Marine sedimentary strata are widely distributed in the coastal zone of the study area, and are rich in brine resources. The exploitation of underground water resources often first caused the intrusion of salt water i...Marine sedimentary strata are widely distributed in the coastal zone of the study area, and are rich in brine resources. The exploitation of underground water resources often first caused the intrusion of salt water in the marine strata. Based on the analysis of sea-salt water intrusion feature, the sea-salt water intrusion is divided into four stages: The occurrence and development stage(1976–1985), the rapid development stage(1986–1990), the slow development stage(1990–2000) and the stable development stage(2000–2015). Based on the comparative analysis of the relationship between seawater intrusion and influencing factors, this paper presents that the groundwater exploitation and the brine resources mining are the main control factors of sea-salt water intrusion. On this basis, we have established a numerical model of the sea-salt water intrusion. Using this model, we predicted the development trend of the sea-salt water intrusion. The results show that if the current development of groundwater and brine is maintained, the sea-salt water intrusion will gradually withdraw; once development of brine stops, sea-salt water will invade again. This provides the scientific basis for the rational exploitation of groundwater and the prevention of sea-salt water intrusion.展开更多
For simulating fresh and salt water mixing in estuaries, a three dimensional nonlinear baroclinic numerical model isdeveloped, in which the gradients of horizontal pressure contain the gradient of barotropic pressure ...For simulating fresh and salt water mixing in estuaries, a three dimensional nonlinear baroclinic numerical model isdeveloped, in which the gradients of horizontal pressure contain the gradient of barotropic pressure arising from the gradi-ent of tidal level and the gradient of baroclinic pressure due to the gradient of salinity. The Eulerian-Lagrangian method isemployed to descretize both the momentum equations of tidal motion and the equation of salt water diffusion so as to im-prove the computational stability and accuracy. The methods to provide the boundary conditions and the initial conditionsare proposed, and the criterion for computational stability of the salinity fields is presented. The present model is used formodeling fresh and salt water mixing in the Yangtze Estuary. Computations show that the salinity distribution has thecharacteristics of partial mixing pattern, and that the present model is suitable for simulation of fresh and salt water mixing in the Yangtze Estuary.展开更多
Using field hydrological data, the relationship between the mixing of salt water and fresh water and the tidal range/ high tidal level in the Changjiang (Yangtze) River estuary is discussed, and the transporting and c...Using field hydrological data, the relationship between the mixing of salt water and fresh water and the tidal range/ high tidal level in the Changjiang (Yangtze) River estuary is discussed, and the transporting and concentrating of suspended sediment in the estuary were also analysed in respect to the circulation, flocculation and stratified interface resulting from mixing.The calculation results by two-dimentional box model have confirmed the effects of the circulation on the concentrating of suspended sediment in the estuary. The conclusions derived from this work have deepened the understanding on the mixing in the Changjiang River estuary and are of significance in bo’th theory and practice.展开更多
Objective: To determine the spread of misinformation on salt water among Nigerians, salt water use for Ebola prophylaxis, and the role played by the social media during the 2014 Ebola outbreak.Methods: Information was...Objective: To determine the spread of misinformation on salt water among Nigerians, salt water use for Ebola prophylaxis, and the role played by the social media during the 2014 Ebola outbreak.Methods: Information was collected from the general Nigerian population through online Google forms which were majorly disseminated via Facebook and WhatsApp platforms. The data retrieved was analysed using descriptive statistics, Chi-square test and multivariate logistic regression.Results: A total of 703 questionnaires were included in the final analysis. The respondents' mean age was(30.2±6.7) years, predominantly male(73.2%). Almost all of them(95.0%) had received some message to use salt water, 37.4% of whom received such message on social media. Around a half of them ever made an attempt to verify the health information they received on social media(50.9%), and about a quarter(24.0%) of them had used salt water during the outbreak. Many of them had used salt water because they believed it would not harm them(52.0%). Salt water was less likely to be used by those who had received such message on social media, as well as by those who had received some contrary information to salt use.Conclusions: Social media could serve as an effective tool in propagating health information and should be actively engaged by health agencies, to spread accurate information.展开更多
Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yan...Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend.展开更多
The corrosive behaviors of hot-dip galvanized steel (GI) sheets and the corresponding interstitial free (IF) steel base sheets for use in automobiles were investigated by the classical salt water drop (SWD) test at ro...The corrosive behaviors of hot-dip galvanized steel (GI) sheets and the corresponding interstitial free (IF) steel base sheets for use in automobiles were investigated by the classical salt water drop (SWD) test at room temperature.The corrosive processes and products were observed and analyzed through morphological observation,a scanning electronic microscope (SEM) and an energy dispersive spectrum (EDS).The results show that the anodic and cathode sites can be distinguished clearly during and after the test.The propagation of rusting,and the color,distribution and composition of the final corrosive products of the two kinds of materials are quite different.The SWD corrosive mechanisms of steel with and without galvanized coating are both discussed in this paper.展开更多
