25 November 2001, Volume 23 Issue 4
    

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  • Estimation of the Water Resources Affected by Climatic Warming and Glacier Shrinkage before 2050 in West China
    SHI Ya-feng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 333-341. https://doi.org/10.7522/j.issn.1000-0240.2001.0060
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    According to a comprehensive prediction with some uncertainties, temperature of the Tibetan Plateau may rise by 2.5 ℃ by 2050 or so as compared to that at the end of the 20th century. It is very likely that the summer temperature, which causes intense ablation of glaciers, will rise by 1.4 ℃. As a result, the equilibrium line altitude will rise more than 100 m; the ablation in the tongue zone will exceed the ice amount moved from the accumulation zone; and glaciers will thin and retreat. In the earlier stage, thinning prevails and meltwater increases. While in the later stage, glacier largely shrinks, meltwater decreases and some glaciers will disappear. There is a large difference in the sensitivity of response of glaciers to climate warming, depending on the size and type of glaciers. Using the statistical data of China’s glacier inventory, several regions were selected to make a prediction of the water resources affected by glacier shrinkage before 2050. In some regions, such as the Hexi Region in the north slopes of the Qilian Mountains, southern margin of the Junggar Basin in the north slopes of the Tianshan Mountains and the Hami-Turpan Basin in the south slopes of the Tianshan Mountains, glaciers, most of them have an area less than 2 km2,are sensitive to the climate warming and hence ablation increases. At the beginning of this century meltwater will reach its peak value, and by the middle part of this century meltwater will decrease. The impact on runoff of different rivers is estimated to be in the order of 106～107m3·a-1. Some basins, such as the Shule River Basin in the Qilian Mountains and the Manas River Basin in the Tianshan Mountains, meltwater can account for one-third or more of the river runoff. It is predicted that several medium-sized glaciers of 5～30 km2 will reach their meltwater peak value by the middle part of this century and their meltwater will increase in the order of 108m3·a-1. In the mountain regions around the Tarim Basin there are totally 22 009 km2 of glaciers, 22 larger ones of which have an area exceeding 100 km2,with their tongues covered by thick debris mantle. Therefore, these glaciers will retreat slowly. Glacier meltwater occupies 50%～80% of the discharge of the Yarkant River, Yurunkax River and Aksu River. At present the main stem of the Tarim River is mainly fed by meltwater of glaciers in the southwest part of the Tianshan Mountains via the Aksu River. It is predicted that glacier meltwater will continue to increase before 2050, the increased volume may reach about 25%～50% more than that at the beginning of this century, and annual increased discharge of 7 major rivers of the Tarim Basin is estimated to be in the order of 108m3·a-1. In order to effectively utilize the increased meltwater, it is necessary to construct mountain reservoirs to increase energy output and irrigation effect. Inland watersheds in the Qaidam Basin and the Tibetan Plateau are dominated by extreme continental type glaciers with lower temperature and slow retreat velocity. Temperature rise and meltwater increase during the first half of this century are favorable to the development of animal husbandry and economic growth. However, in the maritime-type glacier regions at the southeast part of the Tibetan Plateau and the Hengduan Mountains, where precipitation is more and ice temperature is higher, the temperature rise will quicken ablation and retreat of glaciers, perhaps thus causing frequent flood and debris flow disasters.
  • Isolation and Identification of the Antifreeze Proteins in Polygonum viviparum of Altifrigetic Subnival Plants in the Tianshan Mountains
    JI Mei-ju, AN Li-zhe, CHEN Tuo, LIU Yan-hong, FENG Hu-yuan, LIU Guang-xiu, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 342-345. https://doi.org/10.7522/j.issn.1000-0240.2001.0061
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    The altifrigetic subnival plants and eco environmental conditions at the headwaters of the Ürümqi River, Tianshan mountains, China were investigated. The adaptive mechanisms of typical altifrigetic subnival plants to alpine environment in the Tianshan Mountains were studied in this paper. Antifreeze proteins were isolated and identified in the leaves of Polygonum viviparum by the methods of physiology and biochemistry. Thermal hysteresis activity was discovered in leaf apoplastic proteins of Polygonum viviparum(3450 m), which was composed of 7 polypeptides (72.3kD、61.3kD、44.5kD、40.7kD、33.7kD、20.8kD and 15.2kD). PAS reactions showed that the presence of carbohydrate in the polypeptides. The photomicroscope observation indicated that cells with high proteins and polysaccharide contents could be found in leaves tissues. Apoplastic proteins from leaves exhibited antifreeze activity. AFPs were inactivated by the treatments of boiling, proteinase K, periodate and borate caused, suggesting the presence of carbohydrate. The results showed that Polygonum viviparum plants produce AFPs to adapt the special geographical environments, such as low temperature, low concentration of O2 and CO2, strong ultraviolet radiation and wind.
