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Study of thermal properties of supraglacial debris and degree-day factors on Lirung Glacier, Nepal
Mohan Bahadur Chand,Rijan Bhakta Kayastha
Sciences in Cold and Arid Regions    2018, 10 (5): 357-368.   DOI: 10.3724/SP.J.1226.2018.00357
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The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons. Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon (2013), winter (2013), and pre-monsoon (2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors (DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of ?20.81 °C/m, 4.05 °C/m, and ?7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.

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Measurement for coordinated development of "four modernizations" and its efficiency of prefecture level cities or above in China
JingHu Pan, YanXing Hu
Sciences in Cold and Arid Regions    2016, 8 (2): 163-176.   DOI: 10.3724/SP.J.1226.2016.00163
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The efficient and coordinated development of industrialization,urbanization,informatization and agricultural modernization(so called "Sihua Tongbu" in China,and hereinafter referred to as "four modernizations") is not only a practical need but also an important strategic direction of integrating urban-rural development and regional development in recent China.This paper evaluated the comprehensive,coupling and coordinated developmental indices of "four modernizations" of China's 343 prefecture-level administrative units,and calculated their efficiency of "four modernizations" in 2001 and 2011.The efficiency evaluation index system was established.The efficiencies and their changing trend during the period 2001-2011 were investigated using the data envelopment analysis(DEA) model.Spatial-temporal pattern of the efficiency of China's prefecture-level units was explored by using exploratory spatial data analysis(ESDA).Finally,the main influencing factors were revealed with the aid of geographically weighted regression(GWR) model.Results indicate that the comprehensive,coupling and coordinated developmental indices and efficiency of "four modernizations" of China's prefecture-level administrative units have obvious spatial differences and show diverse regional patterns.Overall,the efficiency is relatively low,and only few units with small urban populations and economic scale are in DEA efficiencies.The efficiency changing trends were decreasing during 2001-2011,with a transfer of high efficiency areas from inland to eastern coastal areas.The difference between urban and rural per capita investment in fixed assets boasts the greatest influence on the efficiency.
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Analysis of vegetation changes and dominant factors on the Qinghai-Tibet Plateau, China
HongWei Wang,Yuan Qi,ChunLin Huang,XiaoYing Li,XiaoHong Deng,JinLong Zhang
Sciences in Cold and Arid Regions    2019, 11 (2): 150-158.   DOI: 10.3724/SP.J.1226.2019.00150.
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This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change (GRC) and correlation factors, we analyzed the trend of vegetation change and its dominant factors from 2000 to 2015. The results indicate that the vegetation tended to improve from 2000 to 2015 on the Qinghai-Tibet Plateau, with the improved area accounting for 39.93% of the total; and the degraded area accounting for 19.32%. The areas of degraded vegetation are mainly concentrated in the low-relief and intermediate-relief mountains of the high-altitude and extremely high-altitude areas on the Qinghai-Tibet Plateau, as the vegetation characteristics are impacted by the terrain. Temperature and precipitation have obvious response mechanisms to vegetation growth, but the effects of precipitation and temperature on vegetation degradation are not significant over a short time frame. Overgrazing and population growth are the dominant factors of vegetation degradation on the Qinghai-Tibet Plateau.

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Altitude pattern of carbon stocks in desert grasslands of an arid land region
Rong Yang,JunQia Kong,ZeYu Du,YongZhong Su
Sciences in Cold and Arid Regions    2018, 10 (5): 404-412.   DOI: 10.3724/SP.J.1226.2018.00404
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For estimating the altitude-distribution pattern of carbon stocks in desert grasslands and analyzing the possible mechanism for this distribution, a detailed study was performed through a series of field vegetation surveys and soil samplings from 90 vegetation plots and 45 soil profiles at 9 sites of the Hexi Corridor region, Northwestern China. Aboveground, belowground, and litter-fall biomass-carbon stocks ranged from 43 to 109, 23 to 64, and 5 to 20 g/m2, with mean values of 80.82, 44.91, and 12.15 g/m2, respectively. Soil-carbon stocks varied between 2.88 and 3.98 kg/m2, with a mean value of 3.43 kg/m2 in the 0–100-cm soil layer. Both biomass- and soil-carbon stocks had an increasing tendency corresponding to the altitudinal gradient. A significantly negative correlation was found between soil-carbon stock and mean annual temperature, with further better correlations between soil- and biomass-carbon stocks, and mean annual precipitation. Furthermore, soil carbon was found to be positively correlated with soil-silt and -clay content, and negatively correlated with soil bulk density and the volume percent of gravel. It can be concluded that variations in soil texture and climate condition were the key factors influencing the altitudinal pattern of carbon stocks in this desert-grassland ecosystem. Thus, by using the linear-regression functions between altitude and carbon stocks, approximately 4.18 Tg carbon were predicted from the 1,260 km2 of desert grasslands in the study area.

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Review on simulation of land-surface processes on the Tibetan Plateau
Rui Chen,MeiXue Yang,XueJia Wang,GuoNing Wan
Sciences in Cold and Arid Regions    2019, 11 (2): 93-115.   DOI: 10.3724/SP.J.1226.2019.00093.
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The Tibetan Plateau (TP) has powerful dynamics and thermal effects, which makes the interaction between its land and atmosphere significantly affect climate and environment in the regional or global area. By retrospecting the latest research progress in the simulation of land-surface processes (LSPs) over the past 20 years, this study discusses both the simulation ability of land-surface models (LSMs) and the modification of parameterization schemes from two perspectives, the models' applicability and improved parameterization schemes. Our review suggests that different LSMs can well capture the spatiotemporal variations of the physical quantities of LSPs; but none of them can be fully applied to the plateau, meaning that all need to be revised according to the characteristics specific to the TP. Avoiding the unstable iterative computation and determining the freeze?thaw critical temperature according to the thermodynamic equilibrium equation, the unreasonable freeze?thaw parameterization scheme can be improved. Due to the complex underlying surface of the TP, no parameterization scheme of roughness length can well simulate the various characteristics of the turbulent flux over the TP at different temporal scales. The uniform soil thermodynamic and hydraulic parameterization scheme is unreasonable when it is applied to the plateau, as a result of the strong soil heterogeneity. There is little research on the snow-cover process so far, and the improved scheme has no advantage over the original one due to the lack of some related physical processes. The constant interaction among subprocesses of LSPs makes the improvement of a multiparameterization scheme yield better simulation results. According to the review of existing research, adding high-quality observation stations, developing a parameterization scheme suitable for the special LSPs of the TP, and adjusting the model structures can be helpful to the simulation of LSPs on the TP.

