Amodified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation

Soil salinization,caused by salt migration and accumulation underneath the soil surface,will corrode structures.To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions,a mathematical model consisting of a series of theoretical equations is briefly presented.The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations.Besides,a transition equation to link the solute transport equation before and after salt precipitation is proposed.Meanwhile,a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation.The results show that the calculated values are in good agreement with the published experimental data,especially for the simulation of volume water content and evaporation rate of Toyoura sand,which confirm the reliability and applicability of the proposed model.

Sedimentation rates in the Wanggang salt marshes,Jiangsu

Coastal salt-marshes represent an important coastal wetland system. The total area of coastal wetlands exceeds 5000 km2 in Jiangsu Province, China, but it is decreasing rapidly in response to the intense reclamation activities and coastal erosion along a part of the coastline. Hence, two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coastal areas, in order to protect the coastline from erosion and to increase the accumulation rate. Pb-210 and Cs-137 analyses were carried out for sediment samples from the salt-marshes of Wanggang to determine the sedimentation rate, on the basis of an evaluation of the background activity values and the factors affecting the enrichment of Pb-210. Analysis of a typical sediment column of the tidal flat shows that there is weak absorption of Pb-210 in the silt-dominated sediment. Because of the influences of factors such as storm events, bioturbation, material sources and analytical error, some abnormal data points appear in the Pb-210 record. After ignoring these data the calculated sedimentation rate was 3.3 cm yr-1 on average. Based upon analysis of the Cs-137 dating, the rate since 1963 was 3.1 cm yr-1 on average, similar to the data by Pb-210 dating and the previous studies. The dating results show that there were three stages of sedimentation, with the most rapid accretion being taking place after Spartina angelica was introduced into the area. The study also shows that at the stage of Spartina alterniflora growth, the accretion rate was higher than on the flat surface with the same elevation without the cover of this plant.

Effects of emitter discharge rates on soil salinity distribution and cotton(Gossypium hirsutum L.) yield under drip irrigation with plastic mulch in an arid region of Northwest China

A field experiment was carried out to investigate the effects of different emitter discharge rates under drip irrigation on soil salinity distribution and cotton yield in an extreme arid region of Tarim River catchment in Northwest China. Four treatments of emitter discharge rates, i.e. 1.8, 2.2, 2.6 and 3.2 L/h, were designed under drip irrigation with plastic mulch in this paper. The salt distribution in the range of 70-cm horizontal distance and 100-cm vertical distance from the emitter was measured and analyzed during the cotton growing season. The soil salinity is expressed in terms of electrical conductivity （dS/m） of the saturated soil extract （ECe）, which was measured using Time Domain Reflector （TDR） 20 times a year, including 5 irrigation events and 4 measured times before/after an irrigation event. All the treatments were repeated 3 times. The groundwater depth was observed by SEBA MDS Dipper 3 automatically at three experimental sites. The results showed that the order of reduction in averaged soil salinity was 2.6 L/h 〉 2.2 L/h 〉 1.8 L/h 〉 3.2 L/h after the completion of irrigation for the 3-year cotton growing season. Therefore, the choice of emitter discharge rate is considerably important in arid silt loam. Usually, the ideal emitter discharge rate is 2.4-3.0 L/h for soil desalinization with plastic mulch, which is advisable mainly because of the favorable salt leaching of silt loam and the climatic conditions in the studied arid area. Maximum cotton yield was achieved at the emitter discharge rate of 2.6 L/h under drip irrigation with plastic mulch in silty soil at the study site. Hence, the emitter discharge rate of 2.6 L/h is recommended for drip irrigation with plastiic mulch applied in silty soil in arid regions.

Effect of salt stress on activity of superoxide dismutase （SOD） in Ulmus pumila L.

