The Qaidam Basin(QB)is a concentrated distribution area and chemical industrial bases of salt lakes in China.Lakes in the QB have been expanding during the past 20 years.Rapid lake expansion resulted in some considera...The Qaidam Basin(QB)is a concentrated distribution area and chemical industrial bases of salt lakes in China.Lakes in the QB have been expanding during the past 20 years.Rapid lake expansion resulted in some considerable scientific issues on the protection of salt lake resources and infrastructure,and monitoring of hydrological processes at the lake-basin scale.Although the spatial-temporal trends of lake changes on the Qinghai-Tibet Plateau(QTP)have been well documented,the underlying influencing mechanism and hydrogeological implications of rapid lake changes in the QB are not well understood.Three lakes in the northern QB were selected to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations.The influencing mechanism and hydrogeological implications of rapid changes of terminal lakes were discussed in combination with the reported increasing precipitation rate and mass balance of glaciers in the northern QTP.Results reveal the following:(1)the fluctuation pattern of Sugan Lake was asynchronous and out of phase with that of Xiao Qaidam and Toson lakes during the monitoring period;(2)Sugan Lake water rose gradually,and the rise interval was from late April to early July.In contrast,Xiao Qaidam and Toson lakes took on a rapid and steep rise,and the rise intervalwas from late July to September;(3)the influencing mechanisms for rapid lake fluctuations are controlled by different factors:glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson lakes;(4)in accordance with different intervals and influencing mechanisms of rapid lake expansions in the QB,hydrological risk precaution of lakes and corresponding river catchments was conducted in different parts of the basin.This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution,and protection of salt lake resources along with rapid lake expansions in the arid area.展开更多
The Qarhan Salt Lake(QSL)in western China is K-Sr-Li-B-Br-Rb multi-resource coexisting Quaternary brine deposits.Significant research efforts have been directed to the origin of K-Li resources and evolutionary history...The Qarhan Salt Lake(QSL)in western China is K-Sr-Li-B-Br-Rb multi-resource coexisting Quaternary brine deposits.Significant research efforts have been directed to the origin of K-Li resources and evolutionary history of the QSL.However,the study on the different sources,recharge processes,and differential distribution patterns for these resource elements in brine deposits is still inadequate.Therefore,we measured Li-B concentrations and H-O-Sr-B isotopic compositions of different waters(river,spring,and brine)from the QSL,combined with the reported K-Sr contents and multiple isotopes of waters,to discuss the recharge,source of K-Sr-Li-B and their spatial distributions,by analogy with other evaporite basins in the world.The results show that:(1)the K-Li-B-Sr elemental concentrations of brines and their spatial distribution in the QSL are diverse;(2)high K and Sr values are distributed in Dabuxun and Qarhan sections,respectively,which are controlled by Ca-Cl springs in the northern QSL;on the contrary,Li and B values are enriched in the Bieletan section and are charged by thermal springs in the Kunlun Mountains;(3)the formation and evolution of Ca-Cl and thermal springs constrain fundamentally on the recharge processes of K-Sr and Li-B elements in the terminal salt lakes of the Qaidam Basin(QB);(4)some analogues of recharge processes limit the resource elements of the QSL and other salt lakes(Da Qaidam,Lop Nur,Zhabuye,Atacama,and Guayatayoc)in the world provides a reference for the resource exploration in deep formation waters in the evaporite basins.展开更多
Moisture and salt content of soil are the two predominant factors influencing its shear strength. This study aims to investigate the effects of these two factors on shear strength behavior of loess in the Xining Basin...Moisture and salt content of soil are the two predominant factors influencing its shear strength. This study aims to investigate the effects of these two factors on shear strength behavior of loess in the Xining Basin of Northeast Qinghai-Tibet Plateau, where such geological hazards as soil erosion, landslides collapse and debris flows are widespread due to the highly erodible loess. Salinized loess soil collected from the test site was desalinized through salt-leaching in the laboratory. The desalinized and oven-dried loess samples were also artificially moisturized and salinized in order to examine how soil salinity affects its shear strength at different moisture levels. Soil samples prepared in different ways(moisturizing, salt-leaching, and salinized) were measured to determine soil cohesion and internal friction angle. The results show that salt-leaching up to 18 rounds almost completely removed the salt content and considerably changed the physical components of loess, but the soil type remained unchanged. As salt content increases from 0.00% to 12.00%, both the cohesion and internal friction angle exhibit an initial decrease and then increase with salt content. As moisture content is 12.00%, the salt content threshold value for both cohesion and internal friction angle is identified as 3.00%. As the moisture content rises to 16.0% and 20.00%, the salt content threshold value for cohesion is still 6.00%, but 3.00% for internal friction angle. At these thresholds soil shear strength is the lowest, below which it is inversely related to soil salinity. Beyond the thresholds, however, the relationship is positive. Dissimilar to salinity, soil moisture content exerts an adverse effect on shear strength of loess. The findings of this study can provide a valuable guidance on stabilizing the engineering properties of salinized loess to prevent slope failures during heavy rainfall events.展开更多
Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry...Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry and DO-S-Sr isotopes of these formation waters were determined to study their origin and evolution.The formation waters are enriched in Na-Ca-Cl,and depleted in Mg-K-SO4-HCO3ions with elevated Li-B-Br-Sr elements.The D-O isotopes prove that the formation waters originated from weak-evaporated meteoric waters,and experienced water-rock interactions.Ion comparisons and Caexcess-Nadeficitdiagrams suggest that solute sources of these waters include evaporite dissolution,waterrock interaction,and minor residual lake brines.Bacterial sulfate reduction and water-rock interactions are supported by the high S-Sr isotopes.The enriched Li-B-Br-Sr concentrations of these waters are in accord with the high geochemical background values of the QB.Regarding the genesis of the formation waters,it can be concluded that meteoric waters from the southern Kunlun Mountains were discharged into the basin,weakly evaporated,and then infiltrated into the Neogene strata through faults leaching the soluble ions and mixing with residual lake brines,and all experienced water-rock interactions and a sulphate reduction process.展开更多
This study aims to assess the hydrological effects of four herbs and four shrubs planted in a selfestablished test area in Xining Basin of northeastern Qinghai-Tibet Plateau, China. The RainfallIntercepting Capability...This study aims to assess the hydrological effects of four herbs and four shrubs planted in a selfestablished test area in Xining Basin of northeastern Qinghai-Tibet Plateau, China. The RainfallIntercepting Capability(RIC) of the herbs and shrubs was evaluated in rainfall interception experiment at the end of the third, fourth and fifth month of the growth period in 2007. The leaf transpiration rate and the effects of roots on promoting soil moisture evaporation in these plants were also assessed in transpiration experiment and root-soil composite system evaporation experiment in the five month's growth period. It is found that the RIC of the fourstudied herbs follows the order of E. repens, E. dahuricus, A. trachycaulum and L. secalinus; the RIC of the four shrubs follows the order of A. canescens, Z. xanthoxylon, C. korshinskii and N. tangutorum. The RIC of all the herbs is related linearly to their mean height and canopy area(R^2 ≥ 0.9160). The RIC of all the shrubs bears a logarithmic relationship with their mean height(R^2 ≥ 0.9164), but a linear one with their canopy area(R^2 ≥ 0.9356). Moreover, different species show different transpiration rates. Of the four herbs, E. repens has the highest transpiration rate of 1.07 mg/(m^2·s), and of the four shrubs, A. canescens has the highest transpiration rate(0.74 mg/(m^2·s)). The roots of all the herbs and shrubs can promote soil moisture evaporation. Of the four herbs, the evaporation rate of E. repens root-soil composite system is the highest(2.14%), and of the four shrubs,the root-soil composite system of A. canescens has the highest evaporation rate(1.41%). The evaporation rate of the root-soil composite system of E. dahuricus and Z. xanthoxylon bears a second-power linear relationship with evaporation time(R^2 ≥ 0.9924). The moisture content of all the eight root-soil composite systems decreases exponentially with evaporation time(R^2 ≥ 0.8434). The evaporation rate and moisture content of all the plants' root-soil composite systems increases logarithmically(R^2 ≥ 0.9606) and linearly(R^2 ≥ 0.9777) with root volume density. The findings of this study indicate that among the four herbs and four shrubs, E. repens and A. canescens possess the most effective hydrological effects in reducing the soil erosion and shallow landslide in this region.展开更多
Boron is an essential,widely used,micronutrient element and is abundant in salt lakes on the Qinghai-Tibet Plateau.The origin and distribution of boron brine deposits on the Qinghai-Tibet Plateau is an important found...Boron is an essential,widely used,micronutrient element and is abundant in salt lakes on the Qinghai-Tibet Plateau.The origin and distribution of boron brine deposits on the Qinghai-Tibet Plateau is an important foundation for B resource formation,evolution,and enrichment,which have long been the subject of debate.The boron isotope system is a sensitive geochemical tracer,making it useful for eff ectively and precisely tracking a wide range of geological processes and sources.This study investigates the major cations,[B],andδB values of samples(lake brine,river waters,and cold spring water)from the Bangor Co Lake which is a typical salt lake rich in boron in Tibet,China.There are magnitude-scale diff erences in[B]among diff erent sample types:river samples<cold spring water<<brine lakes.[B]values vary from 0.73 to~1113 mg/L.Similar to[B],theδB values of the samples exhibit magnitude-scale variations as[B],ranging from-7.35‰to+7.66‰.There are also magnitude-scale diff erences inδB among diff erent sample types.TheδB values of cold spring water are relatively low,and the values range from-1.26‰to-7.75‰.However,the river water samples and saline lakes have higher values,from 0.38‰to 4.62‰,and theδB values of river water samples are basically in the distribution range of those of Bangor Co Lake.This indicates that the sources of boron in Bangor Co Lake are mainly the recharge water with higherδB values and spring water with lowerδB values,and the boron sources and the uneven mixing of lake water are two reasons that account for the large change in theδB value of Bangor Co Lake.展开更多
The Gas Hure Salt Lake(GHSL) in the northwestern Qaidam Basin, western China, is rich in boron(B) resources, but its B-resource origin is hardly known. Hydrochemical compositions and B isotope characteristics of diffe...The Gas Hure Salt Lake(GHSL) in the northwestern Qaidam Basin, western China, is rich in boron(B) resources, but its B-resource origin is hardly known. Hydrochemical compositions and B isotope characteristics of different waters were collected around the GHSL, including the river water, stream water, spring water, salt-lake brine, intercrystalline brine, well water, drilling brine, and solar pond brine. The hydrochemical signatures suggest that silicates, carbonates and evaporates are the main B-bearing rocks during the water dynamic. The reservoir estimation of B resources shows that the Kulamulekesay River(KLMR) and the Atekan River(ATKR) contribute annually 18.3 tons and 22.84 tons of B, respectively, with a total amount of 11.72 × 10^(4) tons of B during the past 5.7 ka. In comparison with the known B reservoir(32.96 × 10^(4) tons) in the GHSL, a significant amount of B in the GHSL was probably recharged from deep fluids and sediments around the GHSL. The B concentration and B-enrichment degree are shaped by the evaporation process, which are highly elevated at the carnallite and bischofite stages.展开更多
Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in ord...Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.展开更多
Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these reso...Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin.Here we present results from a comprehensive study on the hydrochemical parameters,whole-rock geochemistry,H-O isotopes,and Li concentrations in surface brine,river water,geothermal springs,and associated rocks from two representative lithium-enriched salt lakes,the Laguo Co(LGC)and Cangmu Co(CMC)in Tibet to understand the genetic mechanisms.Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo(SMZB,~91%)and Donglong Zangbo(DLZB,~75%)rivers,respectively.It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources,respectively.The distinct geological characteristics reflect evolutionary differences between the two lakes,suggesting diverse lithium sources and enrichment processes.The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau.Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river.In contrast,the formation and evolution of CMC are influenced by the northern Lunggar rifts,receiving a prolonged and stable input from the DLZB,resulting in high lithium concentrations and isotopic values.The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks,such as granitic pegmatite veins containing lithium-rich beryl,widely distributed in the upstream area of DLZB.The forward modeling approach,quantifying the contribution fractions of different reservoirs(atmospheric precipitation,silicate,carbonate,and evaporite),indicates that the distinct lithium concentrations in the mainstream(>1 mg/L)and tributaries(<0.1 mg/L)are positively correlated with the ratio of silicate contributions to carbonate contributions,suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks.The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes,topographical features,hydrological factors,fundamental geological settings,and tectonic histories,despite their spatial proximity.Furthermore,our study highlights the significant role of rivers in the formation of young salt lakes,in addition to geothermal springs.展开更多
In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L...In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.展开更多
Assembly processes of prokaryotic and microeukaryotic community is an important issue in microbial ecology.However,unclear remains about the relative contribution of deterministic and stochastic processes to the shapi...Assembly processes of prokaryotic and microeukaryotic community is an important issue in microbial ecology.However,unclear remains about the relative contribution of deterministic and stochastic processes to the shaping of prokaryotic and microeukaryotic communities in saline lake water.Here,we systematically investigated the assembly processes governing the prokaryotic and microeukaryotic communities in Qinghai Lake with the use of Illumina sequencing and a null model.The results showed that both deterministic and stochastic processes play vital roles in shaping the assemblies of prokaryotic and microeukaryotic communities,in which stochastic processes appeared to dominate(> 70%).Prokaryotic communities were mainly governed by non-dominant processes(60.4%),followed by homogeneous selection(15.8%),variable selection(13.6%) and dispersal limitation(10.2%),whereas microeukaryotes were strongly driven by non-dominant processes(68.9%),followed by variable selection(23.6%) and homogenizing dispersal(6.3%).In terms of variable selection,nutrients(e.g.,ammonium,dissolved inorganic carbon,dissolved organic carbon and total nitrogen) were the major factors influencing prokaryotic and microeukaryotic community structures.In summary,prokaryotes and microeukaryotes can be predominantly structured by different assembly mechanisms,in which stochasticity is stronger than deterministic processes.This finding helps to better comprehend the assembly of prokaryotic and eukaryotic communities in saline lakes.展开更多
The Dong-Xi-Taijinaier Salt Lake(DXTSL) of Qaidam Basin is known as one of rich lithium reserves in China.However,the source of lithium deposits in this region remains unclear.The hydrochemistry and lithium isotopes(...The Dong-Xi-Taijinaier Salt Lake(DXTSL) of Qaidam Basin is known as one of rich lithium reserves in China.However,the source of lithium deposits in this region remains unclear.The hydrochemistry and lithium isotopes(δ7Li) of water and solid samples along the Nalenggele River catchment were studied in combination with rock leaching experiments.The results showed the hot springs in the upstream contained high content of lithium and ratio of Li × 1 000/total dissolved solids(1.5–3.5),but the lower δ7Li values(4.33‰–11.59‰),meaning that it is one important lithium sources.The leaching experiments by the rich-lithium volcanic rocks(average content of 474.7 mg/kg) showed that under temperature of 20–80 ℃ and long time duration(24–96 h),the concentration of lithium released by leaching of the sampled volcanic rocks increased from 0.58 to 1.49 mg/L,with the leaching rate decreasing from 0.024 to 0.015 mg/(L·h) and the corresponding lithium release rate increasing from 29% to 74%.Calculation based on water-salt balance showed that the total amount of lithium contribution from hydrothermal fluids and volcanic rock weathering is about 4.99 and 0.29 Mt since 13.1 ka,respectively.Therefore,hot springs and leaching of volcanic rocks are main contributors to lithium deposit in DXTSL.展开更多
Identifying interactions among river water,groundwater and salt lake brine is important for sustainable exploitation of brine mineral resources.In this study,we investigated the water exchange rate in dry and wet seas...Identifying interactions among river water,groundwater and salt lake brine is important for sustainable exploitation of brine mineral resources.In this study,we investigated the water exchange rate in dry and wet seasons,and assessed the influence of seasonal water exchange on brine concentration and crystallization process in the Nalenggele(NLGL)catchment of Qaidam Basin,China.The results show that the surface water infiltration and groundwater recharge rates in the wet season were 2.81×10^(-3)and 1.15×10^(-3)m^(3)/(s·m)in upstream,1.63×10^(-2)and 1.53×10^(-2)m^(3)/(s·m)in midstream,and 2.83×10^(-4)and 6.82×10^(-5)m^(3)/(s·m)in downstream,respectively;while their counterparts in the dry season were 9.81×10^(-4)and 5.05×10^(-4)m^(3)/(s·m)in upstream,and 8.34×10^(-3)and 7.78×10^(-3)m^(3)/(s·m)in midstream,respectively.The water exchange strongly influenced brine concentration and crystallinzation process,with brine chemistry belonging to 3K_(2)SO_(4)·Na_(2)SO_(4) and KCl types in wet and dry seasons,respectively.The strong water exchange in wet season destroyed the water-salt balance,while the low water exchange rate in dry season facilitated preparation of KCl products.展开更多
