Aeolian component records in lacustrine sediments and its atmospheric circulation significance for evolution of Qarhan salt lake,NE Qinghai-Tibetan Plateau

1 Introduction The Qarhan Playa of Qaidam Basin is located at the northeastern QinghaiTibetan Plateau(QTP),in which thick lacustrine and evaporate sediments deposited since the late Pleistocene(Chen et al.,1985,1986).As surrounded by capacious Gobi and yardang fields and suffered strong westerly-northwesterly wind,abundant aeolian materials were trapped in these sediment sequences in the

Extraction of Cesium and Rubidium with 4-tert-butyl-2-(α-methylbenzyl) phenol from Salt Lake Brine

This work shows the extraction of cesium (Cs^+) and rubidium (Rb^+) from salt lake brine containing potassium (K^+) and magnesium (Mg^2+). The results show that 4-tert-butyl-2-(α-methylbenzyl) phenol ( t -BAMBP) diluted in sulfonated kerosene (SK) has an excellent extraction effect. Infrared spectroscopic studies indicate that polymerize to form the dimer in the t -BAMBP when Cs^+ or Rb^+ were extracted. The effects of K^+, Mg^2+, t -BAMBP concentration, the volume ratio of organic phase to aqueous phase (O/A) and the alkalinity (pH) of aqueous phase were investigated. The K^+ and Mg^2+ should be eliminated through precipitating before the extraction and separation of Cs^+ and Rb^+.The optimum extraction conditions of the experimental brine were as follows: 0.8 mol/L t -BAMBP diluted in SK, pH≥13, a phase ratio of 1:1, and an extraction contact time of 2 min at room temperature. The optimal extraction yields of Cs^+ and Rb^+ were as high as 100% and 85.8%, in addition, 8.76% of K^+ was co-extracted. Further work would increase the extraction yield and selectivity of Rb^+ and realize the efficient separation of Cs^+ and Rb^+ from brine.

Boron Isotopic Composition of Halite from 46-m-long Sediment Core in the Qarhan Salt Lake,Western China

Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low

Origin and evolution of oilfield brines from Tertiary strata in western Qaidam Basin:Constraints from ^(87)Sr/^(86)Sr,δD,δ^(18)O,δ^(34)S and water chemistry

Chemistry of major and minor elements,87Sr/86Sr,δD,δ18O and δ34S of brines were measured from Tertiary strata and Quaternary salt lakes in the western Qaidam Basin.The water chemistry data show that all oilfield brines are CaCl2 type.They were enriched in Ca2+,B3+,Li+,Sr2+,Br-,and were depleted in Mg2+,SO42-,which indicated that these brines had the characteristics of deeply circulated water.The relationship between δD and δ18O shows that all data of these brines decline towards the Global Meteoric Water Line(GWL) and Qaidam Meteoric Water Line(QWL),and that the intersection between oilfield brines and Meteoric Water Lines was close to the local spring and fresh water in the piedmont in the western Qaidam Basin.The results suggest that oilfield brines has initially originated from meteoric water,and then might be affected by water-rock metamorphose,because most oilfield brines distribute in the range of metamorphosing water.The 87Sr/86Sr values of most oilfield brines range from 0.71121 to 0.71194,and was less than that in salt lake water(>0.712),but close to that of halite in the study area.These imply that salt dissolution occurred in the process of migration.In addition,all oilfield brines have obviously much positive δ34S values(ranging from 26.46‰ to 54.57‰) than that of salt lake brines,which was caused by bacterial sulfate reduction resulting in positive shift of δ34S value and depleteed SO42-in oilfield brines.Combined with water chemical data and δD,δ18O,87Sr/86Sr,δ34S values,we concluded that oilfield brines mainly originate from the deeply circulated meteoric waters,and then are affected by salt dissolution,water-rock metamorphose,sulfate reduction and dolomitization during the process of migration.These processes alter the chemical compositions of oilfield brines and accumulate rich elements(such as B,Li,Sr,Br,K and so on) for sustainable utilization of salt lake resources in the Qaidam Basin.

