Salt transport in polymeric pervaporation membrane

The salt transport in a PEBA membrane used in pervaporative desalination was studied.The concentration profile of salt in the membrane during pervaporation was investigated experimentally using a multilayer membrane.The salt was found to be sorbed in the membrane but was not removed during the pervaporative desalination process,and the salt concentration in the membrane varied linearly with position.High purity water was obtained as the permeate as long as the permeate side was kept dry under vacuum.The accumulated salt uptake in the membrane follows the order of MgCl2 N NaCl N Na2 SO4.The solubility of salt in the membrane follows the order of MgCl2 N NaCl N Na2 SO4.Both the permeability and diffusivity of salt in the membrane follow the order of NaCl N MgCl2 N Na2 SO4.The permeability of salt in the membrane is not influenced by the feed salt concentration.It is mainly determined by the diffusion coefficients.

Heat and salt transport throughout the North Pacific Ocean

Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport(MHT) and meridional salt transport(MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents(WBCs) are estimated for the fi rst time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacifi c. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area.

Interbasin freshwater, heat and salt transport through the boundaries of the East and South China Seas from a variable-grid global ocean circulation model

The monthly and annual mean freshwater, heat and salt transport through the openboundaries of the South and East China Seas derived from a variable-grid global ocean circulation model is reported. The model has 1/6 resolution for the seas adjacent to China and 3 resolution for the global ocean. The model results are in fairly good agreement with the existing estimates based on measurements. The computation shows that the flows passing through the South China Sea contribute volume, heat and salt transport of 5.3 Sv, 0.57 PW and 184 Ggs-1, respectively (about 1/4) to the Indonesian Throughflow, indicating that the South China Sea is an important pathway of the Pacific to Indian Ocean throughflow. The volume, heat and salt transport of the Kuroshio in the East China Sea is 25.6 Sv, 2.32 PW and 894 Ggs-1, respectively. Less than 1/4 of this transport passes through the passage between Iriomote and Okinawa. The calculation of heat balance indicates that the South China Sea absorbs net heat flux from the sun and atmosphere with a rate of 0.08 PW, while the atmosphere gains net heat flux from the Baohai, Yellow and East China Seas with a rate of 0.05 PW.

Plant salt tolerance and Na^+ sensing and transport

Salinity is a global challenge to agricultural production. Understanding Na^+ sensing and transport in plants under salt stress will be of benefit for breeding robustly salt-tolerant crop species. In this review, first, possible salt stress sensor candidates and the root meristem zone as a tissue harboring salt stress-sensing components are proposed. Then,the importance of Na^+ exclusion and vacuolar Na^+ sequestration in plant overall salt tolerance is highlighted. Other Na^+ regulation processes, including xylem Na^+ loading and unloading, phloem Na^+ recirculation, and Na^+ secretion, are discussed and summarized.Along with a summary of Na^+ transporters and channels, the molecular regulation of Na^+ transporters and channels in response to salt stress is discussed. Finally, some largely neglected issues in plant salt stress tolerance, including Na^+ concentration in cytosol and the role of Na^+ as a nutrient, are reviewed and discussed.

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Playa——A Coupled Model of Reactive Solute Transport and Chemical Equilibrium in a Multi-component Underground Brine System

Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system （salt deposits） was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.

THE CHANGE OF THE GENERAL FORM AND THE TRANSPORT OF THE WATER， LOAD AND SALT ABOUT THE NORTH－BRANCH OF THE CHANGJIANG RIVER MOUTH

The general form of the north-branch of the Changjiang River mouth has changed much as a result of the change of the main stream lines of the Nantong reach of the Changjiang River and the influence of human activities since 1915. By the 1930s, the main stream lines of the Nantong reach of the Changjiang River has shifted to the Tongzhou Bar west channel. The north-branch at the Changjiang River mouth has become atrophic because of Tongzhou Bar east channel's deposition. After 1958, Toughal Bar and Jiangxin Bar were exploited. And in 1970, the north channel of Jiangxin Bar was blocked up. All these things make the water of the north-branch more difficult to pass through. It leads to the decline of the total discharge percentage of the north-branch. And it causes the rising tide to go back to the south-branch. However, since 1978, with the development of Tongzhou Bar east channel and its left bank being scoured, the water amount of the north-branch has been increasing. And the water,load and salt of going back to the south-branch has been becoming less.