  • Climate Change and Its Impact on the Eco-environment in the Source Regions of the Yangtze and Yellow Rivers in Recent 40 Years
    WANG Gen-xu, LI Qi, CHENG Guo-dong, SHEN Yong-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 346-352. https://doi.org/10.7522/j.issn.1000-0240.2001.0062
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    Based on precipitation and temperature data obtained from the five meteorological stations in the source regions of the Yangtze and Yellow Rivers, the features of climate change in the recent 40 a are studied. The results show that the trend of climate change in the regions, as a whole, is both temperature and precipitation rise. However, precipitation increase mostly results from precipitation rise in spring and winter. Precipitation in summer, which takes an important contribution to vegetation growing, declines in the recent 40 years. In the source regions, the decadal mean temperature in the 1980s was higher than that in the 1950s by 0.12～0.9 ℃, and by 0.3 ℃ in most part of the study area. Contrasting to the mean temperature increasing in whole China, 0.2 ℃, the regions are the highest ones with temperature rising, 0.44 ℃ on the average.However, the temperature in April or May and September, which have very important significance to the growth and development of high cold meadow vegetation, decline. The eco environment in the Tibetan Plateau is very vulnerable, which is sensitive to the regional climate change. The climate in the plateau is becoming drier and warmer, resulting in a gradual degradation of permafrost. Both climate change and degradation of permafrost result in degradation of high-cold meadow vegetation.
  • Influence of Climate Warming on Permafrost Table Studied with Different Models and Temperatures
    FENG Wen-jie, LI Dong-qing, MA Wei, ZHANG Lu-xin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 353-359. https://doi.org/10.7522/j.issn.1000-0240.2001.0063
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    Model tests are conducted for studying the influence of air temperature rising on permafrost table under three conditions (without riprap and awning, with riprap, with riprap and awning). All tests were warmed up twice by different freeze-thaw cycle upon a basic temperature, with a temperature step of 0.50 ℃. The scale of the model that simulates the cutting is 1:20. The length, width and height of the model are 140 cm, 70 cm and 70 cm, respectively. Loam from the Fenghuoshang region of the Qinghai Tibetan Plateau is used in the model test, of which the initial dry unit weight is 1 500 kg·m-3 and the initial moisture content is 21%. The tests were performed in the State Key Laboratory of Frozen Soil Engineering, CAREERI, CAS. First, the model was kept at -16.10 ℃ under the nature condition for 3 days. Afterwards, the temperature of the soil surface was warmed up and then cooled down repeatedly in the manner of -16.1～5.8～-13.30 ℃, -15.6～6.3～-12.80 ℃ and -15.1～6.8～-12.30 ℃ in turn. Then, riprap, 0.2～1.0 cm in particle diameter and 2 cm in thickness (simulating actuall thickness of the blocked stone of 40 cm), was added to protect the slopes of the cut, and kept at -16.10 ℃ for 3 days, and then the repeatedly warming and cooling mentioned above was performed. Finally, awning, 30 cm in height (simulating actuall awning height of 6.0 m), was added to the model, and then kept at -16.10 ℃ for 3 days, and then the repeatedly warming and cooling mentioned above was performed. It is found from the tests that there is an obvious influence on the permafrost table under the protection of riprap and the awning, and the change of permafrost table is positively relating to air temperature. With the climate warming up, the permafrost table will descend step by step. But at the same temperature, using the riprap and the awning can uplift obviously the permafrost table, specially at high temperature. The effect is more obvious when jointly using riprap and awning. Therefore, using riprap to protect the cut slopes must be considered more and more in the engineering constructions in cold regions, because it is cheaper. Under special condition, it is necessary to jointly use riprap and awning. In this way, it is very good to reduce the frost heaving and thaw collapse of the road and canal etc. in cold regions.
