scholarly journals Experimental Study on the Lateral Seepage Characteristics in the Tension Saturated Zone

2021 ◽  
Vol 18 (10) ◽  
pp. 5098
Author(s):  
Yongfeng Gong ◽  
Zuo Liu ◽  
Chuanming Ma ◽  
Minghong Li ◽  
Xu Guo
Keyword(s):  
Potential Gradient ◽  
Horizontal Flow ◽  
Saturated Zone ◽  
Total Water ◽  
Seepage Velocity ◽  
Seepage Field ◽  
Recharge Area ◽  
Flow Area ◽  
Discharge Area ◽  
Water Potential Gradient

To study the lateral seepage field in the tension saturated zone (TSZ), an experiment with no evaporation and precipitation infiltration was carried out in a self-made seepage tank filled up with fine sand. Based on the data and plots obtained, the lateral seepage field distribution features in the TSZ can be divided into three area for discussion: ascending area, descending area, and the nearly horizontal flow area. In the ascending and descending area, the total water potential gradient diminished from the recharge area to the discharge area and the seepage velocity was faster. In the nearly horizontal flow area, the total water potential gradient was lower and the seepage velocity was slower. The pressure potential gradually decreased horizontally from the recharge area to the discharge area, while in the vertical profile, it gradually decreased from the bottom to the top in the whole seepage area. In the absence of evaporation, the vertical water exchange among the saturated zone, TSZ, and unsaturated zone in nearly horizontal flow area is weak. Contrarily, in the ascending area and descending area, vertical water flows through both the phreatic surface and the upper interface of the TSZ. When there is lateral seepage in the TSZ, the thickness of the TSZ generally increases from the ascending area to the nearly horizontal area and then to the descending area. It should be pointed out that in the nearly horizontal area, the TSZ thickness is approximately equal to the height of the water column. Overall, the lateral seepage in the TSZ can be regarded as a stable siphon process, hence the siphon tube model can be further used to depict this lateral seepage.

scholarly journals Molecular mechanisms mediating root hydrotropism: what we have observed since the rediscovery of hydrotropism

2019 ◽  
Vol 133 (1) ◽  
pp. 3-14
Author(s):  
Yutaka Miyazawa ◽  
Hideyuki Takahashi
Keyword(s):  
Arabidopsis Thaliana ◽  
Water Potential ◽  
Water Availability ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Potential Gradient ◽  
Regulatory Mechanisms ◽  
Directional Growth ◽  
Plant Adaptation ◽  
Water Potential Gradient

AbstractRoots display directional growth toward moisture in response to a water potential gradient. Root hydrotropism is thought to facilitate plant adaptation to continuously changing water availability. Hydrotropism has not been as extensively studied as gravitropism. However, comparisons of hydrotropic and gravitropic responses identified mechanisms that are unique to hydrotropism. Regulatory mechanisms underlying the hydrotropic response appear to differ among different species. We recently performed molecular and genetic analyses of root hydrotropism in Arabidopsis thaliana. In this review, we summarize the current knowledge of specific mechanisms mediating root hydrotropism in several plant species.

Migration of acidic pore waters at the Waite Amulet tailings site near Rouyn–Noranda, Quebec, Canada

1992 ◽  
Vol 29 (3) ◽  
pp. 466-476 ◽  
Author(s):  
Ernest K. Yanful ◽  
Luc C. St-Arnaud
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Mine Drainage ◽  
Geotechnical Properties ◽  
Horizontal Flow ◽  
Sulphide Mineral ◽  
Saturated Zone ◽  
Pore Waters ◽  
Dissolved Metals ◽  
Water Contents