TIBET’S LAST CARAVAN WITH TRANSPORTING SALT(III)——SALT LANGUAGE AND THE CARAVAN

Saltmen believed aboriginal gods were everywhere. If anyone in a caravan did something bad, offending the local gods, then these would punish the caravan and even bring down disaster upon it. If everyone respected and offered sacrifices to the gods, and followed all the caravan rules, then they the gods would protect them.

TIBET'S LAST CARAVAN CHARGED WITH TRANSPORTING SALT(Ⅸ):Kelsang Wangdul Arrives at Lhasa

The road became worse by the south part of Namtso;streams of melting snow had eroded the road until it resembled a giant comb.The vehicle alternated between speeding along and a sudden brake that made everyone lurch about as though they were all intoxicated.

TIBET'S LAST CARAVAN CHARGED WITH TRANSPORTING SALT(Ⅶ):Barter Trade between Food Grains and Salt

By setting out for saline lakes in spring, Tibetan caravans on horseback return to farmlands in autumn to barter salt for agricultural products.

西北干旱露天煤矿排土场土壤重构与水盐运移机制

矿山排土场生态修复是煤矿露天开采面临的重大环境问题,是制约建设绿色露天煤矿的重要因素。土壤重构是排土场生态修复的重要步骤,以新疆为代表的西北煤炭基地,水资源短缺,盐碱化突出,土壤水盐运移是决定土壤重构是否成功的关键指标。目前研究集中在表层土壤重构改善土壤养分促进植物生长,针对保水控盐的功能化土壤重构的研究甚少,对不同土壤重构方式下的水盐运移机制尚不明晰。研究立足新疆煤炭资源禀赋特征,从煤炭循环经济的角度出发,采用能源化工副产物煤气化渣(CGS)作为重构材料,通过毛细水上升-蒸发试验,分析CGS重构后水盐垂向运移和水分供给能力,通过Van Genuchten模型拟合土壤水分特征曲线,分析CGS重构后土壤持水能力,研究CGS作为含水层重构材料的可行性。采用煤矿开采伴生岩石矿物红泥岩作为重构材料,通过土柱入渗蒸发试验,分析红泥岩重构后不同土壤深度的水盐变化情况,研究泥岩作为隔水层重构材料的可行性。结果表明,CGS重构改善土壤质地,优化孔隙结构,促进了土壤水盐运移,毛细作用增强,促进了下层水分向上供给,同时也增加了盐分表聚,重构改变土水特征曲线参数,增加了饱和含水量θ_(s),降低了参数a和n,改善了土壤持水性能。CGS添加量越高,细渣质量分数越大,效果越明显。CGS作为重构含水层材料具有可行性。红泥岩黏粒和次生矿物含量高,孔隙结构丰富,物理吸附性良好,重构后0~24 cm深度下土壤含水率高于对照组,蒸发后的盐分在20~24 cm达最高值,红泥岩有效阻隔了盐分上移。红泥岩作为重构隔水层材料具有可行性。研究以期探索出一条适合西部煤炭基地排土场土壤重构模式。

垄作和覆膜下盐碱地水盐运移和大豆产量的变化

选择河北省黄骅市中度盐碱土区布置夏播大豆[Glycine max(L.)Merr.]田间试验,共设平播(对照)、平播覆膜、垄作及垄作覆膜4个处理,研究垄作和覆膜对土壤水盐运移和大豆产量的影响。结果表明,与传统平播方式相比,平播覆膜处理对土壤水盐运移和大豆产量的影响不显著;垄作处理能显著改变土壤水盐分布,特别是大豆生长中后期降雨量开始减少后,垄作定植沟会产生叠加集雨效果,显著提高大豆生长中期0~20 cm和20~40 cm土壤含水量,减缓作物生长后期向表层返盐进程,有效降低土壤表层盐分含量,对保障大豆植株生长和产量均有一定的促进效果,可增产27.2%;垄作覆膜处理效果与垄作处理类似,覆膜措施影响不显著。垄作技术可以作为滨海盐碱地夏播大豆种植的农耕措施。