  • Value of the Ecosystem Services in the Heihe River Basin
    ZHANG Zhi-qiang, XU Zhong-min, WANG Jian, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 360-366. https://doi.org/10.7522/j.issn.1000-0240.2001.0065
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    Ecosystem services or nature’s services refers to the ecosystem goods and services, which represent the benefits that human population demand, directly and indirectly, from ecosystem functions. They are the life-support system for all kinds of lives on the Earth, and are the key natural capital of humanity. Continuous existence of the services of ecological systems in taken for granted, never before have human actions so threatened their provision, most of them are public goods and not traded in markets, and thus resulted in the continuous decrease of ecosystem services and the deterioration of ecosystem functions that generate them. In the past ten years, the valuation of ecosystem services has been becoming one of the focuses of sustainable development and one of the frontiers of ecological economics, environmental economics and ecology. Various attempts have been made to calculate the value of global and regional ecosystem services. The valuation of ecosystem services is essential to the integrated accounting of environment and economics. Based on the data of 1:100 000 Landsat TM in the Heihe River Basin in 1987 and 2000, this paper analyzes briefly the landuse and land coverage changes.It is foundthat the landuse and land cover in the Heihe River Basin has changed greatly during the past 13 a,because of human s irrational development and utilization of water resources and ecosystems. The ecosystems of the Heihe River Basin havebeen deteriorating continuously. The ecosystem services of the Heihe River Basin in 1987 and 2000 areevaluatedby ing Constanza’s method. The result shows that the annual value of the ecosystem services in the Heihe River Basin was 2.1623×109 $, equal to 178.822×108 RMB $,in 1987,and 1.7674×109 $,equal to 146.164×108 RMB$ in 2000. The total annual flow value of the ecosystem services in theHeihe River Basin was 0.3949×109 $,equal to 32.658×108 RMB$ during the past 13 a. The value of ecosystem services decreases 2.512×108 RMB$ per year. The great decrease indicates that protection of the ecosystems is essential. Comparing to the gross domestic product (GDP) in the Heihe River Basin in 1999, 102.54×108 RMB$, the annual flow value of the ecosystem services in 2000 was 1.425 times the current GDP of the whole basin. Taking into account that such ecosystems as permanent snow/glaciers, construction land, salt lick, and desert/gravel desert also have ecosystem services value,this value of the ecosystem services in the Heihe River Basin is a conservative estimation.
  • Temporal-Spatial Distribution of the Holocene Vegetation in the Tibetan Plateau
    TANG Ling-yu, LI Chun-hai
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 367-374. https://doi.org/10.7522/j.issn.1000-0240.2001.0066
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    On the basis of pollen records in the lake cores from 30 sites in the Tibetan Plateau, the temporal-spatial distribution of vegetation, climatic changes and the South Asian monsoon development in the plateau in the Holocene are studied. During the early Holocene (12～9 ka BP), mixed conifer and deciduous broad leaved forest and mixed deciduous broad leaved forest dominated the vegetation in the east of the plateau (104°～98°E). At that time the South Asian monsoon was stronger, with mean annual temperature 2～4 ℃ higher than that prior to the Holocene and annual precipitation raging from 350 to 550 mm. In the middle of the plateau (98°～92°E), meadows or shrub meadows appeared, with annual temperature 4 ～4.5 ℃ lower than that of present. Farther west about 80° E, there was a steppe vegetation landscape, which indicated a cold and dry climate.During the middle Holocene (after 9～ 3.2 ka BP), from the east to the west of the plateau, the paleo vegetations were, sequentially, mixed conifer and deciduous broad leaved forest or sclerophyllous broad leaved forest conifer (104°～ 98°E) and mixed deciduous broad leaved forest (98°～ 92°E) or shrub, meadow and steppe (92°～ 80°E). The climate was warmer and wetter than that of the early Holocene. In the southeast, the January temperature was 3 ℃ higher than that of present and the annual precipitation was 250 mm more than that of present. In the northeast, the middle and the south of the plateau, the January temperature was 5 ℃ higher than that of present; and in the west it was 4 ℃ higher than that of present. During the late Holocene (after 3.2 ka BP), from east to west, the paleo vegetations were, sequentially, sclerophyllous broad leaved forest mixed conifer, deciduous broad leaved forest, meadow, steppe and desert. Drop of temperature and precipitation was nonlinear. The January temperature and the July temperature of the southeast were 4～4.5 ℃ and 3～3.5 ℃ lower than that of the middle Holocene, respectively, and annual precipitation was 350 mm lower. In the northeast, the forest shrank back and the coldest month temperature was about 8 ℃ lower than that of the middle Holocene. Lake water descended obviously in the west, indicating a very dry climate. Above all, the timing of vegetation and climatic changes supported the result of global climatic-model experiments that suggested a strengthened monsoon system during early to middle Holocene followed by a weakened monsoon system. The South Asian monsoon became stronger from 11 ka BP to 7 ka BP and weakened gradually from 7 ka BP to the present.
