We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018...We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018,gobies and sediments were collected from 15 stations.We measured the activities of defense enzymes and the contents of malondialdehyde(MDA)and metallothionein(MT)in the goby liver as well as the levels of heavy metals in the sediments and goby muscle tissue.Most of the heavy metal concentrations in sediment at each station were below the Class I criteria set by Chinese Standards for Marine Sediment Quality,and the Håkanson ecological risk index suggested low risk for the heavy metals.We found that A.ommaturus could eff ectively accumulate mercury,cadmium,arsenic,and zinc and that the contents of MT and MDA and the activities of glutathione peroxidase and glutathione reductase were suitable biomarkers of heavy metal pollution in this species.The IBRv2 method integrated these four biomarkers and discriminated stations according to heavy metal pollution.Higher IBRv2 values suggested more adverse eff ects in gobies,corroborating more serious heavy metal contamination.The stations with high IBRv2 values and high contents of heavy metals were mainly distributed in the west and northeast parts of the bay.These results show that the IBRv2 approach is a feasible strategy for assessing heavy metal pollution through biological response and biological status and that it can be implemented for environmental monitoring in Laizhou Bay.展开更多
Biological invasions cause major ecological and economic costs in invaded habitats. The round goby Neogobius me- lanostomus is a successful invasive species and a major threat to the biodiversity and ecological functi...Biological invasions cause major ecological and economic costs in invaded habitats. The round goby Neogobius me- lanostomus is a successful invasive species and a major threat to the biodiversity and ecological function of the Baltic Sea. It is native to the Ponto-Caspian region and has, via ballast water transport of ships, invaded the Gulf of Gdansk in Poland. Since 1990, it has spread as far north as Raahe in Northern Finland （64~41 ＂04＂N, 24~28＂44＂E）. Over the past decade, consistent indi- vidual differences of behavioral expressions have been shown to explain various ecological processes such as dispersal, survival or reproduction. We have previously shown that new and old populations differ in personality trait expression. Individuals in new populations are bolder, less sociable and more active than in old populations. Here we investigate if the behavioral differentiation can be explained by phenotype-dependent dispersal. This was investigated by measuring activity, boldness and sociability of in- dividually marked gobies, and subsequently allowing them to disperse in a system composed of five consecutive tanks connected by tubes. Individual dispersal tendency and distance was measured. Our results revealed that in newly established populations, more active individuals disperse sooner and that latency of a group to disperse depends on the mean sociability of the group. This indicates the presence of personality dependent dispersal in this species and that it is maintained at the invasion front but lost as the populations get older展开更多
The karyotype of Caspian goby was studied, which has been identified as Caspian bighead goby-Neogobius gorlap before. The results of cytogenetic analyses have shown that the diploid set of goby varies from 38 to 40 ch...The karyotype of Caspian goby was studied, which has been identified as Caspian bighead goby-Neogobius gorlap before. The results of cytogenetic analyses have shown that the diploid set of goby varies from 38 to 40 chromosomes, which is different from bighead goby （2n = 43-46）. We assumed that Caspian goby has independence as a species.展开更多
We tested the use of otolith shape analysis to discriminate between species and stocks of five goby species( Ctenotrypauchen chinensis, Odontamblyopus lacepedii, Amblychaeturichthys hexanema, Chaeturichthys stigmatias...We tested the use of otolith shape analysis to discriminate between species and stocks of five goby species( Ctenotrypauchen chinensis, Odontamblyopus lacepedii, Amblychaeturichthys hexanema, Chaeturichthys stigmatias, and Acanthogobius hasta) found in northern Chinese coastal waters. The five species were well differentiated with high overall classification success using shape indices(83.7%), elliptic Fourier coefficients(98.6%), or the combination of both methods(94.9%). However, shape analysis alone was only moderately successful at discriminating among the four stocks(Liaodong Bay, LD; Bohai Bay, BH; Huanghe(Yellow) River estuary HRE, and Jiaozhou Bay, JZ stocks) of A. hasta(50%–54%) and C. stigmatias(65.7%–75.8%). For these two species, shape analysis was moderately successful at discriminating the HRE or JZ stocks from other stocks, but failed to effectively identify the LD and BH stocks. A large number of otoliths were misclassified between the HRE and JZ stocks, which are geographically well separated. The classification success for stock discrimination was higher using elliptic Fourier coefficients alone(70.2%) or in combination with shape indices(75.8%) than using only shape indices(65.7%) in C. stigmatias whereas there was little difference among the three methods for A. hasta. Our results supported the common belief that otolith shape analysis is generally more effective for interspecific identification than intraspecific discrimination. Moreover, compared with shape indices analysis, Fourier analysis improves classification success during inter- and intra-species discrimination by otolith shape analysis, although this did not necessarily always occur in all fish species.展开更多
Despite most eel gobies(Gobionellidae:Amblyopinae)have inhabited brackish or marine waters,few species(such as Taenioides sp.)have been found to invade multiple inland freshwaters via artificial water transfer project...Despite most eel gobies(Gobionellidae:Amblyopinae)have inhabited brackish or marine waters,few species(such as Taenioides sp.)have been found to invade multiple inland freshwaters via artificial water transfer projects.The habitat transfers from brackish water to freshwater zones of Taenioides sp.have caused severe damage to Chinese aquatic ecosystems in recent years.Unfortunately,the molecular mechanism underlying freshwater invasion remains poorly understood.Considering changes of environmental factors,especially salinity,are bound to adjust the demands for energy affected by mitochondria via oxidative phosphorylation,13 Amblyopinae mitogenomes were compared,including the newly assembled Taenioides sp.mitogenome in this study.Comparative mitogenomic analyses revealed a highly conserved structure,composition and arrangements,with the exception of variable control region(CR).All of the CRs possessed tandem repeat sequences except Trypauchenopsis sp.G341,differing in motifs and number of copies,which was the dominant factor resulting in length heterogeneity of CR.The phylogenetic trees reconfirmed the paraphyletic origin of Amblyopinae with respect to Oxudercinae,supporting that these two subfamilies should be merged as an expansion of phenotypic variation within the“terrestrial goby”clade.Furthermore,four protein coding genes(COI,ND3,ND5 and Cyt b)in Taenioides sp.mitogenome have experienced adaptive evolution,indicating their important roles in enhancing the efficiency of ATP production to cope with the osmotic regulation adjustment and reach its current widespread distribution in multiple inland freshwaters of China.These results revealed the functional importance of mitochondrial genes,and provided fresh insights into the molecular mechanisms underlying the freshwater invasion.Also,our results may provide critical reference value for the future control of other invasive species.展开更多