Pore waters found in the unsaturated zone of the Waite Amulet tailings have been modified by sulphide mineral oxidation, resulting in acidic pH (near 4) and high concentrations of dissolved iron and sulphate at about 5 and 12 g/L, respectively. These pore waters have been displaced down into the shallow saturated zone of the tailings by infiltrating water. Most metals are removed from the pore water as a result of pH buffering before they reach the deeper saturated zone. However, some dissolved metals still remain in solution and are transported with the pore water through the tailings. Numerical flow modelling shows that an anisotropy in hydraulic conductivity (ratio of Kx/Ky is estimated to be 100) exists in the tailings, most likely due to the presence of horizontal fine-grained "slime" layers. The estimated horizontal pore-water velocity is almost 20 times higher than the vertical velocity. Anisotropy in hydraulic conductivity has the effect of promoting horizontal flow over vertical flow in the model. The geometry of the tailings impoundment and the assumed impermeability of the varved clay soil underlying the tailings also contribute to increased horizontal flow. To verify that a preferred horizontal flow exists and that the clay subsoil is indeed impermeable, the geotechnical properties and hydrogeochemistry of the clay are also evaluated. The results indicate that clay located beneath the tailings is slightly overconsolidated in the shallow zone but normally consolidated at greater depth by the weight of the tailings. Overconsolidation ratios reach a maximum value of 2.0. In the clay–tailings interface zone, the soil is characterized by lower in situ water contents and slightly higher undrained shear strengths Cu than the deeper clay. The water contents of the near-interface clay average about 40% and the Cu values 80 kPa, compared with an average water content of 55% and a Cu value of only 20 kPa for the clay at greater depths. These geotechnical properties confirm the presence of a desiccated oxidized upper zone identified in previous studies. It is hypothesized that fractures that could have appeared in the oxidized zone before the tailings deposition would have been closed due to consolidation by the tailings mass. Above-background sulphate concentrations observed in the clay layer at a depth of 1 m are believed to be controlled by diffusion and advection. The presence of fractures in the oxidized zone and excess pore-water pressures generated during consolidation of the clay by the tailings mass could have also influenced chemical transport. Key words : acid generation, acid mine drainage, diffusion, geotechnical, hydrogeochemistry, tailings.

Denitrification in the recharge area and discharge area of a transient agricultural nitrate plume in a glacial outwash sand aquifer, Minnesota

2002 ◽  
Vol 38 (7) ◽  
pp. 10-1-10-26 ◽  
Author(s):  
J. K. Böhlke ◽  
R. Wanty ◽  
M. Tuttle ◽  
G. Delin ◽  
M. Landon
Keyword(s):  
Recharge Area ◽  
Discharge Area ◽  
Sand Aquifer ◽  
Glacial Outwash

THE ORIGIN OF HYDROCHEMICAL PATTERNS IN HUMMOCKY MORAINE

1967 ◽  
Vol 4 (6) ◽  
pp. 1065-1092 ◽  
Author(s):  
A. Rozkowski
Keyword(s):  
Groundwater Flow ◽  
Flow Model ◽  
Chemical Analyses ◽  
Soluble Salts ◽  
Recharge Area ◽  
Discharge Area ◽  
Transmission Zone ◽  
Significant Enrichment ◽  
Poorly Soluble ◽  
Shallow Zone

Hydrochemical investigations were carried out in a small local basin in hummocky moraine of southern Saskatchewan. The 'basin' consisted of a hill and surrounding permanent sloughs. The constructed Teledeltos flow model shows the typical pattern of groundwater flow near permanent lakes, where the hills are areas of recharge and the sloughs areas of discharge. Based on the chemical analyses of soil and till extracts as well as on the chemical analyses of slough and groundwater, the development of certain hydrochemical patterns in hummocky moraine can be explained.Three hydrochemical zones can be distinguished: SO4–Ca–Mg in the recharge area, SO4–Mg–Ca in the transmission zone, and SO4–Mg–(Na) in the discharge area. The increase of groundwater salinity from the recharge area to the discharge area is due to evapotranspiration as well as to the poor permeability of the glacial deposits.The SO4–Mg–Ca type of water of the recharge area is already formed in the zone of aeration. The subsequent changes of groundwater chemistry in the zone of saturation are induced by the enrichment of easily soluble salts and by the steady precipitation of poorly soluble salts. The sharp increase in salinity and the significant enrichment of the SO4–Mg type of water by easily soluble salts take place in the shallow zone of the discharge area close to the surface. The study of water extracts suggests the presence of groundwater discharge in the region of the capillary fringe of the recharge area also.The delivery of ions to the sloughs takes place by groundwater flow and inter-flow; therefore, the hydrochemistry of sloughs is primarily determined by the chemistry of these waters. The further metamorphosis of slough water is produced mainly by intensive evaporation as well as by ion exchange within the slough.