  • Studies of the Transformation between Surface Water and Groundwater and the Utilization Ratio of Water Resources in Hexi Region
    ZHANG Ji-shi, KANG Er-si, LAN Yong-chao, CHEN Ren-sheng, CHEN Man-xiang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 375-382. https://doi.org/10.7522/j.issn.1000-0240.2001.0067
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    Desert and arid areas in Northwest accounts for 34.6% of the total territory of China. Precipitation in these areas is rare, resulting in dry climate and short water resources. Therefore land resources are unbalanced with water resources in these areas. Owing to very strong evaporation and transpiration in desert, the surface water decreases with flow distance and finally flows into some inland lakes. The average annual precipitation is only 153.9 mm, whereas the evaporation is very high, from 1 200 mm to 2 692 mm. The water from high mountainous is consumed by evaporation and infiltration. In irrigation districts water can be obtained by capturing nature wastage in desert oasis. Most of water from mountain areas infiltrates in the upper pluvial fan and then transforms into groundwater. This transformation decreases the futile water, that is, decreuses the lost through evaporation and transpiration. The special topography features make the runoff and groundwater change repeatedly. All above made it possible that the water has relative high utilization efficiency in certain extent. So to understand and grasp the mechanism of water cycle and transformation in Northwest China is very important to sustainable development of society economy system. Hexi Region is a typical arid area. The water of Hexi Region derived from the Qilian Mountains flows into desert plain regions and gradually dwindles and finally disappears. Surface water and groundwater transfer each other frequently. In the region the agriculture depends on irrigation. The study of water resources in Hexi Region has a large progress. Repeatedly transform between surface water and groundwater is found, which has a significance for water resources utilization. Because the water utilization efficiency is very high in Hexi Region, 133% on average in 1999. The utilization efficiency in the Shiyang River Basin is 211%, in the Heihe River Basin is 128%, but in the Shule River Basin is 61.4%, depending on geologic structure and water transformation process. Contrary by the high water utilization ratio and irrational utilization, these cause many environment problem that derived from ignorance to hydrological cycle process and mechanism. Illimitably reclaiming and irrational using water resources acutely decreases the downstream runoff, and descendes the groundwater level. The level has descended 3～5 m on average since 1950’s. Especially, in the plains before mountains the descending trend of groundwater level is markedly. Thus less groundwater replenishes surface water. The water flowing into Minqin Basin has decreased from 5.7×108m3·a-1to 1.5×108m3·a-1 since the 1950’s, the groundwater level has descended to 15 m from 3m in the 1950’s, and the exploitable groundwater has decreased to 5.5×108～6.0×108m3·a-1, resulting in many wellsprings disappearing and 0.644×104hm2 oleaster shelter belt vanishing. Moreover, 0.25×104hm2 of farmland is abandoned owing to desertification.
  • Crystals and Fabrics of an Arctic Multi-Year Ice Sample
    LI Zhi-jun, KANG Jian-cheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 383-388. https://doi.org/10.7522/j.issn.1000-0240.2001.0068
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    One of sea ice core samples taken from Arctic by the First Chinese National Arctic Research Expedition in 1999 was cut from top to bottom for ice crystal and fabric analysis. The core was located at 72°24.037’N, 153°33.994’W and 2.2 m in length. After detail description on the ice sample fabric under light, 20 vertical sections and 2 level sections were cut from the core. These ice sections covered the ice sheet from surface to bottom, with some loses during sampling and section cutting. The structure and crystals along the depth of the core were observed and analyzed. A kind of hydrodynamic effect on ice crystals was found and was defined as refrozen clastic pieces. The air bubbles in these refrozen clastic pieces have ball shape with 1 mm in diameter, uniform distribution and about 4% in volume. The air bubbles in the columnar S 2 ice are about 15% by volume and has strip parallel to the crystal long axis. The air bubbles in grain crystal are about 15-30%, with ball shape and 1 to 3 mm in diameter. Ice crystals from surface to bottom of the sample are columnar, refrozen clastic pieces, grain, columnar, refrozen clastic pieces, grain, columnar and refrozen clastic pieces, respectively. Usually, columnar crystal is 10 mm in size, grain crystal is 2.6 mm in size and refrozen clastic piece is less than 1mm in size with columnar ice blocks and refrozen water. From surface to the depth of 95 cm, thin different color crystals enclosed by main crystals. These indicate that the sample was three year old, and the ice surface has been melted and meltwater has immigrated into the ice sheet during summer. Hence, the annual energy balance in the Arctic can be determined as ice surface melting in summer and bottom growing in winter. Ice sheet thickness kept in a constant at a certain position based on the climate and ocean condition. As this point, the three year ice covered the period from 1997 winter to 1999 summer. This division is reasonable to explain the ice crystals, especially the refrozen clastic pieces. The refrozen clastic pieces just occur in thermal growing multi-year ice. It is belong to the ocean dynamic broken ice pieces that contact with ice sheet due to buoyancy and move with whole ice sheet. While these pieces moved to colder zone, they were refrozen. Therefore, its structure is different from that of first year ice. The special ice structure is shown in pictures. Also the division is suitable to explains why there are typical Arctic sea ice micro-algae and where they come from.