In order to clarify the mitochondrial bar code sequence and taxonomic information of common goby fish in Tianjin coastal marine areas,seven species of goby fish were collected from Tianjin coastal marine areas,identif...In order to clarify the mitochondrial bar code sequence and taxonomic information of common goby fish in Tianjin coastal marine areas,seven species of goby fish were collected from Tianjin coastal marine areas,identified by morphology,and DNA was extracted for amplification and sequencing of mitochondrial COI gene fragments.Phylogenetic analysis and molecular identification software MEGA were used to analyze the sequence characteristics and molecular classification of COI gene fragments of 12 common goby species in Tianjin coastal marine areas.Seven COI gene fragments of Goby were amplified and sequenced,the average GC content was lower than AT content,the base had a bias in the codon position distribution,and the highest GC content was the second base,which was similar to the COI gene base of many fishes.The codon base variation rate was 19.4%,and the ratio of transitions to transversions was 1.3.Phylogenetic distance analysis and phylogenetic tree analysis clarified the phylotaxonomic and evolutionary relationships of 12 major goby species in Tianjin coastal marine areas.Genetic distance indicates that Amblychaeturichthys hexanema and Synechogobius ommaturus are the same species.The high codon variation rate of codon encoding gene in Goby may be related to its good environmental adaptability.展开更多
Dunhuang,located in the northwestern part of China,is a town that feels like it's carved out of the pages of a history book.Nestled at the edge of the Gobi Desert in China's Gansu Province,this ancient oasis c...Dunhuang,located in the northwestern part of China,is a town that feels like it's carved out of the pages of a history book.Nestled at the edge of the Gobi Desert in China's Gansu Province,this ancient oasis city has been a crossroads of cultures,religions,and trade for over 2,000 years.展开更多
Tenebrionid beetles represent a crucial arthropod taxon in the Gobi desert ecosystems owing to their species richness and high biomass,both of which are essential for maintaining ecosystem health and stability.However...Tenebrionid beetles represent a crucial arthropod taxon in the Gobi desert ecosystems owing to their species richness and high biomass,both of which are essential for maintaining ecosystem health and stability.However,the spatiotemporal variations of tenebrionid beetle assemblages in the Gobi desert remain poorly understood.In this study,the monthly dynamics of tenebrionid beetles in the central part of the Hexi Corridor,Northwest China,a representative area of the Gobi desert ecosystems,were monitored using pitfall trapping during 2015-2020.The following results were showed:(1)monthly activity of tenebrionid beetles was observed from March to October,with monthly activity peaking in spring and summer,and monthly activity periods and peak of tenebrionid beetle species exhibited interspecific differences that varied from year to year;(2)spatial distribution of tenebrionid beetle community was influenced by structural factors.Specifically,at a spatial scale of 24.00 m,tenebrionid beetle community was strongly and positively correlated with the dominant species,with distinct spatial distribution patterns observed for Blaps gobiensis and Microdera kraatzi alashanica;(3)abundance of tenebrionid beetles was positively correlated with monthly mean precipitation and monthly mean temperature,whereas monthly abundance of B.gobiensis and M.kraatzi alashanica was positively correlated with monthly mean precipitation;and(4)the cover of Reaumuria soongarica(Pall.)Maxim.and Nitraria sphaerocarpa Maxim.had a positive influence on the number of tenebrionid beetles captured.In conclusion,monthly variation in precipitation significantly influences the community dynamic of tenebrionid beetles,with precipitation and shrub cover jointly determining the spatial distribution pattern of these beetles in the Gobi desert ecosystems.展开更多
In the vast hinterland of the Qinghai-Xizang Plateau in western China,a profound green transformation is advancing quietly.On the vast Gobi Desert,arrays of solar panels resemble a shimmering silver sea.White wind tur...In the vast hinterland of the Qinghai-Xizang Plateau in western China,a profound green transformation is advancing quietly.On the vast Gobi Desert,arrays of solar panels resemble a shimmering silver sea.White wind turbines stand tall against the sky,with their blades swirling slowly in the wind.Golmud,a city in west China’s Qinghai Province formerly known for its abundant natural resources.展开更多
The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introdu...The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.展开更多
Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materia...Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi surfaces.It is challenging to describe these processes according to a uniform morphology.Therefore,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3D)size and shape of gravel.Collecting morphology information for Gobi gravels is essential for studying its genesis and sand saltation.To enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3D parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3D parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain size.Leveraging multi-view geometry technology for 3D reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear quality.Additionally,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point clouds.Advanced point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3D parameters of individual gravels.These systematic processes allow precise and detailed characterization of individual gravels.For gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodology for measuring 3D parameters of individual gravels.The proposed workflow yields accurate calculations of relevant parameters for Gobi gravels,providing essential data support for subsequent studies on Gobi environments.展开更多
Our understanding of sexual selection has greatly improved during the last decades. The focus is no longer solely on males, but also on how female competition and male mate choice shape ornamentation and other sexuall...Our understanding of sexual selection has greatly improved during the last decades. The focus is no longer solely on males, but also on how female competition and male mate choice shape ornamentation and other sexually selected traits in females. At the same time, the focus has shifted from documenting sexual selection to exploring variation and spatiotemporal dynamics of sexual selection, and their evolutionary consequences. Here, I review insights from a model system with exceptionally dynamic sexual selection, the two-spotted goby fish Gobiusculus flavescens. The species displays a complete reversal of sex roles over a 3-month breeding season. The reversal is driven by a dramatic change in the operational sex ratio, which is heavily male-biased at the start of the season and heavily female-biased late in the season. Early in the season, breeding-ready males outnumber mature females, causing males to be highly competitive, and leading to sexual selection on males. Late in the season, mating-ready females are in excess, engage more in courtship and aggression than males, and rarely reject mating opportunities. With typically many females simultaneously courting available males late in the season, males become selective and prefer more colorful females. This variable sexual selection regime likely explains why both male and female G. flavescens have ornamental colors. The G. flavescens model system reveals that sexual behavior and sexual selection can be astonishingly dynamic in response to short-term fluctuations in mating competition. Future work should explore whether sexual selection is equally dynamic on a spatial scale, and related spatiotemporal dynamics.展开更多
