共查询到20条相似文献，搜索用时 78 毫秒
1.
Dr. Jiftah Ben-Asher 《GeoJournal》1987,15(3):267-272
The potential of the saline water for irrigation against the background of the world's food shortage is reviewed. It is shown that irrigation has improved food situation wherever it has been used. However, irrigation is always associated with salinity problems. Leaching techniques and drip irrigation suggest a partial solution for the problem. The objective of this paper is to review and examine additional solutions in order to increase the use of saline water for irrigation. A quantitative approach to further research on the use of saline water for irrigation is suggested. An analytical solution to the mass-balance equation of nutrients and salt in the soil, which includes a sink term for absorption by a plant, revealed some valuable derivatives, both for planning further research in irrigation with saline water and making decisions about fertilization and soil leaching throughout the growth period of a crop. Preliminary attempts to meaningfully increase the fertilization level of crops irrigated with saline water support the approach that was developed from one of the model's derivatives. 相似文献
2.
The pH of various saline solutions — waters from the Dead Sea, Red Sea, the Mediterranean and salt springs from the Tiberias area — and of their artificial equivalents was found to increase on dilution with distilled water. The effect is confined to waters containing more than 1.2–1.5% dissolved solids, and is roughly proportional to the original salinity of the solution. The effect is not found in solutions devoid of HCO3− salts. It is concluded that in strong brines, dissociation of bicarbonate salts is depressed; on dilution dissociation increases, hydroxide ions are formed and the pH increases. It follows that in evaporate sediments carbonate minerals might be stable at pH-values as low as 5.5. 相似文献
3.
The effect of ionic strength (I), pCO2, and temperature on the dissolution rate of calcite was investigated in magnesium-free, phosphate-free, low calcium (mCa2+ ≈ 0.01 m) simple KCl and NaCl solutions over the undersaturation range of 0.4 ≤ Ωcalcite ≤ 0.8. First-order kinetics were found sufficient to describe the rate data where the rate constant (k) is dependent on the solution composition. Rates decreased with increasing I and were faster in KCl than NaCl solutions at the same I indicating that Na+ interacts more strongly with the calcite surface than K+ or that water is less available in NaCl solutions. Rates increased with increasing pCO2 and temperature, and their influences diminished at high I. Arrhenius plots yielded a relatively high activation energy (Ea ≈ 20 ± 2 kJ mol− 1) which indicated that dissolution was dominated by surface-controlled processes. The multiple regression model (MR) of Gledhill and Morse (2006a) was found to adequately describe the results at high I in NaCl solutions, but caution must be used when extrapolating to low I or pCO2 values. These results are consistent with the hypothesis that the mole fraction of “free” solvent (X“free”H2O) plays a significant role in the dissolution kinetics of calcite with a minimum value of 45–55% required for dissolution to proceed in undersaturated solutions at 25–55 °C and pCO2 = 0.1–1 atm. This hypothesis has been incorporated into a modified version of the MR model of Gledhill and Morse (2006a) where X“free”H2O has replaced I and the Ca2+ and Mg2+ terms have been dropped: 相似文献
4.
V. P. Isupov A. G. Vladimirov N. Z. Lyakhov S. L. Shvartsev S. Ariunbileg M. N. Kolpakova S. S. Shatskaya L. E. Chupakhina L. V. Kuibida E. N. Moroz 《Doklady Earth Sciences》2011,437(1):352-356
Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia
and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes
and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate
(bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in
Lake Hyargas Nuur (about 6000 ton). 相似文献
5.
In the arid regions of Australia, fine-grained slurried wastes produced during gold mining are typically disposed of in large storages using subaerial deposition. Management of the storage is often aimed at maximising the evaporative drying that occurs, thereby maximising the density achieved. Ore processing is conducted using groundwater that can have salinities that approach solution saturation. Precipitation of salts on the tailings surfaces during evaporation leads to the development of thin salt crusts that can significantly reduce the rate of evaporation. Quantification of the actual rate of evaporation from the drying tailings surfaces is important for assessing disposal strategies. Different methods of estimating evaporation were employed at mine sites in Western Australia (WA) to provide more information on the drying behaviour of saline tailings. These techniques are described and typical results from a saline tailings storage are presented. 相似文献
6.