  • ESR Dating on Tills and the Last Glaciation at the Headwaters of the Ürümqi River, Tianshan Mountains, China
    YI Chao-lu, JIAO Ke-qing, LIU Ke-xin, LI Ling, YE Yu-guang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 389-393. https://doi.org/10.7522/j.issn.1000-0240.2001.0069
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    Using Ge center of quartz grains of size 0.06～0.25 mm, ESR (electron spinning resonance) dating on the glacial quartz sands formed in the Last Glaciation was made at the headwaters of the Ürümqi River in the Tianshan Mountains, Northwest China. ESR dating on a basal till (subglacial melt-out one) of an end moraine formed in the late stage of the Last Glaciation is consistent with the dating under AMS 14C method. But dating on the overlying till (supra glacial melt out one) of the same moraine is different from the dating under AMS 14C method. The underlying till contains much more silt than the overlying till. High content of silt implies a strong subglacial comminution. Based on an experiment, Ge signal in quartz grains decreases by one third after artificial grinding for ten minutes.The till was formed in 50～70 ka BP, the early stage of the Last Glaciation. It was spread in the main valley as low as 2300 m a.s.l. with a length of more than 19 km. Fluvial sandy gravel deposited in the inter glaciation between the early and late stages of the Last Glaciation.
  • Economic Diversity and Sustainable Development in China
    XU Zhong-min, CHENG Dong-jing, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 394-401. https://doi.org/10.7522/j.issn.1000-0240.2001.0070
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    Economic system, developing with time, tends to become more complex with increase in structure and throughput. Energy consumption increases with development of economic sectors and channels for energy flow. Economic diversity is a measure of the number of economic sectors which consume energy and the equitableness of energy consumption between the sectors. Development capacity, as a product of the system energy consumption and the diversity of energy flow, is a measure of the potential output of the system. In this paper the development capacity is calculated for China and its provinces. The measure of the change in the diversity, energy flow and development capacity is a useful tool for predicting whether a country’s development strategies and policies are promoting or hindering sustainable development. An empirical analysis using the data of China and its provinces seems to substantiate the above view point. The analysis shows that the relationship between the change in development capacity and the change in GDP from 1980 to 1998 was significant and positive (r =0.66). The change in development capacity appears to be a reasonably good predictor of the change in GDP. In China, the diversity index was declining slowly from 1980 to 1998. At the same time the energy consumption was increasing. The policy of energy was not suitable for sustainable development. China appears to increase energy consumption to push its economic development, but there was a negative effect, such as pollution and income distribution disparities, which will eventually slow down the economic development. The better approach is to increase economic diversity so that the energy consumption can decline while the development capacity keeps at the same level. The result of a cross sectional analysis is not perfect. The reason is the differences across the sectional provinces. There are other factors at work, which vary across provinces more than they vary with time. According to Ulanowicz’s Formula, there are two distinct development strategies, one is promoting energy consumption and another is economic diversity. A sustainable development policy relies on increasing the diversity of economic system, which results in fewer externalities and increasing cumulative economic efficiency. The economic sustainable development requires to has an efficient system with moderate consumption and high diversity. A sustainable development strategy relies on increasing economic diversity with decreasing or steady energy consumption. Owing to the environmental impact resulted from energy consumption the government should promote a development strategy which focuses on sustainable development by enhancing economic diversity. In China, adjusting energy prices through taxes is one way to keep prices somewhat equitable and to decrease energy consumption and thus increase the diversity.
  • The Design Principles of Embankment of Highway in Permafrost Regions and Their Application
    DOU Ming-jian, HU Chang-shun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 402-406. https://doi.org/10.7522/j.issn.1000-0240.2001.0071
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    The design principles of embankment are an important basis for highway and railway engineering in permafrost regions. Using the general design principles of civil engineering for permafrost regions could lead to many severe problems presented owing to thawing and refreezing of embankment, such as thaw settlement, roadway cracking, foundation elevation, different deformation, slope slip and so on. Characteristics of linearity engineering and permafrost propose that the design principles of embankment in permafrost regions should consist with the section design principles and the site design principles, and various influential factors should also be considered in design stage. The division of the design principles should be from simple and rough outline to detailed and deeply, and the direction limits should be from line to point. First, on the basis of regional conditions determine the section design principles, and then on the basis of the characteristics of the structure and permafrost under the structure determine the site design principles. The section design principles are used for new project engineering and reconstruction project, and the linearity engineering in permafrost regions can be divided into protecting, simply protecting and no protecting the permafrost sections. In stage of the section design many influential factors should be considered, including geologic tectonics, geomorphologic patterns, annual mean air and ground temperatures, and permafrost table and so on. For site design stage the engineering type, ground ice content and soil type should also considered. According to the principles, the Qinghai-Tibetan Highway in permafrost regions is divided into sections; this division can be used in practice.