The paper aimed to determine the true identity of a presumed or commonly believed Sinarapan fish and compare their phylogenetic relationships by using DNA barcoding.The fish samples were collected by researchers from ...The paper aimed to determine the true identity of a presumed or commonly believed Sinarapan fish and compare their phylogenetic relationships by using DNA barcoding.The fish samples were collected by researchers from a fisheries research and development institution in April 2015 from four different lakes of Bicol Region,i.e.,Lakes Buhi,Danao,Manapao and Bato.DNA was extracted using cetyl trimethyl ammonium bromide(CTAB)extraction buffer.The polymerase chain reaction(PCR)profile for the reaction was 94℃for 10 min,followed by 35 cycles of 1 min at 94℃,1 min at 48℃and 1.5 min at 72℃,and a final extension of 10 min at 72℃.The CO 1 region with approximately 650 bp was amplified because of its capability to differentiate taxa.Sequencing was done by Macrogen while phylogenetic analysis was produced using a Molecular Evolutionary Genetics Analysis(MEGA)software version 6.0.The findings showed that CO1 can be used as a DNA marker in molecular identification of the fish samples.Samples from two of the four lakes were successfully sequenced.From basic local alignment search tool(BLAST)results,the maximum parsimony(MP)and neighbor-joining(N J)trees revealed that samples from Lakes Buhi and Bato are not species of Sinarapan but rather species of Leiopotherapon plumbeus and Rhinogobius giurinus,respectively.Furthermore,DNA barcoding is very useful in proving the true identity of unknown samples.展开更多
The most striking contrasts that are found on the continents in paleogeographic reconstructions of the end of the Mesozoic era are the occurrence on the place of the disappeared humid subtropics of the largest Gobi De...The most striking contrasts that are found on the continents in paleogeographic reconstructions of the end of the Mesozoic era are the occurrence on the place of the disappeared humid subtropics of the largest Gobi Desert in Eurasia with air temperatures falling below 50°from the freezing point and annual precipitation totals at the level of 100 mm. Science does not know the processes that can lead to a cooling of the atmosphere at 70°and other equally radical changes in nature with a stable position of the blocks of the earth’s crust in space. Changes in the environment of this magnitude can only be the result of land moving northward for a distance equal to about half the radius of the Earth. Titanosaurs, described by the remains in the Gobi deposits, had a body volume, which at modern gravity corresponds to a mass of 10 to 30 ton. However, animals with such a mass and such growth could not exist now. To create the necessary pressure in the vessels and provide energy to the body, Mongolian sauropods would need a heart of 2 - 3 m in diameter. Known types of muscle tissue are unable to maintain an elongated neck and head with a mass of more than a ton. The femur bones of four-legged dinosaurs had strength sufficient to move on land only animals weighing no more than 5 - 7 tons. The bones of giant bipedal dinosaurs at a constant gravitational field would have to be subjected to specific loads, several times greater than the bones of modern elephants, which is excluded. The natural conclusion about the action of a lesser gravity in the Mesozoic provides a solution to the mystery of the truly global spread in that era of bipedal mode of movement as the most energy efficient.展开更多
Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes i...Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes in desert ecosystems, however, has received little attention in that regard. In this study, we conducted a quantitative field survey （including 187 sampling plots） in a 40-km2 study area to determine the spatial pattern of plant species diversity and analyze the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China. A total of 42 plant species belonging to 16 families and 39 genera were recorded. Shrub and semi-shrub species generally represented the major part of the plant communities （covering 90% of the land surface）, while annual and perennial herbaceous species occupied a large proportion of the total recorded species （71%）. Patrick richness index （R）, Shannon-Wiener diversity index （H）, Simpson＇s dominance index （D）, and Pielou＇s evenness index （I） were all moderately spadaUy variable, and the variability increased with increasing sampling area. The semivariograms for R and H＇ were best fitted with Gaussian models while the semivariograms for D andJ were best fitted with exponential models. Nugget-to-still ratios indicated a moderate spatial autocorrelation for R, H＇, and D while a strong spatial autocorrelation was observed for J. The spatial patterns of R and H＇ were closely related to the geographic location within the study area, with lower values near the oasis and higher values near the mountains. However, there was an opposite trend for D. R, H＇, and D were significantly correlated with elevation, soil texture, bulk density, saturated hydraulic conductivity, and total porosity （P〈0.05）. Generally speaking, locations at higher elevations tended to have higher species richness and diversity and the higher elevations were characterized by higher values in sand and gravel contents, bulk density, and saturated hydraulic conductivity and also by lower values in total porosity. Furthermore, spatial variability of plant species diversity was dependent on the sampling area.展开更多
According to the need of popular land surface process models, characteristics and rules of some key land surface process and soil parameters over Gobi in typical arid region of Northwest China are analyzed by using th...According to the need of popular land surface process models, characteristics and rules of some key land surface process and soil parameters over Gobi in typical arid region of Northwest China are analyzed by using the data observed during the intensive observation period of the Dunhuang Land–Surface Process Field Experiment (DLSPFE) (May–June 2000). Using the relative reflection as weighting factor, the weighted mean of the surface albedo over Dunhuang Gobi in typical arid region is calculated and its values are 0.255 ± 0.021. After canceling the interference of the buildings, the mean values of the roughness length averaged with logarithm is 0.0019 ± 0.00071 m. After removing the influence of the oasis, the soil wetness factor computed with data under condition of no precipitation is 0.0045. After removing the influence of the precipitation , the mean values of the soil heat capacity over Dunhuang Gobi in typical arid region is 1.12 × 10<SUP>6</SUP> J m<SUP>−3</SUP>K<SUP>−1</SUP>, a bit smaller than the values observed in HEIFE. But the soil heat diffusivity and conductivity are about one of those observed in HEIFE. The soil water content over Dunhuang Gobi in typical synoptic condition is very little and does not exceed 1% basically.展开更多
Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCA...Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCAR nonhydrostatic mesoscale model MM5 Version 3. The horizontal grid resolution is set as 1km. By comparing the simulation results with HEIFE observations, it is proved that the model can be used to simulate the surface energy and water mass exchange of arid and semiarid regions in NWC. Based on the above results, the influence of different oasis scales on the local atmospheric field near the ground surface, and the critical scale of oasis maintenance, in NWC are studied dynamically. The following conclusion is obtained: the local thermal circulation between the oasis and the desert/Gobi is formed in the oasis downstream if the oasis scale is larger than 4 km. This local thermal circulation between the oasis and the desert adjacent to the oasis helps to conserve water vapor over the oasis. At the same time, it transfers the abundant water vapor from the oasis into the desert/Gobi near to the oasis to supply relatively plentiful water vapor for desert crops to grow on the fringe of the oasis. So, it is advantageous for oasis extension. However, if the scale of the oasis is smaller than 4 km, it is not easy for the local thermal circulation between the oasis and the desert/Gobi to take shape. This study provides a new standpoint for oasis maintenance and development.展开更多
The parameterization of surface turbulent fluxes over the Gobi Desert in arid regions is studied by using rationally screened observational data. First, the characteristics of Monin-Obukhov similarity functions are an...The parameterization of surface turbulent fluxes over the Gobi Desert in arid regions is studied by using rationally screened observational data. First, the characteristics of Monin-Obukhov similarity functions are analyzed and their empirical formulae are fitted. The results show that fitted curves of changes of similarity functions of wind speed and temperature with stability parameter differ little from the typical empirical curves and are within the ranges of scatter of the empirical curves, but their values in the neutral condition arc different from the typical values to some extent. Furthermore, average values of momentum and scalar (sensible heat) roughness lengths as well as changes of scalar roughness length with friction velocity are determined by utilizing the data. It is found that the average values of scalar roughness length are about one order smaller than that of the momentum roughness length and decrease with increasing friction velocity, but they are evidently larger than their theoretically forecasted values.展开更多
By utilizing the data observed at Dunhuang during August and September 2000 in the 'Field Experiment on Interaction between Land and Atmosphere in the Arid Region of Northwest China (FEILARNC)', the characteri...By utilizing the data observed at Dunhuang during August and September 2000 in the 'Field Experiment on Interaction between Land and Atmosphere in the Arid Region of Northwest China (FEILARNC)', the characteristics of the soil moisture, temperature, and atmospheric humidity are analyzed. It is found that the thickness of the soil temperature active layer is about 5 cm and much thinner than is typical, that not only the atmospheric humidity gradient is often inverted but also the soil moisture gradient in the shallow layer in the Gobi near oasis, that the diurnal variation of soil moisture can be divided into the four stages that are called the wet stage, the losing-water stage, the dry stage, and the attaining-water stage. It is shown that in soil moisture profiles, the depth of the soil moisture active layer is about 10 cm and soil moisture inversion is the main feature in the shallow layer during the wet stage. Such a feature as soil moisture inversion indicates that soil in the shallow layer can inhale moisture from the air through condensation in the nighttime and exhale moisture to the air through evaporation in the daytime. The condensation and evaporation constitute together the full respiration process of moisture on the ground. The formation of soil moisture inversion is related with the state of soil temperature and moisture, the intensity of atmospheric humidity inversion, and the atmospheric thermodynamic stability.展开更多
The lithology of the strata in the Gobi region of the Xinjiang autonomous region of China is mainly composed of mudstone,silty mudstone,and other soft rocks.Because of the low strength of the rock mass and the serious...The lithology of the strata in the Gobi region of the Xinjiang autonomous region of China is mainly composed of mudstone,silty mudstone,and other soft rocks.Because of the low strength of the rock mass and the serious effects of physical weathering in this area,the slope stability in open-pit mines is poor,and creep deformation and instability can readily occur.Taking the Dananhu No.2 open-pit mine as a typical example,the creep test of a mudstone sample under different stress levels was studied.Then,based on a bottom friction experiment and a FLAC3D numerical simulation,the deformation and failure processes of the slope were analyzed.The stress–displacement curve and the displacement–time curve for the monitoring points were plotted to obtain the relationship between the stress and displacement for the slope of the soft rock.The results showed that the long-term strength of the mudstone was between 8.0 and 8.8 MPa,and that stable creep occurred when the slope was under low stress.The potential failure mode for this type of slope is that the front edge creeps along the weak layer and then a crack is formed at the trailing edge of the slope.When the crack penetrates the weak layer,cutting bedding and bedding sliding occur.The deformation process of the stable creep slope includes an initial deformation stage,an initial creep stage,a constant velocity creep stage and a deceleration creep stage.展开更多
基金Supported by the National Key Research and Development Program of China(No.2019YFD0900704)the Yantai Key Research and Development Program(No.2019XDHZ097)+2 种基金the National Natural Science Foundation of China(No.42076137)the Natural Science Foundation of Shandong Province(No.ZR2020QD003)the Shandong Key Laboratory of Coastal Environmental Processes,YICCAS(No.2019SDHADKFJJ16)。
文摘We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018,gobies and sediments were collected from 15 stations.We measured the activities of defense enzymes and the contents of malondialdehyde(MDA)and metallothionein(MT)in the goby liver as well as the levels of heavy metals in the sediments and goby muscle tissue.Most of the heavy metal concentrations in sediment at each station were below the Class I criteria set by Chinese Standards for Marine Sediment Quality,and the Håkanson ecological risk index suggested low risk for the heavy metals.We found that A.ommaturus could eff ectively accumulate mercury,cadmium,arsenic,and zinc and that the contents of MT and MDA and the activities of glutathione peroxidase and glutathione reductase were suitable biomarkers of heavy metal pollution in this species.The IBRv2 method integrated these four biomarkers and discriminated stations according to heavy metal pollution.Higher IBRv2 values suggested more adverse eff ects in gobies,corroborating more serious heavy metal contamination.The stations with high IBRv2 values and high contents of heavy metals were mainly distributed in the west and northeast parts of the bay.These results show that the IBRv2 approach is a feasible strategy for assessing heavy metal pollution through biological response and biological status and that it can be implemented for environmental monitoring in Laizhou Bay.
