1 Introduction A salt lake is a naturally occurring complex body of water and salt interaction.More than 700 salt lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous...1 Introduction A salt lake is a naturally occurring complex body of water and salt interaction.More than 700 salt lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous for their abundance of lithium,potassium,magnesium,and boron resources.It is展开更多
A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns withdifferent soil texture profiles and groundwater levels under crops were conducted to study the changes ...A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns withdifferent soil texture profiles and groundwater levels under crops were conducted to study the changes of salt-waterdynamics induced by water uptake of crops and to propose the theoretical basis for the regulation and control of salt-water dynamics as well as to predict salinity levels. The HYDRUS 1D model was applied to simulate the one-dimensionalmovement of water and salt transport in the soil columns. The results showed that the salts mainly accumulated in theplow layer in the soil columns under crops. Soil water and salt both moved towards the plow layer due to soil waterabsorption by the crop root system. The salt contents in the column with lower groundwater were mostly greater thanthose with high groundwater. The water contents in the soil columns increased from top to the bottom due to plant rootwater uptake. The changes in groundwater level had little influence on water content of the root zone in the soil columnswith crop planting. Comparison between the simulated and the determined values showed that model simulation resultswere ideal, so it is practicable to do numerical simulation of soil salt and water transport by the HYDRUS 1D model.Furthermore, if the actual movement of salt and water in fields is to be described in detail, much work needs to be done.The most important thing is to refine the parameters and select precise boundary conditions.展开更多
Through a simulation test carried out with soil columns (61.8 cm in diameter), the effect of precipitation on salt-water dynamics in soils was studied by in-situ monitoring of salt-water dynamics using soil salinity s...Through a simulation test carried out with soil columns (61.8 cm in diameter), the effect of precipitation on salt-water dynamics in soils was studied by in-situ monitoring of salt-water dynamics using soil salinity sensors and tensiometers. The results show that in the profile of whole silty loam soil, the surface runoff volume due to precipitation and the salt-leaching role of infiltrated precipitation increased with the depth of ground water; and in the profile with an intercalated bed of clay or with a thick upper layer of clay, the amount of surface runoff was greater but the salt-leaching role of precipitation was smaller than those in the profile of whole silty loam soil. In case of soil water being supplemented by precipitation, the evaporation of groundwater in the soil columns reduced, resulting in a great decline of salt accumulation from soil profile to surface soil. The effect of precipitation on the water regime of soil profile was performed via both water infiltration and water pressure transfer. The direct infiltration depth of precipitation was less than 1 m in general, but water pressure transfer could go up to groundwater surface directly.展开更多
Continuous monitoring of salt and water movement in the soil profile of highly salinized topsoil under steadystate infiltration was conducted.It gives that salt and water dynamics during convection-diffusion period ca...Continuous monitoring of salt and water movement in the soil profile of highly salinized topsoil under steadystate infiltration was conducted.It gives that salt and water dynamics during convection-diffusion period can be divided into three stages:1.formation of a salt peak,2.the salt peak moving downwards till the appearance of the summit of the salt peak,3.the salt peak moving further downwards with the peak value decreasing.Results show that the maximum salt peak appears at the same depth if soil texture and outflow condition are the same.Factors affecting salt and water movement and ion components in the outflow solution underinfiltration are discussed.展开更多
The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses o...The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP： 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.展开更多
A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers we...A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers were used to monitor salt and water variation in soils.The experiment revealed that in the process of fresh groundwater moving upwards by capillary rise in the column,the salts in subsoil were brought upwards and accumulated in the surface soil,and consequently the salinization of surface soil took place.The rate of salt accumulation is determined mainly by the volume of capillary water flow and the conditions of salts contained in the soil profile.Water flux in soils decreased obviously when groundwater depths fell below 1.5m.When there was an interbedded clay layer 30cm in thickness in the silty loam soil profile or a clay layer 100cm in thickness at the top layer,the water flux was 3-5 times less than in the soil profile of homogeneous silty loam soil.Therefore,the rate of salt accumulation was decreased and the effect of variation of groundwater depth on the water flux in soils was weakened comparatively.If there was precipitation or irrigation supplying water to the soil,the groundwater could rarely take a direct part in the process of salt accumulation in surface soil,especially,in soil profiles with an interbedded stratum or a clayey surface soil layer.展开更多
Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamic...Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamics in situ,using soil salinity sensors and tensiometers.The results indicated that the amount of water absorbed by crops from the soil was generally larger than the decrement of water consumption from soil surface evaporation reduced by the crop covering the soil surface and improving the soil structure,therefore,under the conditions of crop growing and non-irrigation,water content in soil profile was less than that without crop growing,and the gradient of negative pressure of soil water in soil profile especially in the root zone was enlarged,thus causing the water flowing from subsoils into root zone and increasing the groundwater moving upwards into soil layer via capillary rise,so that the groundwater evaporation increased.Consequently,under the condition of crop growing,the salt was mainly accumulated towards the root zone rather than to the top soil.the accumulating rate of salt in groundwater via capillary rise of soil water to subsoils was increased thereby.展开更多
Solar vapor generation(SVC)represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage.One of its main bottleneck problems is that the evaporation efficiency and...Solar vapor generation(SVC)represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage.One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high-salinity brines.Herein,we demonstrate that the 3D porous melamine-foam(MF)wrapped by a type of self-assembling composite materials based on reduced polyoxometalates(i.e.heteropoly blue,HPB),oleic acid(OA),and polypyrrole(PPy)(labeled with MF@HPB-PPy_(n)-OA)can serve as efficient and stable SVC material at high salinity.Structural characterizations of MF@HPB-PPy_(n)-OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co-exist on the surface of composite materials,optimizing the hydrophilic and hydrophobic interfaces of the SVC materials,and fully exerting its functionality for ultrahigh water-evaporation and anti-salt fouling.The optimal MF@HPB-PPy_(10)-OA operates continuously and stably for over 100 h in 10wt%brine.Furthermore,MF@HPB-PPy_(10)-OA accomplishes complete salt-water separation of 10wt%brine with 3.3kgm^(-2)h^(-1)under 1-sun irradiation,yielding salt harvesting efficiency of 96.5%,which belongs to the record high of high-salinity systems reported so far and is close to achieving zero liquid discharge.Moreover,the low cost of MF@HPB-PPy_(10)-OA(2.56$m^(-2))suggests its potential application in the practical SVC technique.展开更多
基金Financial supports from the NSFCs (21106103, 21276194 and 21306136)the Specialized Research Funds for the Doctoral Program of Chinese Higher Education (20101208110003 and 20111208120003)+1 种基金the Natural Science Foundation of Tianjin (12JCQNJC03400)the Senior Professor Program for TUST (20100405)
文摘1 Introduction A salt lake is a naturally occurring complex body of water and salt interaction.More than 700 salt lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous for their abundance of lithium,potassium,magnesium,and boron resources.It is
基金the National Key Basic Research Support Foundation (NKBRSF) of China (No. G1999011803),the National Natural Science Foundation of China (Nos. 40371058 and 40471018), the Jiangsu Provincial Society Deve-lopment Program of China (No. BS2003005), and the Institute of Geography and Limnology, Chinese Academy of Sciences(No. S250020).
文摘A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns withdifferent soil texture profiles and groundwater levels under crops were conducted to study the changes of salt-waterdynamics induced by water uptake of crops and to propose the theoretical basis for the regulation and control of salt-water dynamics as well as to predict salinity levels. The HYDRUS 1D model was applied to simulate the one-dimensionalmovement of water and salt transport in the soil columns. The results showed that the salts mainly accumulated in theplow layer in the soil columns under crops. Soil water and salt both moved towards the plow layer due to soil waterabsorption by the crop root system. The salt contents in the column with lower groundwater were mostly greater thanthose with high groundwater. The water contents in the soil columns increased from top to the bottom due to plant rootwater uptake. The changes in groundwater level had little influence on water content of the root zone in the soil columnswith crop planting. Comparison between the simulated and the determined values showed that model simulation resultswere ideal, so it is practicable to do numerical simulation of soil salt and water transport by the HYDRUS 1D model.Furthermore, if the actual movement of salt and water in fields is to be described in detail, much work needs to be done.The most important thing is to refine the parameters and select precise boundary conditions.
文摘Through a simulation test carried out with soil columns (61.8 cm in diameter), the effect of precipitation on salt-water dynamics in soils was studied by in-situ monitoring of salt-water dynamics using soil salinity sensors and tensiometers. The results show that in the profile of whole silty loam soil, the surface runoff volume due to precipitation and the salt-leaching role of infiltrated precipitation increased with the depth of ground water; and in the profile with an intercalated bed of clay or with a thick upper layer of clay, the amount of surface runoff was greater but the salt-leaching role of precipitation was smaller than those in the profile of whole silty loam soil. In case of soil water being supplemented by precipitation, the evaporation of groundwater in the soil columns reduced, resulting in a great decline of salt accumulation from soil profile to surface soil. The effect of precipitation on the water regime of soil profile was performed via both water infiltration and water pressure transfer. The direct infiltration depth of precipitation was less than 1 m in general, but water pressure transfer could go up to groundwater surface directly.