  • Palynological Evidences of the Pleistocene Vegetation and Environmental Changes in the East Kunlun Mountains
    XU Qing-hai, YANG Xiao-lan, LIANG Wen-dong, LI Wen-yi, CUI Zhi-jiu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 407-413. https://doi.org/10.7522/j.issn.1000-0240.2001.0072
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    The pollen analysis of the layers of Qiangtang and Sanchahe groups in a saddle of the Kunlun Mountains shows that a dry environment had been come into in the Early Pleistocene in the Qiangtang Plateau. The pollen assemblages show that change in dryness was dominant rather than change in temperature, which could relate to the lift of the Tibetan Plateau. During 2～1.8 Ma BP, the vegetation was the desert or desert grassland consisted of Ephedra, Chenopodiaceous and Artemisia in the plateau. During 1.8～1.3 Ma BP, the climate changed into temperate and moist, the vegetation changed into grassland, and during 1.0～0.68 Ma BP, the vegetation developed badly due to tectonic lift and ice age climate in the plateau. During 0.68～0.65 Ma BP, the climate was in a little interglacial stage, and the vegetation was grassland consisted of Artemisia, Chenopodiaceous, Ephedra and many other herbs. The sediment of 0.65～0.35 Ma BP was missed in the layers of Qiangtang and Sanchahe groups. It is inferred that the vegetation was still the desert controlled by the ice age climate in this period. In the second interglacial stage from the last (0.35～0.15 Ma BP), there was the dark coniferous forest consisted of Piceas and Abies in the gullies and valleys when the layer of Sanchahe group deposited. Afterwards, climate changed to dry obviously, the coniferous forest disappeared (0.15～0.06 Ma BP). After 60 000 a BP, the climate further changed to dry and the vegetation changed to desert again.
  • Prediction Model of Soil Freezing Temperature and Unfrozen Water Content Based on Back-Propagation Neural Network
    SHANG Song-hao, MAO Xiao-min
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 414-418. https://doi.org/10.7522/j.issn.1000-0240.2001.0073
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    Soil freezing temperature and unfrozen water content are important properties of frozen soil and are necessary in the study of water migration in freezing or frozen soils. Both of them are influenced by several factors and their relations are complex. Back-propagation (BP) neural network is a widely used artificial neural network model with the character of self-training and strong capability in solving nonlinear problems. A commonly used three-layer BP network includes an input layer, a hidden layer and an output layer, with several neural cells in each layer. A multi-input and multi-output BP network can be used to describe the relations between influencing factors and freezing temperature or / and unfrozen water content. In the above network, the input variables are main influencing factors, and the output variables may be freezing temperature, unfrozen water content, coefficients of unfrozen water content vs. temperature or their combination. The network structure and parameters can be obtained from self-training with training samples. As an example, the freezing temperature and coefficients A and B in the empirical equation of unfrozen water content vs. temperature of Morin Clay under different water content, dry density and NaCl concentration are predicted with BP network. The prediction results is fairly good, with average absolute errors of freezing temperature,coefficients A and B are 0.12℃, 2.173 and 0.0179 for 20 training samples, and 0.14℃, 1.927 and 0.0290 for 3 prediction samples. Compared with the prediction results of the overlapping model, the BP network model predicted values of coefficients A and B are more close to the experiment data. It shows that the method of artificial neural network is effective in the prediction of freezing temperature and unfrozen water content. The trained network model can be used in the analysis of relationships on freezing temperature and unfrozen water content with their influencing factors. Moreover, It can be expected that this method can be further applied in the study of water and salt migration in freezing and frozen soils. On the other hand, BP network model has its own weakness as a kind of black-box model, such as more parameters in the model without obvious physical meaning, which will limit its application in engineering field. The solving of this problem will depend on the development of artificial neural network theory.
  • Microbial Communitiesin Permafrost of the Tibetan Plateau and Their Significance
    LIU Guang-xiu, HU Chang-qing, ZHANG Jing-bo, SHEN Yong-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 419-422. https://doi.org/10.7522/j.issn.1000-0240.2001.0074
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    A 2-m soil core was extracted from the permafrost at the Kunlun Pass of the Kunlun Mountains within the Tibetan Plateau, China. From this core 21 samples were cut to isolating microorganisms. There were 13 strains of bacteria successfully isolated. The analyses of bacteria growth and resistance to antibiotic foundthat those strains are rare and special. The microbial growth revealed that they were psychrophilic, stopping growth at the environmental temperature of 35 ℃,showing these bacteria characterized by special mechanism of physiologyin extremelycold conditions. All of them grow very slowly in the normal cultivating condition.