The decline in xylem flow to mango fruit at the end of its development is related to the appearance of embolism in the fruit pedicel

2015 ◽  
Vol 42 (7) ◽  
pp. 668 ◽  
Author(s):  
Thibault Nordey ◽  
Mathieu Léchaudel ◽  
Michel Génard
Keyword(s):  
Hydraulic Conductivity ◽  
Water Potential ◽  
Fruit Development ◽  
Hydraulic Properties ◽  
Potential Gradient ◽  
Mango Fruit ◽  
Xylem Flow ◽  
Water Potential Gradient ◽  
The Impact ◽  
Late Growth

The decline in xylem flow during the late growth stage in most fruits may be due either to a decrease in the water potential gradient between the stem bearing the fruit and the fruit tissues or to a decrease in the hydraulic conductivity of xylem vessels, or both. In this study, we analysed changes in xylem flows to the mango Mangifera indica L. fruit during its development to identify the sources of variation by measuring changes in the water potential gradient and in the hydraulic properties of the fruit pedicel. The variations in xylem and transpiration flows were estimated at several stages of mango fruit development from the daily changes in the fresh mass of detached and girdled fruits on branches. The water potential gradient was estimated by monitoring the diurnal water potential in the stem and fruit. The hydraulic properties of the fruit pedicel were estimated using a flow meter. The results indicated that xylem flow increased in the early stages of fruit development and decreased in the late stage. Variations in xylem flow were related to the decrease in the hydraulic conductivity of xylem vessels but not to a decrease in the water potential gradient. The hydraulic conductivity of the fruit pedicel decreased during late growth due to embolism caused by a decrease in the fruit water potential. Further studies should establish the impact of the decrease in the hydraulic conductivity of the fruit pedicel on mango growth.

Simultaneous measurements of tomato fruit and stem water potentials using in situ stem hygrometers

1989 ◽  
Vol 67 (8) ◽  
pp. 2352-2355 ◽  
Author(s):  
D. R. Lee ◽  
M. A. Dixon ◽  
R. W. Johnson
Keyword(s):  
Water Potential ◽  
Tomato Fruit ◽  
Potential Gradient ◽  
Diurnal Changes ◽  
Stem Water Potential ◽  
Simultaneous Measurements ◽  
Water Potentials ◽  
Stem Water ◽  
Water Potential Gradient

Simultaneous measurements were made of the water potentials of the stem and fruit of intact tomato plants (Lycopersicon esculentum Mill. var. Heinz 2653) using in situ temperature-corrected stem psychrometers. Water potential of the fruit remained consistently lower than the water potential of the stem except when the plant had been subjected to prolonged water stress. Stem water potential recovered quickly with rewatering, increasing by approximately 0.5 MPa in 1 h, but the water potential of the fruit remained consistently near −1.0 MPa. The results indicate a significant resistance to water flow between the stem and the fruit and a substantial hydraulic capacitance represented by the volume of the fruit. Diurnal changes in dimensions of tomato fruit were also measured. Fruit diameter expanded at night and contracted during the day even when the water potential gradient favoured flow towards the fruit. This indicates that bidirectional flow (to and from the fruit) is not responsible for the observed diurnal changes in the fruit dimensions.

scholarly journals 275 Water Relations of Fruit Cracking in Single-truss Tomato Plants

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 489E-489
Author(s):  
Takashi Ikeda ◽  
Kunio Okano ◽  
Yuka Sakamoto ◽  
Shin-ichi Watanabe
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Water Status ◽  
Potential Gradient ◽  
Culture Solution ◽  
Tomato Plants ◽  
Fruit Flesh ◽  
Fruit Cracking ◽  
Fruit Skin ◽  
Water Potential Gradient

