The modes and its implications of water accumulation near the freezing front during soil freezing with considering ice segregation北大核心CSCD

Water accumulation associated with water migration is closely related with the ice segregation,but their coupling relationship is still unclear. To decoupling the relationship of water accumulation and ice segrega⁃ tion,herein,the dynamics of water migration and ice segregation during the freezing and thawing of different soil types under different water supplying conditions have been investigated based on pore water pressure mea⁃ surement and layer-scanning technique. Results showed that apparent water accumulation near the freezing front during the freezing of silty clay and loess tested here,but there exist differences in modes. During loess freezing under closed system,no ice segregation was observed,the pore water pressure increased,and there existed ap⁃ parent liquid water accumulation during the early stage of freezing;while during the freezing of silty clay,there existed ice segregation,the pore water pressure decreased,and no apparent liquid water accumulation occurred during the early stage of freezing. The results implied that there exist two modes of water accumulation near the freezing front during soil freezing：one is the water accumulation induced by water pressure gradient induced by pore ice which results in water flowing from the frozen zone and unfrozen zone to the location near the freezing front;the other is the water accumulation induced by cryo-suction of segregation ice which results in the water flowing from the unfrozen zone to the location near the freezing front. Notably,the contribution from each mode associated with water accumulation of soil freezing depends on whether the ice segregation exists. As no ice seg⁃ regation forms,water accumulation induced water pressure gradient predominates during the early stage of freez⁃ ing. As there exists ice segregation during freezing,water accumulation induced cryo-suction predominates dur⁃ ing the later stage of freezing. Investigating on different modes of water accumulations will be helpful for the ex⁃ ploring the mechanisms of freeze-thaw diseases and the ground ice in the cold regions. © 2023 Chinese Journal of General Practitioners. All rights reserved.     

Organic carbon and its oxidation stability characteristics of shallow soil in frozen soil area of Three River Source Region北大核心CSCD

As the most important part of the global carbon cycle,soil carbon pool is the largest carbon pool in terrestrial ecosystems. Soil carbon pool in permafrost regions is the most sensitive carbon pool to climate change. Weak climate change will have a huge impact on the organic carbon production in the shallow soil,and then affect the regional landscape and ecology. As an indicator reflecting the antioxidant capacity of soil organic carbon,oxidation stability affects the quantity and quality of soil organic carbon,and its variation has a certain regularity in the alpine permafrost region under the influence of climatic factors. In order to explore the distribution characteristics of soil organic carbon and its oxidation stability in frozen soil,based on the experimental data and the climatic data from 2011 to 2019,the random forest model was used to conduct multi-factor digital mapping on soil organic carbon content,soil organic carbon components with different oxidation difficulty degrees,and soil organic carbon oxidation stability coefficient and environmental variables（average annual precipitation,average annual sunshine hours,average annual air temperature,and altitude）and analyze the controlling factors. The results showed that the model had an interpretation degree of more than 54% for the shallow soil organic carbon in frozen soil area of Three River Source Region,and the digital mapping could reflect the distribution of soil organic carbon well. Soil organic carbon was mainly affected by precipitation and sunshine duration,and temperature took second place. The spatial distribution of components with different oxidation difficulty is different,but the oxidation stability has the distribution characteristics of high in the north and low in the south. Cold and dry are conducive to improving the oxidation stability of organic carbon in shallow soil of frozen soil area. © 2022 Science Press (China).     

