25 February 2002, Volume 24 Issue 1
    

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  • SHI Ya-feng, YAO Tan-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 1-9. https://doi.org/10.7522/j.issn.1000-0240.2002.0001
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    The records of Guliya ice core showed that there was a MIS 3b cold period between 54~44 ka BP, when temperature was 5 ℃ below present average. In contrast to this, temperatures in the warm periods at MIS 3c (early) and MIS 3a (late) were 3 ℃ and 4 ℃ above present average, respectively. This has been proved to be consistent with the insolation changes caused by a precessional cycle of 23 ka and a significant global impact appeared between 65 N~60 S. From preliminary analysis of the literatures concerning well-dated glacier advances during the Last Glaciation, it has been found that MIS 3b cold period resulted in glacial advances at 23 sites of 12 regions in Asia, Europe, North America, South America and Ocean. In this paper the authors give a brief review to these sites. The plentiful precipitation during MIS 3b coupling with the suppressive effect of low temperature on ice ablation, glaciers advanced beyond the extent of the cold-dry MIS 2 between 25~15 ka BP (LGM). Several new dating methods, such as modified optically stimulated luminescence (OSL) method, infrared stimulated luminescence (IRSC) method, cosmogenic 3He, 10Be, 26Al and 36Al dating method, Uranium series dating method, together with 14C method, TL method, ESR method and fission track method, effectively improve the dating of several glacial advances during the Last Glaciation. Despite the importance of the records of Guliya ice core in defining the MIS 3b cold period, few data was held on glacial advance during that time in West China, further study is essential.
  • LIU Yong-zhi, WU Qing-bai, ZHANG Jian-ming, SHENG Yu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 10-15. https://doi.org/10.7522/j.issn.1000-0240.2002.0002
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    It is a very difficult to solve roadbed deformation in permafrost regions, especially thaw settlement in warm permafrost regions. Thawing and temperature rising due to asphalt pavement has a great influence on roadbed stability. In order to study the process of roadbed deformation for different permafrost types and geophysical environments, roadbed deformation was monitored. There are three monitoring sections with uniform vertical and transverse observation directions and spaces. Each section has four transverse profiles consisting of 5 monitoring points. The relative deformation is monitored by transit instrument for three years since 1998. It is observed twice a month. The following conclusions are obtained: ;(1)Both vertical and transverse deformations due to permafrost thawing show a positive non-uniform feature, with the maximum deformation in the road should other than in the central of roadbed due to the shift of the maximum thaw depth to the road should.;(2)roadbed deformation of frozen soils includes frost heave and thaw settlement. Extensive frost heave occurs from December to January. Extensive thaw settlement occurs from April to July. In other months roadbed deformation is in the way of slow frost heave or thaw settlement.;(3)roadbed deformation mainly depends on mean annual ground temperature and engineering geological conditions of permafrost. For warm permafrost with mean annual ground temperature high than -1.5 ℃, roadbed deformation extensively change with mean annual ground temperature. Roadbed deformation mainly appears in the section with high ice content, and the larger the ice content, the larger the thaw settlement.;(4)Non-uniform deformation of roadbed under thawing is due to the effect of asphalt pavement on permafrost. Its essential is that the absorption of asphalt pavement can results in engineering geological conditions worse, because of continuously changing permafrost thermal regime, permafrost temperature rising and ground ice thawing.