文摘Biological invasions cause major ecological and economic costs in invaded habitats. The round goby Neogobius me- lanostomus is a successful invasive species and a major threat to the biodiversity and ecological function of the Baltic Sea. It is native to the Ponto-Caspian region and has, via ballast water transport of ships, invaded the Gulf of Gdansk in Poland. Since 1990, it has spread as far north as Raahe in Northern Finland （64~41 ＂04＂N, 24~28＂44＂E）. Over the past decade, consistent indi- vidual differences of behavioral expressions have been shown to explain various ecological processes such as dispersal, survival or reproduction. We have previously shown that new and old populations differ in personality trait expression. Individuals in new populations are bolder, less sociable and more active than in old populations. Here we investigate if the behavioral differentiation can be explained by phenotype-dependent dispersal. This was investigated by measuring activity, boldness and sociability of in- dividually marked gobies, and subsequently allowing them to disperse in a system composed of five consecutive tanks connected by tubes. Individual dispersal tendency and distance was measured. Our results revealed that in newly established populations, more active individuals disperse sooner and that latency of a group to disperse depends on the mean sociability of the group. This indicates the presence of personality dependent dispersal in this species and that it is maintained at the invasion front but lost as the populations get older
文摘The karyotype of Caspian goby was studied, which has been identified as Caspian bighead goby-Neogobius gorlap before. The results of cytogenetic analyses have shown that the diploid set of goby varies from 38 to 40 chromosomes, which is different from bighead goby （2n = 43-46）. We assumed that Caspian goby has independence as a species.
基金Supported by the National Natural Science Foundation of China(NSFC)(Nos.40976084,U1406403,41121064)
文摘We tested the use of otolith shape analysis to discriminate between species and stocks of five goby species( Ctenotrypauchen chinensis, Odontamblyopus lacepedii, Amblychaeturichthys hexanema, Chaeturichthys stigmatias, and Acanthogobius hasta) found in northern Chinese coastal waters. The five species were well differentiated with high overall classification success using shape indices(83.7%), elliptic Fourier coefficients(98.6%), or the combination of both methods(94.9%). However, shape analysis alone was only moderately successful at discriminating among the four stocks(Liaodong Bay, LD; Bohai Bay, BH; Huanghe(Yellow) River estuary HRE, and Jiaozhou Bay, JZ stocks) of A. hasta(50%–54%) and C. stigmatias(65.7%–75.8%). For these two species, shape analysis was moderately successful at discriminating the HRE or JZ stocks from other stocks, but failed to effectively identify the LD and BH stocks. A large number of otoliths were misclassified between the HRE and JZ stocks, which are geographically well separated. The classification success for stock discrimination was higher using elliptic Fourier coefficients alone(70.2%) or in combination with shape indices(75.8%) than using only shape indices(65.7%) in C. stigmatias whereas there was little difference among the three methods for A. hasta. Our results supported the common belief that otolith shape analysis is generally more effective for interspecific identification than intraspecific discrimination. Moreover, compared with shape indices analysis, Fourier analysis improves classification success during inter- and intra-species discrimination by otolith shape analysis, although this did not necessarily always occur in all fish species.
基金The National Natural Science Foundation of China under contract Nos 42171069 and 41976121.
文摘Despite most eel gobies(Gobionellidae:Amblyopinae)have inhabited brackish or marine waters,few species(such as Taenioides sp.)have been found to invade multiple inland freshwaters via artificial water transfer projects.The habitat transfers from brackish water to freshwater zones of Taenioides sp.have caused severe damage to Chinese aquatic ecosystems in recent years.Unfortunately,the molecular mechanism underlying freshwater invasion remains poorly understood.Considering changes of environmental factors,especially salinity,are bound to adjust the demands for energy affected by mitochondria via oxidative phosphorylation,13 Amblyopinae mitogenomes were compared,including the newly assembled Taenioides sp.mitogenome in this study.Comparative mitogenomic analyses revealed a highly conserved structure,composition and arrangements,with the exception of variable control region(CR).All of the CRs possessed tandem repeat sequences except Trypauchenopsis sp.G341,differing in motifs and number of copies,which was the dominant factor resulting in length heterogeneity of CR.The phylogenetic trees reconfirmed the paraphyletic origin of Amblyopinae with respect to Oxudercinae,supporting that these two subfamilies should be merged as an expansion of phenotypic variation within the“terrestrial goby”clade.Furthermore,four protein coding genes(COI,ND3,ND5 and Cyt b)in Taenioides sp.mitogenome have experienced adaptive evolution,indicating their important roles in enhancing the efficiency of ATP production to cope with the osmotic regulation adjustment and reach its current widespread distribution in multiple inland freshwaters of China.These results revealed the functional importance of mitochondrial genes,and provided fresh insights into the molecular mechanisms underlying the freshwater invasion.Also,our results may provide critical reference value for the future control of other invasive species.