  • Spatial Variation of Climate for Different Landscape Areas in the Heihe River Basin
    GONG Jia-dong, LI Xiao-yan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 423-431. https://doi.org/10.7522/j.issn.1000-0240.2001.0075
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    For an inland river basin in the arid regions of Northwest, there are many different landscape patterns, such as alpine snow-ice frozen zone, alpine shrub and meadow zone, intermontane basin, mid-montane forest zone, piedmont diluvial-alluvial plain and oasis zone, terminal lake, and Gobi and sandy desert. Therefore, to understand the responses of different landscape patterns, especially the large irrigated oasis, to the global warming is very important for the inland river management effectively. Heihe River Basin, located in the middle section of the Hexi Corridor, is a representative inland watershed in northwest China with relative abundance meteorological records. Most meteorological records of the Heihe River Basin started from the end of the 1950’s, while in the Jiuquan Meteorological Station it is farther. The data for analysis were selected based on the following principles: 1) The station is the in a representative area, 2) The data series must be longer than 30 years, 3) The station less moved its location. There are 14 meteorological stations meeting the above principles. In addition, there are many precipitation stations and hydrological stations operating in the same period, 24 of which are chosen for analysis. Through analyzing the meteorological records during 1961 ～ 1995 in the Heihe River Basin, the change of air temperature and precipitation dependent on vertical zones have been established. It is true that the responses of air temperature and precipitation to climate change were different in different landscape patterns. The increase of air temperature was 0.6 ℃ between the 1960s and the 1990s in the semi-humid and humid areas of high/mid-mountains of the upper reaches, when a higher precipitation increae occurred. While the increase of air temperature was 1.3 ℃ in the desert areas of the outer hills at the same time, when precipitation variation was unstable. In the irrigated oasis of the piedmont plains, the increase of air temperature was 0.5～0.6 ℃ at the same time, when precipitation stably increased a little. In the terminal extreme arid section, air temperature increased 1.4 ℃ and precipitation decreased about 0.5 mm·a-1. It is believed that there are two reasons leastwise for these spatial variations. First, the effect of climate types in an inland river basin, such as humid and semi-humid in the upper reaches of mountainous area, arid in the middle reaches of the piedmont area, and extreme arid in the lower reaches. Secondly, the effect of the local environment, such as the large irrigated areas intensively contrasted with desert areas due to the mesoclimate circulation. However, there are some uncertainties, for example, lack of meteorological station in desert area.
  • Approach to the Application of Ultrasonic Technology to Measuring Physical Properties of Frozen Soils
    SHENG Yu, PENG Wan-wei, Fukuda Masami
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 432-435. https://doi.org/10.7522/j.issn.1000-0240.2001.0076
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    The propagating of ultrasonic wave in a media reflects the dynamic properties of the media, while the dynamic properties should depend on its physical properties. Due to the advantages of the ultrasonic technologies, such as easy operation, fast measurement, and non disturbing sample, it is possible to directly measure the dynamic elastic constants of frozen soils, and indirectly measure some physical properties of frozen soils by the technique. Ultrasonic tests of Lanzhou Loess were carried out to obtain dynamic properties of frozen soils (including Young’s modulus, shear modulus and Poisson’s ratio). Experiments of ultrasonic wave velocity and compressive strength in frozen Lanzhou Loess under different temperatures were conducted to establish the relationship between ultrasonic velocity and compressive strength. Similar test for Tomakomai Silt with different mixed tire powder was also conducted at a unique temperature to qualify the existence of a relationship between compressive strength and ultrasonic velocity. As a sequent study in the effect of unfrozen water contents on the ultrasonic velocities of frozen soil, ultrasonic tests for frozen glass bead were conducted to confirm the response of the ultrasonic velocity to the unfrozen water content. Experimental results indicated that the strength of frozen soil changing with a single factor (such as temperature or mixed tire fraction) could be estimated by measuring its ultrasonic wave velocity. Thus ultrasonic velocity have a good relation to the unfrozen water content of frozen soil under different temperatures. All of the empirical relations imply that the ultrasonic technique may be possibly applied in estimation of physical and mechanical properties of frozen soils.
  • Simulating Snowmelt Runoff in Mountainous Watershed of Italy Using GIS and Remote Sensing Data
    WANG Jian, MA Ming-guo, Paolo Federicis
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 436-441. https://doi.org/10.7522/j.issn.1000-0240.2001.0077
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    Snow meltwater plays a very important role in the effectual usage of the water resource. It is regarded widely in Europe. Now it is possible tomonitor snow cover in the large area. SRM(Snowmelt Runoff Model) has successfully simulatedmore than eighty basins,which are locatedin 25 countries. So it becomes the only snowmelt runoff model recommended by the World Meteorological Organization. In this paper the SRM is appliedto simulate snowmelt runoff in Rienza basin of Italy in spring. The emphasis in this paper is to apply GIS and remote sensing data asinput parameters and factors, resulting inimproving the accuracy of simulating. Abasin can be subdivided into several sub basins.The runoff effect of each sub basin could be controlledby the measurementof a hydro meteorological observation station. Meanwhile, the key environmental influence factors,such as degree day factor and depletion curve, would be discussed in detailfor a single sub basin. In the processing of remote sensing image, a topographic correction will improve the image interpretation. Using compensation method before supervised classification filters the non snow cells. Thussnow cover distribution maps could be obtained accurately. The result shows: 1) The key of simulating spring snowmelt runoff is inputting accurate parameters; 2) In the process of extractingsnow cover parameters from the remote sensing data, eliminating the effect of landformis important. For applying SMR in China, the urgencyis how to treatthe meteorological and hydrological parametersof the sub basins, in case of rarity of surface station data in most snow cover regions.