The accurately determining the lake ^(14)C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence(OSL) dating method is employed to date samples from...The accurately determining the lake ^(14)C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence(OSL) dating method is employed to date samples from highstand lacustrine sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry(AMS) ^(14)C dating was also used to date fossil plants from highstand lacustrine sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative ^(14)C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different sediments on the QTP and Chinese Loess Plateau(CLP), indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon(EASM) and the Indian Summer Monsoon(ISM) resulted in the increase of moisture availability for the Heihai Lake area during this stage.展开更多
The Qaidam Basin on the Qinghai-Tibet Plateau is well endowed with a variety of critical metals,such as Li and Rb.However,little is known about the distribution,source,and enrichment mechanisms of these elements.In th...The Qaidam Basin on the Qinghai-Tibet Plateau is well endowed with a variety of critical metals,such as Li and Rb.However,little is known about the distribution,source,and enrichment mechanisms of these elements.In this paper,we present results of systematic geochemical and H-O-B isotopic analyses of brines in the Tertiary and Quaternary sediments of the Qaidam basin.The results reveal that the paleobrines from oil-bearing anticlines at Dafengshan,Nanyishan,Youquanzi,Jiandingshan,and Jianshishan are significantly enriched in Li and Rb,whose contents are 81.1-128.9 mg L^(-1)and 4.5-29.2 mg L^(-1),respectively,reaching levels of economic significance.High Rb contents(up to 12.5 mg L^(-1))and well-endowment of Li also characterize the Dongtai,Xitai,Yiliping,and Senie salt lakes in the Qaidam Basin.The Tertiary paleobrine average inδD andδ18O at-40.7‰and 2.84‰,respectively.The paleobrine with the highest Li and Rb hasδD andδ^(18)O values close to magmatic water.Theδ^(11)B values are lower than those of river water but close to those of geothermal fluids,suggesting that replenishment by deep magmatic hydrothermal fluid is most likely the key mechanism for the anomalous enrichment of these elements in the paleobrines,though evaporation and water-rock reactions have contributed to the critical metal mineralization.The anomalous enrichment of Li and Rb in modern salt lake brines is closely related to the input of volcanic geothermal water.The relatively high Li and Rb contents of intercrystalline brines in salt lakes of the western Qaidam Basin and the increase of Li and Rb contents with increasing depth were caused by upwelling of local paleobrines along the fault zones.展开更多
Pastoralism is considered a crucial factor in the eventual year-round occupation of high-altitude regions(>3000 m asl)of the Qinghai-Tibetan Plateau,and the northeastern Qinghai-Tibetan Plateau(NE-QTP)was an import...Pastoralism is considered a crucial factor in the eventual year-round occupation of high-altitude regions(>3000 m asl)of the Qinghai-Tibetan Plateau,and the northeastern Qinghai-Tibetan Plateau(NE-QTP)was an important corridor for early human occupation.We analyzed fossil fungal spore records for the last 8500 years from a high resolution aeolian section at Langgeri(LGR)on the NE-QTP.Thirty-two fungal spore types were identified in the LGR section,including seven coprophilous types.We combined analysis of coprophilous fungal spores,Cyperaceae,Artemisia,and Hippophae pollen,and the charcoal>50µm fraction to explore the timing and controls of pastoralism on the NE-QTP since the middle Holocene.Pastoralism commenced at LGR shortly before ca.5.5 ka and gradually increased between ca.5.5–3.5 ka,but markedly intensified after ca.2.2 ka,with three periods of growth at ca.2.1–1.9,1.4–1.2,and 0.6–0 ka,and a decline at ca.1.1–0.6 ka.The timing of changes in pastoral activity on the NE-QTP based on the coprophilous fungal spore record is supported by regional archeology and historical documents.Technological and political developments,rather than climate change,played key roles in the long-term fluctuations of regional pastoralism on the NE-QTP in the late Holocene.展开更多
基金Supported by the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019 QZKK 0805)the National Natural Science Foundation of China(No.U 21 A 2018)the Foundation of Department of Qinghai Science&Technology(No.2020-ZJ-T 06)。
文摘The Qaidam Basin(QB)is a concentrated distribution area and chemical industrial bases of salt lakes in China.Lakes in the QB have been expanding during the past 20 years.Rapid lake expansion resulted in some considerable scientific issues on the protection of salt lake resources and infrastructure,and monitoring of hydrological processes at the lake-basin scale.Although the spatial-temporal trends of lake changes on the Qinghai-Tibet Plateau(QTP)have been well documented,the underlying influencing mechanism and hydrogeological implications of rapid lake changes in the QB are not well understood.Three lakes in the northern QB were selected to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations.The influencing mechanism and hydrogeological implications of rapid changes of terminal lakes were discussed in combination with the reported increasing precipitation rate and mass balance of glaciers in the northern QTP.Results reveal the following:(1)the fluctuation pattern of Sugan Lake was asynchronous and out of phase with that of Xiao Qaidam and Toson lakes during the monitoring period;(2)Sugan Lake water rose gradually,and the rise interval was from late April to early July.In contrast,Xiao Qaidam and Toson lakes took on a rapid and steep rise,and the rise intervalwas from late July to September;(3)the influencing mechanisms for rapid lake fluctuations are controlled by different factors:glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson lakes;(4)in accordance with different intervals and influencing mechanisms of rapid lake expansions in the QB,hydrological risk precaution of lakes and corresponding river catchments was conducted in different parts of the basin.This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution,and protection of salt lake resources along with rapid lake expansions in the arid area.