一种盐岩流变损伤模型 总被引：6，自引：2，他引：6
在Carter流变模型基础上,引进损伤,提出了“损伤增速界限”的概念,从而,建立了一种盐岩流变损伤模型,并根据实验数据验证了模型的正确性。研究表明,这种盐岩流变损伤模型,不但能很好地反映高应力水平下盐岩的流变损伤特性,而且,也能真实地描述低应力水平下盐岩的初始蠕变损伤和稳态蠕变损伤。 损伤增速界限对损伤演化和蠕变发展影响很大,关系着加速蠕变的发生与否。研究还表明,不同产地、不同实验条件下表述盐岩损伤的参数离散性不大,该模型的应用范围较广。 相似文献
7.
S. K. Sasamal 《Journal of Earth System Science》1990,99(3):367-381
Bay of Bengal is well known for less saline waters in the surface layer of northern Indian Ocean. High saline waters of the
Bay are considered as an influx from the Arabian Sea within a depth range of 200 to 900 m. Some of the recent observations
in the western Bay of Bengal have shown salinity values higher than those reported earlier (35-2 × 10−3). Such values are explained on the basis of regional climatology suggesting their local formation on the shallow continental
shelf during pre-monsoon months and their subsequent distribution along the coast. 相似文献
8.
Freezing temperature is an important parameter in studying the freezing mechanism of saline soil. An equation for calculating the freezing temperature is proposed based on the phase transition theory in porous medium, including two main influencing factors, the water activity and pore size. In this equation, the effect of the water activity on the freezing temperature of soil is calculated by Pitzer model, while the impact of pore size is replaced by water content. Through comparing the calculated results with the published experimental data, the equation is proved to be competent in predicting the freezing temperature for the saline soil with sodium chloride or calcium chloride. For the saline soil with sodium carbonate, the effect of salt hydrate crystallization should be taken into consideration. With respect to the saline soil with sodium sulfate, it is difficult to determine the freezing temperature, since there is uncertainty of the resultant when freezing (that is, heptahydrate or decahydrate). In addition, the effects of pore size and multi-component solutes on freezing temperature are also discussed. The study would be helpful for revealing the freezing mechanism and also providing a useful theoretical method for engineering design of saline soil in cold regions. 相似文献
9.
高含盐粉土不仅含盐量较高,而且黏粒含量极低,粉粒含量高,级配不均匀,导致难以压实,强度低。为了了解此类特殊粉土的力学特性,在室内物理化学性质分析的基础上,进行原位旁压试验和原状土样的三轴试验,充分分析了高含盐粉土的力学性质。高含盐粉土的可溶性盐含量高达2.9%,主要是高硅、铝,水溶盐以Cl－和Na+为主,属氯盐碱性土。旁压试验结果表明,临塑压力可取350 kPa、极限压力可取500 kPa、旁压模量Em可取1 750 kPa、剪切模量Gm可以700 kPa作为参考值。室内力学试验进一步分析表明,该土体具有较强的剪胀性,在轴向应变达到12%左右时,试样达到稳态状态。围压150 kPa下的峰值强度能达到600～800 kPa,残余强度也能达到450～550 kPa。 相似文献
10.
11.
作为一种特殊土,盐渍土有着独特的工程性质并由此引发了盐胀、溶陷等工程问题,其发生及发展均与土体含水量密切相关,不同含水量条件下土中的吸力也对土体工程性质有着较大影响.本文选取甘肃酒泉地区的盐渍土,室内利用Ku-pF非饱和导水率仪测试了不同干密度状态下盐渍土试样的土水特征曲线,发现渗透吸力的存在使得盐渍土试样的土水特征曲线转化阶段较一般土平缓,同一含水量条件下土中的吸力较一般土大,土体持水能力有所增强.不同干密度试样土水特征曲线的测试结果表明,干密度增大后土中大孔隙减少,中、小孔隙增多,孔隙连通性变差,导致土样饱和含水量降低,进气值增大,失水速率减慢,土体持水能力有一定增强.对比国内外广泛使用的模型对实测盐渍土土水特征曲线进行拟合,发现Fredlund and Xing模型能较好地反映盐渍土土中吸力与含水量的关系.最后,基于盐渍土的颗粒累积分布曲线及其基本物理指标,依据Fredlund物理-经验预测模型的理论和方法,预测了不同干密度盐渍土的完整土水特征曲线,以期为盐渍土地区土体工程性质的研究和预测提供理论支持和有益参考. 相似文献
12.