  • XIE Zi-chu, FENG Qing-hua, LIU Chao-hai
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 16-27. https://doi.org/10.7522/j.issn.1000-0240.2002.0003
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    In the basins of the Ganges, Yarlung Zangbo and Indus there are 19 575 km2 of glaciers, accounting for one-third of the total glacier area in China. On the basis of the structure of the glacier system and the nature of the equilibrium line altitudes at the steady state, functional model of the variation of glacier system are established, using Kotlyakov-Krenke’s equation relating annual ablation of glacier and mean summer temperature. The models are applied to the study of the response of glacial runoff to climatic change. The effect of decreasing air temperature due to rising of ELA and reduction of glacier area is considered in these model simultaneously. The modeling results under the climatic scenarios with temperature increasing rates of 0.01, 0.03 and 0.05 K·a-1 indicate that the glacial runoff fed by the marine-type glaciers with high levels of mass balance are very sensitive to climate change, it will take 10~30 years to reach a climax, and go back to their initial state in less than 100 years. However, the increasing rate of glacial runoff is small. During a peak period, the discharge-increasing rate will range from 1.01 to 1.14. In contrast, the glacial runoff of the continental-type glaciers, characterized by lower level of mass balance smaller decreasing rate of glacier size, and longer life-span responds climate variation slowly; it will take over 100 years to a climax and hundreds of years to return to their initial state. During a peak period, the discharge-increasing rate will ranged between 1.6~4.0 for extrexly continental-type glaciers. The decreasing rate of size for the marine type glaciers has larger than the continental-type on in case of 0.05 K·a-1 and in 100 a, the former one is -0.82 and the later one is -1.8. At the similar levels of mass balance, smaller glaciers respond quickly to the climate change and also retreat relatively fast. The glacier system with very large elevation difference have the longest life span. The life span of the Rongbuk Glacier on the northern slope of the Himalayas will be over 1 800 years at a temperature-increasing rate of 0.01 K·a-1.
  • LIN Qing, SHI Su-hua, PENG Ping-an, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 28-31. https://doi.org/10.7522/j.issn.1000-0240.2002.0004
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    The plant materials buried in perennial frozen sediments are preserved in a good state due to sub-freezing temperature and insulation. They may be suitable for retrieving ancient DNA.In this work, a routine CTAB method has been used to extract DNA from the plant materials buried in perennial frozen sediments of the Qingshui River and Ngoring Lake, Tibetan Plateau. Agarose gel electrophoresis has used to detect the extraction. The result shows that the DNA can be extracted from buried plant materials, which not only contain degraded DNA with low molecular weight, but also consist of the DNA with high molecular weight that has obvious band. In most cases, the extracted DNA has fuscous color from maple to brown that may result from chemical reaction, for example, the product of Millard reaction or aggregation. The DNA concentration in plant sample decreases with the buried depth or time.Some factors are determined the preservation of ancient DNA in plant materials. First, low temperature obviously slows down the decomposition of DNA. Secondly, lack of liquid water due to soil frozen reduces the hydrolysis of DNA. Thirdly, the insulation due to soil refrozen prevents from oxygen and provides a reductive condition, helpful to the preservation of DNA.This work shows that the DNA in the plant materials buried in perennial frozen sediment can well be preserved and will be the best materials to trace the DNA genetic information in a long time scale.
  • CHEN Jia-qi, SHI Ya-feng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 32-39. https://doi.org/10.7522/j.issn.1000-0240.2002.0005
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    With the help of abundant historical documents in the Yangtze Delta, winter temperature starting from 820’s AC has been reconstructed. In order to calibrate the effect of the record in Guliya ice core, a comparison of the winter temperature with the record has been established. The result shows that it was a close temporal and spatial relation before the 13th century considering cold and warm variations. After the 13th century, it is difficult to find a correlation. During the last 1000 a, a cold trend is clear in the Yangtze Delta, but a warm trend could be found in the record in Guliya ice core. This trend is resulted from the warm phase during the middle centuries (7th and 8th century) both in the Yangtze Delta and the whole China; however, the warm phase could not be seen in the record in Guliya ice core or in the Tibetan Plateau. During the Little Ice Age, 3 typical periods can be found both in Guliya and in the Yangtze Delta. The first phase of the Little Ice Age started earlier and concluded later in the Yangtze Delta than that in Guliya. As the decadal variation, nearly half of the peaks show a simultaneous change in both sites, but the changing amplitude is different. The composition of warm-cold also shows a similarity. Although there is a distance of several thousand kilometers for the two sites, the same decadal climatic response can still be found in the records of temperature and precipitation. Sun activities and volcanic eruptions dominate the regional climate change in both sites.