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Influence of frost weathering on the recession of surfaces of technogenic landforms in Yakutia
Andrey E. Melnikov,Nikolay N. Grib
Sciences in Cold and Arid Regions    2019, 11 (4): 257-266.   DOI: 10.3724/SP.J.1226.2019.00257.
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The article assesses the influence of permafrost weathering on the rate of destruction of technogenic land forms, as exhibited on as illustrated by the railway embankment of the Amur-Yakut mainline in the Sakha Republic (Yakutia). Studies were carried out on a railway section more than 375 km long. The subsidence rate of the embankment slopes and structural excavations was determined using laboratory methods that simulate various mechanisms of temperature (with a transition through 0 °C) impact on rocks. For the first time, a quantitative assessment of the influence of cryogenic weathering on the stability of the railway in the region belonging to the northern building-climatic zone is given. For the territory under consideration, embankment rocks were experimentally determined to undergo more than 100 freezing and thawing cycles during a year. Under the existing climatic conditions, cryogenic weathering actively affects the embankment of the railway to a depth of 30 cm. Most of the embankment deformations detected during field observations are due to defects in the integrity of this particular layer. The size of the disintegrating layer of particular types of rock comprising the railway embankment has been established as reaching 10 cm per year. In 5 years following the formation of embankments comprising the upper structure of the railroad tracks, the physical and mechanical properties of rocks, which initially had a tensile strength for uniaxial compression in the range of 40-70 MPa, were reduced by more than 50%. According to the authors, the establishment of regional cryohypergenesis features is universal in nature and can be applied to solving a wide range of tasks related to the assessment and prediction of the degree of cryogenic transformation of rocks having different structural properties.

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Seed germination and seedling growth of Pycnanthus angolensis (Welw.) Warb., African false nutmeg
Sakpere A.M.A.
Sciences in Cold and Arid Regions    2019, 11 (5): 350-359.   DOI: 10.3724/SP.J.1226.2019.00350.
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This study investigated the germination behavior and seedling growth of Pycnanthus angolensis seeds. The germination study was carried out in the laboratory and included pretreatment studies and observation of the seed-germination process. For each treatment, three replications of 20 seeds were sown in a transparent plastic germination box (12cm × 22cm × 5cm) lined with moistened filter paper at room temperature. To monitor seedling growth, seedlings were transplanted into pots filled with topsoil and laid out in a completely randomized design. Ten seedlings replicated thrice were measured monthly; and the shoot height, leaf area, and root length, as well as the fresh and dry weights of the seedlings, were recorded. Results showed that mechanically scarified seeds exhibited the significantly highest germination percent (83.33%, P <0.005), followed by control seeds (70.83%), whereas seeds treated with 98% sulphuric acid (H2SO4) displayed the lowest germination percent (1.67). The endospermous seeds exhibited cryptogeal germination, while seeds stored for a month (with or without arils) failed to germinate. During seed germination, radicle protrusion continued with a pseudo-opening of the root, through which the brownish cotyledonary petiole was emitted, thus releasing the plumule at the posterior position. Moreover, P. angolensis exhibited a slow growth rate, attaining a shoot height of 73 cm within a year. The highest positive change in leaf number and area was recorded in the fourth month, a period during which the least change in shoot height occurred. The study concluded that mechanical scarification of the seeds ensured significant and faster germination than chemical scarification or no treatment at all. Additionally, P. angolensis displayed a cryptogeal germination, with the seedling growth of the tree species observed to be slow.

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Origin and advances in implementing blowing-snow effects in the Community Land Model
ZeYong Hu,ZhiPeng Xie
Sciences in Cold and Arid Regions    2019, 11 (5): 335-339.   DOI: 10.3724/SP.J.1226.2019.00335.
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now cover on the Tibetan Plateau (TP) is closely related to regional and continental biological and hydrological processes. The vast snow cover, special climatic conditions, and sparse vegetative cover over the TP facilitate the occurrence of blowing snow, leading to substantial heterogeneities in the snow cover and great promotion in the moisture supply from the land surface to the overlying atmospheric boundary layer. However, blowing-snow processes are significantly misrepresented or even neglected in current models, which causes considerable uncertainties of numerical model simulations and leads to erroneous estimates of snow-related processes in mountainous terrain. We present in this paper a brief review of our work in the past 5 years to serve as a basis for further development and improvement of the land-surface model. These studies can be divided into three parts: detection of the problems, development of the land-surface model, and application of the coupled model over the TP (the logical framework is presented in Figure 1). The origin and advances in the development of a land-surface model with consideration of blowing-snow effects are described herein; and the importance of blowing-snow processes in the land-surface model, especially over the TP, is highlighted. We expect that the blowing-snow studies over the TP will play a key role in documenting and understanding the land-surface processes (LSPs) and the cryospheric changes over the TP.

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A mathematical approach to evaluate maximum frost heave of unsaturated silty clay
Lin Geng, XianZhang Ling, Liang Tang, Jun Luo, XiuLi Du
Sciences in Cold and Arid Regions    2017, 9 (5): 438-446.   DOI: 10.3724/SP.J.1226.2017.00438
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Maximum frost heave of unsaturated frost-susceptible soils, in conjunction with a high water table, is an important consideration for the design of foundations in seasonally frozen regions. Therefore, it is necessary to evaluate accurately and efficiently the maximum frost heave for a given soil. For this purpose, a series of one-sided freezing experiments was conducted on unsaturated silty clay in an open system. Multistage cooling of sufficient duration was applied to the soil sample's top, while constant above-zero temperatures were maintained at the bottom. Then, a simple methodology for calculating maximum frost heave at a given cooling temperature was derived utilizing information obtained within the limited time allotted for each stage. On this basis, an empirical equation for defining maximum frost heave as a function of cooling temperature and overburden pressure was determined. Overall, this study provides a simple and practical procedure that is applicable to the evaluation of maximum frost heave of unsaturated frost-susceptible soils.
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Stable isotopes reveal varying water sources of Caragana microphylla in a desert-oasis ecotone near the Badain Jaran Desert
Hai Zhou,WenZhi Zhao,ZhiBin He,Heng Ren
Sciences in Cold and Arid Regions    2018, 10 (6): 458-467.   DOI: 10.3724/SP.J.1226.2018.00458
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Understanding the variation in a plant's water sources is critical to understanding hydrological processes in water-limited environments. Here, we measured the stable-isotope ratios (δ18O) of xylem water of Caragana microphylla, precipitation, soil water from different depths, and groundwater to quantitatively analyze the proportion of water sources for the shrub. We found that the water sources of C. microphylla differed with the plant's ages and the seasons. The main water source for young shrubs was upper-soil water, and it showed significant changes with seasonal precipitation inputs. In summer, the proportion contributed by shallow water was significantly increased with increased precipitation inputs. Then, the contribution from shallow-soil water decreased with the decline in precipitation input in spring and autumn. However, the adult shrubs resorted to deep-soil layers and groundwater as the main water sources during the whole growing season and showed much less seasonal variation. We conclude that the main water source of the young shrubs was upper-soil water and was controlled by precipitation inputs. However, once the shrub gradually grew up and the roots reached sufficient depth, the main water sources change from the upper-soil layer recharged by precipitation to deep-soil water and groundwater, which were relatively stable and abundant in the desert ecosystem. These results also suggest that desert shrubs may be able to switch their main water sources to deep and reliable water sources as their age increases, and this adjustment to water availability carries significant importance for their acclimation to the desert habitat.