The injury tolerance of cell plasma membrane and the correlative enzymes activities of plasma-membrane protection system in the Ulmuspumila leaves treated by nine concentrations （0.3%, 0.6%, 0,9%, 1,2%, 1.5%, 1.8%, 2,1%, 2.4%, 3.0%） of Na2CO3 and NaHCO3 mixtures were studied in a greenhouse of Northeast Forestry University, Harbin, China. The rate of electrolyte leakage （REL） and SOD （Superoxide dismutase） activity in leaves of different samples were determined. Results showed that the REL in leaves of U. pumila presented a slowly increasing trend at the salt concentrations less than 1.5%, which indicated that cell plasma membrane of U. pumila leaves had rather strong resistance to the injury of salt ion, and had a significant increase at the salt concentrations more than 1.5%. The SOD activities in leaves of U, pumila presented an increased trend at salt concentrations less than 1.5%, the growth of seedlings did not decline, and tress and leaves had no symptom of injury, while the salt concentrations exceeded 1.5%, SOD activities sharply decreased and REL increased promptly.

Nitrogen in Relation to Photosynthetic Capacity and Accumulation of Osmoprotectant and Nutrients in Brassica Genotypes Grown Under Salt Stress

Different strategies of the application of nutrients are required to overcome the adverse effects of mustard （Brassica juncea L.） in response to NaCl stress. The objective of the present study was to determine if different added levels of nitrogen （N） in growth medium could alleviate the adverse effects of salt stress on photosynthetic capacity and accumulation of osmoprotectants and nutrients. 14 days mustard seedlings of salt-sensitive （cv. Chuutki） and salt-tolerant （cv. Radha） genotypes were fed with： （i） 0 mmol L^-1 NaCl ＋ 0 mg N kg^-1 sand （control）, （ii） 90 mmol L^-1 NaCl ＋ 30 mg N kg^-1 sand, （iii） 90 mmol L^-1 NaCl ＋60 mg N kg^-1 sand, （iv） 90 mmol L^-1 NaCl ＋90 mg N kg^-1 sand and （v） 90 mmol L^-1NaCl＋ 120 mg N kg^-1 sand. Under the condition of salinity stress, N application caused a significant ameliorative effect on both genotypes with respect to growth attributes [fresh weight （FW） and dry weight （DW）] and physio-biochemical parameters [percent water content （WC）, net photosynthetic rate （PN）, stomatal conductance （gs）, total chlorophyll （Ch1）, carbonic anhydrase （CA） activity and malondialdehyde （MDA）, nitrogen （N）, potassium （K） and sodium （Na） contents, and K/Na ratio] and yield attributes （number of pods/plant, seeds/pod and seed yield/plant）. The salt-tolerant genotype exhibited maximum value for growth, physio-biochemical and yield attributes at 60 mg N kg 1 sand than that of salt-sensitive genotype. These results suggest that application of N may ameliorate most of the attributes and prove to be a physiological remedy to increase the tolerance against the ill effects of salt stress in Brassicas.

Radiation dose distribution of liquid fueled thorium molten salt reactor

A liquid fueled thorium molten salt reactor(TMSR-LF),one of the Generation IV reactors,was designed by the Shanghai Institute of Applied Physics,Chinese Academy of Sciences.This study uses the‘rt code to calculate the neutron and gamma dose rate distributions around the reactor.Multiple types of tallies and variance reduction techniques were employed to reduce calculation time and obtain convergent calculation results.Based on the calculation and analysis results,the TMSR-LF1 radiation shield with a 60-cm serpentine concrete layer and a 120-cm ordinary concrete layer is able to meet radiation requirements.The gamma dose rate outside the reactor biological shield was 16.1 mSv h-1;this is higher than the neutron dose rate of 3.71×10^(–2)mSv h^(-1).The maximum thermal neutron flux density outside the reactor biological shield was 1.899103 cm^(-2)s^(-1),which was below the 19105 cm^(-2)s^(-1)limit.