  • YANG Bao, SHI Ya-feng, ZHOU Qing-bo
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 40-45. https://doi.org/10.7522/j.issn.1000-0240.2002.0006
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    In this paper, the effect of solar and volcanic activities on temperature variations in Guliya ice core record and in the lower reaches of the Yangtze River over the past three centuries has been studied. Results are shown as follows:First, there is a very well correlation between temperature variations and solar activity whether on inter-annual or on decadal time scale. On inter-annual time scale, correlation coefficient is the maximum while Guliya ice core δ18O lags solar irradiance by 8 a. The correlation coefficient is the maximum under the condition that while Hefei winter temperature is in phase with solar irradiance. The best correlation is found when Hefei winter temperature leads Guliya ice core δ18O by 11 a. On decadal time scale, Guliya ice core δ18O, Hangzhou spring temperature and Hefei winter temperature vary more similarly with solar activity. This suggests that solar activity might exert some influence on the temperature recorded in Guliya ice core and in the lower reaches of the Yangtze River.Second, to some extent, volcanic activity is partly responsible for the temperature drop in Hefei region.The periods of higher temperature correspond to those of lower SO42- values, and vise versa. The nine huge volcanic eruptions recorded in GISP2 match with the low-value periods in Hefei winter temperature. The 1690s was the coldest decade both for Hangzhou region and for Northern Hemisphere during the last 400 a. It is found that four massive volcanic eruptions (DVI≥4) occurred in the 1960s, suggesting that volcanic activity may be responsible for the temperature drop in Hefei region.Third, on the variation trends, Guliya ice core δ18O, Hangzhou spring temperature and Hefei winter temperature negatively correlate with ice core acidity. In other words, higher SO42- concentration corresponds to lower temperature while lower SO42- concentration is consistent with higher temperature. The temperature drop during the 1810s~1830s not only can be seen in Hefei winter temperature and Hangzhou spring temperature, but also in Guliya ice core δ18O series. Meanwhile, the reconstructed temperature curve of Northern Hemisphere was also characterized by cold valley. In addition, precipitation of 7 stations located in North China decreased during this period. All these facts indicate that the climate in the 1810s~1830s might be global and attributable to intensive volcanic activity and weak solar activity.
  • LIU Yan-xiang, GAO Xiao-qing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 46-50. https://doi.org/10.7522/j.issn.1000-0240.2002.0007
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    Based on spatial-geomagnetic coupling, air temperature series were simulated and reconstructed by using SCL (sunspot circle length) change and its relation with geomagnetic (on geothermal in this paper) over East China in historic times. Except individual period, the simulative curve is similar as Zhu Kezhen’s climatic change curve. The decade change of climate was analyzed in East China over the last 2 500 years, which can reflect the warm-cold change of climate. There are a few disputes in some periods with Zhu’s curve, for example, 150~350 A.D. was in a warm and wet period, 1050~1150 A.D. was the Little Climatic Optimum in China, when solar was activity with mean SCL of 8.0~10.0 years, similar to later researcher’s result. From Mid-Tang Dynasty to Wudai Dynasty, climate change was unstable with warm-cold alternation. The climate change in the Little Ice Age in East China has been clearly revealed, which can be divided into 3 cold periods and can be sub-divided into 2~3 phases in each period. The result also shows the climate change at present. For example, from the beginning of the 1900s, air temperature was going up to the 1940s, then dropped down to the 1960-1970s, and again increases from the mid-1980s up to now.