文化人类学视野下自贡井盐生产工具与技艺——竹笕输卤系统

竹笕输卤系统是自贡盐场传统井盐生产体系中的重要组成部分。文章立足于文化人类学的视野,综合利用晚清民国时期的盐业志书、盐场调查报告、盐务报刊、地方志、历史图片,结合田野调查,探析自贡盐场竹笕输卤产生的背景、竹笕制作安设及其主要装置和笕业,揭示自贡盐场竹笕及其输卤系统的基本面貌,为竹笕输卤技艺的保护、保存和再利用提供基础依据。

明清山东食盐运销网络与地方社会

明清山东食盐运输水路与陆路结合,舳舻相接的水路与车马辐辏的陆路交错相通。其运输网络包括三条线路:一是沿大清河或小清河溯流西行,在沿线的关卡、码头和盐园地区分运,如蒲台批验所、泺口批验所、南桥、黄台桥,再继续沿河溯流水运,或向北向南陆运入境;二是沿运河南下北向,在运河沿线的关所、码头和盐园分运,如阿城、安居、南阳、夏镇,再继续沿河水运,或向东向西陆运入境;三是自沿海盐场直接陆运至境内,如大多数票地。水陆联运的综合运输网络,既保证了山东全境,以及河南、安徽和江苏三省部分地区的食盐问题,也促进了当地经济和社会的发展。

基于尺寸效应的夯土水盐运移分布特征研究

水盐循环作用是夯土遗址渐进式破坏的主要影响因素之一。为了研究尺寸对夯土水盐运移分布特征的影响规律,制备5组含盐量为0.3%、边长为50、100、200、500、900 mm立方体夯土试样,并将其置于温度为10~27℃、相对湿度为20%~50%的室内环境进行自然失水试验。在失水周期内,通过钻孔取样,检测夯土试样表层至内部土体的含水率及含盐量,并分析不同尺寸夯土试样水盐运移特征及尺寸效应。试验结果表明:夯土试样的失水周期及表层土体盐分富集量随尺寸的增大而增大,失水速率随尺寸的增大而减小。不同尺寸夯土试样的失水周期分为快速失水、缓慢失水、稳定失水3个阶段,水盐运移活动主要发生在快速失水阶段。失水过程中,盐分随水分向试样表层运移,表层土体盐分含量增加,内部土体盐分含量降低,盐分集中富集在表层土体上。该研究可以为土遗址室内小块体试验、模拟足尺试验和野外观测试验研究提供理论支撑。

遮荫对滨海盐碱地水盐运移及油葵生长和生理的影响

盐碱地是建设光伏的主要土地类型之一。盐碱地光伏系统中光伏组件的遮荫作用会改变局地微气候进而影响土壤水盐动态,系统内作物的生长会受到遮荫和土壤盐分的双重胁迫,阐明遮荫下盐碱地水盐动态和作物生理响应对指导盐碱地光伏农业开发利用具有重要意义。采用大田试验方法,以油葵(Helianthus annuus Linn.)为试验对象,分别设0%、30%、60%和90%遮荫水平,探究遮荫对滨海盐碱地水盐动态及油葵生长特性、光合特性、叶片解剖结构、生物量、籽粒产量及品质的影响,以揭示遮荫下滨海盐碱地水盐运移规律及作物生长和生理变化。结果表明,与无遮荫相比,遮荫能够显著增加滨海盐碱地油葵全生育期内土壤剖面含水量,降低土壤剖面含盐量。遮荫会显著降低油葵净光合速率,抑制茎粗和花盘的生长,减少籽粒粗脂肪,并提高籽粒粗蛋白。弱光下油葵自身会通过增加株高、提高光合色素含量、降低光合色素比值、提高光合酶活性、减小叶片厚度、改变碳同化产物分配方向等方式来促进光合作用。在遮荫率约为30%—60%时,能够增加18%—38%的耕作层土壤含水量,降低6%—18%的耕作层土壤含盐量,并维持15%—38%的油葵生物量和29%—55%的油葵籽粒产量。以上结果表明,遮荫能够改善滨海盐碱地水盐条件,减轻作物盐胁迫,但油葵作为喜光作物,遮荫会显著抑制其光合作用,影响籽粒产量和品质,因此,建议在光伏组件上限遮荫率约为30%—60%的盐碱地光伏系统内种植油葵,以维持油葵的籽粒产量。

