For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This stu...For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This study examines the Atterberg limits,shear strength,and compressibility of carbonate saline soil samples with different NaHCO3 contents in Northeast China.The mechanism underlying the influence of salt content on soil macroscopic properties was investigated based on a volumetric flask test,a mercury intrusion porosimetry(MIP)test,and a scanning electron microscopic(SEM)test.The results demonstrated that when NaHCO3 contents were lower than the threshold value of 1.5%,the bound water film adsorbed on the surface of clay particles thickened continuously,and correspondingly,the Atterberg limits and plasticity index increased rapidly as the increase of sodium ion content.Meanwhile,the bonding force between particles was weakened,the dispersion of large aggregates was enhanced,and the soil structure became looser.Macroscopically,the compressibility increased and the shear strength(mainly cohesion)decreased by 28.64%.However,when the NaHCO3 content exceeded the threshold value of 1.5%,the salt gradually approached solubility and filled the pores between particles in the form of crystals,resulting in a decrease in soil porosity.The cementation effect generated by salt crystals increased the bonding force between soil particles,leading to a decrease in plasticity index and an improvement in soil mechanical properties.Moreover,this work provides valuable suggestions and theoretical guidance for the scientific utilization of carbonate saline soil in backfill engineering projects.展开更多
Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation...Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation,the thermal-water-salt coupling mathematical model of unsaturated frozen saline soil was established.The model considered the latent heat of phase change,crystallization impedance,crystallization consumption and complete precipitation of solute crystallization in ice.In order to verify the rationality of the model,the unidirectional freezing test of unsaturated saline soil was carried out in an open system with no-pressure water supplement to obtain the spatial distribution of temperature,moisture and salt in the saline soil.Finally,numerical simulations are implemented with the assistance of COMSOL Multiphysics.Validation of the model is illustrated by comparisons between the simulation and experimental data.The results demonstrated that the temperature within saline soil changes with time and can be divided into three stages,namely quick freezing stage,transitional stage and stable stage.The water and salt contents in the freezing zone are layered,with peak values at the freezing front.The coupled model could reveal the heat-mass migration mechanism of unsaturated frozen saline soil and dynamically describe the freezing depth and the movement law of the freezing front,ice and salt crystal formation mechanism,and the change law of thermal conductivity and permeability coefficient.展开更多
To reveal the deterioration mechanism and service life of concrete durability in the western saline soil area,the indoor accelerated test of the concrete specimen was simulated in the coupled environment of salt erosi...To reveal the deterioration mechanism and service life of concrete durability in the western saline soil area,the indoor accelerated test of the concrete specimen was simulated in the coupled environment of salt erosion and dry-wet cycles in the west saline soil area of China.The deterioration mechanism of concrete durability was revealed through the relative dynamic elastic modulus,relative quality evaluation parameters,SEM,and XRD evaluation indexes.Random Wiener distribution function was used for modeling life prediction.The results show that the relative dynamic elastic modulus evaluation parameter as an evaluation index of concrete durability under various environmental coupling effects is more reliable than the relative quality,there were holes and cracks in the concrete,and needle-like and layered crystals grow from the internal cracks.The corrosion products include ettringite,gypsum and other expansive crystals and non-gelling Mg(OH)_(2);the expansion stress caused by physical,chemical reaction,and temperature change under the action of drywet cycle aggravates the formation and development of cracks.The random Wiener distribution function can describe the degradation process of concrete specimen durability,and the established concrete reliability function can intuitively reflect the service life of concrete specimens.展开更多
Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,t...Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.Therefore,a four-year (2015–2018) field experiment was conducted with four levels (i.e.,0,6,12and 18 Mg ha~(–1)) of straw returned as an interlayer.Compared with no straw interlayer (CK),straw addition increased SOC concentration by 14–32 and 11–57%in the 20–40 and 40–60 cm soil layers,respectively.The increases in soil TN concentration (8–22 and 6–34%in the 20–40 and 40–60 cm soil layers,respectively) were lower than that for SOC concentration,which led to increased soil C:N ratio in the 20–60 cm soil depth.Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm),which promoted uniform distributions of SOC and TN in the soil profile.Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.Generally,compared with other treatments,the application of 12 Mg ha~(–1) straw had higher SOC,TN and C:N ratio,and lower soil stratification ratio in the2015–2017 period.The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years,and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.展开更多
In order to investigate the corrosion mechanism of recycled reinforced concrete (RRC) under harsh environments,four recycled coarse aggregate (RCA) contents were selected,and saline soil was used as an electrolyte to ...In order to investigate the corrosion mechanism of recycled reinforced concrete (RRC) under harsh environments,four recycled coarse aggregate (RCA) contents were selected,and saline soil was used as an electrolyte to perform electrified accelerated corrosion experiments.The relative dynamic elastic modulus and relative corrosion current density were considered to describe the deterioration law of the RRC in saline soil.The results indicated that as the energization time increased,the corrosion current density,corrosion potential,and polarization resistance of the steel bar decreased gradually.Compared with ordinary reinforced concrete,when the RCA content was 30%,the ability of the RRC to resist corrosion was improved slightly;however,when the RCA content exceeded 30%,the corrosion resistance of the RRC deteriorated rapidly.Scanning electron microscopy revealed that for a dense RRC,less corrosion products were generated in the pores inside the concrete and on the surface of the steel bar.X-ray diffraction results indicated that SO_(4)^(2-) can generate ettringite and other corrosion products,along with volume expansion.The main corrosion products generated on the surface of the steel bars included Fe_(2)O_(3),Fe_(3)O_(4) and FeO(OH),which were the corrosion products generated by steel bars under natural environments.Therefore,using saline soil as an electrolyte is more consistent with the actual service environments of RRC.Both the relative dynamic mode and relative corrosion current density of the degradation parameters conform to the Weibull distribution;furthermore,the relative dynamic mode is more sensitive and the corresponding reliability curve can better describe the degradation law of RRC under saline soil environments.展开更多