Research status and prospect of tensile strength of frozen soil北大核心CSCD

A comprehensive grasp of the research status of tensile strength of frozen soil is the basis for further research. Firstly,the typical methods that can be used to test the tensile strength of frozen soil are introduced,and the test conditions,sample forms and stress mechanism of different test methods are described in detail. The advantages and disadvantages of typical tensile strength test methods are compared and listed. Secondly,the research work and shortcomings based on different test methods are summarized. Then,the latest research progress of the influence of temperature,water content,loading（deformation）rate,soil quality and sample size on the change law of frozen soil tensile strength is comprehensively analyzed. Finally,it is proposed to develop and improve the research method and system of frozen soil tensile strength,and increase the testing research of warm frozen soil tensile strength,so as to obtain the prospect of more accurately simulating the tensile failure behavior of frozen soil. It is pointed out that the internal cause of the formation of the tensile strength and the tensile failure mechanism of frozen soil should be thoroughly revealed by combining the research methods of microstructure and digital image technology of frozen soil. Based on the multi-factor test,a more perfect prediction method of frozen soil tensile strength is explored. Meanwhile,expand the in-situ test research on the tensile strength of frozen soil,and strengthen the parallel research ideas of indoor and outdoor double tracks. Through the analysis of the research status and development trend at home and abroad,it provides reference and guidance for the experimental study of frozen soil tensile strength,the improvement of theoretical model of frost heave,geotechnical engineering design in cold regions and artificial freezing reinforcement engineering. © 2022 Science Press (China).     

Effects of aspects on soil environment and plant growth on the Qinghai-Tibet Plateau北大核心CSCD

The different aspects lead to great differences in the processes of water,heat,and energy balance,which further affect the soil environment and the growth of alpine plants. Based on an experimental study with eight aspects（abbreviated as octagonal platform）of Huashixia frozen soil observation base on the Qinghai-Tibet Plateau,the influence of aspects on soil environments and alpine vegetation growth was studied. The results showed that：（1）After 6 years,the soil temperature of each slope near the surface（10 cm and 30 cm depth）from high to low was as follows：south > southeast > southwest > west > east > northwest > northeast > north,that is,the relatively sunny slope（east,southeast,south and southwest）was higher than the relatively shady slope（west,northwest,north and northeast）. However,there was no significant difference in soil water con⁃ tent between the sunny slope and the shady slope at the depth of 0~30 cm. （2）The growth trend of aboveground vegetation（including plant height,coverage and aboveground biomass）on sunny slope was better than that on shady slope. The growth trend of underground vegetation（including root depth and underground biomass）on sunny slope was worse than that on shady slope. （3）In the depth of 0~10 cm,the content of soil organic carbon and total nitrogen on sunny slope was higher than that on shady slope. However,the content of total phosphorus on sunny slope was lower than that on shady slope. There was no significant difference in total potassium and available nutrients among different slopes（P>0. 05）. In general,the effect of temperature on vegetation growth and nutrient distribution is significant in alpine regions,and these findings provides an important reference for vegetation restoration and energy balance research in different aspects. © 2023 The Author(s).     

Long-term strength attenuation characteristics and yield criterion of frozen soil北大核心CSCD

Frozen soil is generally regarded as a strongly rheological geomaterial. The strength attenuation of frozen soil is an important inducement for disease and instability in subgrade engineering, pile engineering and artificial freezing construction. Few efforts have been made to investigate the attenuation characteristics of strength envelope surface for frozen soil under complex stress states experimentally and theoretically. Considering this, at a temperature of -6 ℃, a series of triaxial stress relaxation tests under various confining pressures were carried out on the frozen subgrade soil specimens at strength points. The degeneration of strength parameters and stress attenuation process of frozen soil under complex stress states were systematically studied. The degradation law and mechanism of cohesion and internal friction angle are synchronously revealed in the stress relaxation process. Testing results indicate that the stress relaxation process of compacted frozen soil is significantly influenced by confining pressure. The stress relaxation ratio is increasing linearly with the rise of confining pressure if the confining pressure is beyond 1. 5 MPa. The anti-relaxation ability of frozen soil is greatly reduced during high confining pressure conditions:the stress relaxation ratio of frozen soil is only 41. 94% under 1. 5 MPa, but exceeds 90. 30% under 16 MPa. The strength of frozen soil attenuates linearly with time in the semi-logarithmic coordinate system. When the confining pressure is higher than 1. 5 MPa, the strength attenuation rate of frozen soil increases with the rise of confining pressure. As the development of stress relaxation of frozen soil, cohesion decreases linearly but internal friction angle increases linearly with time in the semi-logarithmic coordinate system. It manifested that the cementation in frozen soil shows evident rheological features and it is a key inducement for strength attenuation. Moreover, the attenuation law and value of cohesion in frozen soil which is measured by triaxial stress relaxation test are similar to the spherical template indenter test results. This may provide a new test method for obtaining the long-term strength and cohesion of frozen soil. On the basis of test results, the stress states of frozen soil in all stress relaxation curves at 12 relaxation durations were captured, and the rate-dependent variation characteristics of strength envelope in p-q stress space were analyzed in detail. Under high confining pressures, the strength envelope of frozen soil shows different geometric features as time goes on. In addition to the decline of level, the strength surface exhibits clockwise rotation with time, and the third stage sharply decreases at first and then becomes flat. Based on the analysis of characteristics of experimental strength surface and evolution law of strength parameters during the stress relaxation process, a rate-dependent strength theory for frozen soil considering the stress relaxation effect is established in this paper. © 2022 Science Press (China). All rights reserved.     