玉米转录因子ZmNAC59调控植物抗盐性

【目的】NAC转录因子家族是植物中研究较多的一类转录因子,在调控植物生长发育和响应非生物胁迫过程中起重要作用。玉米是三大粮食作物之一,其生长过程常会面临各种逆境胁迫,盐害被认为是限制作物生长和生产的主要环境因素之一。因此鉴定玉米抗盐基因,解析其抗盐机制对培育玉米抗逆品种具有重要意义。【方法】研究克隆了玉米转录因子ZmNAC59,并用生物信息学手段分析其保守结构域和系统进化关系,用实时荧光定量PCR方法分析该基因在NaCl和MeJA处理下的表达模式,并用稳定转基因体系将该基因异源表达拟南芥观察表型,同时还用病毒诱导沉默技术将该基因在玉米中沉默后进行盐处理表型观察,并进行酶活性检测。【结果】ZmNAC59能够被NaCl和MeJA诱导上调。病毒诱导沉默ZmNAC59后进行盐胁迫,沉默株系对盐胁迫更敏感,ROS积累更多;而ZmNAC59过表达拟南芥后,过表达株系在盐胁迫处理下存活率更高,活性氧积累更少,Na^(+)/K^(+)比率低,表明ZmNAC59作为盐胁迫中的正调控因子可以通过调节离子流动提高植物抗盐性。实时荧光定量PCR结果表明拟南芥过表达株系中Na^(+)、K^(+)转运相关的基因显著上调;在玉米原生质体中瞬时过表达ZmNAC59后进行盐处理发现ZmSOS1、ZmNHX1和ZmNHX7的表达显著上调,Dual-LUC实验表明ZmSOS1是Zm-NAC59的靶基因。【结论】研究表明ZmNAC59通过激活ZmSOS1启动子的活性调控其表达而促进盐胁迫下的离子转运,从而提高植物抗盐性,为玉米抗逆基因资源的筛选和品种培育提供了科学理论依据。

饱和溶液电导率法在滨海高盐土壤水盐运移规律分析中的应用

分析海涂围垦区土壤水盐运移规律对改良滨海区域盐碱地有着重要意义。而在高盐土壤中实现含水率和可溶解盐分浓度的连续测量是掌握海涂围垦区土壤水盐运移规律的关键,因此以江苏如东海涂围垦试验区内的重度盐土为研究对象,利用耐盐度较好的土壤水分—盐分传感器连续监测土壤含水率、表观电导率变化,以土壤饱和溶液电导率(E_(C_(sat)))为盐分当量指标,分析受降雨、蒸发影响的水盐运移规律。结果表明,E_(C_(sat))可用以指示土壤中最大可溶解盐分含量。此外,土壤盐分在年内呈显著的季节性变化,即在冬季土壤中盐分较高,春季土壤脱盐,夏季土壤盐分波动剧烈,秋季土壤积盐明显。在蒸发和降雨过程中,E_(C_(sat))可有效指示不同埋深处土壤盐分的变化特征,结合土壤水分运移规律可直观佐证“盐随水走”的运移特征。