This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkl...This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkler irrigation in three stages was used to regulate soil matric potential at a 20-cm soil depth.Continued regulation of soil water and salt through micro-sprinkler irrigation consistently resulted in an increasingly large low-salinity region.The application of the three stages of soil wateresalt regulation resulted in an absence of salt accumulation throughout the soil profile and the conversion of highly saline soils into moderately saline soils.There were increases in the plant height,leaf width,leaf length,and tiller numbers of tall fescue throughout the leaching process.The results showed that micro-sprinkler irrigation in three soil water and salt regulation stages can be used to successfully cultivate tall festuca in highly saline coastal soil.This approach achieved better effects in sandy loam soil than in silt soil.Tall fescue showed greater survival rates in sandy loam soil due to the rapid reclamation process,whereas plant growth was higher in silt soil because of effective water conservation.In sandy loam,soil moisture should be maintained during soil reclamation,and in silt soil,soil root-zone environments optimal for the emergence of plants should be quickly established.Micro-sprinkler irrigation can be successfully applied to the cultivation of tall fescue in coastal heavy saline soils under a three-stage soil wateresalt regulation regime.展开更多
Soil salinity is a serious land degradation issue in agriculture.It is a major threat to agriculture productivity.Extra irrigation water is applied to leach down the salts from the root zone of the plants in the form ...Soil salinity is a serious land degradation issue in agriculture.It is a major threat to agriculture productivity.Extra irrigation water is applied to leach down the salts from the root zone of the plants in the form of a Leaching fraction(LF)of irrigation water.For the leaching process to be effective,the LF of irriga-tion water needs to be adjusted according to the environmental conditions and soil salinity level in the form of Evapotranspiration(ET)rate.The relationship between environmental conditions and ET rate is hard to be defined by a linear relationship and data-driven Machine learning(ML)based decisions are required to determine the calibrated Evapotranspiration(ETc)rate.ML-assisted ETc is pro-posed to adjust the LF according to the ETc and soil salinity level.A regression model is proposed to determine the ETc rate according to the prevailing tempera-ture,humidity,and sunshine,which would be used to determine the smart LF according to the ETc and soil salinity level.The proposed model is trained and tested against the Blaney Criddle method of Reference evapotranspiration(ETo)determination.The validation of the model from the test dataset reveals the accu-racy of the ML model in terms of Root mean squared errors(RMSE)are 0.41,Mean absolute errors(MAE)are 0.34,and Mean squared errors(MSE)are 0.28 mm day-1.The applications of the proposed solution in a real-time environ-ment show that the LF by the proposed solution is more effective in reducing the soil salinity as compared to the traditional process of leaching.展开更多
Salt expansion in sulfate saline soils that are widely distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temp...Salt expansion in sulfate saline soils that are widely distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temperatures is not clear. In this study, we conducted a series of cooling experiments combined with salt crystallization to study this mechanism, and employed an ionic model to calculate the supersaturation ratio of the solution. During the experiments, the strength and the process of salt expansion were examined under different cooling rates and various crystal morphologies. The relationship between temperature and supersaturation ratio under transient conditions was also considered. Results indicate that the initial supersaturation ratio of a sodium sulfate solution is closely related to environmental conditions, and that this ratio decreases with slowing the cooling rates and stabilizing the crystal forms. Higher initial supersaturation ratios lead to an increased non-steady-state zone, resulting in less salt expansion. On the other hand, chloride ion content has a distinct influence on the crystallization supersaturation ratio of the sodium sulfate solution, and higher chloride ion content can inhibit salt expansion in sodium saline soils. These findings help explain salt expansion mechanisms in complex conditions such as seasonally frozen soils, and thus help search for improved methods of preventing salt expansion in sulfate saline soils.展开更多
The instability of saline soil foundation affects the safety of artificial construction,and may cause ground collapse,building destruction and road damage.It is fundamental to reduce the potential engineering geologic...The instability of saline soil foundation affects the safety of artificial construction,and may cause ground collapse,building destruction and road damage.It is fundamental to reduce the potential engineering geological disasters by exploring the dynamic evolution of saline soil.Most of the previous researches of saline soil were conducted by simulated experiments and traditional geodetic surveying methods.Restricted to the limited sampling points,the spatiotemporal evolution characteristics of saline soil were difficult to find out in a large scale.This paper exploited SBAS-InSAR method to extract the deformation of the Qarhan Salt Lake(in Qinghai,China)section along Qinghai-Tibet railway,based on 119 image data acquired by Sentinel-1A from 2015 to 2020.The results showed that the deformation trends varied frequently in this saline mud flat.Between the adjacent areas with different deformation trends along Qinghai-Tibet railway,discontinuities caused by uplift and subsidence were very obvious.Besides,among the areas with brine exploitation or artificial construction,the maximum subsidence rate reached50 mm/yr,and the maximum cumulative subsidence exceeded 320 mm in the latest 5 years.In the saline mud flat closed to the rivers and lakes,the deformation trend was continuous uplift.Nevertheless,there were obvious seasonal deformation characteristics in those areas far away from the water body.Further analysis found out a sharply subsidence caused by the salt collapsibility appeared in rainy seasons.While an uplift trend induced by the salt swelling or frost heave was remarkable in dry seasons.Subsequently,the relationships were analyzed between the time series deformation and external environmental fac-tors.Furthermore,the deformation mechanism of saline soilin the Qarhan Salt Lake region was inter-preted then.In general,this study provides complete spatiotemporal evolution information of saline soil,and demonstrates the deformation characteristics of saline soil in the Qarhan Salt Lake region suc-cessfully.Related results would contribute to the safety monitoring for large-scale infrastructure con-struction in the saline soil areas.展开更多
To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to e...To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.展开更多
Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation du...Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation due to season replacement limits the conventional multi-temporal interferometric synthetic aperture radar(MT-InSAR)technique and its application in such areas.To extend the monitoring capability in the salt desert area,we select a vast basin of saline soil around Howz-e-Soltan Salt Lake of Iran as the study area and present an improved MTInSAR for experimental research.Based on 131 C-band Sentinel-1 A images collected between October 2014 to July 2020,1896 refined interferograms in total are selected from all interferogram candidates.Interferometric coherence analysis shows that the coherence in the saline soil area has an apparent seasonal variation,and the soil moisture affected by the precipitation may be the main factor that leads to the seasonal variation.Subsequently,the deformation characteristics of saline soil under different environmental conditions and human activity factors are compared and analyzed in detail.Related deformation mechanisms of different saline soil types are initially revealed by combining interferometric coherence,meteorological data,and engineering geological characteristics of saline soil.Related results would provide reference for the large-scale infrastructure construction engineering in similar saline soil areas.展开更多
We conducted a pot experiment to examine the feasibility of applying a reaction-finished solution of hydrochar(HRFS)to enhance rice production in a saline soil.With this purpose,HRFS was applied(0,10,20,40,60,80 and 1...We conducted a pot experiment to examine the feasibility of applying a reaction-finished solution of hydrochar(HRFS)to enhance rice production in a saline soil.With this purpose,HRFS was applied(0,10,20,40,60,80 and 100 mL/pot)and rice yield and nitrogen(N)use efficiency(NUE)were determined.HRFS application significantly(P<0.05)increased rice grain yield by 19.6%-30.0%compared to the control treatment(CKU,with N but without HRFS addition).Moreover,HRFS application promoted plant height and straw biomass of rice.Increases of rice yield were mainly achieved by increases in the number of panicles and grains per panicle.Compared with the CKU treatment,the NUE of HRFS amendments significantly(P<0.05)increased by 56.3%-71.7%.This indicated that the improvement of NUE was one of the mechanisms to improve rice grain yield with HRFS amendment.The results of regression analysis showed that there was a positive relationship(R^(2)=0.8332)between rice yield and HRFS application rate within an appropriate range.The highest rice yield was recorded with the HRFS application of 40 mL/pot,but a further increase in HRFS application rate appeared to reduce rice yield.Based on the results of this pot study,HRFS application can increase rice yield in a saline soil by regulating its yield components and enhancing NUE.However,impact of HRFS on these variables showed a“dose effect”.展开更多
Biochar application is claimed to improve nutrient availability in many problem soils;however, pristine biochars are often reported to produce inconsistent results. Therefore, appropriate biochar modification techniqu...Biochar application is claimed to improve nutrient availability in many problem soils;however, pristine biochars are often reported to produce inconsistent results. Therefore, appropriate biochar modification techniques are required to retain soil nutrients at an optimum level. To increase Nitrogen (N) and Phosphorus (P) availability in coastal saline soil, two slow pyrolyzed biochars viz domestic organic waste (DWB) and farmyard manure (FMB) were modified with MgCl<sub>2</sub>. Ten different treatments comprising the biochars (pristine and modified) with and without the recommended fertilizer were applied (2% w/w) to the soil and incubated for ninety days. The soils were analyzed for pH, EC, available <img src="Edit_0d6ce0cb-4936-4874-a480-35d5b2f585ff.png" alt="" />, <img src="Edit_64cd5bd3-ddeb-4e08-ad2e-48f0710feace.png" alt="" /> and different phosphorus fractions sequentially extracted by NH<sub>4</sub>Cl, NaHCO<sub>3</sub>, NaOH, and HCl. During the incubation period, biochar treatments increased all phosphorus and nitrogen fractions than the control and recommended fertilizer treatment. The application of FMB significantly (<em>p</em> < 0.05) increased NH<sub>4</sub>Cl, NaHCO<sub>3</sub>, and NaOH extractable P fractions from DWB, while HCl soluble fraction was enhanced (<em>p</em> > 0.05) by DWB. The increased Al and/or Fe bound phosphate after 60 days of incubation had significant correlations to decreasing soil pH and NaHCO<sub>3</sub>-P, indicating reduced availability with time. Further Mg modification slightly increased P availability only after 60 days of incubation. The modification also improved both nitrogen fractions but significantly (<em>p</em> < 0.05) increased the NO<sub>3</sub>-N content which could be the result of electrostatic attraction between Mg<sup>2</sup>+ and <img src="Edit_c55861ac-dd25-4c26-9ecc-2e134a948b8e.png" alt="" /> ions. Overall, Mg-modified biochar may retain both phosphates and nitrates in soil. However, the magnitude of retention will vary depending on biochar type, nutrient species, and aging in soil.展开更多
In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore ...In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore characteristics of concrete,analyze the pore characteristics,porosity and pore distribution of concrete in different hydration stages,and reveal the relationship between pore structure and permeability of concrete.The results show that the pore-size distribution of concrete in fresh water condition is better than that in sulfate environment and mixed salt environment,and therefore,sulfate as well as mixed salt are not conducive to the development of pore structure of non-dispersible underwater concrete;chlorine salt has little effect on the pore structure of nondispersible underwater concrete;under the three conditions of sulfate,chlorine and mixed salt,the porosity of concrete mixed with slag powder is lower than that of concrete without slag powder.The results indicate that the addition of slag powder can ameliorate the pore size distribution of non-dispersed underwater concrete,reduce the porosity,and make the concrete structure more compact,which is beneficial to improve the permeability resistance of concrete at the macro level.展开更多
In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible u...In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible underwater concrete in sulfate,chloride,and mixed salt environments,the compressive strength and deterioration resistance coefficient of the studied concrete mixed with different amounts of ground granulated blast-furnace slag(GGBS)were analyzed in this paper.At the same time,the micro morphology and corrosion products distribution of the studied concrete were observed by means of SEM,plus XRD diffraction,TG-DTG and FT-IR analyses to explore the influence of corrosive solutions on the hydration products of concrete.We also analyzed the mechanism of improving the deterioration resistance of the studied concrete by adding GGBS in a saline soil environment.The results show that the compressive strength of the studied concrete in a chloride environment was close to that in a fresh water environment,which means that chloride has no adverse effect on compressive strength.The deterioration of the studied concrete was most serious in a sulfate environment,followed by mixed salt environment,and the lowest in a chloride environment.In addition,by adding GGBS,the compressive strength and deterioration resistance of the studied concrete could be effectively improved.展开更多