The solution of the double-sphere model and experimental research of the longterm shear strength of frozen sand based on spherical template indenter test北大核心CSCD

The distribution of frozen soil in our country is very broad, and the area of permafrost alone accounts for 22. 4% of the total land area. As a special kind of soil, frozen soil has many properties that thawing soil does not have due to the influence of ice cement in the soil. Among the many properties of frozen soil, the deformation and strength of frozen soil are the basic problems affecting engineering construction in frozen soil areas. The spherical template indenter test is widely used in the test of the mechanical properties of frozen soil because of its simple test process and relatively accurate test results. Compared with the conventional triaxial test or direct shear test, the test process of the spherical template indenter test is simple and easy to implement, the test period is short, and the sample preparation requirements are low. The advantage of effective cohesion is more significant. Therefore, based on the spherical template indenter test of the frozen soil, this paper estimates the strength and mechanical index of the soil through the indentation depth of the spherical template indenter test, and establishes the relationship between the force of the sample and the indentation depth of the indenter test. The specific test method is as follows:take the water-saturated frozen sandy soil made of different particle size groups(the moisture content of the sample is affected by the particle size in the saturated state)as the research object, study the variation law of the depth of the frozen soil sample pressed into the soil by the spherical indenter with time under the conditions of different fixed loads. By comparing and referring to the frozen sands of each particle size group, the long-term equivalent cohesion of the frozen sands of different particle size groups is summarized. The change law of force(long-term shear strength)with time, and the research method of elastic mechanics to solve space problems, summed up the mutual conversion between the depth St of spherical template indenters pressed into frozen sand samples under different fixed load test conditions relation. The research results show that the long-term shear strength of frozen sand based on the spherical mold test is positively correlated with its particle size. At the same time, since the ice content of frozen soil samples is proportional to its particle size, the long-term shear strength of frozen sand is also proportional to the test. The ice content of the sample increases year-on-year;the long-term shear strength of the frozen sand is related to the maximum contact pressure on the contact surface between the frozen soil and the indenter during the test, which can be expressed as Ct = γq0. The size of the relationship coefficient γ is inversely proportional to the diameter of the spherical indenter. In this paper, the spherical indenter is selected as 22 mm, and γ=3. 82×10-3. By establishing the relationship between the maximum contact pressure q0 and the long-term shear strength Ct When the maximum contact pressure q0 is the same under different fixed loads, the long-term shear strength Ct is also the same. According to this, the depth curve and the freezing depth of the frozen sand pressed into the soil by the spherical indenter over time under different fixed loads can be converted. Long-term shear strength curve of frozen sandy soil with time. It has been verified by experiments that the conversion curve of the depth of the indenter pressed into the soil with time under a fixed load of 7. 0 kg is highly consistent with the measured curve of the depth of the indenter pressed into the soil with time under a fixed load of 5. 1 kg and 7. 0 kg. © 2022 Nanjing Forestry University. All rights reserved.     