大型灌区土壤水盐运移模拟研究进展

土壤盐渍化是一种由自然和人类活动综合作用引起的土地退化现象,灌区人类活动频繁,影响土壤盐渍化的因素多样,深入理解土壤水盐运移过程将有助于灌区的土壤盐渍化防治。在对灌区土壤水盐运移的影响因素、国内外水盐模型特点和应用研究梳理的基础上,提出了灌区水盐运移模拟的可能发展方向。灌区盐渍化的形成与气候干旱、地形、土壤季节性冻融、地下水含盐量和成土母质等自然因素,以及不合理的灌溉管理措施、耕作方式和施肥制度等人为因素密切相关。水盐运移模型是研究土壤水盐运移过程的有效工具,目前常用的水盐运移模型包括水盐平衡模型、物理模型和统计模型。由于模型率定和验证所需的土壤水盐运移过程、作物生长过程观测资料较难获取,水盐运移模型多用于田间尺度的节水控盐策略和灌排管理措施优化研究,在区域应用较为有限。现代大型灌区的快速发展导致灌区土壤水盐运移时空分布规律变化较大,对模型的不断改进以及计算机技术的快速发展为探究大型灌区水盐运移时空演变机制提供了可能性。未来应加强基于生态安全的灌区土壤水盐运移机制研究,构建耦合气候模式或经济模型的多过程水盐运移模型。

春汇/夏浇灌溉制度对盐碱土壤水盐运移及向日葵水分利用的影响

【目的】确定河套灌区向日葵适宜的节水控盐春汇—夏浇灌溉制度,提高灌区农业灌溉水资源利用效率。【方法】设置非生育期畦灌(春汇S,灌溉定额135、95mm)和作物生育期滴灌(夏浇W,灌溉定额135、100、68 mm)田间小区试验,研究了不同春汇/夏浇条件下的向日葵农田土壤水盐分布规律、盐分淋洗效果、作物生长特征及水分利用效率。【结果】S135W135处理下的整个生育期内平均土壤含水率较高,为17.10%,为饱和含水率的75.53%;S95W135处理下的土壤含水率变异系数最小,为22.40%。S135、S95处理下的土壤脱盐率分别介于50.50%~32.64%、38.87%~21.87%,春汇后S135和S95处理下的0~80 cm土层的土壤盐分量无显著差异;S135W100、S95W135处理下的灌溉水淋洗深度较高,脱盐效果较好,土壤脱盐率均显著高于除S135W135处理以外的其他处理,0~80 cm土层脱盐率为40.77%和33.37%,较S135W135处理分别提高68.39%、37.86%。S95W135、S135W100处理下的地上部干物质量显著大于其他处理,相比S135W135处理增加10.55%和9.94%。S135W100处理的作物水分利用效率最高(21.59%),较S135W135处理显著增加13.03%。【结论】常规春汇水量减少30%(95mm)与夏浇滴灌(135 mm)是河套灌区向日葵农田适宜的灌溉制度。

春灌定额对不同盐碱度农田水盐分布影响研究

为探究春灌定额对不同盐碱度农田土壤水盐分布的影响,确定适宜保墒洗盐的春灌定额。分别在中度盐碱地S1(5.23 g/kg)和重度盐碱地S2(8.27 g/kg)设置3种春灌定额处理(W1:1 800 m^(3)/hm^(2),W2:2 250 m^(3)/hm^(2),W3:2 700 m^(3)/hm^(2)),分析比较了春灌后至棉花播种前0~100 cm土壤水盐运移和分布情况。结果表明:春灌后14~21 d,S1W2处理71.37%的水量可保持在土体内,S2W3处理77.26%水量保持在土体内,可使农田土壤达到适宜作物生长的土壤墒情;盐分淋洗主要发生在0~60 cm土层内,0~30 cm内淋洗效果更加显著,春灌定额越大将盐分带入深层的作用越强,春灌后21 d开始出现返盐现象;春灌时间在播前21 d左右为宜,中度盐碱地春灌定额2 284.7 m^(3)/hm^(2),重度盐碱地春灌定额2 700 m^(3)/hm^(2)左右时,可达到较为良好的节水保墒洗盐效果,重度盐碱地可以根据实际情况适当提高春灌定额。研究结果可为图木舒克市不同盐碱度农田春灌提供一定的理论依据和技术参考。