基金supported by the National Key R&D Plan(2019YFD0902102 and 2019YFE01223000)Innovation Team Project of Marine Aquaculture Modern Agricultural Industry System in Tianjin City(ITTMRS2021005).
文摘In order to clarify the mitochondrial bar code sequence and taxonomic information of common goby fish in Tianjin coastal marine areas,seven species of goby fish were collected from Tianjin coastal marine areas,identified by morphology,and DNA was extracted for amplification and sequencing of mitochondrial COI gene fragments.Phylogenetic analysis and molecular identification software MEGA were used to analyze the sequence characteristics and molecular classification of COI gene fragments of 12 common goby species in Tianjin coastal marine areas.Seven COI gene fragments of Goby were amplified and sequenced,the average GC content was lower than AT content,the base had a bias in the codon position distribution,and the highest GC content was the second base,which was similar to the COI gene base of many fishes.The codon base variation rate was 19.4%,and the ratio of transitions to transversions was 1.3.Phylogenetic distance analysis and phylogenetic tree analysis clarified the phylotaxonomic and evolutionary relationships of 12 major goby species in Tianjin coastal marine areas.Genetic distance indicates that Amblychaeturichthys hexanema and Synechogobius ommaturus are the same species.The high codon variation rate of codon encoding gene in Goby may be related to its good environmental adaptability.
文摘Dunhuang,located in the northwestern part of China,is a town that feels like it's carved out of the pages of a history book.Nestled at the edge of the Gobi Desert in China's Gansu Province,this ancient oasis city has been a crossroads of cultures,religions,and trade for over 2,000 years.
基金funded by the National Natural Science Foundation of China(U23A2063)the Gansu Province Top-notch Leading Talents Project(E339040101)the National Natural Science Foundation of China(41771290,42377043,41773086).
文摘Tenebrionid beetles represent a crucial arthropod taxon in the Gobi desert ecosystems owing to their species richness and high biomass,both of which are essential for maintaining ecosystem health and stability.However,the spatiotemporal variations of tenebrionid beetle assemblages in the Gobi desert remain poorly understood.In this study,the monthly dynamics of tenebrionid beetles in the central part of the Hexi Corridor,Northwest China,a representative area of the Gobi desert ecosystems,were monitored using pitfall trapping during 2015-2020.The following results were showed:(1)monthly activity of tenebrionid beetles was observed from March to October,with monthly activity peaking in spring and summer,and monthly activity periods and peak of tenebrionid beetle species exhibited interspecific differences that varied from year to year;(2)spatial distribution of tenebrionid beetle community was influenced by structural factors.Specifically,at a spatial scale of 24.00 m,tenebrionid beetle community was strongly and positively correlated with the dominant species,with distinct spatial distribution patterns observed for Blaps gobiensis and Microdera kraatzi alashanica;(3)abundance of tenebrionid beetles was positively correlated with monthly mean precipitation and monthly mean temperature,whereas monthly abundance of B.gobiensis and M.kraatzi alashanica was positively correlated with monthly mean precipitation;and(4)the cover of Reaumuria soongarica(Pall.)Maxim.and Nitraria sphaerocarpa Maxim.had a positive influence on the number of tenebrionid beetles captured.In conclusion,monthly variation in precipitation significantly influences the community dynamic of tenebrionid beetles,with precipitation and shrub cover jointly determining the spatial distribution pattern of these beetles in the Gobi desert ecosystems.
文摘In the vast hinterland of the Qinghai-Xizang Plateau in western China,a profound green transformation is advancing quietly.On the vast Gobi Desert,arrays of solar panels resemble a shimmering silver sea.White wind turbines stand tall against the sky,with their blades swirling slowly in the wind.Golmud,a city in west China’s Qinghai Province formerly known for its abundant natural resources.
基金financially supported by the Chang Jiang Scholar and Innovation Team Development Plan of China(IRT_15R29)the Basic Research Innovation Group Project of Gansu Province,China(21JR7RA347)the Natural Science Foundation of Gansu Province,China(20JR10RA231)。
文摘The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.
基金funded by the National Natural Science Foundation of China(42071014).
文摘Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi surfaces.It is challenging to describe these processes according to a uniform morphology.Therefore,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3D)size and shape of gravel.Collecting morphology information for Gobi gravels is essential for studying its genesis and sand saltation.To enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3D parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3D parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain size.Leveraging multi-view geometry technology for 3D reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear quality.Additionally,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point clouds.Advanced point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3D parameters of individual gravels.These systematic processes allow precise and detailed characterization of individual gravels.For gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodology for measuring 3D parameters of individual gravels.The proposed workflow yields accurate calculations of relevant parameters for Gobi gravels,providing essential data support for subsequent studies on Gobi environments.
基金The work on which this review article is based has been funded by grants from the Research Council of Norway [Gram Nos. 133553, 146744, 166596, and 178444], the Norwegian University of Science and Technology, the Norwegian Academy of Science and Letters, the Royal Swedish Academy of Sciences, the Nordic Marine Academy, the EU Transnational Access to Research Infrastructures Scheme, the Nordic Council program NORDFORSK, and the National Science Foundation [USA, Grant No. OISE/0701086].