Lynton S. Land 《Aquatic Geochemistry》1995,1(2):137-145
Most sedimentary basins contain saline pore water. Saline formation waters can form during burial diagenesis as the result of normal processes of water/rock interaction involving incongruent halite dissolution, bittern salt destruction, and albitization of detrital plagioclase. The kinds of Na-Ca-Cl saline formation waters typical of sedimentary basins can also result from modification of surficial brines formed by the precipitation of NaCl from evaporated seawater. As the porosity of rocks is reduced during burial, discharge of saline formation waters contributes to crustal chloride cycling, and helps explain riverine chloride loads. During burial, the dissolution of metastable detrital minerals derived from crustal rocks in corrosive, saline water transfers incompatible elements such as Li and B from the igneous crust to the sedimentary crust. Similarly, albitization transfers Ca from the crustal silicate (igneous) mineral reservoir to the crustal carbonate and aqueous (sedimentary) reservoirs. Metamorphism and then melting of albite-enriched rocks accounts for the elevated sodium contents of igneous rocks relative to sedimentary rocks. In this way average sediments have become enriched through time in Ca, Cl, Br, S, Li, and B, and depleted in Na relative to average igneous crust. 相似文献
13.
全球蒸发岩从震旦纪到新近纪均有发育, 其最发育时期为震旦纪-寒武纪、二叠纪-三叠纪以及侏罗纪-白垩纪, 且具有幕式分布特点.它们在一定区域(低纬区)常大规模集中发育, 跨越不同的沉积盆地类型, 面积和厚度巨大, 时代跨度较短且连续, 笔者称之为巨量蒸发岩省.本文基于全球蒸发岩层系古板块再造、沉积岩相恢复、地层柱状对比、盆地构造分析等方法, 对巨量蒸发岩省的发育、分布、成因及其地质意义进行了探讨.巨量蒸发岩省形成、分布与地史中的造山带演化、超大陆的聚合与裂解、干旱气候带(南北纬30°之间)、海平面变化等因素有着密切联系; 其主要形成于干旱环境下相对封闭、靠海水潜流补给的台地和盆地中; 所处的构造单元主要为泛大陆板块内部狭长的裂谷带、特提斯造山带的残余洋盆、海-陆过渡带、陆表海或孤立板块的台地中心. 相似文献
14.
Observation under the electron microscope of diatom frustules from Bolivian Altiplano saline lakes shows that many of these are coated with particles occurring as tiny sheets. The frustules can be found to be almost completely replaced by these sheets. Isolated sheet aggregates seem to have resulted from completely transformed frustules. Section observations of altered frustules bear out that the sheets have grown from biogenic silica through replacement. Selected area diffraction, dark field observation, microdiffraction, and elemental microanalysis show that the particles on the diatom frustules consist of a poorly crystallized MG-smectite.The unambiguous localisation of this authigenesis allows us to reconstruct its hydrochemical and sedimentological environment. Observation of the most recent lake sediments has pointed out that at least two main conditions are required for this authigenesis at 5°C: saturation with respect to amorphous silica, and a pH above 8.2. Variations in the Mg concentration have no significant effect. 相似文献
15.
Arid saline soils are well-distributed over the globe, with a variety of nomenclature. Along the seaboard of the Arabian Gulf, these soils exist widely and are known as “sabkhas”. Despite the cemented and saline characteristics of the sabkha matrix, a recent investigation indicated that flooding the saline sabkha with distilled water in the conventional oedometer apparatus was incapable of producing a sudden reduction in volume and/or a significant collapse. This study proposes a modification to the conventional oedometer on undisturbed sabkha specimens to consolidating specimens under a constant head. Tests were, therefore, conducted on undisturbed sabkha specimens to assess their compressibility and collapse potential whereby percolation of water was commenced under two pressures to evaluate the role of sustained pressure on the collapse mechanisms.
Despite the low compressibility of sabkhas, results of these tests indicated that these arid, saline soils possess a high collapse potential attributable primarily to dissolution of sodium chlorides, leaching of calcium ions and soil grain adjustment. The collapse potential increases with an increase in the acting pressure at which percolation of water takes place. In contrast to other typical soils, the collapse of arid, saline soils is not instantaneous but requires sufficient volume of water to percolate in order to enhance the dissolution of the cementing agents. 相似文献
16.