  • Biogeochemistry of Organic Acids in Snow and Ice: A Review
    LI Xin-qing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 442-449. https://doi.org/10.7522/j.issn.1000-0240.2001.0078
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    The study of organic acids recorded in snow and ice provides a unique way to obtain information on a variety of the species in response topast climate change,past environment and past ecosystem, and represents one of the main fields in glaciochemistry. It also provides insight into biogeochemical cycles of carbon, hydrogen and oxygen and other major biological elements. In August 1987, a special session on organic acids and related compounds in the atmosphere was held at the Sixth International Symposium of the Commission on Atmospheric Chemistry and Global Pollution in Peterborough, Canada, which symbolized that studies of organic acids had drawn attention of researchers around the world. The organic acids detected in snow and ice are formic, acetic, propionic, pyruvic, oxalic and glycolic. The former two represent the most abundant ones. In some places, their concentrations are even higher than inorganic acids such as sulfate, nitrate and chloride. For the past decade, the study of the organic acids mainly focused on Greenland and Antarctica. Recent two years, however, the study turns to alpine glaciers in the middle and low latitude areas because organic acids recorded in alpine glaciers are much closer to the sources than those in polar areas. Studies show that formic and acetic in Greenland ice cores reached up to 10ng·g-1 in their average concentrations with the former higher than the latter, while the oxalic and glycolic are below 1 ng·g-1 . They mainly came from biomass burning, which accounts for about 20 %, and vegetation emissions in the north hemisphere that contribute to the background of the organic acids. In even lower concentrations, the formic acids recorded in Antarctic ice cores are below 2 ng·g-1, whereas the acetic below 0.15ng·g-1 . They are considered as from the atmospheric oxidation of numerous hydrocarbons such as methane and alkenes. MSA in Greenland ice cores is below 5ng·g-1 on an average, whereas that in Antarctica up 7ng·g-1 . They all came from the oceanic emission of DMS. In sharp contrast, formic and acetic acids in the Glacier No.1 at the headwaters of the Ürümqi River, a middle latitude alpine glacier in the Tianshan Mountains, West China, are several ten-fold higher than those in Greenland, and a few thousands times more than those in Antarctica. Moreover, resolution of organic acid records in middle latitude alpine glaciers is also higher than those in polar areas. This demonstrates that the organic records in alpine glaciers are more conducive to understanding the biogeochemical cycles of the organic acids. Climate changes affect the terrestrial vegetation, the source for the carboxylic acids, and the oceanic production of DMS, the precursor of MSA, thus the secular trends of the organic acid records in ice cores. It is interested to note that MSA connects the climate change in different ways for the two hemispheres. Greenland ice cores demonstrate the MSA correlates positively with climate change, while it does somewhat negatively in Antarctica. ENSO affects the production of DMS in the southern hemisphere and it probably causes the disparity. The change of the formic/acetic ratio in the Greenland ice core from 1945 suggests the anthropogenic impact from the northern hemisphere, which caused an increase of acetic acid while a decrease of formic.
  • Ecohydrology——A Science for Studying the Hydrologic Mechanisms of Ecological Patterns and Processes
    ZHAO Wen-zhi, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2001, 23(4): 450-457. https://doi.org/10.7522/j.issn.1000-0240.2001.0079
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    The spatiotemporal linkage between the hydrological and ecological dynamics is one of the keystones to manage the water resources and keep the natural ecosystems run normally, and will be one of the most exciting frontiers in future. Ecohydrology may be defined as a science that studies the hydrologic mechanisms of ecological patterns and processes. Plant water relation is its theoretical basis,soil moisture dynamics and evapotranspiration are its key subject, and scale issues are its critical problem. In this paper, the connotation, basic theories and current main research topics of ecohydrology are briefly described. The current research situation, prospect for the future and application of ecohydrology are also outlined. Finally, how to study ecohydrology with the eco-environmental construction in West China is suggested. For example,first,the hydrological mechanisms of wetlands and lakes,streams and rivers should be better understood in order to guide the conservation of these water resources. Secondly,more efforts on interaction between hydrological dynamics and vegetation establishment should be done to get more useful information for eco environmental construction in West China. Thirdly, water ecological demand should be studied in the inland river basins in arid regions to keep the environment and economics sustainability at the basins.
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