This study was undertaken to investigate the water relations of tomato (Lycopersicon esculentum Mill.) fruit cracking for single-truss tomato plants. The tomato plants were cultured on a closed hydroponic system in greenhouse. Water status of culture solution and plant tissues was measured with psychrometers. Water potential of the culture solution for the stressed plant was changed from -0.06 MPa (control plants) to -0.36 MPa at 24 days after anthesis. Hardness of the fruit skin was not different significantly between the stressed plants and the control plants. Fruit cracking occurred frequently in the control plants, but not in the stressed plants. Water potential gradient between the tissue of fruit flesh and water source for the control plants was bigger than that of the stressed plants. Turgors were increased at the tissues of fruit flesh and fruit skin at the control plants between predawn and morning but not at the stressed plants. These results indicated that the water potential gradient and the increased turgor in these tissues might be a trigger for the occurrence of fruit cracking on single-truss tomato plants.

scholarly journals Intermittent CaCl2 Sprays during Rain to Prevent Sweet Cherry Cracking

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 793F-793 ◽  
Author(s):  
R. Thomas Fernandez ◽  
James A. Flore
Keyword(s):  
Water Potential ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Irrigation System ◽  
Potential Gradient ◽  
Daily Rainfall ◽  
Controlled Irrigation ◽  
Computer Controlled ◽  
Water Potential Gradient ◽  
Rain Events

Fruit of sweet cherry (Prunus avium L.) crack during or after rain due, in part, to absorption of water through the fruit surface driven by the water potential gradient. In 1972, J. Vittrup-Christensen suggested that overhead misting of calcium salts during precipitation may be an effective way to prevent cherry cracking by reducing the water potential gradient. We tested this hypothesis by designing a computer-controlled irrigation system to intermittently spray a 10% CaCl2 solution on trees during rain events. Spray emitters were placed in the middle and at the top of the canopy. The program turned the system on for 90 s at each 0.3 mm of rain and monitored daily rainfall and accumulated mist times. Two `Emperor Francis' and two `Ulster' were treated with equal number of controls. Intact and cracked cherries were counted on four branches per tree at three times when cherries were susceptible to cracking. Overall, cracking was reduced from 33% to 11% by the CaCl2 spray at the end of the experiment. Treated `Ulster' had 9% cracked fruit, while control had 43% cracked fruit. Differences for `Emperor Francis' were not significant. Phytotoxicity was estimated at about 15 % of leaf area. This system will be reevaluated in 1995 with the added objective of quantifying and reducing phytotoxicity.

Transport of Tritiated Water and 14C-Labelled Assimilate Into Grains of Wheat. I. Entry of Tho Through and in Association With the Stalk of the Grain

1985 ◽  
Vol 12 (6) ◽  
pp. 573 ◽  
Author(s):  
CF Jenner
Keyword(s):  
Water Potential ◽  
Dry Matter ◽  
Tritiated Water ◽  
Potential Gradient ◽  
Grain Filling ◽  
Vapour Phase ◽  
Reasonable Estimate ◽  
Intact Plants ◽  
Water Potential Gradient ◽  
Negligible Contribution

Dry matter is transported through the stalk of the wheat grain, and during grain filling is accumulated within it with no change in the quantity of water in the grain, and with little or no net transfer of water through the stalk. Accumulation of dry matter is also independent of the magnitude and the direction of a water potential gradient imposed between the plant and the atmosphere surrounding the grain. A procedure is described, based on sealing the grain (minus its bracts) within an impermeable capsule, for measuring the total net influx of radioactive water into the grain (FT). Tritiated water, THO, is used as a tracer for water. FT is assumed to comprise transport in the liquid phase and transport in the vapour phase, by mass flow and by diffusion. Apoplastic flow makes a negligible contribution in the system described because the water potential gradient is minimized. FT was obtained by adding to the quantity of THO accumulating in the encapsulated assemblies an estimate of the amount of THO lost from the assemblies by leakage. Two types of ears were compared: ears on intact plants assimilating 14CO2 and growing in small pots watered with THO, and detached ears cultured on [14C]sucrose in a solution of THO. Both types gave similar results but the detached ear system probably furnished the most reasonable estimate, a rate of 10.1 �l of THO per assembly per day.

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