Engineering activities in the salt lake region continue to increase where fresh water resources are scarce.This paper investigates the physical properties of saline soils during mixing with brine.Fine-grained saline s...Engineering activities in the salt lake region continue to increase where fresh water resources are scarce.This paper investigates the physical properties of saline soils during mixing with brine.Fine-grained saline soils with salt content varying from 2.6%to 78.5%were collected along Qarhan-Golmud Highway(QGH)and Sebei-Qarhan Highway(SQH)on the Qinghai-Tibet Plateau to conduct laboratory physical properties tests.Liquid plastic limit tests were conducted.Results show that liquid plastic limit parameters will decrease with an increase of salt content ranging from 2.6% to 78.5%,and the relationship between them is linear.After considering the content ratio of chloride and sulfate,results show that liquid plastic limit parameters will decrease with an increase of the ratio of chloride to sulfate ranging from 0.7% to 7.0%;liquid plastic limit parameters enter a stable period at the ratio of chloride to sulfate ranging from 7.0% to 37.4%;liquid plastic limit parameters enter a decline period at the ratio of chloride to sulfate ranging from 37.4% to 77.2%.After brine and fresh water are separately mixed into saline soil,the optimal moisture content of the soil samples after the brine action is lower than the saline soil under the action of fresh water,and the maximum dry density of the soil sample is higher than that under the action of fresh water.At the same time,these changing laws show a certain correlation with the chloride ion content and the ratio of chloride to sulfate in saline soils.The results are of significance for engineering activities in salt lake regions with extensive saline soil distribution.展开更多
Based on salt-frost heave tests of sulfate saline soil under repeated freeze−thaw cycles,this paper discusses the mechanism of the salt-frost heave under long-term freeze−thaw cycles.The results show that the salt-fro...Based on salt-frost heave tests of sulfate saline soil under repeated freeze−thaw cycles,this paper discusses the mechanism of the salt-frost heave under long-term freeze−thaw cycles.The results show that the salt-frost heave can be restricted considerably by loads,and there is a critical load for the salt-frost heave cumulative effect.Under this load,peak values of salt-frost heave approach a constant,and the residual values become 0.There is no longer structure heave or cumulative effect of saline soil exposed to freeze−thaw cycles under the critical load.Taking cumulative effect into account in calculations of salt-frost heave,a salt-frost heave model under freeze−thaw cycles is developed.展开更多
A study was carried out to assess the interaction of Arsenic with excess Sulphur present in saline soil and their impact on plant growth. Two different types of saline soils S<sub>1 </sub>(2.0 dS/m) and S&...A study was carried out to assess the interaction of Arsenic with excess Sulphur present in saline soil and their impact on plant growth. Two different types of saline soils S<sub>1 </sub>(2.0 dS/m) and S<sub>2 </sub>(5.061 dS/m) were collected from the southwestern part of Bangladesh. The experiment was conducted in two parts: in vitro incubation study and pot experiment. Arsenic treatments at the rates of 0, 0.05 and 1.0 mg/L were applied with water. The incubated soils were sequentially extracted with three different extractants, viz, distilled water, 0.01 M CaCl<sub>2</sub>, and 1 M HCl. 1 M HCl was found to extract the maximum amounts of soluble salts as well as arsenic from the saline soil. Rice was selected as the test plant for pot experiment. An improved variety of rice (BRRI 41) was grown on the experimental soils. Sulphur in saline soil was found to reduce the accumulation of Arsenic by rice plant.展开更多
Coastal soils of Bangladesh are affected by salinity. This study investigated salinity as a stress factor on coastal soils in Bangladesh. It was also observed if incorporation of rice straw could remediate negative im...Coastal soils of Bangladesh are affected by salinity. This study investigated salinity as a stress factor on coastal soils in Bangladesh. It was also observed if incorporation of rice straw could remediate negative impacts of soil salinity (if any) on microbial activ-ity. The microbial biomass carbon ranged from 137.85 to 614.88 μg/g among the soils (n = 11). Microbial biomass carbon content and number of both cultivable bacteria and fungi decreased in the soils with higher EC<sub>e</sub>s (electrical conductivity). Respiration was measured over 30 days with each soil pre incubated at 50% of water holding capacity. Basal respiration rate as well as soil organic carbon content (r = 0.88, p - 37.73 mS/cm) (12.91 - 16.89 mg CO2/g dry soil) than in the nonsaline soils (0.98 - 2.33 mS/cm) (5.79 - 6.51 mg CO2/g dry soil). Application of rice straw at 0.50%, 1.00%, 1.50% and 2.00% reduced the negative impact of soil salinity especially at higher EC<sub>e</sub>s (6.63 - 37.73 mS/cm). Application of 1.00% rice straw appeared to be acceptable for successful amelioration of saline soils of the study area.展开更多
Plants have to cope with several abiotic stresses,including salinity and heavymetals(HMs).Under these stresses,several extracts have been used as effective natural biostimulants,however,the use of Spirulina platensis(...Plants have to cope with several abiotic stresses,including salinity and heavymetals(HMs).Under these stresses,several extracts have been used as effective natural biostimulants,however,the use of Spirulina platensis(SP)extract(SPE)remains elusive.The effects of SPE were evaluated as soil addition(SA)and/or foliar spraying(FS)on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs.Individual(40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS)or integrative(SA+FS)applications of SPE showed significant improvements in the following order:SA-80+FS-40>SA-80+FS-20>SA-40+FS-40>SA-40+FS-20>SA-80>SA-40>FS-40>FS-20>control.Therefore,the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production,overcoming stress effects and minimizing contamination of the edible part.It significantly increased plant growth(74%–185%)and yield(107%–227%)by enhancing net photosynthetic rate(78.5%),stomatal conductance(104%),transpiration rate(124%),and contents of carotenoids(60.0%),chlorophylls(49%–51%),and NPK(271%–366%).These results were concurrent with the marked reductions in malondialdehyde(61.6%),hydrogen peroxide(42.2%),nickel(91%–94%),lead(80%–9%),and cadmium(74%–91%)contents due to the improved contents of glutathione(87.1%),ascorbate(37.0%),andα-tocopherol(77.2%),and the activities of catalase(18.1%),ascorbate peroxidase(18.3%),superoxide dismutase(192%),and glutathione reductase(52.2%)as reinforcing mechanisms.Therefore,this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42330708 and 41820104001)。
文摘For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This study examines the Atterberg limits,shear strength,and compressibility of carbonate saline soil samples with different NaHCO3 contents in Northeast China.The mechanism underlying the influence of salt content on soil macroscopic properties was investigated based on a volumetric flask test,a mercury intrusion porosimetry(MIP)test,and a scanning electron microscopic(SEM)test.The results demonstrated that when NaHCO3 contents were lower than the threshold value of 1.5%,the bound water film adsorbed on the surface of clay particles thickened continuously,and correspondingly,the Atterberg limits and plasticity index increased rapidly as the increase of sodium ion content.Meanwhile,the bonding force between particles was weakened,the dispersion of large aggregates was enhanced,and the soil structure became looser.Macroscopically,the compressibility increased and the shear strength(mainly cohesion)decreased by 28.64%.However,when the NaHCO3 content exceeded the threshold value of 1.5%,the salt gradually approached solubility and filled the pores between particles in the form of crystals,resulting in a decrease in soil porosity.The cementation effect generated by salt crystals increased the bonding force between soil particles,leading to a decrease in plasticity index and an improvement in soil mechanical properties.Moreover,this work provides valuable suggestions and theoretical guidance for the scientific utilization of carbonate saline soil in backfill engineering projects.