基金Supported by the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019 QZKK 0805)the National Natural Science Foundation of China(No.U 21 A 2018)the Foundation of Department of Qinghai Science&Technology(No.2020-ZJ-T 06)。
文摘The Qarhan Salt Lake(QSL)in western China is K-Sr-Li-B-Br-Rb multi-resource coexisting Quaternary brine deposits.Significant research efforts have been directed to the origin of K-Li resources and evolutionary history of the QSL.However,the study on the different sources,recharge processes,and differential distribution patterns for these resource elements in brine deposits is still inadequate.Therefore,we measured Li-B concentrations and H-O-Sr-B isotopic compositions of different waters(river,spring,and brine)from the QSL,combined with the reported K-Sr contents and multiple isotopes of waters,to discuss the recharge,source of K-Sr-Li-B and their spatial distributions,by analogy with other evaporite basins in the world.The results show that:(1)the K-Li-B-Sr elemental concentrations of brines and their spatial distribution in the QSL are diverse;(2)high K and Sr values are distributed in Dabuxun and Qarhan sections,respectively,which are controlled by Ca-Cl springs in the northern QSL;on the contrary,Li and B values are enriched in the Bieletan section and are charged by thermal springs in the Kunlun Mountains;(3)the formation and evolution of Ca-Cl and thermal springs constrain fundamentally on the recharge processes of K-Sr and Li-B elements in the terminal salt lakes of the Qaidam Basin(QB);(4)some analogues of recharge processes limit the resource elements of the QSL and other salt lakes(Da Qaidam,Lop Nur,Zhabuye,Atacama,and Guayatayoc)in the world provides a reference for the resource exploration in deep formation waters in the evaporite basins.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 41572306, 41162010)Natural Science Foundation of Qinghai Province (Grant No.2014ZJ-906)+3 种基金Hundred Talents Program in Chinese Academy of Sciences (Grant No. Y110091025)Scientific and Technologic Support Plan of Qinghai Province (2015-SF-117)Changjiang Scholar Program and Innovative Research Team Building, MOE Grant Number (IRT_17R62)the 111 Project (Grant No. D18013)
文摘Moisture and salt content of soil are the two predominant factors influencing its shear strength. This study aims to investigate the effects of these two factors on shear strength behavior of loess in the Xining Basin of Northeast Qinghai-Tibet Plateau, where such geological hazards as soil erosion, landslides collapse and debris flows are widespread due to the highly erodible loess. Salinized loess soil collected from the test site was desalinized through salt-leaching in the laboratory. The desalinized and oven-dried loess samples were also artificially moisturized and salinized in order to examine how soil salinity affects its shear strength at different moisture levels. Soil samples prepared in different ways(moisturizing, salt-leaching, and salinized) were measured to determine soil cohesion and internal friction angle. The results show that salt-leaching up to 18 rounds almost completely removed the salt content and considerably changed the physical components of loess, but the soil type remained unchanged. As salt content increases from 0.00% to 12.00%, both the cohesion and internal friction angle exhibit an initial decrease and then increase with salt content. As moisture content is 12.00%, the salt content threshold value for both cohesion and internal friction angle is identified as 3.00%. As the moisture content rises to 16.0% and 20.00%, the salt content threshold value for cohesion is still 6.00%, but 3.00% for internal friction angle. At these thresholds soil shear strength is the lowest, below which it is inversely related to soil salinity. Beyond the thresholds, however, the relationship is positive. Dissimilar to salinity, soil moisture content exerts an adverse effect on shear strength of loess. The findings of this study can provide a valuable guidance on stabilizing the engineering properties of salinized loess to prevent slope failures during heavy rainfall events.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK0805)the Special Project of Qinghai Scholars(Grant No.QHS201802)+1 种基金National Natural Science Foundation of China(NSFC,Grant Nos.41872093,U21A2018)Foundation of Qinghai Science&Technology Department(Grant No.2021-ZJ-932)。
文摘Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry and DO-S-Sr isotopes of these formation waters were determined to study their origin and evolution.The formation waters are enriched in Na-Ca-Cl,and depleted in Mg-K-SO4-HCO3ions with elevated Li-B-Br-Sr elements.The D-O isotopes prove that the formation waters originated from weak-evaporated meteoric waters,and experienced water-rock interactions.Ion comparisons and Caexcess-Nadeficitdiagrams suggest that solute sources of these waters include evaporite dissolution,waterrock interaction,and minor residual lake brines.Bacterial sulfate reduction and water-rock interactions are supported by the high S-Sr isotopes.The enriched Li-B-Br-Sr concentrations of these waters are in accord with the high geochemical background values of the QB.Regarding the genesis of the formation waters,it can be concluded that meteoric waters from the southern Kunlun Mountains were discharged into the basin,weakly evaporated,and then infiltrated into the Neogene strata through faults leaching the soluble ions and mixing with residual lake brines,and all experienced water-rock interactions and a sulphate reduction process.