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Qualitative and quantitative phytochemical analysis of selected mosses with different alcoholic solvents
Kehinde O. Olasoji,Amos M. Makinde,Bolajoko A. Akinpelu,Musibau O. Isa
Sciences in Cold and Arid Regions    2019, 11 (5): 382-388.   DOI: 10.3724/SP.J.1226.2019.00382.
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This study was conducted to investigate the qualitative and quantitative phytochemical content of the crude extracts of Archidium ohioense, Pelekium gratum, and Hyophila involuta with different alcoholic solvents (ethanol, methanol, Seaman's Schnapps, fresh oil-palm wine, and fresh Raffia-palm wine). The mosses were collected from their natural populations on the central campus of the Obafemi Awolowo University, Ile-Ife, Nigeria. The yield of the extracts was weighed for all the solvents, and the qualitative and quantitative evaluations of the extracts were carried out using standard methods. The results of phytochemical analysis of the crude extracts from the mosses showed the presence of saponins, cardiac glycosides, triterpenes, alkaloids, flavonoids, and steroids. The quantitative phytochemical analysis of the crude extracts showed that ethanolic extracts of Hyophila involuta had the highest flavonoid content (288.37±0.10 mg RE/g), and Raffia-palm-wine extracts of Hyophila involuta had the highest saponin content (224.70±0.02 mg/g), while the methanolic extract of Archidium ohioense had the highest cardiac glycosides content (63.71±0.14 mg/g), and the Raffia-palm wine extract of Hyophila involuta had the highest alkaloids content (102.50±0.12 mg/g). Raffia- and oil-palm wines were observed to be the most effective solvents for all the mosses studied, followed by Seaman's Schnapp, while methanol and ethanol were less effective. The study concluded that the extracts of the mosses studied contain pharmacologically active constituents that can be used for therapeutic purposes.

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An evaluation of soil moisture from AMSR-E over source area of the Yellow River, China
TangTang Zhang,Mekonnen Gebremichael,Akash Koppa,XianHong Meng,Qun Du,Jun Wen
Sciences in Cold and Arid Regions    2019, 11 (6): 461-469.   DOI: 10.3724/SP.J.1226.2019.00461.
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In this study, in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture products from NASA (National Aeronautics and Space Administration), JAXA (Japanese Aerospace Exploration Agency) and VUA (Vrije University Amsterdam and NASA) over Maqu County, Source Area of the Yellow River (SAYR), China. Results show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area, with a minimum RMSE (root mean square error) of 0.08 (0.10) m3/m3 and smallest absolute error of 0.07 (0.08) m3/m3 at the grassland area with ascending (descending) data. Therefore, the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR. The VUA soil moisture product shows that soil moisture presents a declining trend from east south (0.42 m3/m3) to west north (0.23 m3/m3), with good agreement with a general precipitation distribution. The center of SAYR presents extreme wetness (0.60 m3/m3) during the whole study period, especially in July, while the head of SAYR presents a high level soil moisture (0.23 m3/m3) in July, August and September.

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Characterization of landscape pattern based on land economic niche change: A case study in Ganzhou, Gansu Province, China
HuaLi Tong, PeiJi Shi, XueBin Zhang, ZaiYan Li
Sciences in Cold and Arid Regions    2018, 10 (3): 261-270.   DOI: 10.3724/SP.J.1226.2018.00261
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Land use change has a profound impact on biodiversity and ecological processes, and is closely related to changes in landscape patterns. This paper introduces the theory and method of land economic niche into landscape ecology, which provides a new method for spatial characterization of urban and rural spatial landscape patterns. Based on this theory, this paper analyzes the landscape pattern of Ganzhou District by using Landsat images as data source in 1995, 2000, 2005, 2010 and 2015. We calculated the land economic niche by applying the niche potential theory. Combined with the theory of landscape ecology, we explored the effects of the land economic niche change on the landscape pattern at a county scale. The results show that economic niche of construction land, watershed and farmland increased during 1995-2015, and grassland declined significantly. The economic niche of farmland, construction land, watershed and grassland show a negative correlation with the number of patches (NP), fragmentation index (FN) and the fractal dimension index (FD), and had a positive correlation with the aggregation index (AI). There was no significant correlation between the forest land economic niche and landscape metrics. The change of land economic niche has a driving effect on the landscape pattern of the county, which can represent the economic development direction of Ganzhou District. The land economic niche is closely related to the landscape type which can directly obtain an economic benefit.
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Intersection-pavement de-icing: comprehensive review and the state of the practice
Yang ZhaoHui Joey
Sciences in Cold and Arid Regions    2019, 11 (1): 1-12.   DOI: 10.3724/SP.J.1226.2019.00001
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Winter maintenance operations are crucial for pedestrian and motorist safety and public mobility on urban streets and highways in cold regions, especially during winter storms. This study provides a comprehensive literature review of existing deicing technologies, with emphasis on electrical resistance-heating deicing technologies for possible applications in areas with concentrated traffic, such as street intersections and crosswalks. A thorough review of existing and emerging deicing technology for snow/ice melting was conducted. The performance of various deicing methods was evaluated and the installation and operation cost of the electrical resistance-heating methods compared. Finally, current state of the practice of intersection/crosswalk winter maintenance was surveyed among state departments of transportation in North America. The intersection/crosswalk winter maintenance procedure adopted by the State of Alaska Department of Transportation and Public Facilities was described, and the annual winter maintenance and operation cost per intersection was estimated. It was found that the annual energy cost of an electrical resistance-heating method such as the carbon-fiber-tape deicing technology is about the same as the average annual maintenance and operation cost of current practice. In addition, an automatic electrical resistance-heating deicing system will bring benefits such as minimized delay time and improved safety for pedestrian and vehicular traffic in an urban application.

