Content ◽  
Soil Stabilization ◽  
Clay Soil ◽  
Soil Aggregates ◽  
Optical Microscope ◽  
Initial Water Content ◽  
Reaction Products ◽  
Unconfined Compression Test ◽  
Initial Water ◽  
X Ray

Initial water content significantly affects the efficiency of soil stabilization. In this study, the effects of initial water content on the compressibility, strength, microstructure, and composition of a lean clay soil stabilized by compound calcium-based stabilizer were investigated by static compaction test, unconfined compression test, optical microscope observations, environment scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results indicate that as the initial water content increases in the range studied, both the compaction energy and the maximum compaction force decrease linearly and there are less soil aggregates or agglomerations, and a smaller proportion of large pores in the compacted mixture structure. In addition, for specimens cured with or without external water supply and under different compaction degrees, the variation law of the unconfined compressive strength with initial water content is different and the highest strength value is obtained at various initial water contents. With the increase of initial water content, the percentage of the oxygen element tends to increase in the reaction products of the calcium-based stabilizer, whereas the primary mineral composition of the soil-stabilizer mixture did not change notably.

scholarly journals Solidification of High Organic Matter Content Sludge by Cement, Lime and Metakaolin

2018 ◽  
Author(s):  
Ke Rui ◽  
Wang Hongxing ◽  
Tan Yunzhi ◽  
Wang Lehua
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Organic Matter Content ◽  
Microscopic Analysis ◽  
Chemical Components ◽  
Orthogonal Experimental Design ◽  
Initial Water Content ◽  
Initial Water ◽  
Lime Content ◽  
Sheet Structure

Based on orthogonal experimental design, the key solidification controlling technology of Solidified/Stabilized (S/S) sludge with high total organic content (TOC) by cement, lime and metakaolin was explored by macroscopic tests, chemical components measurements and microscopic analysis. The macroscopic tests show that, the permeability coefficient is mainly affected by initial water content and lime content, and the unconfined compression strength is mainly affected by cement content and lime content. The chemical components measurements show that, the solidification effect of S/S sludge with high TOC is controlled by organic matter consumption, and organic matter consumption is determined by the alkaline environment from the cement and lime hydration reactions, which is mainly affect by the initial water content and lime-metakaolin content ratio. The microscopic analysis results show that, lime consumes parts of organic matter while excess lime produces weak Ca(OH)2 crystal fluffy sheet structure, matakaolin produces pozzolanic reactions with cement and lime instead of soil particles, and consumes the weak Ca(OH)2 crystal fluffy sheet structure produced by superfluous lime. The research has confirmed key controlling points of S/S sludge in case of high TOC, which will provide theoretical guidance and technical support for S/S sludge promotion with high TOC.

Determination of the tensile strength of unsaturated tailings using bending tests

2015 ◽  
Vol 52 (11) ◽  
pp. 1874-1885 ◽  
Author(s):  
Bibiana Narvaez ◽  
Michel Aubertin ◽  
Faustin Saleh-Mbemba
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Initial Water Content ◽  
Ambient Conditions ◽  
Initial Water ◽  
Bending Tests ◽  
Retention Curve ◽  
Apparent Cohesion

Bending tests were conducted on specimens of unsaturated tailings from three hard rock mines to evaluate their tensile strength. Saturated samples were prepared at an initial water content, w0, of 40% and then naturally dried under ambient conditions to pre-selected degrees of saturation, Sr, which can be related to the corresponding suction using the water retention curve. The basic interpretation of the bending tests results is based on an elastic–brittle behavior. The results show how the tensile strength, σt, of unsaturated tailings varies with water content, w (and Sr). The experimental data are also used to evaluate Young’s modulus in tension, Et, and to estimate the apparent cohesion, capp, as a function of Sr. Predictive equations are also applied to estimate the values of σt of unsaturated tailings using the water retention curve.

scholarly journals Temperature and seed moisture content affect electrical conductivity test in pea seeds

2017 ◽  
Vol 39 (4) ◽  
pp. 410-416 ◽  
Author(s):  
Lara Bernardes da Silva Ferreira ◽  
Nayara Alves Fernandes ◽  
Luan Costa de Aquino ◽  
Anderson Rodrigo da Silva ◽  
Warley Marcos Nascimento ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Moisture Content ◽  
Water Content ◽  
Initial Water Content ◽  
Seed Moisture Content ◽  
Initial Water ◽  
Test Efficiency ◽  
Seed Moisture ◽  
Pea Seeds ◽  
Initial Seed

Abstract: Several factors affect the electrical conductivity test efficiency, with emphasis given to the initial water content and the temperature during imbibition. This study aimed to evaluate the effect of the initial water content of pea seeds and the temperature on the electrical conductivity test efficiency. Six lots of ‘Mikado’ pea were used, which were previously tested for initial characterization. In the first trial, based on the initial value of the samples, the seed moisture content was adjusted to 9, 11, 13 and 15% and then the seeds were submitted to the electrical conductivity test. In the second trial, the water for seed imbibition was kept for 24 hours at 10, 15, 20, 25 and 30 ºC, and after that time the seeds were added and soaked for other 24 hours at the temperatures already mentioned. It was observed that initial seed moisture content and water temperature during imbibition influenced the results of the electrical conductivity test. This test should be carried out with distilled water, previously maintained for 24 hours at 25 °C for temperature stabilization. Then, the seeds with seed moisture content between 11 and 15% should be put to soak at 25 °C, and maintained at this temperature for 24 hours.

scholarly journals Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution

2020 ◽  
Vol 10 (24) ◽  
pp. 8981
Author(s):  
Yuhang Liu ◽  
Dongqing Li ◽  
Lei Chen ◽  
Feng Ming
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Water Content ◽  
Size Distribution ◽  
Initial Water Content ◽  
Mean Stress ◽  
Initial Water ◽  
Unfrozen Water Content ◽  
The Mean ◽  
Lens Formation

Ice lens is the key factor which determines the frost heave in engineering construction in cold regions. At present, several theories have been proposed to describe the formation of ice lens. However, most of these theories analyzed the ice lens formation from a macroscopic view and ignored the influence of microscopic pore sizes and structures. Meanwhile, these theories lacked the support of measured data. To solve this problem, the microscopic crystallization stress was converted into the macro mean stress through the principle of statistics with the consideration of pore size distribution. The mean stress was treated as the driving force of the formation of ice lens and induced into the criterion of ice lens formation. The influence of pore structure and unfrozen water content on the mean stress was analyzed. The results indicate that the microcosmic crystallization pressure can be converted into the macro mean stress through the principle of statistics. Larger mean stress means the ice lens will be formed easier in the soil. The mean stress is positively correlated with initial water content. At the same temperature, an increase to both the initial water content and the number of pores can result in a larger mean stress. Under the same initial water content, mean stress increases with decreasing temperature. The result provides a theoretical basis for studying ice lens formation from the crystallization theory.

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