Examining the descriptions of piezometric heads at two points in both the salt water and fresh water zones reveals that when the groundwater flow system is in steady state and satisfies the Dupuit assumption,the locat...Examining the descriptions of piezometric heads at two points in both the salt water and fresh water zones reveals that when the groundwater flow system is in steady state and satisfies the Dupuit assumption,the location of the fresh water—salt water interface in a homogeneous,isotropic,and unconfined coastal aquifer can be estimated based on a piezometric head of fresh water at a point in the fresh water zone(from the water table to the interface) vertically lined up with a piezometric head of salt water at a point in the salt water zone(from the interface down).Research shows that the new method is a general relation and that both the Hubbert relation describing the location of the interface and the Ghyben—Herzberg relation are special cases of this method.The method requires two piezometric wells to be close to each other and each tapping into a different zone.Measurements of piezometric heads at a well cluster consisting of piezometric wells tapping separately into fresh water and salt water zones near Beihai. China at 5-day intervals for 15 months are used to illustrate the estimation of interface location.The depth of the interface for well H5 ranges from 32 to 72 m below the sea level. (?) 2011,China University of Geosciences(Beijing) and Peking University.Production and hosting by Elsevier B.V.All rights reserved.展开更多
To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were ch...To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.展开更多
Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and...Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.展开更多
The molecular dynamics simulation method was adopted to study the transient characteristics of Li^+,CO3^2-,and SO4^2- in Na^+,K^+,Li^+,Cl^-,and SO4^2-/H2O system.The composition of Na^+,K^+,Li^+,Cl^-,SO4^2- and CO3^2-...The molecular dynamics simulation method was adopted to study the transient characteristics of Li^+,CO3^2-,and SO4^2- in Na^+,K^+,Li^+,Cl^-,and SO4^2-/H2O system.The composition of Na^+,K^+,Li^+,Cl^-,SO4^2- and CO3^2- was selected to optimize the initial structural model and conduct dynamic simulation.The mean azimuth shift and diffusion coefficient of Li^+,CO3^2-,and SO4^2- in the system,the radial distribution function and potential energy between Li^+ and -OW,SO4^2- and -OW as well as CO3^2- and -OW,and the dielectric constant of hydrogen bond were expounded and analyzed.At the same time,the Li enrichment behavior in the evaporation process of salt lake brine was analyzed based on the simulated data.The results show that the simulation results are in good agreement with the experimental values,which verifies that,compared with other ions,the crystallization of Li^+ and SO4^2- occurs earlier after reaching saturation.展开更多
Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用...Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用大肠埃舍利希氏 杆菌的基因培育出了耐干旱、耐咸水、耐严寒的稻米。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 (61.8cm 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 sen...Through a simulation test carried out with soil columns (61.8cm 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 tensioneters.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 1m 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
Using the methods of empirical correlation and numerical analogue computation of the longitudinal distribution of two-dimensional chlorinity and combined with the actual situation of water supply in the Changjiang Est...Using the methods of empirical correlation and numerical analogue computation of the longitudinal distribution of two-dimensional chlorinity and combined with the actual situation of water supply in the Changjiang Estuary, a calculation and analysis have been made in this paper of the impacts of sea level rise of 0.5—1.0 m in the Changjiang Estuary in the next century on the probabilities of hourly chlorinity of more than 100×10<sup>-6</sup>, 200×10<sup>-6</sup> and 250×10<sup>-6</sup> during the dry season st Wusong station and on the intrusion distance of the isohalines of 1×10<sup>-3</sup> and 5×10<sup>-3</sup> during the ebb tide stand of the dry season in the South Branch as well as on the longitudinal distribution of the chlorinity of the South Branch in the most unfavorable situation with the minimum monthly mean discharge during the special dry year.展开更多
基金supported by Geological prospecting project in Shandong Province([2011]14)
文摘Marine sedimentary strata are widely distributed in the coastal zone of the study area, and are rich in brine resources. The exploitation of underground water resources often first caused the intrusion of salt water in the marine strata. Based on the analysis of sea-salt water intrusion feature, the sea-salt water intrusion is divided into four stages: The occurrence and development stage(1976–1985), the rapid development stage(1986–1990), the slow development stage(1990–2000) and the stable development stage(2000–2015). Based on the comparative analysis of the relationship between seawater intrusion and influencing factors, this paper presents that the groundwater exploitation and the brine resources mining are the main control factors of sea-salt water intrusion. On this basis, we have established a numerical model of the sea-salt water intrusion. Using this model, we predicted the development trend of the sea-salt water intrusion. The results show that if the current development of groundwater and brine is maintained, the sea-salt water intrusion will gradually withdraw; once development of brine stops, sea-salt water will invade again. This provides the scientific basis for the rational exploitation of groundwater and the prevention of sea-salt water intrusion.