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Soil freezing process and different expressions for the soil-freezing characteristic curve
JunPing Ren, Sai K. Vanapalli, Zhong Han
Sciences in Cold and Arid Regions    2017, 9 (3): 221-228.   DOI: 10.3724/SP.J.1226.2017.00221
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The soil-freezing characteristic curve (SFCC), which represents the relationship between unfrozen water content and sub-freezing temperature (or suction at ice-water interface) in a freezing soil, can be used for understanding the transportation of heat, water, and solute in frozen soils. In this paper, the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve (SWCC) of unfrozen unsaturated soil are reviewed. Based on similar characteristics between SWCC and SFCC, a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes. Various SFCC expressions from the literature are summarized. Four widely used expressions (i.e., power relationship, exponential relationship, van Genuchten 1980 equation and Fredlund and Xing 1994 equation) are evaluated using published experimental data on four different soils (i.e., sandy loam, silt, clay, and saline silt). Results show that the exponential relationship and van Genuchten (1980) equation are more suitable for sandy soils. The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes; however, it exhibits limitations when fitting the saline silt data. The Fredlund and Xing (1994) equation is suitable for fitting the SFCCs for all soils studied in this paper.
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Fossil Taiwannia from the Lower Cretaceous Yixian Formation of western Liaoning, Northeast China and its phytogeography significance
MingZhen Zhang,BaoXia Du,PeiHong Jin,BaiNian Sun
Sciences in Cold and Arid Regions    2018, 10 (6): 502-515.   DOI: 10.3724/SP.J.1226.2018.00502
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Fossil Taiwania was discovered from the Lower Cretaceous Yixian Formation of Lingyuan City, western Liaoning Province, Northeast China. It is identified as a new species, Taiwania lingyuanensis sp. nov.. The present specimen is preserved as impressions with well defined leaf shoots system and reproductive structures. Leaves are dimorphic, spirally and imbricately arranged. They are scale-like on the main and cone-bearing branchlets, and subulate to falcate-subulate on the juvenile or sterile shoots. The seed cones are singly elliptic, ovate or elongate-ovate and terminally borne on ultimate shoots, bearing 22–24 scale-bracts complexes imbricately and helically arranged around the cone axis, the bracts are broad-ovate, rhomboidal or hexagonal with entire margins. Both the leafy shoots morphology and reproductive structures are similar to extant Taiwania. Furthermore, geological distribution and molecular biological evidences support that Taiwania is probably originated from the eastern Asia at least in the Early Cretaceous and widely distributed in the North Hemisphere thereafter.