基金financially supported by the National Natural Science Foundation of China (Grant Nos.41572306,41162010)Natural Science Foundation of Qinghai Province (Grant No.2014ZJ-906)+2 种基金Hundred Talents Program in Chinese Academy of Sciences (Grant No.Y110091025)Scientific and Technologic Support Plan of Qinghai Province (2015-SF-117)Ministry of Education 'Innovative Team Development Scheme' (IRT_17R62)
文摘This study aims to assess the hydrological effects of four herbs and four shrubs planted in a selfestablished test area in Xining Basin of northeastern Qinghai-Tibet Plateau, China. The RainfallIntercepting Capability(RIC) of the herbs and shrubs was evaluated in rainfall interception experiment at the end of the third, fourth and fifth month of the growth period in 2007. The leaf transpiration rate and the effects of roots on promoting soil moisture evaporation in these plants were also assessed in transpiration experiment and root-soil composite system evaporation experiment in the five month's growth period. It is found that the RIC of the fourstudied herbs follows the order of E. repens, E. dahuricus, A. trachycaulum and L. secalinus; the RIC of the four shrubs follows the order of A. canescens, Z. xanthoxylon, C. korshinskii and N. tangutorum. The RIC of all the herbs is related linearly to their mean height and canopy area(R^2 ≥ 0.9160). The RIC of all the shrubs bears a logarithmic relationship with their mean height(R^2 ≥ 0.9164), but a linear one with their canopy area(R^2 ≥ 0.9356). Moreover, different species show different transpiration rates. Of the four herbs, E. repens has the highest transpiration rate of 1.07 mg/(m^2·s), and of the four shrubs, A. canescens has the highest transpiration rate(0.74 mg/(m^2·s)). The roots of all the herbs and shrubs can promote soil moisture evaporation. Of the four herbs, the evaporation rate of E. repens root-soil composite system is the highest(2.14%), and of the four shrubs,the root-soil composite system of A. canescens has the highest evaporation rate(1.41%). The evaporation rate of the root-soil composite system of E. dahuricus and Z. xanthoxylon bears a second-power linear relationship with evaporation time(R^2 ≥ 0.9924). The moisture content of all the eight root-soil composite systems decreases exponentially with evaporation time(R^2 ≥ 0.8434). The evaporation rate and moisture content of all the plants' root-soil composite systems increases logarithmically(R^2 ≥ 0.9606) and linearly(R^2 ≥ 0.9777) with root volume density. The findings of this study indicate that among the four herbs and four shrubs, E. repens and A. canescens possess the most effective hydrological effects in reducing the soil erosion and shallow landslide in this region.
基金the Shaanxi Provincial Natural Science Foundation for Distinguished Young Scholars(No.2022JC)the 2nd Tibetan Plateau Scientific Expedition and Research(Nos.2019QZKK0805 and 2019QZKK0707)+1 种基金the Innovation Academy for Green Manufacture,Joint Fund Projects(No.IAGM2020C09)Basic Research Program of Qinghai Province(No.2020-ZJ-734)。
文摘Boron is an essential,widely used,micronutrient element and is abundant in salt lakes on the Qinghai-Tibet Plateau.The origin and distribution of boron brine deposits on the Qinghai-Tibet Plateau is an important foundation for B resource formation,evolution,and enrichment,which have long been the subject of debate.The boron isotope system is a sensitive geochemical tracer,making it useful for eff ectively and precisely tracking a wide range of geological processes and sources.This study investigates the major cations,[B],andδB values of samples(lake brine,river waters,and cold spring water)from the Bangor Co Lake which is a typical salt lake rich in boron in Tibet,China.There are magnitude-scale diff erences in[B]among diff erent sample types:river samples<cold spring water<<brine lakes.[B]values vary from 0.73 to~1113 mg/L.Similar to[B],theδB values of the samples exhibit magnitude-scale variations as[B],ranging from-7.35‰to+7.66‰.There are also magnitude-scale diff erences inδB among diff erent sample types.TheδB values of cold spring water are relatively low,and the values range from-1.26‰to-7.75‰.However,the river water samples and saline lakes have higher values,from 0.38‰to 4.62‰,and theδB values of river water samples are basically in the distribution range of those of Bangor Co Lake.This indicates that the sources of boron in Bangor Co Lake are mainly the recharge water with higherδB values and spring water with lowerδB values,and the boron sources and the uneven mixing of lake water are two reasons that account for the large change in theδB value of Bangor Co Lake.
基金Financial support for this research was provided by the “Western Light” Fund of the Chinese Academy of Science Foundation (Y910061016)The National Natural Science Foundation of China (No. 42007169)+3 种基金The Key deployment projects of the Chinese academy of sciences (ZDRW-ZS-2020-3)Funds for the Natural Science Foundation of Qinghai Province (No. 2020-ZJ-932Q2020-ZJ-7322019-ZJ-7028)。
文摘The Gas Hure Salt Lake(GHSL) in the northwestern Qaidam Basin, western China, is rich in boron(B) resources, but its B-resource origin is hardly known. Hydrochemical compositions and B isotope characteristics of different waters were collected around the GHSL, including the river water, stream water, spring water, salt-lake brine, intercrystalline brine, well water, drilling brine, and solar pond brine. The hydrochemical signatures suggest that silicates, carbonates and evaporates are the main B-bearing rocks during the water dynamic. The reservoir estimation of B resources shows that the Kulamulekesay River(KLMR) and the Atekan River(ATKR) contribute annually 18.3 tons and 22.84 tons of B, respectively, with a total amount of 11.72 × 10^(4) tons of B during the past 5.7 ka. In comparison with the known B reservoir(32.96 × 10^(4) tons) in the GHSL, a significant amount of B in the GHSL was probably recharged from deep fluids and sediments around the GHSL. The B concentration and B-enrichment degree are shaped by the evaporation process, which are highly elevated at the carnallite and bischofite stages.
基金funded by the National Natural Science Foundation of China (42002283, 42062019)the Science and Technology Plan Project of Qinghai Province,China (2022-ZJ-Y08)the Second Tibetan Plateau Scientific Expedition and Research (STEP) Program (2019QZKK0905, 2019QZKK0805)
文摘Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.
基金This project was jointly supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2022QZKK0202)the National Natural Science Foundation of China(Grant No.U22A20573)the Fundamental Research Funds for the Central Universities(Grant No.B230201014).