基金The project is financially supported by the Research Fund of the College of Harbor,Waterway and Coastal Engineering,Hohai University.
文摘For simulating fresh and salt water mixing in estuaries, a three dimensional nonlinear baroclinic numerical model isdeveloped, in which the gradients of horizontal pressure contain the gradient of barotropic pressure arising from the gradi-ent of tidal level and the gradient of baroclinic pressure due to the gradient of salinity. The Eulerian-Lagrangian method isemployed to descretize both the momentum equations of tidal motion and the equation of salt water diffusion so as to im-prove the computational stability and accuracy. The methods to provide the boundary conditions and the initial conditionsare proposed, and the criterion for computational stability of the salinity fields is presented. The present model is used formodeling fresh and salt water mixing in the Yangtze Estuary. Computations show that the salinity distribution has thecharacteristics of partial mixing pattern, and that the present model is suitable for simulation of fresh and salt water mixing in the Yangtze Estuary.
文摘Using field hydrological data, the relationship between the mixing of salt water and fresh water and the tidal range/ high tidal level in the Changjiang (Yangtze) River estuary is discussed, and the transporting and concentrating of suspended sediment in the estuary were also analysed in respect to the circulation, flocculation and stratified interface resulting from mixing.The calculation results by two-dimentional box model have confirmed the effects of the circulation on the concentrating of suspended sediment in the estuary. The conclusions derived from this work have deepened the understanding on the mixing in the Changjiang River estuary and are of significance in bo’th theory and practice.
文摘Objective: To determine the spread of misinformation on salt water among Nigerians, salt water use for Ebola prophylaxis, and the role played by the social media during the 2014 Ebola outbreak.Methods: Information was collected from the general Nigerian population through online Google forms which were majorly disseminated via Facebook and WhatsApp platforms. The data retrieved was analysed using descriptive statistics, Chi-square test and multivariate logistic regression.Results: A total of 703 questionnaires were included in the final analysis. The respondents' mean age was(30.2±6.7) years, predominantly male(73.2%). Almost all of them(95.0%) had received some message to use salt water, 37.4% of whom received such message on social media. Around a half of them ever made an attempt to verify the health information they received on social media(50.9%), and about a quarter(24.0%) of them had used salt water during the outbreak. Many of them had used salt water because they believed it would not harm them(52.0%). Salt water was less likely to be used by those who had received such message on social media, as well as by those who had received some contrary information to salt use.Conclusions: Social media could serve as an effective tool in propagating health information and should be actively engaged by health agencies, to spread accurate information.
基金Project Supported by the National Science Foundation of China and the Chinese Academy of Sci-ences
文摘Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend.
文摘The corrosive behaviors of hot-dip galvanized steel (GI) sheets and the corresponding interstitial free (IF) steel base sheets for use in automobiles were investigated by the classical salt water drop (SWD) test at room temperature.The corrosive processes and products were observed and analyzed through morphological observation,a scanning electronic microscope (SEM) and an energy dispersive spectrum (EDS).The results show that the anodic and cathode sites can be distinguished clearly during and after the test.The propagation of rusting,and the color,distribution and composition of the final corrosive products of the two kinds of materials are quite different.The SWD corrosive mechanisms of steel with and without galvanized coating are both discussed in this paper.