文摘Our understanding of sexual selection has greatly improved during the last decades. The focus is no longer solely on males, but also on how female competition and male mate choice shape ornamentation and other sexually selected traits in females. At the same time, the focus has shifted from documenting sexual selection to exploring variation and spatiotemporal dynamics of sexual selection, and their evolutionary consequences. Here, I review insights from a model system with exceptionally dynamic sexual selection, the two-spotted goby fish Gobiusculus flavescens. The species displays a complete reversal of sex roles over a 3-month breeding season. The reversal is driven by a dramatic change in the operational sex ratio, which is heavily male-biased at the start of the season and heavily female-biased late in the season. Early in the season, breeding-ready males outnumber mature females, causing males to be highly competitive, and leading to sexual selection on males. Late in the season, mating-ready females are in excess, engage more in courtship and aggression than males, and rarely reject mating opportunities. With typically many females simultaneously courting available males late in the season, males become selective and prefer more colorful females. This variable sexual selection regime likely explains why both male and female G. flavescens have ornamental colors. The G. flavescens model system reveals that sexual behavior and sexual selection can be astonishingly dynamic in response to short-term fluctuations in mating competition. Future work should explore whether sexual selection is equally dynamic on a spatial scale, and related spatiotemporal dynamics.
文摘The paper aimed to determine the true identity of a presumed or commonly believed Sinarapan fish and compare their phylogenetic relationships by using DNA barcoding.The fish samples were collected by researchers from a fisheries research and development institution in April 2015 from four different lakes of Bicol Region,i.e.,Lakes Buhi,Danao,Manapao and Bato.DNA was extracted using cetyl trimethyl ammonium bromide(CTAB)extraction buffer.The polymerase chain reaction(PCR)profile for the reaction was 94℃for 10 min,followed by 35 cycles of 1 min at 94℃,1 min at 48℃and 1.5 min at 72℃,and a final extension of 10 min at 72℃.The CO 1 region with approximately 650 bp was amplified because of its capability to differentiate taxa.Sequencing was done by Macrogen while phylogenetic analysis was produced using a Molecular Evolutionary Genetics Analysis(MEGA)software version 6.0.The findings showed that CO1 can be used as a DNA marker in molecular identification of the fish samples.Samples from two of the four lakes were successfully sequenced.From basic local alignment search tool(BLAST)results,the maximum parsimony(MP)and neighbor-joining(N J)trees revealed that samples from Lakes Buhi and Bato are not species of Sinarapan but rather species of Leiopotherapon plumbeus and Rhinogobius giurinus,respectively.Furthermore,DNA barcoding is very useful in proving the true identity of unknown samples.
文摘The most striking contrasts that are found on the continents in paleogeographic reconstructions of the end of the Mesozoic era are the occurrence on the place of the disappeared humid subtropics of the largest Gobi Desert in Eurasia with air temperatures falling below 50°from the freezing point and annual precipitation totals at the level of 100 mm. Science does not know the processes that can lead to a cooling of the atmosphere at 70°and other equally radical changes in nature with a stable position of the blocks of the earth’s crust in space. Changes in the environment of this magnitude can only be the result of land moving northward for a distance equal to about half the radius of the Earth. Titanosaurs, described by the remains in the Gobi deposits, had a body volume, which at modern gravity corresponds to a mass of 10 to 30 ton. However, animals with such a mass and such growth could not exist now. To create the necessary pressure in the vessels and provide energy to the body, Mongolian sauropods would need a heart of 2 - 3 m in diameter. Known types of muscle tissue are unable to maintain an elongated neck and head with a mass of more than a ton. The femur bones of four-legged dinosaurs had strength sufficient to move on land only animals weighing no more than 5 - 7 tons. The bones of giant bipedal dinosaurs at a constant gravitational field would have to be subjected to specific loads, several times greater than the bones of modern elephants, which is excluded. The natural conclusion about the action of a lesser gravity in the Mesozoic provides a solution to the mystery of the truly global spread in that era of bipedal mode of movement as the most energy efficient.
基金financially supported by the National Natural Science Foundation of China(91025018)the Action Plan for West Development Project of Chinese Academy of Sciences(KZCX2-XB3-13)
文摘Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes in desert ecosystems, however, has received little attention in that regard. In this study, we conducted a quantitative field survey （including 187 sampling plots） in a 40-km2 study area to determine the spatial pattern of plant species diversity and analyze the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China. A total of 42 plant species belonging to 16 families and 39 genera were recorded. Shrub and semi-shrub species generally represented the major part of the plant communities （covering 90% of the land surface）, while annual and perennial herbaceous species occupied a large proportion of the total recorded species （71%）. Patrick richness index （R）, Shannon-Wiener diversity index （H）, Simpson＇s dominance index （D）, and Pielou＇s evenness index （I） were all moderately spadaUy variable, and the variability increased with increasing sampling area. The semivariograms for R and H＇ were best fitted with Gaussian models while the semivariograms for D andJ were best fitted with exponential models. Nugget-to-still ratios indicated a moderate spatial autocorrelation for R, H＇, and D while a strong spatial autocorrelation was observed for J. The spatial patterns of R and H＇ were closely related to the geographic location within the study area, with lower values near the oasis and higher values near the mountains. However, there was an opposite trend for D. R, H＇, and D were significantly correlated with elevation, soil texture, bulk density, saturated hydraulic conductivity, and total porosity （P〈0.05）. Generally speaking, locations at higher elevations tended to have higher species richness and diversity and the higher elevations were characterized by higher values in sand and gravel contents, bulk density, and saturated hydraulic conductivity and also by lower values in total porosity. Furthermore, spatial variability of plant species diversity was dependent on the sampling area.