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An improvement of soil temperature simulations on the Tibetan Plateau
SiQiong Luo, BoLi Chen, ShiHua Lyu, XueWei Fang, JingYuan Wang, XianHong Meng, LunYu Shang, ShaoYing Wang, Di Ma
Sciences in Cold and Arid Regions    2018, 10 (1): 80-94.   DOI: 10.3724/SP.J.1226.2018.00080
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The simulation of soil temperature on the Tibetan Plateau (TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5 (CLM3.5) and Regional Climatic Model 4 (RegCM4). The improved CLM3.5 and RegCM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.
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Research on pile performance and state-of-the-art practice in cold regions
JianKun Liu, TengFei Wang, Zhi Wen
Sciences in Cold and Arid Regions    2018, 10 (1): 1-11.   DOI: 10.3724/SP.J.1226.2018.00001
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A pile foundation is commonly adopted in geotechnical engineering to support structures, and its application has been extended to cold-regions engineering. In past decades, a host of scholars investigated pile behaviors and proposed design guidelines for seasonally frozen ground or permafrost. This paper reviews the research with respect to pile performance and engineering practice in cold regions, organized as follows: (1) creep tests and bearing capacity, (2) frost-jacking hazards, (3) laterally loaded piles, (4) dynamic responses, (5) refreezing due to concrete-hydration heat, and (6) improved countermeasures and design methods. We first summarize previous research and recent progress; then, predict the development trend of pile foundations in cold regions and recommend further research.
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Spatial variations of Pb, As, and Cu in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica
XingXing Jiang, ShuGui Hou, YuanSheng Li, HongXi Pang, Rong Hua, Mayewski Paul, Sneed Sharon, ChunLei An, Handley Michael, Ke Liu, WangBin Zhang
Sciences in Cold and Arid Regions    2018, 10 (3): 219-231.   DOI: 10.3724/SP.J.1226.2018.00219
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The spatial distributions of lead, arsenic, and copper (Pb, As, and Cu, respectively) in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica, are presented. The mean concentrations of Pb, As, and Cu are 1.04±1.56 pg/g, 0.39±0.08 pg/g, and 11.2±14.4 pg/g, respectively. It is estimated that anthropogenic contributions are dominant for Pb, As, and Cu. Spatially, Pb concentrations show an exponentially decreasing trend from the coast inland, while a moderate decreasing trend is observed for Cu concentrations in the coastal area (below 2,000 m above sea level (a.s.l.)). In the intermediate area (2,000-3,000 m a.s.l.), the concentrations and enrichment factors of all these elements show high variability due to the complicated characteristics of climate and environment. On the inland plateau (above 3,000 m a.s.l.), the high concentrations of As and Pb are induced by high deposition efficiency, the existence of polar stratospheric precipitation, and the different fraction deposition to East Antarctica. The extremely high concentrations with maximum values of 9.59 pg/g and 69.9 pg/g for Pb and Cu, respectively, are suggested to result mainly from local human activities at the station. Our results suggest that source, transport pathway, and deposition pattern, rather than distance from the coast or altitude, lead to the spatial distributions of Pb, As, and Cu; and it is further confirmed by spatial variations of the three metals deposited over the whole continent of Antarctica.
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High-resolution mass spectrometric characterization of dissolved organic matter from warm and cold periods in the NEEM ice core
JianZhong Xu, Amanda Grannas, CunDe Xiao, ZhiHeng Du, Amanda Willoughby, Patrick Hatcher, YanQing An
Sciences in Cold and Arid Regions    2018, 10 (1): 38-46.   DOI: 10.3724/SP.J.1226.2018.00038
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Dissolved organic matter (DOM) is an important component of ice cores but is currently poorly characterized. DOM from one Holocene sample (HS, aged at 1600-4500 B.P.) and one Last Glacial Maximum sample (LS, aged at 21000-25000 B.P.) from the North Greenland Eemian Ice Drilling (NEEM) ice core were analyzed by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). CHO compounds contributed 50% of the compounds identified in negative-ionization mode in these two samples, with significant contributions from organic N, S, and P compounds, likely suggesting that marine DOM was an important source in these samples. Overall, the chemical compositions are similar between these two samples, suggesting their consistent DOM sources. However, subtle differences in the DOM between these two samples are apparent and could indicate differences in source strength or chemistry occurring through both pre- and post-depositional processes. For example, higher relative amounts of condensed carbon compounds in the HS DOM (5%), compared to the LS DOM (2%), suggest potentially important contributions from terrestrial sources. Greater incorporation of P in the observed DOM in the LS DOM (22%), compared to the HS DOM (13%), indicate more active microbiological processes that likely contribute to phosphorus incorporation into the DOM pool. Although these two samples present only a preliminary analysis of DOM in glacial/interglacial periods, the data indicate a need to expand the analysis into a broader range of ice-core samples, geographical locations, and glacial/interglacial periods.
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Laboratory and field performance of recycled aggregate base in a seasonally cold region
Tuncer B. Edil, Bora Cetin, Ali Soleimanbeigi
Sciences in Cold and Arid Regions    2017, 9 (3): 183-191.   DOI: 10.3724/SP.J.1226.2017.00183
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The objective of this project was to characterize the freeze-thaw properties of recycled concrete (RCA) and asphalt (RAP) as unbound base and to assess how they behaved in the field for nearly 8 years. This paper includes an examination of existing information, laboratory studies of freeze-thaw behavior, and evaluation of data from MnROAD field-test sections in a seasonally cold region, i.e., in Minnesota, USA. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. One test section included 100% RAP, another 100% RCA, a third one a 50/50 blend of RCA/natural aggregate, and a fourth one only natural aggregate (Class 5) as a control. The stiffness (i.e., elastic modulus) was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation, along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance. The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a, as well as by field-scale tests incorporating a falling-weight deflectometer. Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory, and the change in their resilient modulus was measured. In the field-test sections constructed with the same materials as the base course, temperature, moisture, and field modulus (from falling-weight deflectometer tests) were monitored seasonally for nearly 8 years. From the temperatures in the base course layer, the number of freeze-thaw cycles experienced in the field was determined for each test section. Inferences were made relative to modulus change versus freeze-thaw cycles. Conclusions were drawn for long-term field performances of the recycled base (RAB) in comparison to natural aggregate.
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The temporal and spatial variation of positive degree-day factors on the Koxkar Glacier over the south slope of the Tianshan Mountains, China, from 2005 to 2010
Min Xu, HaiDong Han, ShiChang Kang
Sciences in Cold and Arid Regions    2017, 9 (5): 425-431.   DOI: 10.3724/SP.J.1226.2017.00425
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The degree-day model is one important method to estimate glacier melt, which is based on the specific relationship between glacial melting and the sum of daily mean temperatures above the melting point. According to the observation data on the Koxkar Glacier (KG) from 2005 to 2010, we analyzed the temporal and spatial variation of degree-day factors (DDF) and its influential factors. The results indicate that the average value of DDF was 7.2~10.4 mm/(℃·d) on the KG from 2005 to 2010. It showed a decreasing trend between 3,700 m and 4,200 m, and the deceasing trend was more obvious in the upper part of the KG. On a spatial scale, the DDF increased evidently with increasing altitude. The DDF ranged from 3.6 to 9.3 mm/(℃·d) at 3,700 m a.s.l., with the average value of 9.3 mm/(℃·d). It varied from 6.9 to 13.0 mm/(℃·d) at 4,000 m a.s.l., with the average value of 10.2 mm/(℃·d). During the period of ablation, the fluctuation of DDF was not significant at the lower altitude (3,700 m a.s.l.), but it decreased at the higher altitudes (4,000 m a.s.l. and 4,200 m a.s.l.). The debris changes the transmission of heat, which accelerates the melting of a glacier; and the DDF showed high value. This paper will provide the reference for temporal-spatial parameterization schemes of DDF on Tuomuer glaciers of the Tianshan Mountains.
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Intrastorm stemflow variability of a xerophytic shrub within a water-limited arid desert ecosystem of northern China
YaFeng Zhang, XinPing Wang, YanXia Pan, Rui Hu
Sciences in Cold and Arid Regions    2017, 9 (5): 495-502.   DOI: 10.3724/SP.J.1226.2017.00495
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An increasing number of studies in recent years has elucidated distinguishable effects of stemflow on hydrology and biogeochemistry within a variety of ecosystems. Nonetheless, no known studies have investigated the temporal variability of stemflow volume within discrete rainfall events for xerophytic shrubs. Here, stemflow was monitored at 5-min intervals using a tipping-bucket rain gage during the 2015 growing season for a xerophytic shrub (Caragana korshinskii) within a water-limited arid desert ecosystem of northern China. We characterized the stemflow temporal variability, along with rainfall, and found the temporal heterogeneity of rainfall clearly affected the timing of stemflow inputs into basal soil within discrete rainfall events. The rainfall threshold value for stemflow generation is not a constant value but a range (0.6~2.1mm, with an average of 1.1 mm) across rainfall events and is closely associated with the antecedent dry period. Time lags existed between the onset of rainfall and the onset of stemflow, and between rainfall peaks and stemflow peaks. Our findings are expected to be helpful for an improved process-based understanding of the temporal stemflow yield of xerophytic shrubs within water-limited arid desert ecosystems.
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Cracking in an expansive soil under freeze–thaw cycles
Yang Lu, SiHong Liu
Sciences in Cold and Arid Regions    2017, 9 (4): 392-397.   DOI: 10.3724/SP.J.1226.2017.00392
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Expansive soils located in cold regions can easily endure the action of frost heaving and cyclic freezing–thawing. Cracking can also occur in expansive clayey soils under freeze–thaw cycles, of which little attention has been paid on this issue. In this study, laboratory experiment and cracking analysis were performed on an expansive soil. Crack patterns were quantitatively analyzed using the fractal concept. The relationships among crack pattern, water loss, number of freeze–thaw cycles, and fractal dimension were discussed. It was found that crack patterns on the surface exhibit a hierarchical network structure that is fractal at a statistical level. Cracks induced by freeze–thaw cycles are shorter, more irregularly oriented, and slowly evolves from an irregularly rectilinear pattern towards a polygonal or quasi–hexagonal one; water loss, closely related to specimen thickness, plays a significant role in the process of soil cracking; crack development under freeze-thaw cycles are not only attributed to capillary effect, but also to expansion and absorption effects.
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Soil hydraulic conductivity and its influence on soil moisture simulations in the source region of the Yellow River―take Maqu as an example
DongYu Jia,Jun Wen,Xin Wang,ZuoLiang Wang
Sciences in Cold and Arid Regions    2019, 11 (5): 360-370.   DOI: 10.3724/SP.J.1226.2019.00360.
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aturated hydraulic conductivity and unsaturated hydraulic conductivity which are influenced by soil are two important factors that affect soil water transport. In this paper, data supplied by the Chinese Academy of Sciences are used to determine true unsaturated hydrology values. Furthermore, in combination with observed, model simulation and experimental data, an improved saturated hydraulic conductivity parameterization scheme is carried out in CLM4.5 at a single point in the summer. The main results show that: (1) After improving saturated hydraulic conductivity in CLM4.5 through a parameterization modification, it is found that shallow layer soil moisture increases compared to the initial value; and (2) The numerical values of unsaturated hydraulic conductivities in the model are obviously larger than experimental values. By substituting the Brooks-Corey soil water characteristic curve into the Mualem model, the value of unsaturated hydraulic conductivity is modified; (3) By using the modified value, it is found that the attenuating magnitude of simulated soil moisture caused by each rainfall event is reduced. The soil moisture variation in shallow layers (5, 10 and 20 cm) could be better displayed.