Numerical analyses of uplift behavior of pile foundation for transmission line structure in frozen soil regions北大核心CSCD

Pile foundation is one of the most commonly used and suitable foundations to support transmission line structure, especially in seasonally frozen soil regions and permafrost regions. Axial compression is the controlling condition in the design of foundations for such structures as bridges and buildings, while uplift and overturning will control the design of transmission line structure foundations. This paper presents an extensive overview of previous studies including experimental (e. g., laboratory model test and full-scale field load test), analytical/theoretical (e. g., limit equilibrium and limit analysis based on plasticity)and numerical(e. g., finite difference and finite element methods). The review indicates that study on the uplift behavior of pile foundation in frozen soil is relatively limited, particularly in the case of combined effect of axial uplift and lateral loading. Interaction between pile and frozen soil and mechanism of load transfer along the pile shaft and around the pile tip still remain unclear. Therefore, this paper implements finite difference analysis within FLAC3D to investigate the behavior of pile foundation in frozen silty clay and gravelly sand under axial uplift behavior and the effect of ground condition and lateral loading on the uplift behavior. Because of the axisymmetric condition of the problem studied, only half of the model is simulated. The chosen domain of the medium is discretized into a set of quadrilateral elements and the pile is discretized by the cylinder element. The interaction between the soil and pile is considered according to interface elements. Mohr-Coulomb criterion is adopted to model the soil behavior (perfectly elastic-plastic), while the pile is simply considered as a rigid body. The soil parameters such as Young’s modulus, cohesion and internal friction angle used for numerical analyses are determined by laboratory tests and estimated according to the empirical correlations with in-situ tests. The present numerical modeling is verified with the results from field loading tests on pile foundations in Qinghai-Tibet ±550 kV transmission line project. On this basis, parametric studies are carried out to uncover the behavior of pile in frozen soil. It is observed that pullout is the dominant failure mechanism of pile and the uplift load-displacement curve clearly exhibits an asymptote, consisting of initially linear elastic, nonlinear transition, and finally linear regions. These results are consistent with the observations in a few previous studies. In addition, larger uplift capacity of pile foundation in freezing period and gravelly sand is gained (about 20%). Lateral loading increases the deflection and therefore, decreases the uplift capacity of pile foundation. For the convenience of using the results obtained in practice, the values of uplift factor for pile foundation in silty clay and gravelly sand are provided. Finally, it should be noted that the method used, and the results obtained in the current work could be useful for engineers and designers, at least providing them some qualitative evidence for pile design in seasonally frozen soil regions and permafrost regions. This is important and necessary to ensure the safety of construction in such regions. Meanwhile, numerical analyses in the current work can be a benchmark example for subsequent research studies. © 2022 Science Press (China).     

Changes in surface soil mositure during freeze-thaw process under different vegetated status using Sentinel-1A in Beiluhe北大核心CSCD

Beiluhe basin lies in a permafrost region where is located in the interior of Tibetan Plateau. Ecosystem in the area is subjected to the freeze-thaw process of the active tjaele,and there is conspicuous correlation between soil moisture（SM）and vegetation coverage. To retrieve the soil moisture content of Beiluhe basin with a total area of 2 037. 94 km2,a synergistic method,which combined improved water cloud model,Oh,Dubois and Topp model,was presented in this paper base on Sentinel-1A multi-polarization SAR and Landsat-8 time series images data. The accuracy was validated with the in-situ point SM data：Adjusted-R2 of the regression equation is 0. 6848,and RMSE is 0. 039 cm3·cm-3. The analysis of correlation among freeze-thaw process,SM and vegetation cover from macro watershed scale manifests：Vegetation coverage has a significant delayed effect on the freeze-thaw process of the active tjaele,that is,the higher vegetation coverage,the more lagging freeze-thaw time;These study results are basically consistent with predecessors in-situ observation data,verifying the feasibility of studying correlation among soil freeze-thaw process,SM,and vegetation coverage from the macro watershed scale based on Sentinel-1A annual time series data. © 2022 Science Press (China).     