基金supported by the Special Funds for Guiding Local Scientific and Technological Development by The Central Government(22ZY1QA005)the Science and Technology Program of Gansu Province"Outstanding Doctoral Students Project"(22JR5RA325)+3 种基金"Innovation Star"Funding Project for Outstanding Graduate Students of Gansu Province(2022CXZX-528)the Science and Technology Project of Gansu Province(21YF5GA050)Education Department of Gansu Province Industrial Support Plan Project(2021CYZC-28)Transport Department of Gansu Province Science and Technology R&D Projects(No.2021-12).
文摘Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation,the thermal-water-salt coupling mathematical model of unsaturated frozen saline soil was established.The model considered the latent heat of phase change,crystallization impedance,crystallization consumption and complete precipitation of solute crystallization in ice.In order to verify the rationality of the model,the unidirectional freezing test of unsaturated saline soil was carried out in an open system with no-pressure water supplement to obtain the spatial distribution of temperature,moisture and salt in the saline soil.Finally,numerical simulations are implemented with the assistance of COMSOL Multiphysics.Validation of the model is illustrated by comparisons between the simulation and experimental data.The results demonstrated that the temperature within saline soil changes with time and can be divided into three stages,namely quick freezing stage,transitional stage and stable stage.The water and salt contents in the freezing zone are layered,with peak values at the freezing front.The coupled model could reveal the heat-mass migration mechanism of unsaturated frozen saline soil and dynamically describe the freezing depth and the movement law of the freezing front,ice and salt crystal formation mechanism,and the change law of thermal conductivity and permeability coefficient.
基金Funded by National Natural Science Foundation of China(NSFC)(Nos.52178216,51868044)。
文摘To reveal the deterioration mechanism and service life of concrete durability in the western saline soil area,the indoor accelerated test of the concrete specimen was simulated in the coupled environment of salt erosion and dry-wet cycles in the west saline soil area of China.The deterioration mechanism of concrete durability was revealed through the relative dynamic elastic modulus,relative quality evaluation parameters,SEM,and XRD evaluation indexes.Random Wiener distribution function was used for modeling life prediction.The results show that the relative dynamic elastic modulus evaluation parameter as an evaluation index of concrete durability under various environmental coupling effects is more reliable than the relative quality,there were holes and cracks in the concrete,and needle-like and layered crystals grow from the internal cracks.The corrosion products include ettringite,gypsum and other expansive crystals and non-gelling Mg(OH)_(2);the expansion stress caused by physical,chemical reaction,and temperature change under the action of drywet cycle aggravates the formation and development of cracks.The random Wiener distribution function can describe the degradation process of concrete specimen durability,and the established concrete reliability function can intuitively reflect the service life of concrete specimens.
基金funded by the National Natural Science Foundation of China (31871584)the Agricultural Science and Technology Innovation Program, Chinese Academy of Agricultural Sciences (CAAS-ZDRW202201)+2 种基金the Fundamental Research Funds for Central Non-profit Scientific Institution, China (1610132020011)the “Open the list” in charge of the Science and Technology Project of Ordos, Center for Agro-pastoral Ecology and Resource Conservation of Ordos City, Inner Mongolia, China (JBGS2021-001)the Inner Mongolia Autonomous Region Research Project (2021EEDSCXSFQZD011)。
文摘Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.Therefore,a four-year (2015–2018) field experiment was conducted with four levels (i.e.,0,6,12and 18 Mg ha~(–1)) of straw returned as an interlayer.Compared with no straw interlayer (CK),straw addition increased SOC concentration by 14–32 and 11–57%in the 20–40 and 40–60 cm soil layers,respectively.The increases in soil TN concentration (8–22 and 6–34%in the 20–40 and 40–60 cm soil layers,respectively) were lower than that for SOC concentration,which led to increased soil C:N ratio in the 20–60 cm soil depth.Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm),which promoted uniform distributions of SOC and TN in the soil profile.Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.Generally,compared with other treatments,the application of 12 Mg ha~(–1) straw had higher SOC,TN and C:N ratio,and lower soil stratification ratio in the2015–2017 period.The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years,and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.
基金Funded by National Natural Science Foundation of China (Nos. 51468039, 51868044)。
文摘In order to investigate the corrosion mechanism of recycled reinforced concrete (RRC) under harsh environments,four recycled coarse aggregate (RCA) contents were selected,and saline soil was used as an electrolyte to perform electrified accelerated corrosion experiments.The relative dynamic elastic modulus and relative corrosion current density were considered to describe the deterioration law of the RRC in saline soil.The results indicated that as the energization time increased,the corrosion current density,corrosion potential,and polarization resistance of the steel bar decreased gradually.Compared with ordinary reinforced concrete,when the RCA content was 30%,the ability of the RRC to resist corrosion was improved slightly;however,when the RCA content exceeded 30%,the corrosion resistance of the RRC deteriorated rapidly.Scanning electron microscopy revealed that for a dense RRC,less corrosion products were generated in the pores inside the concrete and on the surface of the steel bar.X-ray diffraction results indicated that SO_(4)^(2-) can generate ettringite and other corrosion products,along with volume expansion.The main corrosion products generated on the surface of the steel bars included Fe_(2)O_(3),Fe_(3)O_(4) and FeO(OH),which were the corrosion products generated by steel bars under natural environments.Therefore,using saline soil as an electrolyte is more consistent with the actual service environments of RRC.Both the relative dynamic mode and relative corrosion current density of the degradation parameters conform to the Weibull distribution;furthermore,the relative dynamic mode is more sensitive and the corresponding reliability curve can better describe the degradation law of RRC under saline soil environments.
基金supported by the China Scholarship Council(Grant No.201906715015)the Priority Academic Development Program of Jiangsu Higher Education Institutions.