The Salt Attack Performance of Magnesium Oxychloride Cement Exposure to Three Kinds of Brines

Salt attack performance of magnesium oxychloride cement(MOC) in brine was investigated from the viewpoints of strength development and strength coefficient. Microstructure was studied using quantitative X-ray diffraction(QXRD), thermogravimetry(TG) and scanning electron microscopy(SEM). The results show that MOC mortars have outstanding salt attack performance after aging brine and raw brine immersion. The salt attack coefficients of MOC mortars are higher than 0.8, which is qualified for application in saline soil and salt lake area. The reason is that salt brine solution enters into the voids of MOC and plays a role of toughening and strengthening in the MOC.

A Raman Investigation on the Boron form Occurring in Salt Lake Brine during Evaporation

Boron resources are abundant in the Da Qaidam Salt Lake of the Qaidamu basin in China, which has generated significant attention due to the presence of polyborate species in brine from this lake. In this study, Raman spectroscopy was used to investigate the existing form of boron in brine during evaporation. MgO·2B2O3 -H2O, MgO·2B2O3 -MgCl2 -H2O, and MgO·2B2O3 -MgSO4 - H2O solutions were also studied to determine the influence of boron concentration, pH, and electrolytes on the borate speciation from brine. The mononborates B(OH)3 and B(OH)4^- were found to be the only forms present in natural salt lake brine. Brine evaporation promoted the formation of the polyborate anions B3O3(OH)4^-,B5O6(OH)4^-, and B6O7(OH)6^2- and also promoted the disappearance of the B(OH)4^- ion from brine at boron concentrations of more than 11 g/L B2O3. The pentaborate ion B5O6(OH)4^- was sensitive to the solution pH and appeared only at pH values less than 8.0. Meanwhile, the hexaborate ion B6O7(OH)6^2- was observed to be more dependent on the electrolyte magnesium chloride due to its special properties, such as promoting boron accumulation, lowering solution pH, and also its strong affinity for water molecules, which were all beneficial for the polymerization of borate ions in brine. Interaction mechanisms between polyborate anions during evaporation are also proposed herein.ake;evaporation;polyborate species;interaction mechanism.

Clay Mineralogical and Geochemical Studies of Detrital Rocks of the Upper Cretaceous Salt-bearing Strata,Simao Basin,SW China:Implication for Provenance and Source Weathering

1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and

Clean Separation Process of Chabocuo Saline Lake in Tibet

1 Introduction Chabocuo Lake is located in the territory of Gaize County Ali area Tibet,the altitude of the lake-surface is4505 m with a total area of 32 Km2.It is a typical sulfate type saline and rich in boron and lithium.In the natural evaporation process,several mineral sylvites cocrystallize out,thus increases the difficulties for separating and

Stable Isotope and Element Geochemistry of Saline Springs in Evaporite-bearing Mengla Basin,South Yunnan,China

1 Introduction Mengla Basin is a sub-basin in southern evaporitebearing Lanping-Simao Basin.There are many salt springs in the basin.In 2012,11 spring samples were collected for analyses of chemistry and boron,hydrogen and oxygen

Formation of Li Salts from Natural Brines during Isothermal Evaporation at 25℃

Li brines are the primary resources for Li salt industries.Evaporation is necessary to concentrate Li due to its low level of concentration in raw brines.The salt sequences during the evaporation of Li brines,especially the behavior of Li salts,represent key data for solar technologies.However,chemists cannot use any phase diagram to estimate Li salt sequences during evaporation at 25℃.The thermodynamic model proposed by us in 2003 represents the only tool for the prediction of equilibrium conditions during the evaporation of solutions containing Li^+,Na^+,K^+,Mg^2+/Cl^-,SO4^2-,and-H2O components at 25℃.In this paper,the predicted salt sequences of 20 brines are reported.The results indicate that (1) the first crystallized Li salt during evaporation of Li brine varies in brine composition;(2) lithium sulfate is crystallized in many cases initially for brines of magnesium sulfate subtype,while Db4 (Li2SO4 ·K2SO4 ) or Db3 (2Li2SO4 ·Na2SO4 ·K2SO4 ) appears first for sodium sulfate and magnesium sulfate subtypes with lower Mg/Li composition,and the final eutectic point is H+LiC+Lc+Ls+Car;(3) the final eutectic point is H+LiC+Lc+Car for brines of chloride type;and (4) Li content corresponding to the first crystallized Li salt is in the range of 0.43%-1%.These findings enhance our knowledge of Li chemistry and provide insights into solar pond technology of the Li-brine process.