Research advances in passive microwave remote sensing of surface freeze-thaw state北大核心CSCD

Soil freeze-thaw cycles have important effects on surface water and energy balance,and then affect vegetation growth,soil water content,carbon cycle and terrestrial ecosystem. Passive microwave plays an important role in monitoring global and regional surface freeze-thaw processes due to its high temporal resolution,abundant data and sensitivity to soil moisture. With the launch of passive microwave sensors at home and abroad,it provides conditions for the study of permafrost interannual variation,seasonal variation,diurnal variation and long time series of near-surface soil freeze-thaw cycle. In recent years,the study of surface freeze-thaw cycle using passive microwave data has gradually increased. Based on previous studies,this paper summarizes the types of passive microwave remote sensing data and the characteristics of the bands contained in them. Expounded the principle of passive microwave monitoring data used for freezing and thawing,focus on passive microwave data in five categories in the study of freezing and thawing monitoring algorithms,including double index algorithm,the decision tree algorithm,freeze-thaw discriminant algorithm,seasonal threshold algorithm and based on the freezing L-band relative factors discriminant algorithm threshold,and analysis of 5 kinds of algorithms are compared;The freeze-thaw products based on different algorithms and passive microwave data were combed. Finally,the problems and future research directions of passive microwave remote sensing in surface freeze-thaw applications are summarized. In the acquisition of passive microwave data,it is found that the passive microwave data is missing due to the physical characteristics of the sensor,the shape and orbit of the earth,and the low resolution of passive microwave data leads to the low precision of freeze-thaw discrimination. For the problem of missing passive microwave data,it is proposed to use the average value of passive microwave data before and after two days to fill the missing brightness temperature data,or establish statistical function to complement the missing data. For the problem of low passive microwave resolution,the current development trend is to scale down based on passive microwave data and combine with multiple data products,such as ground temperature and active microwave data,or perform probability discrimination on surface freezing-thawing state in pixels,so as to better describe surface freeze-thaw state. In terms of the algorithm for discriminating surface freezing-thawing,based on the problem that dual-index algorithm,decision tree algorithm,freezing-thawing discriminant algorithm and seasonal threshold algorithm cannot accurately distinguish snow and frozen soil,this paper proposes to adopt the method of data assimilation or start from the snow radiation and frozen soil dielectric model. Optimization of the algorithm for the snow covered surface can further improve the accuracy of freeze-thaw classification. Based on existing freeze-thaw products,Although SMAP freeze-thaw products continue to be updated,SAMP satellite was launched late,and SAMP freeze-thaw products have a short time series. In the future,the time span of this algorithm for freezing-thawing products can be extended by combining L-band data provided by SMOS satellite. The problems mentioned above and the direction of further research are of great significance for improving the accuracy of freezing and thawing discrimination and improving the understanding of the variation law of freezing and thawing cycles,and also have certain research space. © 2022 Science Press (China).     

冻融试验对土中含水量分布的影响

The silty clay and silty loam are two typical soil types obtained from two test sites along the Qinghai-Tibet railway. The two types of soil have been designed various initial dry densities, water eontents, temperature conditions in repeated freezing and thawing tests with free access to water at the bottom. Afterfreeze-thaw cycles, the moisture content in the freeze-thaw zone increases more than that in the unfrozen zone to the peak approximately at the top of the samples. With comparison of the water contents in the frozen and thawed states, the moisture content in the upper freeze-thaw zone in the frozen state is greater than that in the thawed state, while that in unfrozen zone in the frozen state is smaller than that in the thawed state. Within the region of the frost front, the water content in frozen state is smaller than that in thawed state. These findings help to study the freeze-thaw mechanisms deeply and perfect the forecasting module of moisture transferring in freeze-thaw cycles.     

冻胀过程与冻结缘特性

The complex process of soil freezing which relates to moisture field, temperature and stress field usually accompanies water migration and crystallization. The mechanism of water migration in the -frozen fringe is blurry though there have rather mature theory analyzing water migration in the unfrozen zone and fully-frozen zone. It is a visualized and easy method to calculate the potential gradient of frozen fringe by frost heave amount, the duration of the steady state of frost heaving and the coefficient of permeability based on the Darcy penetration theory, not directly considering water driving force, ice segregation temperature and the thickness of frozen fringe. The method is feasible by comparing the calculated amount of frost-heaving with the test data.     