基金This research was sponsored by the National Key Program for Developing Basic Sciences Research on the Formation Mechanism and Pr
文摘According to the need of popular land surface process models, characteristics and rules of some key land surface process and soil parameters over Gobi in typical arid region of Northwest China are analyzed by using the data observed during the intensive observation period of the Dunhuang Land–Surface Process Field Experiment (DLSPFE) (May–June 2000). Using the relative reflection as weighting factor, the weighted mean of the surface albedo over Dunhuang Gobi in typical arid region is calculated and its values are 0.255 ± 0.021. After canceling the interference of the buildings, the mean values of the roughness length averaged with logarithm is 0.0019 ± 0.00071 m. After removing the influence of the oasis, the soil wetness factor computed with data under condition of no precipitation is 0.0045. After removing the influence of the precipitation , the mean values of the soil heat capacity over Dunhuang Gobi in typical arid region is 1.12 × 10<SUP>6</SUP> J m<SUP>−3</SUP>K<SUP>−1</SUP>, a bit smaller than the values observed in HEIFE. But the soil heat diffusivity and conductivity are about one of those observed in HEIFE. The soil water content over Dunhuang Gobi in typical synoptic condition is very little and does not exceed 1% basically.
基金supported by the National Natural Science Foundation of China under Grant Nos.40233035,and 40075022the Innovative Project of the Chinese Academy Sciences (No.KZCX3-SW-329).
文摘Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCAR nonhydrostatic mesoscale model MM5 Version 3. The horizontal grid resolution is set as 1km. By comparing the simulation results with HEIFE observations, it is proved that the model can be used to simulate the surface energy and water mass exchange of arid and semiarid regions in NWC. Based on the above results, the influence of different oasis scales on the local atmospheric field near the ground surface, and the critical scale of oasis maintenance, in NWC are studied dynamically. The following conclusion is obtained: the local thermal circulation between the oasis and the desert/Gobi is formed in the oasis downstream if the oasis scale is larger than 4 km. This local thermal circulation between the oasis and the desert adjacent to the oasis helps to conserve water vapor over the oasis. At the same time, it transfers the abundant water vapor from the oasis into the desert/Gobi near to the oasis to supply relatively plentiful water vapor for desert crops to grow on the fringe of the oasis. So, it is advantageous for oasis extension. However, if the scale of the oasis is smaller than 4 km, it is not easy for the local thermal circulation between the oasis and the desert/Gobi to take shape. This study provides a new standpoint for oasis maintenance and development.
基金This work was supported by the National Natu-ral Science Foundation of China under Grant No.40175004 and the National Key Program for Developing Basic Sci-ences of China under Grant No.G1998040904-2.
文摘The parameterization of surface turbulent fluxes over the Gobi Desert in arid regions is studied by using rationally screened observational data. First, the characteristics of Monin-Obukhov similarity functions are analyzed and their empirical formulae are fitted. The results show that fitted curves of changes of similarity functions of wind speed and temperature with stability parameter differ little from the typical empirical curves and are within the ranges of scatter of the empirical curves, but their values in the neutral condition arc different from the typical values to some extent. Furthermore, average values of momentum and scalar (sensible heat) roughness lengths as well as changes of scalar roughness length with friction velocity are determined by utilizing the data. It is found that the average values of scalar roughness length are about one order smaller than that of the momentum roughness length and decrease with increasing friction velocity, but they are evidently larger than their theoretically forecasted values.
基金the National Nat-ural Science Foundation of China(No.40175004)and theNational Key Program for Developing Basic Sciences ofChina(No.G1998040904-2).
文摘By utilizing the data observed at Dunhuang during August and September 2000 in the 'Field Experiment on Interaction between Land and Atmosphere in the Arid Region of Northwest China (FEILARNC)', the characteristics of the soil moisture, temperature, and atmospheric humidity are analyzed. It is found that the thickness of the soil temperature active layer is about 5 cm and much thinner than is typical, that not only the atmospheric humidity gradient is often inverted but also the soil moisture gradient in the shallow layer in the Gobi near oasis, that the diurnal variation of soil moisture can be divided into the four stages that are called the wet stage, the losing-water stage, the dry stage, and the attaining-water stage. It is shown that in soil moisture profiles, the depth of the soil moisture active layer is about 10 cm and soil moisture inversion is the main feature in the shallow layer during the wet stage. Such a feature as soil moisture inversion indicates that soil in the shallow layer can inhale moisture from the air through condensation in the nighttime and exhale moisture to the air through evaporation in the daytime. The condensation and evaporation constitute together the full respiration process of moisture on the ground. The formation of soil moisture inversion is related with the state of soil temperature and moisture, the intensity of atmospheric humidity inversion, and the atmospheric thermodynamic stability.
基金The work was Supported by State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Beijing(No.SKLGDUEK1923)National Key Research and Development Program(No.2018YFC0808301).
文摘The lithology of the strata in the Gobi region of the Xinjiang autonomous region of China is mainly composed of mudstone,silty mudstone,and other soft rocks.Because of the low strength of the rock mass and the serious effects of physical weathering in this area,the slope stability in open-pit mines is poor,and creep deformation and instability can readily occur.Taking the Dananhu No.2 open-pit mine as a typical example,the creep test of a mudstone sample under different stress levels was studied.Then,based on a bottom friction experiment and a FLAC3D numerical simulation,the deformation and failure processes of the slope were analyzed.The stress–displacement curve and the displacement–time curve for the monitoring points were plotted to obtain the relationship between the stress and displacement for the slope of the soft rock.The results showed that the long-term strength of the mudstone was between 8.0 and 8.8 MPa,and that stable creep occurred when the slope was under low stress.The potential failure mode for this type of slope is that the front edge creeps along the weak layer and then a crack is formed at the trailing edge of the slope.When the crack penetrates the weak layer,cutting bedding and bedding sliding occur.The deformation process of the stable creep slope includes an initial deformation stage,an initial creep stage,a constant velocity creep stage and a deceleration creep stage.