文摘Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin.Here we present results from a comprehensive study on the hydrochemical parameters,whole-rock geochemistry,H-O isotopes,and Li concentrations in surface brine,river water,geothermal springs,and associated rocks from two representative lithium-enriched salt lakes,the Laguo Co(LGC)and Cangmu Co(CMC)in Tibet to understand the genetic mechanisms.Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo(SMZB,~91%)and Donglong Zangbo(DLZB,~75%)rivers,respectively.It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources,respectively.The distinct geological characteristics reflect evolutionary differences between the two lakes,suggesting diverse lithium sources and enrichment processes.The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau.Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river.In contrast,the formation and evolution of CMC are influenced by the northern Lunggar rifts,receiving a prolonged and stable input from the DLZB,resulting in high lithium concentrations and isotopic values.The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks,such as granitic pegmatite veins containing lithium-rich beryl,widely distributed in the upstream area of DLZB.The forward modeling approach,quantifying the contribution fractions of different reservoirs(atmospheric precipitation,silicate,carbonate,and evaporite),indicates that the distinct lithium concentrations in the mainstream(>1 mg/L)and tributaries(<0.1 mg/L)are positively correlated with the ratio of silicate contributions to carbonate contributions,suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks.The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes,topographical features,hydrological factors,fundamental geological settings,and tectonic histories,despite their spatial proximity.Furthermore,our study highlights the significant role of rivers in the formation of young salt lakes,in addition to geothermal springs.
基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0905)the National Natural Science Foundation of China(Grant Nos.42002283,41572306,42041006 and 42062019)+2 种基金the Project of the Qinghai Science&Technology Department(Grant Nos.2020-ZJ-906 and 2014-ZJ-906)the Key Discipline Construction Project for Geological Resources and Geological Engineering of Qinghai University(Grant No.41250103)the Ministry of Education’s‘Innovative Team Development Scheme’(IRT17R62)。
文摘In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.
基金supported by grants from the National Natural Science Foundation of China (Nos.92251304 and 41972317)the 111 Program (State Administration of Foreign Experts Affairs&the Ministry of Education of China,No.B18049)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(No.2019QZKK0805)the Science and Technology Plan Project of Qinghai Province (No.2022-ZJ-Y08)State Key Laboratory of Biogeology and Environmental Geology,CUG (No.GBL11805)。
文摘Assembly processes of prokaryotic and microeukaryotic community is an important issue in microbial ecology.However,unclear remains about the relative contribution of deterministic and stochastic processes to the shaping of prokaryotic and microeukaryotic communities in saline lake water.Here,we systematically investigated the assembly processes governing the prokaryotic and microeukaryotic communities in Qinghai Lake with the use of Illumina sequencing and a null model.The results showed that both deterministic and stochastic processes play vital roles in shaping the assemblies of prokaryotic and microeukaryotic communities,in which stochastic processes appeared to dominate(> 70%).Prokaryotic communities were mainly governed by non-dominant processes(60.4%),followed by homogeneous selection(15.8%),variable selection(13.6%) and dispersal limitation(10.2%),whereas microeukaryotes were strongly driven by non-dominant processes(68.9%),followed by variable selection(23.6%) and homogenizing dispersal(6.3%).In terms of variable selection,nutrients(e.g.,ammonium,dissolved inorganic carbon,dissolved organic carbon and total nitrogen) were the major factors influencing prokaryotic and microeukaryotic community structures.In summary,prokaryotes and microeukaryotes can be predominantly structured by different assembly mechanisms,in which stochasticity is stronger than deterministic processes.This finding helps to better comprehend the assembly of prokaryotic and eukaryotic communities in saline lakes.
基金supported by the Funds for the Qinghai Province (Nos.2020-ZJ-7322020-ZJ-932Q)+3 种基金Key Deployment projects of the Chinese Academy of Sciences (No.ZDRW-ZS-2020-3)the National Natural Science Foundation of China (No.42007169)The Fourth Batch of Qinghai Province “Thousand Talents Program for High-End Innovative Talents”(Jibin Han)supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(No.2019QZKK0805)。
文摘The Dong-Xi-Taijinaier Salt Lake(DXTSL) of Qaidam Basin is known as one of rich lithium reserves in China.However,the source of lithium deposits in this region remains unclear.The hydrochemistry and lithium isotopes(δ7Li) of water and solid samples along the Nalenggele River catchment were studied in combination with rock leaching experiments.The results showed the hot springs in the upstream contained high content of lithium and ratio of Li × 1 000/total dissolved solids(1.5–3.5),but the lower δ7Li values(4.33‰–11.59‰),meaning that it is one important lithium sources.The leaching experiments by the rich-lithium volcanic rocks(average content of 474.7 mg/kg) showed that under temperature of 20–80 ℃ and long time duration(24–96 h),the concentration of lithium released by leaching of the sampled volcanic rocks increased from 0.58 to 1.49 mg/L,with the leaching rate decreasing from 0.024 to 0.015 mg/(L·h) and the corresponding lithium release rate increasing from 29% to 74%.Calculation based on water-salt balance showed that the total amount of lithium contribution from hydrothermal fluids and volcanic rock weathering is about 4.99 and 0.29 Mt since 13.1 ka,respectively.Therefore,hot springs and leaching of volcanic rocks are main contributors to lithium deposit in DXTSL.