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Effects of N:P ratio of Artemisia ordosica on growth influenced by soil calcium carbonate
YuTing Liang,XingDong He,JianTan Guo,HongJuan Jing
Sciences in Cold and Arid Regions    2018, 10 (4): 333-339.   DOI: 10.3724/SP.J.1226.2018.00333
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Soil calcium carbonate (CaCO3) has a strong solid phosphorus effect, and high content of CaCO3 can significantly reduce the effectiveness of soil phosphorus. To reveal the limiting effect of soil CaCO3 on the growth of plants on sand land and its mechanism of plant physiology, we performed pot experiments with a two-factor randomized block design and a three-factor orthogonal design for different soil CaCO3 content treatments using Artemisia ordosica seedlings. In the experiments, we surveyed plant height, aboveground biomass, root length and root weight and analyzed N, P concentrations and RNA content of the seedlings, and discussed the relationships between relative growth rate (RGR) of the seedlings and N:P ratio as well as RNA. Results show that, the RGRs of plant height and above-ground biomass of the seedlings decreased significantly with the increase of soil CaCO3 content, and those for root length and root weight decreased. The RGRs of plant height and above-ground biomass of the seedlings were significantly negatively correlated with leaf N:P ratios, but significantly positively correlated with leaf RNA content and leaf P concentrations. It can be seen that soil CaCO3 is a stress factor for the growth of A. ordosica seedlings, and the growth response of the seedlings under the influence of soil CaCO3 is in line with the Growth Rate Hypothesis.

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Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains, northern Northeast China
RuiXia He, HuiJun Jin, XiaoLi Chang, YongPing Wang, LiZhong Wang
Sciences in Cold and Arid Regions    2018, 10 (2): 104-113.   DOI: 10.3724/SP.J.1226.2018.00104
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The active-layer soils overlying the permafrost are the most thermodynamically active zone of rock or soil and play important roles in the earth-atmosphere energy system. The processes of thawing and freezing and their associated complex hydrothermal coupling can significantly affect variation in mean annual temperatures and the formation of ground ice in permafrost regions. Using soil-temperature and -moisture data obtained from the active layer between September 2011 and October 2014 in the permafrost region of the Nanweng'he River in the Da Xing'anling Mountains, the freeze-thaw characteristics of the permafrost were studied. Based on analysis of ground-temperature variation and hydrothermal transport characteristics, the thawing and freezing processes of the active layer were divided into three stages: (1) autumn-winter freezing, (2) winter freeze-up, and (3) spring-summer thawing. Variations in the soil temperature and moisture were analyzed during each stage of the freeze-thaw process, and the effects of the soil moisture and ground vegetation on the freeze-thaw are discussed in this paper. The study's results show that thawing in the active layer was unidirectional, while the ground freezing was bidirectional (upward from the bottom of the active layer and downward from the ground surface). During the annual freeze-thaw cycle, the migration of soil moisture had different characteristics at different stages. In general, during a freezing-thawing cycle, the soil-water molecules migrate downward, i.e., soil moisture transports from the entire active layer to the upper limit of the permafrost. In the meantime, freeze-thaw in the active layer can be significantly affected by the soil-moisture content and vegetation.
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Studies on eco-environmental change in source regions of the Yangtze and Yellow Rivers of China:present and future
JianPing Yang
Sciences in Cold and Arid Regions    2019, 11 (3): 173-183.   DOI: 10.3724/SP.J.1226.2019.00173.
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The source regions of the Yangtze and Yellow Rivers are important in the field of eco-environmental change research in China because of its distinct alpine ecosystem and cryosphere environment. At present, there are three different concepts on the extent of source areas of the Yangtze and Yellow Rivers: hydrological, geographical, and eco-environmental. Over the past decades, annual average air temperature has warmed significantly; moreover, the temperature rise rate increases notably with increase of time of the data series. Annual precipitation has no obvious increase or decrease trend, and the climate has become warm and dry in the source regions. As a result, the cryosphere in the regions has shrunk significantly since 1960s. A warm and dry climate and changing cryosphere together induced a substantial declination of alpine wetlands, marked decrease in river runoff, significant degradation of alpine grassland, and a reduction of engineering stability. The ecological environment, however, has a tendency for restoration in the regions because the climate has become gradually warm and wet since 2000. Thus, studies on eco-environmental change is transforming from a single element to multidisciplinary integration. Climate change-cryopshere change-physical and socioeconomic impacts/risk-adaptation constitute a chain of multidisciplinary integration research.

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Surface-deformation monitoring in the permafrost regions over the Tibetan Plateau, using Sentinel-1 data
ZhenMing Wu, Lin Zhao, Lin Liu, Rui Zhu, ZeShen Gao, YongPing Qiao, LiMing Tian, HuaYun Zhou, MeiZhen Xie
Sciences in Cold and Arid Regions    2018, 10 (2): 114-125.   DOI: 10.3724/SP.J.1226.2018.00114
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Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to measure surface deformation over the Tibetan Plateau. However, the accuracy and applicability of the D-InSAR method are not well estimated due to the lack of in-situ validation. In this paper, we mapped the seasonal and long-term displacement of Tanggula (TGL) and Liangdaohe (LDH) permafrost regions with a stack of Sentinel-1 acquisitions using the Small Baseline Subset InSAR (SBAS-InSAR) method. In the TGL region, with its dry soils and sparse vegetation, the InSAR-derived surface-deformation trend was consistent with ground-based leveling results; long-term changes of the active layer showed a settlement rate of around 1 to 3 mm/a due to the melting of ground ice, indicating a degrading permafrost in this area. Around half of the deformation was picked up on monitoring, in contrast with in-situ measurements in LDH, implying that the D-InSAR method remarkably underestimated the surface-deformation. This phenomenon may be induced by the large soil-water content, high vegetation coverage, or a combination of these two factors in this region. This study demonstrates that surface deformation could be mapped accurately for a specific region with Sentinel-1 C-band data, such as in the TGL region. Moreover, although the D-InSAR technology provides an efficient solution for broad surface-deformation monitoring in permafrost regions, it shows a poor performance in the region with high soil-water content and dense vegetation coverage.
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Numerical simulation of the climate effect of high-altitude lakes on the Tibetan Plateau
YinHuan Ao,ShiHua Lyu,ZhaoGuo Li,LiJuan Wen,Lin Zhao
Sciences in Cold and Arid Regions    2018, 10 (5): 379-391.   DOI: 10.3724/SP.J.1226.2018.00379
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Lakes regulate the water and heat exchange between the ground and the atmosphere on different temporal and spatial scales. However, studies of the lake effect in the high-altitude Tibetan Plateau (TP) rarely have been performed until recently, and little attention has been paid to modelling of frozen lakes. In this study, the Weather Research and Forecasting Model (WRF v. 3.6.1) is employed to conduct three numerical experiments in the Ngoring Lake Basin (the original experiment, an experiment with a tuned model, and a no-lake experiment) to investigate the influences of parameter optimization on the lake simulation and of the high-altitude lake on the regional climate. After the lake depth, the roughness lengths, and initial surface temperature are corrected in the model, the simulation of the air temperature is distinctly improved. In the experiment using a tuned model, the simulated sensible-heat flux (H) is clearly improved, especially during periods of ice melting (from late spring to early summer) and freezing (late fall). The improvement of latent-heat flux (LE) is mainly manifested by the sharp increase in the correlation coefficient between simulation and observation, whereas the improvement in the average value is small. The optimization of initial surface temperature shows the most prominent effect in the first year and distinctly weakens after a freezing period. After the lakes become grassland in the model, the daytime temperature clearly increases during the freezing and melting periods; but the nocturnal cooling appears in other stages, especially from September to October. The annual mean H increases by 6.4 times in the regions of the Ngoring Lake and the Gyaring Lake, and the LE declines by 56.2%. The sum of H and LE increases from 71.2 W/m2 (with lake) to 84.6 W/m2 (no lake). For the entire simulation region, the sum of H and LE also increases slightly. After the lakes are removed, the air temperature increases significantly from June to September over the area corresponding to the two lakes, and an abnormal convergence field appears; at the same time, the precipitation clearly increases over the two lakes and surrounding areas.