  • QU Jian-jun, WANG Jia-cheng, CHENG Guo-dong, LI Fang, ZU Rui-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 51-56. https://doi.org/10.7522/j.issn.1000-0240.2002.0008
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    There are many ruins of ancient adobe constructions in Northwest China, such as the famous ancient Great Wall built in the Ming and Han Dynasties in Hexi Corridor, the Changhe and Gaochang Ancient Cites in Xinjiang Region, and so on. All of these constructions are precious mankind s cultural heritage, and their valuable artistic value is rare worldwide. Due to the unique natural conditions, under cold and dry climate, the ancient adobe constructions could be constructed and preserved in Northwest China, meanwhile, the violent processes of the freeze-thaw and wind erosion caused many ancient adobe constructions collapsed, resulting in destruction of these unrecoverable resources. Limited by various factors, few studies about mechanisms of the freeze-thaw and wind erosion of ancient adobe constructions have been conducted before. Recently, numerous research works about the mechanisms and protection of them have been done. However, the study about the coupling mechanism between freeze-thaw and wind erosion is seldom. By simulated experiment on the freeze-thaw and wind erosion of the ancient adobe constructions, this paper conclude that the freeze-thaw and wind erosion is the primary cause of the destruction of many ancient adobe constructions. If the frequency of the freeze-thaw cycle is invariant, the wind erosion intensity will increase with the increasing of the water content in earth. Similarly, if the water content in earth keeps invariant, the wind erosion intensity will increase distinctly with the increasing of freeze-thaw times. Based on these findings, the authors conclude that the destruction of the microstructure in earth resulted from the process of the freezing-thawing cycle is the major cause of the destruction of ancient adobe construction. According to the result of wind tunnel experiment, the earth sample reinforced with 5% of LS and 15% of PS is a bear for wind erosion. So this reinforced method could be effective in protecting the rare ancient adobe constructions from rigorous natural conditions in Northwest China.
  • ZHANG Xin-ping, YAO Tan-dong, JIAO Ke-qin, SUN Wei-zhen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 57-62. https://doi.org/10.7522/j.issn.1000-0240.2002.0009
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    The δ18O in the surface and near-surface firn layers of the east breach of the Glacier No. 1 at the headwaters of the *arümqi River was measured from June to July 2000. Then its variation with altitude and time, the temperature effect of the stable isotope and the effect of melting and evaporation were analyzed.No altitude effect was found in such a small glacier, showing that precipitation on the glacier was originated from the cloud cluster with same condensation level. Moreover, the anti-altitude effect, namely the δ18O in firn increases with altitude, was found sometimes. Such a phenomenon is related to the strong melt and evaporation. Because meltwater generates mainly in the upper part of snow/firn, 5 cm in depth, and because the loss of mass due to evaporation occurs mainly on snow surface, the surface mass is progressively replacing under continuous melt and evaporation. Therefore, the δ18O in a sample of surface firn at different time probably comes from different precipitation processes. Usually, the melting and evaporation at low altitude are stronger than that at high altitude. Therefore, the surface firn at low altitude is maybe the outcome of earlier precipitation event after strong melt and evaporation.The stable isotopic fractionation generated between gaseous and solid owing to evaporation and between liquid and solid owing to melt makes the stable isotope in the surface firn enriched. The stable isotopic composition in the meltwater from upper snow/firn layers influences that in the lower snow/firn layers. As the δ18O in the upper snow/firn layers was low, the δ18O beneath the upper layers decreases with time progressively, and vice versa.The analyses display that there were all the positive correlations between the δ18O in the sampling series with three time lags and the mean daily temperature in snowfall day to a certain degree. The correlative coefficients reach 0.70, 0.73, and 0.67, respectively. However, the correlations have shifted owing to melt and evaporation. The ratios of δ18O/temperature gradient are 1.0036, 0.6757 and 0.4938 K-1, respectively, progressively decreasing with the delay of sampling time. It is revealed that the temperature-sensitivity of the δ18O in firn of the glacier during the melt season is decreasing with time, and consequently the synoptic and climatic information hid in snow/firn will change with time.