A Promising style of growth velocity model of green algae and diatoms in local lake area

A serious and difficult problem confronting those water plants which use reservoirs as water resources is how to predict the time when algae bloom would happen. A series of experiments have been designed and finished after efforts of nearly one year, and achieved some important and useful regulations which can do great help to the problem. In order to study the correlation between changes of several typical indices and growth regulation, algae were cultivated in an artificial environment. The raw water of these experiments came from subsurface water at the Dashahe Reservoir in Guangdong Province, China. During the cultivating process, it strictly controlled original indexes as trophic factors, ecological factors and topographic factors, and has successfully achieved 64 sets of experiment data, which indicate some suggested conclusions. Water temperature and light intensity are the prime inducements of algae bloom when water environment is nutritionally sufficient. It has proved that original trophic status, light intensity and water temperature have important effects on algae growth velocity. It has analyzed different algae growth velocities due to different original total nitrogen and total phosphorus, as well as light intensity, and used the data of algae biomass in lag phase and log phase to study the correlation between time and algal biomass with SPSS software. Results indicated that both under different original nutritional conditions and under different light intensities, the relationship between algae biomass and time matches an exponential function very well. So, it proposes a very promising style algal growing velocity model, which can be expressed as：dDdt = kent. According to the model, original trophic status, light intensity and water temperature will affect the concrete values of variants k and n.     

Numerical Simulation of Moisture Movement in Unsaturated Expansive Soil Slope Suffering Permeationq

This study develops a way of analyzing moisture movement in unsaturated expansive soil slope. The basic equations and the integrated finite difference method for moisture movement in unsaturated soils are briefly described, and the calculation code MFUS2 has been developed. The moisture movements in unsaturated expansive soil slopes suffering precipitation were simulated numerically. The simulation results show that expansion or contraction must be taken into account in an analysis model. A simplified equivalent model for calculating rainwater infiltration into expansive soil slopes has been developed. The simplified equivalent model divides the soil slope into two layers according to the extent of weathering of the soil mass at depth. Layer Ⅰ is intensively weathered and moisture can be fully evaporated or rapidly absorbed. The moisture movement parameters take into account the greater soil permeability caused by fissures. Layer Ⅱ is unweathered and the soil is basically undisturbed. The moisture movement parameters of homogeneous soils are applicable. The moisture movements in unsaturated ex- pansive soil slopes suffering precipitation were simulated numerically using the simplified equivalent model. The simulation results show that the moisture movement in the expansive soil slope under rainfall permeation mainly takes place in the extensively weathered layer Ⅰ which closely simulates the real situation.     

Climate change and groundwater conditions in the Mekong Region–A review

Changes in the climatic system introduce uncertainties in the supply and management of water resources. The Intergovernmental Panel on Climate Change(IPCC) predicts an increase of 2 to 4 °C over the next 100 years. Temperature increases will impact the hydrologic cycle by directly increasing the evaporation of surface water sources. Consequently, changes in precipitation will indirectly impact the flux and storage of water in surface and subsurface reservoirs(i.e., lakes, soil moisture, groundwater, etc.). In addition, increases in temperature contribute to increases in the sea level, which may lead to sea water intrusions, water quality deterioration, potable water shortages, etc. Climate change has direct impacts on the surface water and the control of storage in rivers, lakes and reservoirs, which indirectly controls the groundwater recharge process. The main and direct impact of climate change on groundwater is changes in the volume and distribution of groundwater recharge. The impact of climate change on groundwater resources requires reliable forecasting of changes in the major climatic variables and accurate estimations of groundwater recharge. A number of Global Climate Models(GCMs) are available for understanding climate and projecting climate change.These GCMs can be downscaled to a basin scale, and when they are coupled with relevant hydrological models, the output of these coupled models can be used to quantify the groundwater recharge, which will facilitate the adoption of appropriate adaptation strategies under the impact of climate change.     