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Comparative foliar anatomy of three Khaya species (Meliaceae) used in Nigeria as antisickling agent
Ololade A. Oyedapo,Joseph M. Agbedahunsi,H. C Illoh,Akinwumi J. Akinloye
Sciences in Cold and Arid Regions    2018, 10 (4): 279-285.   DOI: 10.3724/SP.J.1226.2018.00279
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Khaya belongs to the family Meliaceae. In Nigeria the genus is represented by three species viz; K. senegalensis A. Juss., K. grandifoliola C. DC. and K. ivorensis A. Chev. Comparative foliar anatomy of the three Khaya species was carried out to identify and describe distinctive anatomical characters that could possibly be used to delimit the three taxa. Transverse section, epidermal peels and cleared leaves of these three species were made. Characteristic similarity and disparity in the tissues arrangement as well as cell inclusions were noted for description and delimitation. The three Khaya species studied had essentially the same anatomical features, e.g., venation pattern having open polygonal areoles and the veins terminals biforkated. However, there were characters that seem to be species specific, e.g., vien termination number and areole width. The leaf epidermal studies of the three species revealed similarities in stomatal type which are generally staurocytic, epidermal cells and undulating anticlinal cell walls but stomata density varied. Hexacytic stomata is only observed in the abaxial surface of K. grandifoliola which distinguished this species from the others. The leaf petiole shape of the three species are round and difficult to distinguish into adaxial and abaxial surfaces. The cuticle is striated, vascular bundles are heart shape, conjoint, concentric and amphivasal, but are different in epidermal and collenchyma cell layer numbers. The leaf transverse sections of the three Khaya species studied have conjoint, concentric and amphicribral bundles while the leaf cuticle of K. senegalensis and K. grandifoliola are striated but that of Khaya ivorensis is non-striated.

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Numerical analysis on the thermal regimes of thermosyphon embankment in snowy permafrost area
Yan Lu, Xin Yi, WenBing Yu, WeiBo Liu
Sciences in Cold and Arid Regions    2017, 9 (6): 580-586.   DOI: 10.3724/SP.J.1226.2017.00580
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Snow covers the road embankments in winter in high latitude permafrost zones. The effect of snow cover on embankments was simulated based on field measurements of boundary conditions and initial ground temperature profile in Mohe, China. The effect of thermosyphons on the embankment warmed by snow cover was evaluated by numerical simulations as well. The results indicate that the difference of thermal regimes between non-thermosyphon and thermosyphon embankments reaches to 22 m in depth below the ground surface. It is much warmer in the non-thermosyphon embankment body in winter. Affected by the snow cover, heat flux gradually spreads into the deep ground of the subgrade over time. The permafrost table under the slope toe of a thermosyphon embankment is 1.2 m higher than that of a non-thermosyphon embankment in the 20th year. In addition, the permafrost table at the slope toe of a thermosyphon embankment is 26 cm deeper over 20 years. These results indicate that thermosyphons can greatly weaken the warm effect of snow cover. However, thermosyphons cannot avoid the degradation of permafrost under the scenarios of snow cover. Therefore, composite measures need to be adopted to keep embankment stability in snowy permafrost zones.
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Numerical simulation of artificial ground freezing in a fluid-saturated rock mass with account for filtration and mechanical processes
Ivan A. Panteleev, Anastasiia A. Kostina, Oleg A. Plekhov, Lev Yu. Levin
Sciences in Cold and Arid Regions    2017, 9 (4): 363-377.   DOI: 10.3724/SP.J.1226.2017.00363
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This study is devoted to the numerical simulation of the artificial ground freezing process in a fluid-saturated rock mass of the potassium salt deposit. A coupled model of nonstationary thermal conductivity, filtration and thermo-poroelasticity, which takes into account dependence of the physical properties on temperature and pressure, is proposed on the basis of the accepted hypotheses. The considered area is a cylinder with a depth of 256 meters and diameter of 26.5 meters and includes 13 layers with different thermophysical and filtration properties. Numerical simulation was carried out by the finite-element method. It has been shown that substantial ice wall formation occurs non-uniformly along the layers. This can be connected with geometry of the freezing wells and with difference in physical properties. The average width of the ice wall in each layer was calculated. It was demonstrated that two toroidal convective cells induced by thermogravitational convection were created from the very beginning of the freezing process. The effect of the constant seepage flow on the ice wall formation was investigated. It was shown that the presence of the slow flow lead to the delay in ice wall closure. In case of the flow with a velocity of more than 30 mm per day, closure of the ice wall was not observed at all in the foreseeable time.
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Numerical simulation and experimental validation of moisture-heat coupling for saturated frozen soils
ZhiMing Li, Jian Chen, Kai Sun, Bin Zhang
Sciences in Cold and Arid Regions    2017, 9 (3): 250-257.   DOI: 10.3724/SP.J.1226.2017.00250
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In seasonally frozen regions, freezing-and-thawing action is the main cause responsible for the destruction of canals, which is closely linked to the temperature gradient and water transport. To investigate the behaviour of soils under freezing-and-thawing actions, many numerical models have been established that consider the important coupling of moisture transport and temperature evolution; but they contain excessive parameters, some of which are rather difficult to determine. Based on the well-known Harlan's theory, a simple moisture-heat coupling model was recently proposed to quantify the coupled moisture-heat transport performance of soils in terms of the central temperature and porosity. The mathematical module of COMSOL Multiphysics was further employed to solve the governing equations numerically. To validate our model, a thorough experimental scheme was carried out in our lab. The measured temperature distribution was found to be consistent with the predicted results.
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Analysis of chaotic climatic process in the Tarim River Basin (I)
ZuHan Liu
Sciences in Cold and Arid Regions    2019, 11 (5): 340-349.   DOI: 10.3724/SP.J.1226.2019.00340.
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Based on observational data obtained from 1961 to 2011 in the Tarim River Basin, China, we investigated the chaotic dynamics of temperature, precipitation, relative humidity, and evaporation. The main findings are as follow: (1) The four data series have significant chaotic and fractal behaviors, which are the result of the evolution of a nonlinear chaotic dynamic system. The climatic process in the Tarim River Basin also has deterministic and stochastic characteristics. (2) To describe the temperature, precipitation, relative humidity, and evaporation dynamics, at least three independent variables at daily scale are required; in terms of complexity, their order is evaporation > temperature > precipitation > relative humidity. (3) Their respective largest Lyapunov exponent λ 1 shows the order of their degree of complexity is relative humidity > temperature > precipitation ≈ evaporation; the maximum time scales for which the four systems can be predicted are 17 days, 17 days, 16 days, and 16 days, if calculated separately. (4) The Kolmogorov entropy K illustrates that the complexity of the nonlinear precipitation system is much greater than that of the other three systems. Both temperature and evaporation systems exhibit weaker chaotic behavior, their predictability is better, and the degree of complexity is less than that of the other two factors.