Corrosion performance of friction stir welded AA2024 aluminium alloy under salt fog conditions

Aluminium alloy（AA） 2024 is an important engineering material due to its widespread use in the aerospace industry. However, it is very prone to corrosion attack in chloride containing media. In the present investigation, AA2024 aluminium alloy rolled plates of 5 mm in thickness were friction stir welded. Corrosion performances of the specimens were evaluated by conducting salt fog tests in Na Cl solution at different p H values, chloride ion concentrations and spraying time. In addition, an empirical relationship was established to predict the corrosion rate of friction stir welds of AA2024 aluminium alloy. A central composite rotatable design including three factors and five levels was used to minimize the number of experiments. Response surface methodology（RSM） was used to develop the relationship. The corrosion rate decreased under neutral p H conditions. The corrosion rate increased in acidic and basic conditions. It was also found that the corrosion rate decreased with the increase of spraying time, but the corrosion tended to be uniform with the increment of time and with the increase in the chloride ion concentration, and the corrosion rate increased in the salt spray corrosion test.

Numerical simulation and experimental study on dissolving characteristics of layered salt rocks

Underground salt cavern reservoirs are ideal spaces for energy storage. China is rich in salt rock resources with layered lacustrine sedimentary structures. However, the dissolution mechanism of layered salt rocks remains poorly understood, resulting in significant differences between the actual measurements and the designed indices for the layered salt rock water-soluble cavity-making cycle and the cavity shape. In this work, the dissolution rates of 600 groups of layered salt rocks in China under different conditions were determined experimentally.Thus, the established artificial neural network prediction model was used to assess the effects of the contents of NaCl, Na2 SO4, and CaSO4 in the salt rocks, concentrations, dissolution angles, and flow rates on their dissolution rates by performing ANOVA and F-test. The results provide a theoretical basis for evaluating the dissolution rate of layered salt rocks under different conditions and for the numerical simulation of the layered salt rock water-soluble cavity-making process.

An experimental study of salt expansion in sodium saline soils under transient conditions

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.

Stress-Activated Protein Kinase OsSAPK7 Regulates Salt- Stress Tolerance by Modulating Diverse Stress-Defensive Responses in Rice

Soil salinity is an environmental threat limiting rice productivity.Identification of salinity tolerance genes and exploitation of their mechanisms in plants are vital for crop breeding.In this study,the function of stress-activated protein kinase 7(OsSAPK7),a SnRK2 family member,was characterized in response to salt stress in rice.Compared with variety 9804,OsSAPK7-overexpression plants had a greater survival rate,increased chlorophyll and proline contents,and superoxide dismutase and catalase activities at the seedling stage under salt-stress conditio ns,as well as decreased sodium potassium ratio(Na+/K+)and malondialdehyde contents.After salt stress,the OsSAPK7 knockout plants had lower survival rates,in creased Na^K*ratios and malomdiadehyde contents,and decreased physiological parameters compared with 9804.These changes in transgenic lines suggested that OsSAPK7 increased the salt tolerance of rice by modulating ion homeostasis,redox reactions and photosynthesis.The results of RNA-Seq indicated that genes involved in redox-dependent signaling pathway,photosynthesis and zeatin synthesis pathways were significantly down-regulated in the OsSAPK7 knockout line compared with 9804 un der salt-stress conditio n,which con firmed that OsSAPK7 positively regulated salt tolera nee by modulating diverse stress-defe nsive resp on ses in rice.These findings provided novel in sights for the genetic improvement of rice and for understanding the regulatory mechanisms of salt-stress toleranee.