Effects of tree species and soil depths on ethylene and methane consumption in tropical and temperate forest soils

To date our knowledge is limited with regard to the responses of ethylene and methane consumption by forest soils to tree species and soil types, and to the effect of presence of ethylene on atmospheric methane consumption. The soils at depths from tropical and temperate forests in China were used to study the responses of ethylene and methane consumption to tree species and soil types. The ethylene and methane consumption by soils beneath each forest floor was measured under the same oxic conditions, along with main properties of forest soils. The accumulation of ethylene was studied in the soil slurry （soil/water, 1/2.5）. In temperate soils under spruce and birch forests, maximal consumption rates of ethylene and methane were observed in the 2.5-5.0 cm and 5.0-7.5 cm soil layers, respectively （P〈0.05）. However, a maximal consumption of both occurred in the 0-2.5 cm soil layer under temperate Korean pine forest （P〈0.05）. Contrary to temperate forest soils, there was a significant lower consumption of ethylene and methane in tropical forest soils at less than 20 cm depths under a seasonal rainforest and secondary rubber forest （P〈0.05）. Hence, the potential of ethylene and methane consumption in the 0-20 cm soil profile was variable with tree species and soil types. According to ethylene formation in the soil slurry, there was greater accumulation of ethylene in the 0-2.5 cm soil under temperate forests than under tropical forests, and its accumulation under spruce and birch forests was more than under Korean pine forest （P〈0.05）. The presence of extrinsic ethylene can significantly inhibit the consumption of atmospheric methane by forest soils.     

Analysis of water vapor characteristics in snowstorm process on the northern slope of Tianshan Mountains北大核心CSCD

Based on the daily precipitation data of 16 national meteorological observation stations on the north⁃ ern slope of Tianshan Mountains from 2000 to 2020（September to April the following year）,28 blizzard weath⁃ er processes were screened out. Then NCEP/NCAR reanalysis data and HYSPLIT model were used to simulate backward tracking of the water vapor during the snowstorm,analysis of the circulation background of the snow⁃ storm process on the northern slope of the Tianshan Mountains,as well as the main sources and transport of wa⁃ ter vapor and its contribution to the snowstorm. The research showed that the snowstorm area in the northern slope of the Tianshan Mountains was located on the right side of the axis of the southwest jet at 300 hPa high,the southwest airflow in front of the West Siberia trough at 500 hPa,the front convergence of the exit area of the southwest jet at low level at 700 hPa,and the convergence area of water vapor flux divergence and the overlap near the ground cold front area. The water vapor affecting the blizzard on the northern slope of the Tianshan Mountains mainly came from the Mediterranean Sea,the Black Sea and its vicinity,Southwest Asia,Central Asia,the Atlantic Ocean and its coasts,as well as the 850 hPa water vapor in Europe and northern Xinjiang. The water vapor from North America and other places had a relatively small contribution to the blizzard;after each water vapor source reaches the key area with the westerly airflow,under suitable circulation conditions. It mainly entered the blizzard area along the westward（southwest）and the northwest paths. But there were some differences between the layers. Based on the above characteristics,the structure of the source and transport of wa⁃ ter vapor in the snowstorm process on the northern slope of the Tianshan Mountains was established and the char⁃ acteristics of vapor transport at various heights were revealed. © 2023 The Author(s).     

中国西部降水中/D及相关气候研究(英文)

The spatial variation of δD in precipitation in West China is discussed in this paper, and the relationship between δD in precipitation and temperature is analyzed as well based on the measured δD in precipitation samples collected in 6 sites in West China during mainly the summer of 1996. δD in precipitation in West China shows an intensive spatial variation: lower in the south of the Tibetan Plateau and higher in the north of West China. Analysis shows that the low value of δD is caused by obvious impact of southwest monsoon, and a very high value is due to the regional water cycle in the arid regions. δD in precipitation in the interior of the continent shows a strong “temperature effect”, while not in the south of the Tibetan Plateau.     