文摘This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation.The experiments were run using moderately salt-tolerant tall fescue grass.Micro-sprinkler irrigation in three stages was used to regulate soil matric potential at a 20-cm soil depth.Continued regulation of soil water and salt through micro-sprinkler irrigation consistently resulted in an increasingly large low-salinity region.The application of the three stages of soil wateresalt regulation resulted in an absence of salt accumulation throughout the soil profile and the conversion of highly saline soils into moderately saline soils.There were increases in the plant height,leaf width,leaf length,and tiller numbers of tall fescue throughout the leaching process.The results showed that micro-sprinkler irrigation in three soil water and salt regulation stages can be used to successfully cultivate tall festuca in highly saline coastal soil.This approach achieved better effects in sandy loam soil than in silt soil.Tall fescue showed greater survival rates in sandy loam soil due to the rapid reclamation process,whereas plant growth was higher in silt soil because of effective water conservation.In sandy loam,soil moisture should be maintained during soil reclamation,and in silt soil,soil root-zone environments optimal for the emergence of plants should be quickly established.Micro-sprinkler irrigation can be successfully applied to the cultivation of tall fescue in coastal heavy saline soils under a three-stage soil wateresalt regulation regime.
基金funded by the Deanship of Scientific Research(DSR),King AbdulAziz University,Jeddah,Saudi Arabia under Grant No.(RG-11-611-43).
文摘Soil salinity is a serious land degradation issue in agriculture.It is a major threat to agriculture productivity.Extra irrigation water is applied to leach down the salts from the root zone of the plants in the form of a Leaching fraction(LF)of irrigation water.For the leaching process to be effective,the LF of irriga-tion water needs to be adjusted according to the environmental conditions and soil salinity level in the form of Evapotranspiration(ET)rate.The relationship between environmental conditions and ET rate is hard to be defined by a linear relationship and data-driven Machine learning(ML)based decisions are required to determine the calibrated Evapotranspiration(ETc)rate.ML-assisted ETc is pro-posed to adjust the LF according to the ETc and soil salinity level.A regression model is proposed to determine the ETc rate according to the prevailing tempera-ture,humidity,and sunshine,which would be used to determine the smart LF according to the ETc and soil salinity level.The proposed model is trained and tested against the Blaney Criddle method of Reference evapotranspiration(ETo)determination.The validation of the model from the test dataset reveals the accu-racy of the ML model in terms of Root mean squared errors(RMSE)are 0.41,Mean absolute errors(MAE)are 0.34,and Mean squared errors(MSE)are 0.28 mm day-1.The applications of the proposed solution in a real-time environ-ment show that the LF by the proposed solution is more effective in reducing the soil salinity as compared to the traditional process of leaching.
基金supported by the National Natural Science Foundation of China (41601068, 31602001, 41230630)the Young Scholars Development Fund of Southwest Petroleum University (201599010104)the Scientific Research Starting Project of Southwest Petroleum University (2015QHZ025)
文摘Salt expansion in sulfate saline soils that are widely distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temperatures is not clear. In this study, we conducted a series of cooling experiments combined with salt crystallization to study this mechanism, and employed an ionic model to calculate the supersaturation ratio of the solution. During the experiments, the strength and the process of salt expansion were examined under different cooling rates and various crystal morphologies. The relationship between temperature and supersaturation ratio under transient conditions was also considered. Results indicate that the initial supersaturation ratio of a sodium sulfate solution is closely related to environmental conditions, and that this ratio decreases with slowing the cooling rates and stabilizing the crystal forms. Higher initial supersaturation ratios lead to an increased non-steady-state zone, resulting in less salt expansion. On the other hand, chloride ion content has a distinct influence on the crystallization supersaturation ratio of the sodium sulfate solution, and higher chloride ion content can inhibit salt expansion in sodium saline soils. These findings help explain salt expansion mechanisms in complex conditions such as seasonally frozen soils, and thus help search for improved methods of preventing salt expansion in sulfate saline soils.
基金This research was jointly funded by the National Key R&D Program of China(Grant No.2017YFB0502700)the National Natural Science Foundation of China(Grant No.41771402,41804009,42071410)+1 种基金the Scientific R&D Plan of China Railway Corporation(No.JXKT-1801-2-2-7,P2018G004)the Sichuan Science and Technology Support Project(No.2018JY0664,20YYJC4292,2020YJ0322)。
文摘The instability of saline soil foundation affects the safety of artificial construction,and may cause ground collapse,building destruction and road damage.It is fundamental to reduce the potential engineering geological disasters by exploring the dynamic evolution of saline soil.Most of the previous researches of saline soil were conducted by simulated experiments and traditional geodetic surveying methods.Restricted to the limited sampling points,the spatiotemporal evolution characteristics of saline soil were difficult to find out in a large scale.This paper exploited SBAS-InSAR method to extract the deformation of the Qarhan Salt Lake(in Qinghai,China)section along Qinghai-Tibet railway,based on 119 image data acquired by Sentinel-1A from 2015 to 2020.The results showed that the deformation trends varied frequently in this saline mud flat.Between the adjacent areas with different deformation trends along Qinghai-Tibet railway,discontinuities caused by uplift and subsidence were very obvious.Besides,among the areas with brine exploitation or artificial construction,the maximum subsidence rate reached50 mm/yr,and the maximum cumulative subsidence exceeded 320 mm in the latest 5 years.In the saline mud flat closed to the rivers and lakes,the deformation trend was continuous uplift.Nevertheless,there were obvious seasonal deformation characteristics in those areas far away from the water body.Further analysis found out a sharply subsidence caused by the salt collapsibility appeared in rainy seasons.While an uplift trend induced by the salt swelling or frost heave was remarkable in dry seasons.Subsequently,the relationships were analyzed between the time series deformation and external environmental fac-tors.Furthermore,the deformation mechanism of saline soilin the Qarhan Salt Lake region was inter-preted then.In general,this study provides complete spatiotemporal evolution information of saline soil,and demonstrates the deformation characteristics of saline soil in the Qarhan Salt Lake region suc-cessfully.Related results would contribute to the safety monitoring for large-scale infrastructure con-struction in the saline soil areas.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2016B14614)the Program of China Scholarship Council(Grant No.201906715015)+1 种基金the National Key Research and Development Program of China(Grant No.2017YFC040320502)a project funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.