Study on Hatching Rate of Artemia fanciscana Cysts in Different Sources of Saline

A comparison of Arternia cysts hatching （Artemia franciscana） were conducted on bleaching and non-bleaching with sodium hypochloride on five dilution of salt solution by using sea water, sea salt solution, artificial sea salt solutions, iodine added cooking salt solution, and rock salt solutions. All solutions were adjusted at 30 ppt of salinity in 1 litter cylinder. The experiment was carried out with Factorial Experiment in CRD. After 24 hours, a randomized count of living Artemia was taken a photograph of Artemia size by stereo microscope. A statistic analysis showed that all data of bleaching and non-bleaching were no significant difference （P 〉 0.05）. The hatching ability of Artemia cysts in solutions was examined and the results showed that sea salt solution was 327.33 × 103.4. 28,536.5263 Nauplii/liter, sea water 316 ×10^3± 20,420.5779 Nauplii/liter, artificial sea salt solutions 314.33× 10^3 ± 34,268.5473 Nauplii/liter, iodine added cooking salt solution 309.66 ± 10^3 .4- 22,898.3260 Nauplii/liter, and rock salt solutions 305.33 ± 10^3 ± 25,579.9401 Nauplii/liter, respectively. The body length of Artemia was compared and the data showed that there was no significant difference （P 〉 0.05）. The highest body length was found in sea salt solution 527.32 ± 4.70μm, sea water 521.65±8.51 μm, artificial sea salt solutions 522.08 ± 10.04 μm, iodine added cooking salt solution 522.67 ±7.87 μm, and rock salt solutions 516.33 ±11.15μm, respectively.

An Eco-Friendly High-Effective Scale Inhibitor for High Salt Brine

Now the mining of high salt underground brine has been an important aspect of salt lake mining,which is the necessary support to the development of national economy.With the change of underground geological

Kinetic Approach of Iodine Quantification in Dietary Salts

Iodization of dietary salt is recommended to prevent and control iodine deficiency disorders. The kinetic study of dietary iodized salt proves to be of interest not only for the determination of the conditions of production of iodine, but also for a good knowledge of the kinetic and thermodynamic parameters of the reaction. In this work, two salt brands were studied and one of them was used for the kinetic study. The kinetic study showed that the reaction proceeded slowly at a medium rate. Since the reaction admits a global order equal to 1, potassium iodide has no influence on this reaction rate. The concentration of iodate ions introduced in the dietary salt is a kinetic parameter that affects the reaction rate. Calculated rate constant was inversely proportional to time. The study has therefore determined experimentally kinetic parameters of the reaction between iodate and iodide ions.

Ferro-vanadium Slag in Improving Inner Chloride Solidification Rate of Cement Materials

We investigated the effects of ferro-vanadium slag(FVS)as a supplemental cementing material which can dissolve a large amount of active aluminum phases without excessive pretreatment or excitation to enhance the inner chloride solidified rate(CSR)of cement-based materials.Cement-FVS pastes with 0-30%content of FVS was designed,and the CSR was examined.Hydrates at different curing ages were studied by X-ray diffraction(XRD)and thermo-gravimetric analysis(TGA);hydration heat and^(29)Si nuclear magnetic resonance(^(29)Si-NMR)were tested to analyze the hydration degree of the system;mechanical properties in cement-FVS system were evaluated by compressive strength test,pore structure and the fractal regression.Results revealed that the incorporation of FVS could greatly promote the CSR of cement-FVS system.Compared with the control groups,30%dosage of FVS could increase the CSR by 69%at 3 d,47%at 7d,36%at 28 d and 34%at 60 d.It was demonstrated that the incorporation of FVS could enhance the chemical solidifying ability of chloride,and the main reason was the promoted generation of Kuzel’s salt and the Friedel’s salt in hydrate products,and the enhanced chloride migration resistance capacity by increasing the volume of gel pores in the cement-FVS system.Considering the influence of FVS on strength performance,this paper suggested that the suitable dosage of FVS as a supplemental cementing material was around 10%.The study in this paper might provide one efficient path to promote the chloride solidifying capacity of cement-based material and meanwhile the comprehensive utilization of FVS.