  • LI Xiao-ze, YAO Tan-dong, QU Jian-jun, ZHANG Wei-min
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 63-67. https://doi.org/10.7522/j.issn.1000-0240.2002.0010
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    There are proglacial dunes and gobi planes in the west side of the Puruogangri Ice Field at the central Tibetan Plateau, China. Different from the other deserts in general, there are the following five features of the proglacial dunes and gobi planes: 1) In spatial, they are distributed near to their correlative glaciers; 2) They are based on the layers of till formed by correlative glacier movement; 3) Gobi planes and gravel ventifacts are well-developed; 4) The dunes are of active, with single direction of lunar type and very slow movement; 5) There are laminae-slice layers of humic materials in the laminae system of dunes.The proglacial dunes better reflect the evolution of the ice field. Because the dunes formed after glacier retreating and after exposure of till, followed by providing plentiful sand materials. So, in this way, the proglacial eolian sandy geomorphology mainly depends on the retreat of glacier in the west edge of the ice field, and on the yield of sand materials. Also the eolian geomorphology indicates the trajectory of retreating glacier.From the eolian geomorphology and deposits one can see: 1) The ice field formed at 18 ka BP at least, which can be inferred from the age of dune section, 10.8 ka BP (14C dating), and the correlation with Guliya ice core records; 2) Precipitation on the ice field is mainly due to planetary westerly, which can be reconstructed from the dune s morphology and attitudes of fore laminae bedding of dunes; 3) In the west edge, the equilibrium line of the ice field has retreated with the mean rate of 0.88~1.02 m5a-1 in the horizontal direction and 24~32 mm·a-1 in the vertical direction, respectively, since 10.8 ka BP.
  • MA Ming-guo, JIAO Yuan-mei, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 68-72. https://doi.org/10.7522/j.issn.1000-0240.2002.0011
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    During the past ten years, the land coverage has changed a lot in Northwest China. Using the Land Coverage Dynamic Monitoring System NOAACHAIN, the NOAAAVHRR image data of Northwest China in August 1990 and 1999 is pre-processed. In this article the detail processes of atmosphere correction and geo-correction, and the calculation of system parameters are described. Through the statistics of vegetation index NDVI, the change in land coverage is obtained between these two periods. The results showed that the NDVI decreases in the whole Northwest China, and the vegetation degeneration is serious. The July NDVI peak difference is -0.1439 with a decreasing area of 1.77 106km2 and an increasing area of 0.46 106km2. The August NDVI peak difference is -0.1528 with a decreasing area of 2.01 106km2 and an increasing area of 0.402 106km2. The most serious degradation areas are distributed in the agri-herd interleaving areas in eastern Qinghai Province, the Tianshan Mountains and the lower reaches of the Tarim River in Xinjiang Region. And the more serious degradation areas are distributed in the Qaidam Basin in Qinghai Province, the Junggar Basin and southern Tarim Basin in Xinjiang Region, the northern Shaanxi Province, and the Minqin County and Qingyang Prefecture in Gansu Province. At the same time, the NDVI increases in some areas, such as, the Ili River Basin in northern Xinjiang Province, southern Qinghai Province, Lanzhou City of Gansu Province and the Qinling Mountains. NOAACHAIN is a pre-processing system of NOAAAVHRR data. As the result of the pre-processing, the NDVI can efficiently show the change in land coverage in Northwest China. Also the system exhibits a rather perfect stability. The key steps for NOAACHAIN are the confirmation and calculation of the parameters for atmosphere correction and the number of the GCPs for geo-correction.
  • LU An-xin, CHEN Xian-zhang, WANG Jian, WANG Li-hong, WU Li-zong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 73-78. https://doi.org/10.7522/j.issn.1000-0240.2002.0012
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    The Heihe River is the second large inland river by basin area in the arid areas of Northwest China, with a total area of 128 000 km2. In the middle reaches of it, the desertification is severe because of the over-usage of irrigation water in the oasis agriculture areas, expending of farmland, over pasture and etc. Especially in the lower reaches of it, the ecology and environment are turning worse in recent years. A major monitoring area was selected in Jinta of the middle reaches of the Heihe River Basin and the Landsat TM data in summer of 1990 and 2000 was used for interpretation on computer screen, classification and setting up ecological and environmental investigation database (1:100 000) combined with DEM, land cover/land use, land type data and etc., according to the ecological and environmental classification system. The dynamic monitoring results in 1990 and 2000 show that the changing percentage in area of 6 ground objects are as follows: land use and agriculture land use increasing by 34.17% and 19.47%, respectively, wet land and water-body also increasing by 6.29% and 8.03%, respectively; unused land increasing by 1.73%, and the biggest change is decrease in natural/semi-natural vegetation area, 42.78%. Dynamic monitoring found that the area of natural/semi-natural vegetation in the middle reaches of the Heihe River largely reduced. On the one hand, it is resulted from the increasing of cultivated land within oases, and is also resulted from the desertification, on the other hand. So it is a dangerous signal of large area desertification, if the natural/semi-natural vegetation reduces continuously and dramatically. In the past years, both the number and the area of small reservoirs increased remarkably in the middle reaches, which met the increasing water requirement due to largely increasing cultivated area. This is the direct cause of the cutting off runoff and the ecology and environment going from bad to worse in the lower reaches. So unified allocation of water utilization and development of save-water agriculture are very important.