基金supported by the National Natural Science Foundation of China(41771402,41804009)the National Key R&D Program of China(2017YFB0502700)Sichuan Science and Technology Program(2018JY0564,2019ZDZX0042,2020JDTD0003)。
文摘Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation due to season replacement limits the conventional multi-temporal interferometric synthetic aperture radar(MT-InSAR)technique and its application in such areas.To extend the monitoring capability in the salt desert area,we select a vast basin of saline soil around Howz-e-Soltan Salt Lake of Iran as the study area and present an improved MTInSAR for experimental research.Based on 131 C-band Sentinel-1 A images collected between October 2014 to July 2020,1896 refined interferograms in total are selected from all interferogram candidates.Interferometric coherence analysis shows that the coherence in the saline soil area has an apparent seasonal variation,and the soil moisture affected by the precipitation may be the main factor that leads to the seasonal variation.Subsequently,the deformation characteristics of saline soil under different environmental conditions and human activity factors are compared and analyzed in detail.Related deformation mechanisms of different saline soil types are initially revealed by combining interferometric coherence,meteorological data,and engineering geological characteristics of saline soil.Related results would provide reference for the large-scale infrastructure construction engineering in similar saline soil areas.
基金The Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21-0926)the National Natural Science Foundation of China(31972518)and the Qing Lan Project of Jiangsu Province financially supported this work.
文摘We conducted a pot experiment to examine the feasibility of applying a reaction-finished solution of hydrochar(HRFS)to enhance rice production in a saline soil.With this purpose,HRFS was applied(0,10,20,40,60,80 and 100 mL/pot)and rice yield and nitrogen(N)use efficiency(NUE)were determined.HRFS application significantly(P<0.05)increased rice grain yield by 19.6%-30.0%compared to the control treatment(CKU,with N but without HRFS addition).Moreover,HRFS application promoted plant height and straw biomass of rice.Increases of rice yield were mainly achieved by increases in the number of panicles and grains per panicle.Compared with the CKU treatment,the NUE of HRFS amendments significantly(P<0.05)increased by 56.3%-71.7%.This indicated that the improvement of NUE was one of the mechanisms to improve rice grain yield with HRFS amendment.The results of regression analysis showed that there was a positive relationship(R^(2)=0.8332)between rice yield and HRFS application rate within an appropriate range.The highest rice yield was recorded with the HRFS application of 40 mL/pot,but a further increase in HRFS application rate appeared to reduce rice yield.Based on the results of this pot study,HRFS application can increase rice yield in a saline soil by regulating its yield components and enhancing NUE.However,impact of HRFS on these variables showed a“dose effect”.
文摘Biochar application is claimed to improve nutrient availability in many problem soils;however, pristine biochars are often reported to produce inconsistent results. Therefore, appropriate biochar modification techniques are required to retain soil nutrients at an optimum level. To increase Nitrogen (N) and Phosphorus (P) availability in coastal saline soil, two slow pyrolyzed biochars viz domestic organic waste (DWB) and farmyard manure (FMB) were modified with MgCl<sub>2</sub>. Ten different treatments comprising the biochars (pristine and modified) with and without the recommended fertilizer were applied (2% w/w) to the soil and incubated for ninety days. The soils were analyzed for pH, EC, available <img src="Edit_0d6ce0cb-4936-4874-a480-35d5b2f585ff.png" alt="" />, <img src="Edit_64cd5bd3-ddeb-4e08-ad2e-48f0710feace.png" alt="" /> and different phosphorus fractions sequentially extracted by NH<sub>4</sub>Cl, NaHCO<sub>3</sub>, NaOH, and HCl. During the incubation period, biochar treatments increased all phosphorus and nitrogen fractions than the control and recommended fertilizer treatment. The application of FMB significantly (<em>p</em> < 0.05) increased NH<sub>4</sub>Cl, NaHCO<sub>3</sub>, and NaOH extractable P fractions from DWB, while HCl soluble fraction was enhanced (<em>p</em> > 0.05) by DWB. The increased Al and/or Fe bound phosphate after 60 days of incubation had significant correlations to decreasing soil pH and NaHCO<sub>3</sub>-P, indicating reduced availability with time. Further Mg modification slightly increased P availability only after 60 days of incubation. The modification also improved both nitrogen fractions but significantly (<em>p</em> < 0.05) increased the NO<sub>3</sub>-N content which could be the result of electrostatic attraction between Mg<sup>2</sup>+ and <img src="Edit_c55861ac-dd25-4c26-9ecc-2e134a948b8e.png" alt="" /> ions. Overall, Mg-modified biochar may retain both phosphates and nitrates in soil. However, the magnitude of retention will vary depending on biochar type, nutrient species, and aging in soil.
基金This work is supported by the National Natural Science Foundation of China(51878116 and 51902270)Liaoning Province Key Project of Research and Development Plan(2020JH2/10100016)+1 种基金Dalian Science and Technology Innovation Fund Project(2020JJ26SN060)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basins(China Institute of Water Resources and Hydropower Research),Grant No.IWHR-SKL-201910.
文摘In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore characteristics of concrete,analyze the pore characteristics,porosity and pore distribution of concrete in different hydration stages,and reveal the relationship between pore structure and permeability of concrete.The results show that the pore-size distribution of concrete in fresh water condition is better than that in sulfate environment and mixed salt environment,and therefore,sulfate as well as mixed salt are not conducive to the development of pore structure of non-dispersible underwater concrete;chlorine salt has little effect on the pore structure of nondispersible underwater concrete;under the three conditions of sulfate,chlorine and mixed salt,the porosity of concrete mixed with slag powder is lower than that of concrete without slag powder.The results indicate that the addition of slag powder can ameliorate the pore size distribution of non-dispersed underwater concrete,reduce the porosity,and make the concrete structure more compact,which is beneficial to improve the permeability resistance of concrete at the macro level.
基金supported by the National Natural Science Foundation of China(51878116 and 51902270)Liaoning Province Key Project of Research and Development Plan(2020JH2/10100016)+3 种基金Dalian Science and Technology Innovation Fund Project(2020JJ26 SN060)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basins(China Institute of Water Resources and Hydropower Research),Grant No.IWHR-SKL-201910the Special Fund for the Launch of Scientific Research in Xijing University(XJ21T01)the Youth Innovation Team of Shaanxi Universities
文摘In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible underwater concrete in sulfate,chloride,and mixed salt environments,the compressive strength and deterioration resistance coefficient of the studied concrete mixed with different amounts of ground granulated blast-furnace slag(GGBS)were analyzed in this paper.At the same time,the micro morphology and corrosion products distribution of the studied concrete were observed by means of SEM,plus XRD diffraction,TG-DTG and FT-IR analyses to explore the influence of corrosive solutions on the hydration products of concrete.We also analyzed the mechanism of improving the deterioration resistance of the studied concrete by adding GGBS in a saline soil environment.The results show that the compressive strength of the studied concrete in a chloride environment was close to that in a fresh water environment,which means that chloride has no adverse effect on compressive strength.The deterioration of the studied concrete was most serious in a sulfate environment,followed by mixed salt environment,and the lowest in a chloride environment.In addition,by adding GGBS,the compressive strength and deterioration resistance of the studied concrete could be effectively improved.