文摘Continuous monitoring of salt and water movement in the soil profile of highly salinized topsoil under steadystate infiltration was conducted.It gives that salt and water dynamics during convection-diffusion period can be divided into three stages:1.formation of a salt peak,2.the salt peak moving downwards till the appearance of the summit of the salt peak,3.the salt peak moving further downwards with the peak value decreasing.Results show that the maximum salt peak appears at the same depth if soil texture and outflow condition are the same.Factors affecting salt and water movement and ion components in the outflow solution underinfiltration are discussed.
基金National Natural Science Foundation of China, No.40471122
文摘The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP： 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.
文摘A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers were used to monitor salt and water variation in soils.The experiment revealed that in the process of fresh groundwater moving upwards by capillary rise in the column,the salts in subsoil were brought upwards and accumulated in the surface soil,and consequently the salinization of surface soil took place.The rate of salt accumulation is determined mainly by the volume of capillary water flow and the conditions of salts contained in the soil profile.Water flux in soils decreased obviously when groundwater depths fell below 1.5m.When there was an interbedded clay layer 30cm in thickness in the silty loam soil profile or a clay layer 100cm in thickness at the top layer,the water flux was 3-5 times less than in the soil profile of homogeneous silty loam soil.Therefore,the rate of salt accumulation was decreased and the effect of variation of groundwater depth on the water flux in soils was weakened comparatively.If there was precipitation or irrigation supplying water to the soil,the groundwater could rarely take a direct part in the process of salt accumulation in surface soil,especially,in soil profiles with an interbedded stratum or a clayey surface soil layer.
文摘Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamics in situ,using soil salinity sensors and tensiometers.The results indicated that the amount of water absorbed by crops from the soil was generally larger than the decrement of water consumption from soil surface evaporation reduced by the crop covering the soil surface and improving the soil structure,therefore,under the conditions of crop growing and non-irrigation,water content in soil profile was less than that without crop growing,and the gradient of negative pressure of soil water in soil profile especially in the root zone was enlarged,thus causing the water flowing from subsoils into root zone and increasing the groundwater moving upwards into soil layer via capillary rise,so that the groundwater evaporation increased.Consequently,under the condition of crop growing,the salt was mainly accumulated towards the root zone rather than to the top soil.the accumulating rate of salt in groundwater via capillary rise of soil water to subsoils was increased thereby.
基金financially supported by the National Key Basic Research Program of China(grant no.2020YFA0406101)National Natural Science Foundation of China(grant nos.22171041,22071020,21901035,22271043)+1 种基金Natural Science Foundation of Jilin Province Science and Technology Department(grant nos.20230508094RC,20220101045JC)the Fundamental Research Funds for the Central Universities(grant no.2412021QD008)
文摘Solar vapor generation(SVC)represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage.One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high-salinity brines.Herein,we demonstrate that the 3D porous melamine-foam(MF)wrapped by a type of self-assembling composite materials based on reduced polyoxometalates(i.e.heteropoly blue,HPB),oleic acid(OA),and polypyrrole(PPy)(labeled with MF@HPB-PPy_(n)-OA)can serve as efficient and stable SVC material at high salinity.Structural characterizations of MF@HPB-PPy_(n)-OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co-exist on the surface of composite materials,optimizing the hydrophilic and hydrophobic interfaces of the SVC materials,and fully exerting its functionality for ultrahigh water-evaporation and anti-salt fouling.The optimal MF@HPB-PPy_(10)-OA operates continuously and stably for over 100 h in 10wt%brine.Furthermore,MF@HPB-PPy_(10)-OA accomplishes complete salt-water separation of 10wt%brine with 3.3kgm^(-2)h^(-1)under 1-sun irradiation,yielding salt harvesting efficiency of 96.5%,which belongs to the record high of high-salinity systems reported so far and is close to achieving zero liquid discharge.Moreover,the low cost of MF@HPB-PPy_(10)-OA(2.56$m^(-2))suggests its potential application in the practical SVC technique.