Iodized salt consumption and iodine deficiency status in China: a cross-sectional study

Objective:To monitor iodized salt consumption and evaluate iodine deficiency status in 2014 in China.Materials and Methods:In 2014,a nationwide cross-sectional survey was conducted in 31 provinces (in this study,provinces,autonomous regions and municipalities in China's Mainland were named as provinces).Probability proportional to size sampling method was adopted to recruit children ages 8-10 and pregnant women.47,467 children's and 18,994 pregnant women's urine samples were collected and 47,706 children's thyroid volumes were examined.Iodine content in salt was determined with 46,900 edible salt samples from children's households;urinary iodine concentration (UIC) was tested from children and pregnant women's urine samples;thyroid volume of children was assessed by ultrasound.Results:The national coverage rate of iodized salt and consumption rate of qualified iodized salt were 96.3％ and 91.5％,respectively.Median iodine content in iodized salt was 25.2 mg/kg.In 22 of 31 provinces,the provincial coverage rates of iodized salt were over 95％.And consumption rates of qualified iodized salt were more than 90％ in 21 provinces.In this study,the national median urinary iodine concentration (MUIC) of children in China was 197.9 μg/L.At the provincial level,MUIC of children in 19 provinces was 100-199 μg/L,which in 12 provinces was 200-299 μg/L.The national MUIC of pregnant women in 2014 was 154.6 μg/L,slightly higher than the lower limit of the WHO criteria for adequate (150-249 μg/L).At the provincial level,MUIC of pregnant women in 18 provinces was 100-149 μg/L,which in 13 provinces was 150-249 μg/L.The national prevalence of goiter among children in 2014 was 2.6％,of which only Shandong province (5.6％) exceeded the national standard (5％).Conclusions:In China,iodine deficiency disorders (IDD) has been eliminated since 2005.And in 2014,the IDD-free status still remained.

植物免疫诱抗剂对玉米耐盐性及产量的影响

为探究植物免疫诱抗剂对玉米耐盐性及产量的影响,以智能聪(ZNC)为材料,于2022年在山东烟台开展试验,对盐分胁迫条件下不同浓度智能聪浸种处理的玉米种子发芽率、根系生长指标和产量进行比较分析。结果表明:在8、10 g/L NaCl溶液中,玉米种子发芽率分别为27.5%、17.5%,主根长度分别为19.8、13.0 mm,显著低于其在水溶液中的发芽率(52.5%)和主根长度(55.9 mm),说明盐溶液对玉米发芽和根系生长有抑制作用。20 ng/mL智能聪浸种处理后,8、10 g/L NaCl溶液下的玉米种子发芽率分别为38.0%、25.0%,主根长度分别为24.5、15.1 mm,说明智能聪浸种能够缓解盐溶液对玉米种子发芽和根系生长的抑制作用。采用智能聪拌种结合玉米生长期兑水喷施处理,玉米产量提高5.02%。综合分析,在盐分胁迫条件下,施用智能聪可促进玉米生长,提高其产量。

盐冻耦合环境下再生砖粉ECC的耐久性研究

利用再生砖粉取代工程水泥基复合材料(ECC)中的石英砂,制备再生砖粉ECC,采用混凝土快速冻融试验,研究了氯盐、硫酸盐及复合盐(氯盐+硫酸盐)溶液侵蚀作用下再生砖粉ECC的质量损失率和相对动弹性模量变化规律,建立了ECC在盐冻侵蚀环境下的损伤模型,并对其耐久性进行评价。结果表明:冻融循环300次后,再生砖粉ECC在清水、氯盐、硫酸盐及复合盐四种介质中的质量损失率分别为2.884%、4.984%、1.955%和6.891%,相对动弹性模量分别下降了6.468%、16.300%、24.303%和39.861%;再生砖粉ECC在单一盐冻情况下的抗冻等级大于F300,在复合盐冻情况下的抗冻等级大于F250,具有良好的抗盐冻性能;建立的冻融损伤模型可较好地反映ECC在不同冻融介质下的损伤度Dn与冻融循环次数的关系,可以为严寒地区的结构耐久性设计提供有效参考。