17.
Lake Qarun is an inland saline lake of the type Na---(Mg)---Cl---(SO4). The SO4/Cl weight ratio exceeds 0.6. The sequence of salt deposition, upon mechanical evaporation at 70°C, starts with basanite and halite, passes with magnesium sulphate minerals and ends with sylvite and carnallite. High concentrations of Sr in the gypsiferous fraction and B in the end-residue are recorded. 相似文献
18.
The mid‐Permian Nippewalla Group of Kansas consists of bedded evaporites, red‐bed siliciclastics and grey siliciclastics deposited in a non‐marine environment. Lithologies and sedimentary features indicate lacustrine and aeolian deposition, subaerial exposure and palaeosol formation. Grey siliciclastic mudstones characterized by planar and convolute laminations, ostracods, peloids and plant material represent a freshwater‐brackish perennial lake facies. Bedded anhydrites containing gypsum‐crystal pseudomorphs, clastic anhydrite grains and grey mud drapes and partings suggest deposition in saline lakes. Bedded halites consist of chevron and cumulate crystals, dissolution surfaces and pipes and mudcracked microcrystalline salt crusts, which were deposited in saline pans dominated by flooding, evaporative concentration and desiccation. Chaotic halite, composed of red‐bed mudstone and siltstone with displacive halite crystals, formed in saline mudflats. Red‐bed mudstone and siltstone with little or no displacive halite, but with abundant cracking, root and plant features, suggest deposition in a dry mudflat. Red‐bed sandstone, composed of well‐sorted, well‐rounded quartz grains cemented with halite, indicate aeolian and rare shallow‐water deposition. Most deposition took place in halite‐dominated ephemeral saline lakes surrounded by saline and dry mudflats, sandflats and sand dunes. Evaporation, desiccation, flooding and wind played significant roles in this environment. The Nippewalla Group siliciclastics and evaporites represent an evolution from a perennial lacustrine system to a non‐marine, acidic saline pan system in the mid‐continent of North America. The problem of distinguishing between ancient marine and non‐marine evaporites, as well as recognizing those evaporites deposited in acid settings, with detailed field, core and petrographical study of both evaporite deposits and associated sedimentary rocks has successfully been addressed. In addition, interpretations of mid‐Permian palaeoclimate data in the form of short‐term air temperature proxies within longer‐term wet–dry trends have been made. These data provide a new palaeogeographic and palaeoclimatic model for the mid‐Permian of western Pangaea. 相似文献
19.
滨海盐渍土的固化方法及固化土的偏应力-应变 总被引：2，自引：0，他引：2
滨海盐渍土可使用水泥、石灰、粉煤灰和高分子材料SH固土剂单独及联合固化,以提高土的强度、抗变形能力和水稳性。为研究各种固化方法固化盐渍土的抗变形能力和偏应力-应变特征,通过三轴UU压缩试验得到盐渍土和6种固化盐渍土的偏应力-应变曲线。曲线显示：水泥＋石灰类固化土呈应变软化型、石灰＋粉煤灰类固化土呈应变软化型、石灰类固化土呈应变硬化型。掺入SH固土剂,提高了固化土的浸水前后的强度,同时也增强了固化土的水稳性。掺入SH固土剂使固化土达到偏应力峰值所需的应变增加,即抗变形能力增强;0.9%SH固土剂+12%石灰+36%粉煤灰固化土具有适中的强度、良好的弹性变形和水稳性的优点,作为轻质路堤填料使用,还可减少滨海地区软土路基的沉降量,这使其成为滨海盐渍土的6种固化方案中的最适宜方案。 相似文献
20.
S. L. Shvartsev M. N. Kolpakova V. P. Isupov A. G. Vladimirov S. Ariunbileg 《Geochemistry International》2014,52(5):388-403
This paper presents data on the major and trace element composition of saline lakes of western Mongolia. The main geochemical types of lakes distinguished in the study are soda-, chloride-, and sulfaterich lakes. Lake water equilibria with major carbonate, sulfate, chloride, and other rock-forming minerals were calculated. The results show that the major factors controlling the formation of each lake type include evaporation and water-rock interaction processes, and the latter factor plays a critical role in freshwater and soda lakes and only a minor role in chloride lakes. Special attention was given to the soda lakes and the factors controlling lake water chemistry. 相似文献