  • ZHANG Ming-jun, LI Zhong-qin, XIAO Cun-de, QIN Da-he, KANG Jian-cheng, LI Jun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 79-82. https://doi.org/10.7522/j.issn.1000-0240.2002.0013
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    A 50-m firn core collected from the Site LGB65 (with an accumulation rate of 127 kg·m-2·a-1, and an mean annual temperature of -33.1 ℃) on Princess Elizabeth Land, East Antarctica, during 1996/1997 Chinese First Antarctic Inland Expedition has been analyzed for chemical composition and oxygen isotope ratio. The dating is accurate within ±3 years due to the well-preserved seasonal cycles of major ions. Based on the analyses, the glaciochemistry features in the study region in the past 250 a have first been revealed. It is found that the variations of three kinds of sea salt ions (Cl-, Na+ and Mg2+) in the past 250 a were rather smooth, except for the high concentrations in the very few years, and showed a very similarly slightly rising trend. The variations of Ca2+ and K+ are smoother than those of sea salt ions with a variation trend not obvious. However, the variations of NO3-, NH4+ and SO42- were rather large, the variations of NO3- and NH4+ showed a very similarly rising trend. The most positive variation feature of SO42- was that by SO42- concentrations 16 volcanic eruptions were detected in the past 250 a.
  • CHEN Tuo, QIN Da-he, LIU Xiao-hong, LI Jiang-feng, REN Jia-wen, SUN Wei-zhen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 83-86. https://doi.org/10.7522/j.issn.1000-0240.2002.0014
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    Increasing concern on future climate changes and their potential impacts on mankind prompts scientists to explore a variety of historical and natural archives that can infer the past climate changes. Of the various land-based short-term palaeoclimatic indicators, tree rings offer a great promise because of their high resolution (1 year or less). In this context, ring width, ring density and stable isotope ratios of tree ring have been studied for possible climatic correlations. The δ13C values in annual growth rings of trees should represent a high resolution record of δ13C values of atmospheric CO2, or physiological response of plant relating to climatic and environmental changes or a combination of both. There is currently an expectation thatδ13C values in tree rings could be less sensitive to random effects than radial growth. So a ca 450-year chronology of tree-ring stable carbon isotope was developed from Larix sibirica in the Altay County of Xinjiang Region. A rapidly decreasing trend, the most dramatic isotopic event in the chronology, has appeared since 1850, which was attributed to combustion of fossil fuel and change in land use. From 1550 to 1850, there were obvious changes of tree-ring δ13C or temperature in the chronology: Tree-ring δ13C or temperature was lower in the whole 17th Century while was higher during the 18th Century. Using the available temperature coefficient of tree-ring δ13C, a decrease of 0.67~2.46 ℃ in the 17th Century is found. All kinds of evidence from different regions showed that the temperature changes of the Little Ice Age disclosed by the tree-ring δ13C chronology were reliable.
  • PU Jian-chen, YAO Tan-dong, WANG Ning-lian, DING Liang-fu, ZHANG Qi-hua
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 87-92. https://doi.org/10.7522/j.issn.1000-0240.2002.0015
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    Puruogangri ice field is the largest ice field in the Northern Tibet Plateau composed of several ice caps, with an area of about 422.58 km2 and a volume of 52.5153 km3, ELA ranging from 5 620 to 5 860 m a.s.l. More than 50 ice tongues with different lengths extend around to wide and shallow valleys, of which the longest one has a wide terminus reaching the foothill, In the area with lower tongues, there are many ice pyramids, mainly in an initial stage and with connected bases. Since the Little Ice Age the ice field has trended to retreat. There are three moraines around the tongues in the north and southeast. They belong to three cold periods when glacier advanced. At those time, less advance presented in the west. From the Little Ice Age up to now, glacier area decreases 24.20 km2, 5.7% of the original area, equivalent to 3.6583 km3 of ice loss. In the west it is found that the glacier retreated by 20 m from the post Little Ice Age to the 1970 s, and 40~50 m from the 1970 s to the end of the 1990 s, with an average rate of 1.5~1.9 m·a-1. It retreated 4~5 m from September 1999 to October 2000, showing an intensified retreating. However, the Puruogangri Ice Field is relatively stable as compared with other glaciers.