Fractions and Bioavailability of Soil Inorganic Phosphorus in the Loess Plateau of China under Different Vegetations

Plants play an important role in soil phosphorus nutrition. However, the effect of plants on phosphorus nutrition in soils of the Loess Plateau of China is not well understood. This study was conducted to reveal the relationships between plants and phosphorus’ fractions and availability in the Loess Plateau of China. Twenty-two plant communities were surveyed and soil samples under different plant canopies were collected for the determination of soil properties and inorganic phosphorus fractionation. The results showed that Leguminosae and Lilaceae reduced pH and increased organic matter, cation exchange capacity, total and Olsen phosphorus in soils under their canopies, while Labiatae and Rosaceae increased pH and decreased organic matter, cation exchange capacity, total and Olsen phosphorus in soils under their canopies. The contents of Ca2P, Ca8P, Al-P and Fe-P were highly related with soil Olsen phosphorus. They were all higher in soils under Leguminosae and Lilaceae and lower in soils under Labiatae and Rosaceae. The results of this study indicate that Leguminosae and Lilaceae improved phosphorus nutrition in soils, yet Labiatae and Rosaceae impeded the improvement of phosphorus nutrition in soils under their canopies, which will be of more help to instruct vegetation restoration in the region and provide information for soil development.     

Advances on bioremediation of off-contaminated soil in cold region

Petroleum pollution in the soil is a common problem in the world. The pollution may not only cause resource waste, but also may result in environment destruction, biology subsistence crisis and human health damage gradually. Biological techniques can be used to remove and transfer petroleum contaminants in the soil. Bioremediation of petroleum-contaminated soil, which is cost-effective,safe and friendly to environment, is promising. Low temperatures and lack of available nutrients often limit the rate of microbial degradation of petroleum hydrocarbons in contaminated soils in cold region. Some scholars carried out bioremediation technology research on oily soil in cold area. Scientists attempted many measures to increase the temperature of the field. A multidisciplinary team of engineers, microbiologists and electricians has designed and installed a thermally （TIS） enhanced biopile in oil-contaminated soil in Prudhoe Bay, AK. Covered with a black plastic sheet, the pile can also improve temperature condition. Nutrient is another important factor affecting bioremediation. Because of the different constituents in the soil, the proportion of elements is different. To optimize nutrient amendments for the remediation of a long-term hydrocarbon-contaminated site at the Old Casey Station in Antarctica, results showed that the effects of nitrogen （and phosphorus） on microbial are evident. If the method of fertilizing inorganic nutrients is improper, salinity of the soil may be increased and the osmotic potential may be impacted. J.L.Walworth et al.     

Comparison of antimony behavior with arsenic under various soil redox conditions

Antimony （Sb） is a toxic element and belongs to group 15 of the periodic table, under arsenic （As）. The geochemical behavior of Sb in the environment is still largely unknown. Since the behavior of Sb in the environment depends on its oxidation state, Sb analysis in environmental samples requires quantitative measurement of Sb （Ⅲ） and Sb （Ⅴ）. The aim of this study is the speciation of Sb in both solid and water phases to understand the reaction and dynamics of Sb in soil-water system. Accordingly, we employed X-ray absorption fine structure （XAFS） analysis to determine the Sb and As species in soil in laboratory and natural systems, while we also determined the oxidation states in soil water by the conventional HPLC-ICP-MS method. Natural soil and soil water samples containing Sb and As were collected around the Ichinokawa mine pithead, Ehime, Japan. To observe the species under various redox conditions, the soil and soil water samples were collected at four depths. Soil containing Sb and As were incubated for 7 days at 25℃ to observe their oxidation states under various redox condition by changing the total amount of water in the soil. Antimony K-edge XAFS spectra were measured at the beamline BL01B 1 at SPring-8 （Hyogo, Japan） and K-edge XAFS spectra of As, Fe, and Mn at the beamline BL12C in Photon Factory, KEK （Thukuba, Japan）. In the natural soil-water system, Sb was present exclusively as Sb （Ⅴ） over a wide redox range （from Eh=-140 to 360 mV; pH 8）, while As was present as a mixture of As （Ⅲ） and As （Ⅴ）. This trend was confirmed in the laboratory experiments. These results suggest that Sb （Ⅴ） is a very stable form in the environment and that Sb is oxidized under more oxic condition than As. Combining the results of Fe and Mn XAFS analyses and a positive correlation among Sb, As, and Fe abundances in the soil, the host phases of Sb and As in soil were Fe （Ⅲ） hydroxide. EXAFS analyses of Sb and As are also consistent with this fact. Under reducing conditions, the concentrations of As in the soil water increased whereas those of Sb decreased in both the natural and laboratory systems.