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Influence of proximity to the Qinghai-Tibet highway and railway on variations of soil heavy metal concentrations and bacterial community diversity on the Tibetan Plateau
Xia Zhao,JunFeng Wang,Yun Wang,Xiang Lu,ShaoFang Liu,YuBao Zhang,ZhiHong Guo,ZhongKui Xie,RuoYu Wang
Sciences in Cold and Arid Regions    2019, 11 (6): 407-418.   DOI: 10.3724/SP.J.1226.2019.00407.
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An understanding of soil microbial communities is crucial in roadside soil environmental assessments. The 16S rRNA sequencing of a stressed microbial community in soil adjacent to the Qinghai-Tibet Highway (QTH) revealed that the accumulation of heavy metals (over about 10 years) has affected the diversity of bacterial abundance and microbial community structure. The proximity of a sampling site to the QTH/Qinghai-Tibet Railway (QTR), which is effectively a measure of the density of human engineering, was the dominant factor influencing bacterial community diversity. The diversity of bacterial communities shows that 16S rRNA gene abundance decreased in relation to proximity to the QTH and QTR in both alpine wetland and meadow areas. The dominant phyla across all samples were Actinobacteria and Proteobacteria. The concentration of Cr and Cd in the soil were positively correlated with proximity to the QTH and QTR (MC/WC sampling sites), and Ni, Co, and V were positively correlated with proximity to the QTH and QTR (MA/WA sampling sites). The results presented in this study provide an insight into the relationships among heavy metals and soil microbial communities, and have important implications for assessing and predicting the impacts of human-induced activities from the QTH and QTR in such an extreme and fragile environment.

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Systematization of features and requirements for geological survey of railroad subgrades functioning in cold regions
Aleksey Lanis, Denis Razuvaev
Sciences in Cold and Arid Regions    2017, 9 (3): 205-212.   DOI: 10.3724/SP.J.1226.2017.00205
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The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance. Identification and calculation of the thawing degree of permafrost soils, frost heaving of clays, and groundwater flooding require careful engineering and geological surveying. The paper describes the unique, long-standing experience of the university scientists connected with maintaining the Russian East-Siberian and Trans-Baikal Railways' facilities. Specific features of and requirements for the surveying, depending on the geological and climatic conditions, are identified.
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Contamination and risk assessment of heavy metals in farmland soils of Baghrash County, Xinjiang, Northwest China
Ajigul Mamut, Mamattursun Eziz, Anwar Mohammad, Mattohti Anayit, Atiyagul Rixit
Sciences in Cold and Arid Regions    2017, 9 (5): 467-475.   DOI: 10.3724/SP.J.1226.2017.00467
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Soil pollution significantly reduces environmental quality. In this study, farmland soil samples were collected from 25 sites in Baghrash County, Northwest China; and the concentrations of eight heavy-metal elements (arsenic, As; cadmium, Cd; chromium, Cr; copper, Cu; manganese, Mn; nickel, Ni; lead, Pb; zinc, Zn) were determined by standard methods. The spatial distribution, contamination level, and ecological risk stature of heavy metals were analyzed based on GIS technology, the Geo-accumulation Index (Igeo), the Pollution Load Index (PLI), and the Potential Ecological Risk Index (RI). Results indicated that (1) The average concentrations of Cd exceeded 12.12 times the allowed national standard for soil environmental quality of China. The average concentrations of Cd, Cr, Ni, Pb, and Zn exceeded the background values of irrigation soils in Xinjiang by 60.58, 1.25, 1.50, 4.95, and 5.10 times, respectively. (2) The pollution order of the average value of Igeo for heavy metals was ranked as Cd > Zn > Pb > Ni > Cr > Cu > As > Mn. The individual potential ecological risk index for heavy metals was ranked in the order of Cd > As > Ni > Cu > Pb > Cr > Zn. The average PLI for the study area showed a heavy pollution level, while the average RI showed a considerable ecological risk stature, as compared to the classification standard. (3) The spatial distribution patterns of eight heavy metal elements were substantially heterogeneous. The moderately polluted areas with moderate potential ecological risks were distributed in the southern parts of the study area, whereas the heavily polluted areas with considerable potential ecological risks were distributed in the northern parts. Overall, it was observed that Cd contributed most to the PLI and RI of the farmland soils in Baghrash County. The pollution risk of Cd should be a major concern, and human activities in the region should be cautious.
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Effects of heavy metal (Pb) concentration on some growth parameters of plants grown in lead polluted soil under organic fertilizer amendment
Ojo M. Oseni, Adekunle A. Adelusi, Esther O. Dada, Abdulfatai B. Rufai
Sciences in Cold and Arid Regions    2016, 8 (1): 36-45.   DOI: 10.3724/SP.J.1226.2016.00036
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This study investigated morphological variation and biomass accumulation that occurred in Sida acuta and Chromolaena odorata plants grown in lead polluted soil under organic fertilizer amendment. The study was carried out in the screen house at the Biological Gardens of the Obafemi Awolowo University, Ile-Ife, Osun State. The experiment was a factorial combination of one heavy metal (Pb) at five levels of concentration (0, 200, 400, 800 and 1,000 mg/kg) in a completely randomized design, and were replicated three times for each of the two plants and two levels (0 g/kg and 9.4 g/kg) of organic fertilizer (OBD-Plus). Each pot was filled with 5 kg of air-dried and sieved soil and placed on a plastic tray for the collection of excess water. Two weeks after planting, seedlings of uniform height were transplanted from the nursery to experimental pots at the rate of one seedling per pot and grown for 10 weeks. The growth parameters of the plants were biomonitored for 7 weeks. After 10 weeks of treatment, the plants were harvested and dried to calculate the biomass accumulation. The two plant species performed better under fertilizer application than without it. For each of the plant species the growth parameters decreased as the levels of Pb concentration increased. Furthermore, the plants' biomass decreased significantly (p<0.05) as the levels of Pb concentration increased. The organic fertilizer helped to improve the plants' performance in lead-polluted soil.
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The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line
YanLi Xie, QiHao Yu, YanHui You, ZhongQiu Zhang, TingTao Gou
Sciences in Cold and Arid Regions    2019, 11 (1): 13-0020.   DOI: 10.3724/SP.J.1226.2019.00013
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After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission (QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons, while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.

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