基金jointly supported by grants from the National Natural Science Foundation of China(No.41501062)the Longyuan Youth Innovation and Entrepreneurship Talent(Team)Project of Gansu Province and Natural Science Foundation of Gansu Province(No.20JR10RA227).
文摘Engineering activities in the salt lake region continue to increase where fresh water resources are scarce.This paper investigates the physical properties of saline soils during mixing with brine.Fine-grained saline soils with salt content varying from 2.6%to 78.5%were collected along Qarhan-Golmud Highway(QGH)and Sebei-Qarhan Highway(SQH)on the Qinghai-Tibet Plateau to conduct laboratory physical properties tests.Liquid plastic limit tests were conducted.Results show that liquid plastic limit parameters will decrease with an increase of salt content ranging from 2.6% to 78.5%,and the relationship between them is linear.After considering the content ratio of chloride and sulfate,results show that liquid plastic limit parameters will decrease with an increase of the ratio of chloride to sulfate ranging from 0.7% to 7.0%;liquid plastic limit parameters enter a stable period at the ratio of chloride to sulfate ranging from 7.0% to 37.4%;liquid plastic limit parameters enter a decline period at the ratio of chloride to sulfate ranging from 37.4% to 77.2%.After brine and fresh water are separately mixed into saline soil,the optimal moisture content of the soil samples after the brine action is lower than the saline soil under the action of fresh water,and the maximum dry density of the soil sample is higher than that under the action of fresh water.At the same time,these changing laws show a certain correlation with the chloride ion content and the ratio of chloride to sulfate in saline soils.The results are of significance for engineering activities in salt lake regions with extensive saline soil distribution.
基金the General project of Chongqing Science and Technology Commission Scientific(Grant No.cstc2019jcyj-msxmX0813)Youth Program of Scientific and Technological Innovation Fund of Gansu Academy of Sciences(Grant No.2019QN-04)and is a part of the Scientific Project of Yangtze Normal University(Grant No.2017 XJQN16).
文摘Based on salt-frost heave tests of sulfate saline soil under repeated freeze−thaw cycles,this paper discusses the mechanism of the salt-frost heave under long-term freeze−thaw cycles.The results show that the salt-frost heave can be restricted considerably by loads,and there is a critical load for the salt-frost heave cumulative effect.Under this load,peak values of salt-frost heave approach a constant,and the residual values become 0.There is no longer structure heave or cumulative effect of saline soil exposed to freeze−thaw cycles under the critical load.Taking cumulative effect into account in calculations of salt-frost heave,a salt-frost heave model under freeze−thaw cycles is developed.
文摘A study was carried out to assess the interaction of Arsenic with excess Sulphur present in saline soil and their impact on plant growth. Two different types of saline soils S<sub>1 </sub>(2.0 dS/m) and S<sub>2 </sub>(5.061 dS/m) were collected from the southwestern part of Bangladesh. The experiment was conducted in two parts: in vitro incubation study and pot experiment. Arsenic treatments at the rates of 0, 0.05 and 1.0 mg/L were applied with water. The incubated soils were sequentially extracted with three different extractants, viz, distilled water, 0.01 M CaCl<sub>2</sub>, and 1 M HCl. 1 M HCl was found to extract the maximum amounts of soluble salts as well as arsenic from the saline soil. Rice was selected as the test plant for pot experiment. An improved variety of rice (BRRI 41) was grown on the experimental soils. Sulphur in saline soil was found to reduce the accumulation of Arsenic by rice plant.
文摘Coastal soils of Bangladesh are affected by salinity. This study investigated salinity as a stress factor on coastal soils in Bangladesh. It was also observed if incorporation of rice straw could remediate negative impacts of soil salinity (if any) on microbial activ-ity. The microbial biomass carbon ranged from 137.85 to 614.88 μg/g among the soils (n = 11). Microbial biomass carbon content and number of both cultivable bacteria and fungi decreased in the soils with higher EC<sub>e</sub>s (electrical conductivity). Respiration was measured over 30 days with each soil pre incubated at 50% of water holding capacity. Basal respiration rate as well as soil organic carbon content (r = 0.88, p - 37.73 mS/cm) (12.91 - 16.89 mg CO2/g dry soil) than in the nonsaline soils (0.98 - 2.33 mS/cm) (5.79 - 6.51 mg CO2/g dry soil). Application of rice straw at 0.50%, 1.00%, 1.50% and 2.00% reduced the negative impact of soil salinity especially at higher EC<sub>e</sub>s (6.63 - 37.73 mS/cm). Application of 1.00% rice straw appeared to be acceptable for successful amelioration of saline soils of the study area.
基金This work was funded by Abu Dhabi Award for Research Excellence-Department of Education and Knowledge(No.21S105)to Khaled A.El-Tarabily.
文摘Plants have to cope with several abiotic stresses,including salinity and heavymetals(HMs).Under these stresses,several extracts have been used as effective natural biostimulants,however,the use of Spirulina platensis(SP)extract(SPE)remains elusive.The effects of SPE were evaluated as soil addition(SA)and/or foliar spraying(FS)on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs.Individual(40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS)or integrative(SA+FS)applications of SPE showed significant improvements in the following order:SA-80+FS-40>SA-80+FS-20>SA-40+FS-40>SA-40+FS-20>SA-80>SA-40>FS-40>FS-20>control.Therefore,the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production,overcoming stress effects and minimizing contamination of the edible part.It significantly increased plant growth(74%–185%)and yield(107%–227%)by enhancing net photosynthetic rate(78.5%),stomatal conductance(104%),transpiration rate(124%),and contents of carotenoids(60.0%),chlorophylls(49%–51%),and NPK(271%–366%).These results were concurrent with the marked reductions in malondialdehyde(61.6%),hydrogen peroxide(42.2%),nickel(91%–94%),lead(80%–9%),and cadmium(74%–91%)contents due to the improved contents of glutathione(87.1%),ascorbate(37.0%),andα-tocopherol(77.2%),and the activities of catalase(18.1%),ascorbate peroxidase(18.3%),superoxide dismutase(192%),and glutathione reductase(52.2%)as reinforcing mechanisms.Therefore,this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.