盐穴储气库运行参数设计及稳定性评价研究

盐岩具有低渗透性和良好的蠕变行为,是天然气存储的理想介质。在长期注采运行过程中,其上下限压力大小、采气速率、运行工况和注采过程中温度变化等因素对储气库稳定性及安全运营产生重要影响。在对盐岩蠕变特性及理论分析的基础上,建立了盐穴储气库的稳定性综合评价准则,基于Lemaître蠕变模型对某盐穴储气库盐岩的蠕变特性进行了分析,通过数值模拟的方法确定了某拟建储气库上限运行压力为14MPa,下限运行压力为5MPa,注采速率应小于1MPa/d。为避免温度效应造成的拉应力,采气时腔内温度应高于10℃。对3种不同运行工况下盐穴储气库的稳定性进行评价,结果表明:纯循环和一般循环下盐腔较为稳定;在极端循环下,储气库有可能发生破坏,建议尽量缩短极端运行时间。文章为盐穴储气库运行方案的设计和稳定性评价提供了指导作用。

地下盐岩溶腔储库单井水平溶解建造流体运移研究

为提高水平盐穴储库单井后退式溶腔建腔速率,通过相似模型试验与数值计算开展建腔期注水方向对腔内流体运移规律影响研究。数值模拟结果表明:注入淡水接触腔内卤水后浓度会迅速升高,当浓度达到23%左右变为缓慢升高;上下同时入射有利于快速溶腔,垂直向下入射有利于建造更大腔体。相似模型试验流体运移规律与数值模拟基本一致,证明了数值模型的正确性。试验发现:腔内流体主要分为羽流区、边界溶解区、对流扩散区和底部饱和区4个区域;改变注水方向使羽流区流体浓度和流速改变,进而影响边界溶解区高度,与水平入射相比,垂直向上入射、上下型入射、四周型入射和垂直向下入射高度增加了22.2%、26.9%、51.1%、135.6%;改变注水方向使淡水初始向下流速改变,进而改变底部饱和区高度,与水平入射相比,垂上、四周、上下、垂下入射高度降低0%、12.9%、29.9%、70.1%。

盐胁迫对食用型向日葵现蕾期叶片光合性能与冠层结构的影响

为探明不同程度盐胁迫对现蕾期食用型向日葵(下称“食葵”)光合作用的影响,测定分析轻度(全盐量1.00 g∙kg^(−1),LS)、中度(全盐量2.68 g∙kg^(−1),MS)和重度(全盐量4.93 g∙kg^(−1),HS)盐胁迫下,现蕾期食葵不同叶位叶片的光合性能和冠层结构参数。结果表明,盐胁迫降低了食葵叶片的净光合速率(Pn),其中MS和HS处理的Pn最大值较LS分别降低5.09%和38.69%,并减少了具有较高光合速率的叶片数量。盐胁迫降低了食葵顶叶的Pn,MS、HS处理的食葵顶叶Pn最大值较LS分别降低8.08%、14.66%。LS处理的光合速率受到气孔和非气孔双重因素的影响,而MS、HS处理主要受非气孔因素的影响。盐胁迫改变了食葵的株型,LS处理的冠层结构呈宝塔型,而MS和HS处理的冠层结构分别呈平展型和圆柱体型。盐胁迫会减小食葵总叶面积和主要功能叶面积,其中HS处理的总叶面积较LS、MS处理分别降低56.03%、47.74%,HS处理的最大单叶面积较LS、MS处理分别降低38.71%、49.46%;同时HS处理叶倾角最大值与LS、MS处理相比分别提高30.92%、14.59%。总之,盐胁迫会明显降低食葵主要功能叶片的光合性能和叶面积,并使其冠层结构由伸展型向收缩型变化,进而抑制植株正常生长。