  • LI Yue-fang, WANG Ning-lian, YAO Tan-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 93-97. https://doi.org/10.7522/j.issn.1000-0240.2002.0016
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    A new directly determining Cd and Pb in ice core with ng·L-1 level by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is presented in this paper. The procedures of labware cleaning and the preparing standard solution are described. The blank values are also showed in order to illustrate the reliability of labware cleaning. The determined concentration is in the range of 5 to 200 ng·L-1. Solutions with national standard certificate are used to insure the reliability of the determining. The blank value of Cd is less than 2 ng·L-1 and that of Pb is less than 10 ng·L-1, respectively. For individual determining, the precision for both Cd and Pb is less 10%. The precision among several determined values for a individual concentration value is less 5% for Cd and <10% for Pb, respectively. The recovery determined from standard solutions is in the range of 85%~107%. The limit of detection is 0.15 ng·L-1 for Cd and 0.62 ng·L-1 for Pb, respectively, based on ten repeatedly determined blank values. The decontamination method is described, and the concentration of Cd and Pb decreases from the outside to the inner of a core, showing proficiency in the decontamination.;Concentrations of Cd and Pb changing with depth of Malan Ice Core drilled in Hoh Xil of Qinghai Province are also presented. The concentration of Cd is in the range of 0.399~14.735 ng·L-1 with a mean value of 4.6 ng·L-1; the concentration of Pb is in the range of 9~51 ng·L-1 with a mean value of 20 ng·L-1. No obvious change trend of concentrations with depth is found.
  • TIAN Li-de, LI Yue-fang, YAO Tan-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 98-101. https://doi.org/10.7522/j.issn.1000-0240.2002.0017
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    Based on the measured results for some natural surface water (including river water, lake water and so on) on the Tibetan Plateau, the spatial distribution of As concentration is discussed in this paper. An obvious spatial variation of As in surface water is found. There is an extremely high As concentration in the Shiquanhe Basin, west of the Plateau. Its spatial distribution is dependent on the geochemistry in soil and rock. Higher concentration in the river water of Nagqu Prefecture may be resulted from human activity, such as mining. As compared with river water, lake water has a higher As concentration, with the measured maximum of 1 200 μg·L-1. The higher As concentration in lake water (especially in inner lake water) can be attributed to evaporation condensation, together with high As input within river water.
  • Yu Qi-hao, Cheng Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(1): 102-108. https://doi.org/10.7522/j.issn.1000-0240.2002.0018
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    Modern geophysical methods and techniques play an important role in investigating and studying permafrost. In China the application of geophysical methods to permafrost began from the early 1960 s. Since, it develops from single and simple methods to integrated methods to investigate different kinds of frozen soils, from getting single geophysical parameter to multi-parameters to reflect the general characteristics of frozen soils. Through more than 40 years hard working, great progress has been made in study and application of geophysical techniques in permafrost regions, especially in continuously improving the ability and precision in distinguishing frozen soils, and get some important information and parameters about frozen soils. The application of modern geophysical methods has become one of the key methods in investigating the state and three-dimensional properties of permafrost and monitoring the permafrost change and development. In this paper the foundations, based on which geophysical methods can be used in permafrost exploration, the development of geophysical technique in recent years; the great improvement of ability of resolving practical problems, the precision in distinguishing frozen soils; and the advantage and disadvantage of these methods are described. And farther more, this paper points out the large gap between China and the other countries and the scientific application abroad. What problems exist, what should be paid attention to and what should do in China in the future are also put forward.