Deep Drilling Campaign in the Western Qaidam Basin,NE Tibetan Plateau and their Revealed Global Temperature Forcing of Salt Formation in the Late Miocene-Quaternary

The Qaidam Basin in the NE Tibetan Plateau has contributed the largest amount of potash in China.However,how the potash was formed has long been a subject of debate.Here we carried out a deep drilling

Palynological Assemblage Age and Palaeoenvironment of the Cretaceous Salt-bearing Strata in Laos and Yunnan,China

The study of Cretaceous-Palaeogene salt-bearing strata of the Khorat Basin Laos and the Lanping-Simao Basin in Yunnan,China has an great significance not only in explaining the basin evolution and the genesis of potash

Selective recovery of lithium from simulated brine using different organic synergist

The organic synergists, including Octanol, ethyl acetate(EA), butyl acetate(BA), methyl isobutyl ketone(MIBK),diisobutyl ketone(DIBK), N,N-bis(2-ethylhexyl) acetamide(N523) and 8-hydroxylquiolate, were added to the TBP–FeCl_3 extraction system to extract lithium from brine. The effects of concentration of organic synergist and total organic extractant, molar ratio of Fe/Li, phase ratio, counter-current extraction and the acidity of stripping agent on lithium extraction were investigated to optimize the extraction conditions. Under the optimize conditions, the results of counter-current extraction showed the mixed extraction system was the preponderance on the lithium extraction. Especially the separation of lithium in organic phase and aqueous phase and the separation mass ratio of Mg/Li increased greatly. An extraction mechanism was proposed based on the analysis of FT-IR spectra and Raman spectra.

Recent Progress on Structure of Aqueous Polyborate Solutions

The crystal structure of metal borates has been extensively investigated by X-ray and neutron diffraction,but,the structure of aqueous polyborate solutions are still largely unknown.Over the last decade,our group has focused on studying the structure of complex aqueous polyborate solutions of Li,Na,K,Rb,Cs,and Mg using synchrotron radiation X-ray scattering (XRS),EXAFS,Raman,NMR,and DFT,as well as determining the density,conductivity and pH of such solutions.Polyborate species distributions were calculated using pH measurements,and the main species in the solution have been confirmed by NMR and Raman spectra.For alkali-metal metaborates,the dominant species is always B(OH)4^- in a wide range of concentration,while the presence of others species is negligible.For alkali metal tetraborates,when concentration is in the extreme low range,only B(OH)3 and B(OH)4^- are present in these solutions.As the total boron concentration increases,B(OH)3 and B(OH)4^- polycondensated to form more complex oligomers.Of them,while B4O5(OH)4^2- in the tetraborate solutions is the main species,B(OH)3 ,B(OH)4^-,and B3O3(OH)4^- are minor species,and B3O3 (OH)5^2- and B5O6 OH)4^- are present only in negligible amounts.As solution continues to concentrate,B4O5(OH)4^2- eventually becomes the dominant species,which is consistent with the congruent compound M2B4O7·nH2O (M=Li,Na,K,Rb,Cs) in the system M2O-B2O3-H2O (M=Li,Na,K,Rb,Cs).For alkali metal pentaborates,B(OH)3 and B(OH)4^- are the main species at low concentrations.The species distribution,Raman and NMR spectroscopy results verified that the dominant species in concentrated pentaborate solutions with Li and Na is pentaborate B5O6 OH)4^-,but it is surprising that the main species with K,Rb,and Cs is always the triborate monoanion B3O3(OH)4^-.Although all M[B5O6 OH)4 ]·nH2O (M=Li,Na,K,Rb,Cs) are all congruent compounds in the system M2O-B2O3 -H2O (M=Li,Na,K,Rb,Cs),the main species in aqueous solutions are quite different because of various cation hydration distance (d),hydration number (CN),and configuration,especially charge (Z).For bivalent Mg^2+,three borate minerals,namely,Inderite (2MgO ·3B2O3 ·15H2O),Hungchaoite (MgO ·2B2O3 ·9H2O),and Mcallisterite (MgO ·3B2O3 ·7.5H2O),exist in the system MgO-B2O3 -H2O at 298K.Inderite is a congruent compound,but Hungchaoite and Mcallisterite are incongruent compounds.The species distribution and Raman spectra demonstrat that the predominant species in all the solutions with magnesium borates is bivalent triborate B 3O3(OH)5^2-,while the subordinate species are B(OH)4^- at a low B2O3 /MgO ratio and B(OH)3 at a high B2O3 /MgO ratio,and the other anions are negligible,as the high Z of the borate anion must match that of Mg 2+.The disappearance of divalent B4O5(OH)4^2- is in agreement with its incongruent nature.The DFT and XRS results showed that tetrahedral Li(H2O)4^+(d=0.20 nm,CN=4),octahedral Na(H2O) 6 ^+(d=0.236 nm,CN=6),and Mg(H2O)6^2+(d=0.210 nm,CN=6) in the first hydration shell belong to Platonic polyhedra.However,K(H2O)+ 8 (d=0.28 nm,CN=8,XRS and DFT),Rb(H2O)8^+(d=0.293 nm,CN=7.7-8.2,EXAFS),and Cs(H2O)8^+(d=0.320-0.326 nm,CN=7.6-7.9,EXAFS) are inclined Voronoi polyhedra.Therefore,the effects of cation Z and d on the structure of polyborates in aqueous solutions are deterministic,while the effect of hydrated-cation symmetry is secondary.Their hydrolysis order was:Mg>Li>Na>K>Rb>Cs,in step with hydration power.Among them,Mg^2+ and Li^+ have a strong tendency towards hydrolysis,but Na^+ scarcely hydrolyzes,especially Rb^+ and Cs^+ have a little protonation.X-ray scattering of aqueous alkaline sodium borohydride solutions confirmed that dihydrogen bonds exist in an aqueous solution.The four distinct features of dihydrogen bonds in aqueous solution-unidirectionality,divaricativity,multicentricity,and multidentativity have been also described here in brief.