基金supported by the Key Deployment projects of the Chinese academy of sciences(No.ZDRW-ZS-2020-3)the Funds for the Qinghai Province(Nos.2020-ZJ-932Q+4 种基金2020-ZJ-732)the National Natural Science Foundation of China(No.42007169)the“Western Light”of Chinese Academy of Sciencesthe Fourth Batch of Qinghai Province“Thousand Talents Program for High-end Innovative Talents”(No.2020000051)supported by the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0805)。
文摘Identifying interactions among river water,groundwater and salt lake brine is important for sustainable exploitation of brine mineral resources.In this study,we investigated the water exchange rate in dry and wet seasons,and assessed the influence of seasonal water exchange on brine concentration and crystallization process in the Nalenggele(NLGL)catchment of Qaidam Basin,China.The results show that the surface water infiltration and groundwater recharge rates in the wet season were 2.81×10^(-3)and 1.15×10^(-3)m^(3)/(s·m)in upstream,1.63×10^(-2)and 1.53×10^(-2)m^(3)/(s·m)in midstream,and 2.83×10^(-4)and 6.82×10^(-5)m^(3)/(s·m)in downstream,respectively;while their counterparts in the dry season were 9.81×10^(-4)and 5.05×10^(-4)m^(3)/(s·m)in upstream,and 8.34×10^(-3)and 7.78×10^(-3)m^(3)/(s·m)in midstream,respectively.The water exchange strongly influenced brine concentration and crystallinzation process,with brine chemistry belonging to 3K_(2)SO_(4)·Na_(2)SO_(4) and KCl types in wet and dry seasons,respectively.The strong water exchange in wet season destroyed the water-salt balance,while the low water exchange rate in dry season facilitated preparation of KCl products.
基金supported by the National Natural Science Foundation of China(No.41401008)West Light Foundation of the Chinese Academy of Sciences(No.Y412021005)+1 种基金Natural Science Foundation of Qinghai Province(No.2016-ZJ-926Q)the instrument function development program of the Chinese Academy of Sciences(No.Y410041013)
文摘The accurately determining the lake ^(14)C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence(OSL) dating method is employed to date samples from highstand lacustrine sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry(AMS) ^(14)C dating was also used to date fossil plants from highstand lacustrine sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative ^(14)C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different sediments on the QTP and Chinese Loess Plateau(CLP), indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon(EASM) and the Indian Summer Monsoon(ISM) resulted in the increase of moisture availability for the Heihai Lake area during this stage.
基金supported by the National Natural Science Foundation of China(Grant Nos.41972258,U1407128,and 41402229)the Talent Program of Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020428)+1 种基金the Natural Science Foundation of Qinghai Province(Grant No.2021-ZJ-980Q)the Second Comprehensive Scientific Expedition to the Qinghai-Tibet Plateau(Grant No.2019QZKK0805)。
文摘The Qaidam Basin on the Qinghai-Tibet Plateau is well endowed with a variety of critical metals,such as Li and Rb.However,little is known about the distribution,source,and enrichment mechanisms of these elements.In this paper,we present results of systematic geochemical and H-O-B isotopic analyses of brines in the Tertiary and Quaternary sediments of the Qaidam basin.The results reveal that the paleobrines from oil-bearing anticlines at Dafengshan,Nanyishan,Youquanzi,Jiandingshan,and Jianshishan are significantly enriched in Li and Rb,whose contents are 81.1-128.9 mg L^(-1)and 4.5-29.2 mg L^(-1),respectively,reaching levels of economic significance.High Rb contents(up to 12.5 mg L^(-1))and well-endowment of Li also characterize the Dongtai,Xitai,Yiliping,and Senie salt lakes in the Qaidam Basin.The Tertiary paleobrine average inδD andδ18O at-40.7‰and 2.84‰,respectively.The paleobrine with the highest Li and Rb hasδD andδ^(18)O values close to magmatic water.Theδ^(11)B values are lower than those of river water but close to those of geothermal fluids,suggesting that replenishment by deep magmatic hydrothermal fluid is most likely the key mechanism for the anomalous enrichment of these elements in the paleobrines,though evaporation and water-rock reactions have contributed to the critical metal mineralization.The anomalous enrichment of Li and Rb in modern salt lake brines is closely related to the input of volcanic geothermal water.The relatively high Li and Rb contents of intercrystalline brines in salt lakes of the western Qaidam Basin and the increase of Li and Rb contents with increasing depth were caused by upwelling of local paleobrines along the fault zones.
基金supported by the National Natural Science Foundation of China(Grant No.41877455)the Science and Technology Innovation Platform Project of Qinghai Province(Grant No.2020-ZJ-T06)+2 种基金the Open Foundation of State Key Laboratory of Paleobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CASGrant No.183123)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0805).
文摘Pastoralism is considered a crucial factor in the eventual year-round occupation of high-altitude regions(>3000 m asl)of the Qinghai-Tibetan Plateau,and the northeastern Qinghai-Tibetan Plateau(NE-QTP)was an important corridor for early human occupation.We analyzed fossil fungal spore records for the last 8500 years from a high resolution aeolian section at Langgeri(LGR)on the NE-QTP.Thirty-two fungal spore types were identified in the LGR section,including seven coprophilous types.We combined analysis of coprophilous fungal spores,Cyperaceae,Artemisia,and Hippophae pollen,and the charcoal>50µm fraction to explore the timing and controls of pastoralism on the NE-QTP since the middle Holocene.Pastoralism commenced at LGR shortly before ca.5.5 ka and gradually increased between ca.5.5–3.5 ka,but markedly intensified after ca.2.2 ka,with three periods of growth at ca.2.1–1.9,1.4–1.2,and 0.6–0 ka,and a decline at ca.1.1–0.6 ka.The timing of changes in pastoral activity on the NE-QTP based on the coprophilous fungal spore record is supported by regional archeology and historical documents.Technological and political developments,rather than climate change,played key roles in the long-term fluctuations of regional pastoralism on the NE-QTP in the late Holocene.