基金supported by the Fund for the Special Research of Doctorate Subjects of the Ministry of Education of China (No.20070491522)
文摘Examining the descriptions of piezometric heads at two points in both the salt water and fresh water zones reveals that when the groundwater flow system is in steady state and satisfies the Dupuit assumption,the location of the fresh water—salt water interface in a homogeneous,isotropic,and unconfined coastal aquifer can be estimated based on a piezometric head of fresh water at a point in the fresh water zone(from the water table to the interface) vertically lined up with a piezometric head of salt water at a point in the salt water zone(from the interface down).Research shows that the new method is a general relation and that both the Hubbert relation describing the location of the interface and the Ghyben—Herzberg relation are special cases of this method.The method requires two piezometric wells to be close to each other and each tapping into a different zone.Measurements of piezometric heads at a well cluster consisting of piezometric wells tapping separately into fresh water and salt water zones near Beihai. China at 5-day intervals for 15 months are used to illustrate the estimation of interface location.The depth of the interface for well H5 ranges from 32 to 72 m below the sea level. (?) 2011,China University of Geosciences(Beijing) and Peking University.Production and hosting by Elsevier B.V.All rights reserved.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(U2006215)the National Natural Science Foundation of China(31770761)+2 种基金the Shandong Key Laboratory of Coastal Environmental Processes,YICCAS(2019SDHADKFJJ16)the Natural Science Foundation of Shangdong Province(ZR2020QD003)Taishan Scholars Program of Shandong Province,China(TSQN201909152)。
文摘To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.
基金Under the auspices of National Key Research and Development Program of China(No.2022YFD1500501)National Natural Science Foundation of China(No.41971066)+1 种基金Key Laboratory Foundation of Mollisols Agroecology(No.2020ZKHT-03)High Tech Fund Project of S&T Cooperation Between Jilin Province and Chinese Academy of Sciences(No.2022SYHZ0018)。
文摘Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.
基金Funded by the Innovation Academy for Green Manufacture,CAS“IAGM2020C01”the Key R&D and the Transformation Projects in Qinghai Province(2019-GX-167)CAS“Light of West China”。
文摘The molecular dynamics simulation method was adopted to study the transient characteristics of Li^+,CO3^2-,and SO4^2- in Na^+,K^+,Li^+,Cl^-,and SO4^2-/H2O system.The composition of Na^+,K^+,Li^+,Cl^-,SO4^2- and CO3^2- was selected to optimize the initial structural model and conduct dynamic simulation.The mean azimuth shift and diffusion coefficient of Li^+,CO3^2-,and SO4^2- in the system,the radial distribution function and potential energy between Li^+ and -OW,SO4^2- and -OW as well as CO3^2- and -OW,and the dielectric constant of hydrogen bond were expounded and analyzed.At the same time,the Li enrichment behavior in the evaporation process of salt lake brine was analyzed based on the simulated data.The results show that the simulation results are in good agreement with the experimental values,which verifies that,compared with other ions,the crystallization of Li^+ and SO4^2- occurs earlier after reaching saturation.
文摘Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用大肠埃舍利希氏 杆菌的基因培育出了耐干旱、耐咸水、耐严寒的稻米。
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 (61.8cm 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 tensioneters.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 1m 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Project supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.
文摘Using the methods of empirical correlation and numerical analogue computation of the longitudinal distribution of two-dimensional chlorinity and combined with the actual situation of water supply in the Changjiang Estuary, a calculation and analysis have been made in this paper of the impacts of sea level rise of 0.5—1.0 m in the Changjiang Estuary in the next century on the probabilities of hourly chlorinity of more than 100×10<sup>-6</sup>, 200×10<sup>-6</sup> and 250×10<sup>-6</sup> during the dry season st Wusong station and on the intrusion distance of the isohalines of 1×10<sup>-3</sup> and 5×10<sup>-3</sup> during the ebb tide stand of the dry season in the South Branch as well as on the longitudinal distribution of the chlorinity of the South Branch in the most unfavorable situation with the minimum monthly mean discharge during the special dry year.