OSL chronology and paleoclimatic implications of paleodunes in the middle and southwestern Qaidam Basin, Qinghai-Tibetan Plateau

Aeolian sediments are widely distributed in the Qaidam Basin, northeastern Qinghai-Ti^tan Plateau （QTP）. The pale（xiunes are mainly located at the southeastern, middle and southwestem Qaidam Basin. However, ages ofpaleodunes in the middle and southwestern Qaidam Basin have not been well studied, although they are close to and might connect to the evolution of salt lakes in the cenWal basin. In this study, we use single aliquot regeneration （SAR） protocol of Optically Stimulated Luminescence （OSL） to date the dune sand in these two regions. The results show that： （1） Sand accumulation in these regions started at ca. 4-3 ka and lasted to ca. 0.5 ka when they were stabilized, due to the arid climate in the late Holocene. （2） The underlying fluvial sand was fomaed during deghcialion at 12.6±0.8 ka. （3） The stabilization pe- riods of the paleodunes correspond to stages of glacier advance in the northeastem QTP, during which lower temperatures caused the decrease of evapomlion and increase of the effective moisttwe, leading to an increase of vegetation cover and stabilizalion of the dunes.

Preparation of Fe3O4-octadecyltrichlorosilane for Removal of Methyl Orange and Methylene Blue:Influence of p H and Ionic Strength on Competitive Adsorption

Fe3O4-octadecyltrichlorosilane（Fe3O4-OTS）was synthesized and used to remove dyes in a competitive system.Fe3O4-OTS was prepared by slow hydrolysis of OTS in cyclohexane on the surface of Fe3O4obtained through coprecipitation method.Scanning electron microscope（SEM）,energy dispersive spectrometer（EDS）,and contact angle analyzer（CA）were used to analyze the properties of Fe3O4-OTS.Methyl orange（MO）and methylene blue（MB）were selected as model molecules to study the influence mechanism of p H and ionic strength on competitive adsorption.The results of EDS and CA indicated that Fe3O4 was modified successfully with OTS on the surface.Silicon appeared and carbon content increased obviously on the surface of adsorbent.Contact angle of adsorbent increased from 0~o to 107~o after being modified by OTS.Fe3O4-OTS showed good separation for MO and MB in competitive system,which has potential to separate dyes in sewage.Separation factor（β~OB）changed from 18.724 to 0.017,when p H changed from 7 to 12,revealing that MO and MB could be separated almost thoroughly by Fe3O4-OTS.p H could change the surface charge of Fe3O4-OTS and structure of dyes,and thus change the interactions of competitive system indirectly.Even though hydrophobic interaction was enhanced,ionic strength reduced the difference of electrostatic interaction between dyes and Fe3O4-OTS.So it is unfavorable to separate dyes with opposite charges when ionic strength increases.These findings may provide theoretical guidances to separate two-component dye pollutants.

Characterizing properties of magnesium oxychloride cement concrete pavement

The performance of magnesium oxychloride cement concrete(MOCC)in road engineering in the arid region in northwest China was investigated over a two-year period.Two categories of MOCC pavement,light-burnt magnesia concrete road(Road-L)and dolomite concrete road(Road-D),were prepared with light-burnt magnesia and a mixture of light-burnt magnesia and caustic dolomite(1:3 by mass),respectively.Variations in the properties of the MOCC pavement,such as compressive and flexural strength,mineralogical phase,and microstructure,after being exposed to two rainy seasons in the field were monitored.The compressive strength of the cored samples were conducted after being aged for 28 d,and the compressive and flexural strength were tested at ages of 1,2,3,28,90,180,270,360 and 720 d.The mineralogical phase and microstructure of the pavement were also analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results demonstrate that MOCC pavement obtained desirable compressive and flexural strengths after curing for 3 d for Road-L and 28 d for Road-D.Both of the compressive and flexural strength of Road-L and Road-D decreased slightly after experiencing two rainy seasons,with the major hydration products being 5Mg(OH)2 MgCl28H2O(Phase 5)and 3Mg(OH)2 MgCl28H2O(Phase 3).The decomposition of Phase 5 is mainly responsible for reducing the mechanical strength of the MOCC pavement.

Volumetric and Transport Properties of Aqueous NaB（OH）4 Solutions

Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB（OH）4 solutions precisely measured as functions of concentration at different temperatures （293.15, 298.15, 303.15, 313.15 and 323.15 K） are presented. Polyborate distributions in aqueous NaB（OH）4 solution were calculated, covering all the concentration range, B（OH）4 is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that B（OH）4 behaves as a struc- ture-disordered anion.

Sample preparation for isotopic determination of boron in clay sediments

The procedures of sample preparation for isotopic determination of boron in clay sediments is very cumbersome, by far, there haven't been relevant reports on that. In order to establish an effective method for sample preparation, a series of experiments were carried out. In this paper, boron in clay sediments was extracted with HCl solution and purified by two-step ion exchange method. Extracted HCl solution should be adjusted to alkalescency before passing through the Amberlite IRA 743 resin column due to the fact that Amberlite IRA 743 resin absorbs boron only from alkalescent solution. However, a mass of hydroxides of Al and Fe will be precipitated when the extracted HCl solution becomes alkalescent. Hydroxides of Al and Fe have a strong adsorption capacity for boron, which can cause boron isotope fractionation. To treat precipitated hydroxides of Al and Fe, four procedures, namely direct ion exchange (DRIE), decationizing ion exchange (DCIE), once sedimentation ion exchange (OSIE) and repeated sedimentation ion exchange (RSIE) were used and assessed. The influences of the four procedures on separation and extraction and isotopic composition of boron in experimental solutions and clay sediments were also discussed. According to the results, the DRIE, DCIE and OSIE are improper. The result of sample determination indicates that when extracting boron via RSIE, with the increase of precipitation times, there's an obvious decrease in boron content in the precipitated hydroxides while a sharp increase in recovery of boron and it is favorable for weakening the influence of boron isotope fractionation. But the process of RSIE is time consuming and it may introduce boron. It needs further research to establish a more effective sample preparation method for isotopic deter- mination of boron in clay sediments.

Synthesis, Structure, and Luminescent Property of a 3-D Strontium Complex [Sr_3(pda)_2(Hpda)_2(H2O)_2]_n·2nH_2O

The title complex [Sr3（pda）2（Hpda）2（H2O）2]n·2nH2O（H2pda = pyridine-2,6-dicar- boxylic acid） has been prepared under solvothermal conditions. It has been characterized by X-ray single-crystal diffraction, IR and elemental analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 10.3795（8）, b = 9.2225（7）, c = 18.5726（14） , β = 104.377（2）o, V = 1722.2（2） 3, C28H22N4O20Sr3, Mr = 997.36, Z = 2, Dc = 1.923 g/cm3, μ = 4.722 mm-1, F（000） = 984, the final R = 0.0269 and wR = 0.0538. This complex possesses a 3-D structure which is constructed from 1-D chain motifs linked by carboxylate groups. The luminescent property of the title complex has been investigated.