The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountai...The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountain,in the northeastern Tibetan Plateau,China in the past 30 years.The total glacier area decreased from 492.9km2 in 1966 to 458.2km2 in 1999.The volume loss of the studied glaciers reached 1.4 km3 from 1966 to 2000.This agrees with documented changes in other mountain glaciers of the whole Tibetan Plateau.展开更多
The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from -13.4℃ to -1.84℃, indicating the glaciers are cold throughout the bo...The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from -13.4℃ to -1.84℃, indicating the glaciers are cold throughout the boreholes. The negative gradient （i.e., the temperature decreasing with the increasing of depth） due to the advection of ice and climate warming, and the negative gradient moving downwards relates to climate warming, are probably responsible for the observed minimum temperature moving to lower depth in boreholes of the Gyabrag glacier and Miaoergou glacier compared to the previously investigated continental ice core borehole temperature in West China. The borehole temperature at 10m depth ranges from -8.0℃ in the Gyabrag glacier in the central Himalayas to -12.9℃ in the Tsabagarav glacier in the Altai range. The borehole temperature at 10 m depth is 3-4 degrees higher than the calculated mean annual air temperature on the surface of the glaciers and the higher 10 m depth temperature is mainly caused by the production of latent heat due to melt-water percolation and refreezing. The basal temperature is far below the melting point, indicating that the glaciers are frozen to bedrock. The very low temperature gradients near the bedrock suggest that the influence of geothermal flux and ice flow on basal temperature is very weak. The low temperature and small velocity of ice flow of glaciers are beneficial for preservation of the chemical and isotopic information in ice cores.展开更多
Dome Argus （Dome A） in East Antarctica is a potentially likely site to meet one of the major objectives of the International Partnerships in Ice Core Sciences （IPICS） on the oldest ice core, and thus has aroused...Dome Argus （Dome A） in East Antarctica is a potentially likely site to meet one of the major objectives of the International Partnerships in Ice Core Sciences （IPICS） on the oldest ice core, and thus has aroused wide public and scientific interest. Since 2004/2005, many glaciological investigations have been conducted in this region. These have included GPS and ground-penetrating radar surveys, snow pit and ice core drilling, stake network measurements, and meteorological observations. In this article, the main results of these glaciological investigations in the Dome A region are summarized. We present details of the surface mass balance on different timescales and its spatial variability, geochemical characteristics of the surface snow, and paleo-environment reconstruction of ice cores. Finally, perspectives on the prospects for future studies are suggested.展开更多
Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altit...Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altitude） as the primary predictors and incorporates inverse distance weighting （IDW） technique. The method was applied to a high-resolution digital elevation model （DEM） to produce a grid map of multi-year mean δD values with lkm spatial resolution for Antarctica. The mean absolute deviation between observed and estimated data in the map is about 5.4‰, and the standard deviation is 9‰. The resulting δD pattern resembles well known characteristics such as the depletion of the heavy isotopes with increasing latitude and distance from coast line, but also reveals the complex topographic effects.展开更多
Ice cores have revolutionized our views of the Earth system.They record past climatic and environmental parameters that range on time scales from synoptic events to hundreds of thousands of years.For instance,the Vost...Ice cores have revolutionized our views of the Earth system.They record past climatic and environmental parameters that range on time scales from synoptic events to hundreds of thousands of years.For instance,the Vostok ice core reached an age of 420 ka(thousand years)(Figure 1),revealing a close linkage between climate and greenhouse gas concentrations over the last four glacial-interglacial cycles(Petit et al.,1999).展开更多
The ^(17)O anomaly of oxygen(Δ^(17)O,calculated from δ^(17)O and δ^(18)O)trapped in ice-core bubbles and dissolved in ocean has been respectively used to evaluate the past biosphere productivity at a global scale a...The ^(17)O anomaly of oxygen(Δ^(17)O,calculated from δ^(17)O and δ^(18)O)trapped in ice-core bubbles and dissolved in ocean has been respectively used to evaluate the past biosphere productivity at a global scale and gross oxygen production(GOP)in the mixed layer(ML)of ocean.Compared to traditional methods in GOP estimation,triple oxygen isotope(TOI)method provides estimates that ignore incubation bottle effects and calculates GOP on larger spatial and temporal scales.Calculated from TOI of O_(2) trapped in ice-core bubbles,the averaged global biological productivities in past glacial periods were about 0.83-0.94 of the present,and the longest time record reached 400 ka BP(thousand years before the present).TOI-derived GOP estimation has also been widely applied in open oceans and coastal oceans,with emphasis on the ML.Although the TOI method has been widely used in aquatic ecosystems,TOI-based GOP is assumed to be constant at a steady state,and the influence of physical transports below the ML is neglected.The TOI method applied to evaluate past total biospheric productivity is limited by rare samples as well as uncertainties related to O_(2) consumption mechanisms and terrestrial biosphere’s hydrological processes.Future studies should take into account the physical transports below the ML and apply the TOI method in deep ocean.In addition,study on the complex land biosphere mechanisms by triple isotope composition of O_(2) trapped in ice-core bubbles needs to be strengthened.展开更多
Over the past 15 years there has been much effort invested in microorganisms of glacial snow and ice on the Tibetan Plateau.These studies include:phenotypic characteristics of recovered isolates;factors(dust,temperatu...Over the past 15 years there has been much effort invested in microorganisms of glacial snow and ice on the Tibetan Plateau.These studies include:phenotypic characteristics of recovered isolates;factors(dust,temperature,altitude)influencing microbial abundance,diversity and community in one glacier;distribution of bacterial number,diversity,community along ice core depth;similarities and differences of regionally distributed ice core isolates;seasonal variation of bacterial abundance and diversity.The following need further study.Better methods for more information about the diversity,survival mechanism of glacial microorganism;more research about archaea and fungi;microbial resources;relation of glacial microorganisms with biogeochemical cycle and mass balance;research on altitude distribution.展开更多
Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded ...Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was -58.3℃ in 2005 and -58.2℃ in 2006, re-spectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δ D) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the "pole of cold" on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.展开更多
Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Ant-arctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumu-lation rates...Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Ant-arctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumu-lation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity.展开更多
Ice core records from polar regions are of great value to study long-term climate and environmental change. Greenland ice-core records are celebrated for their high resolution and have provided very important knowledg...Ice core records from polar regions are of great value to study long-term climate and environmental change. Greenland ice-core records are celebrated for their high resolution and have provided very important knowledge for understanding the late Quaternary palaeoclimate, especially in reference to millennial-scale abrupt climatic flips during the last glaciation. Recently, a new project to retrieve a deep ice-core from Greenland known as NEEM for North Greenland Eemian Ice Drilling, has been launched with the main target being the last interglacial period. The new core will help us understand further details of climate changes during a period of warmth as the present. Antarctic ice cores have a unique advantage in providing recovery of longer time-scale paleclimate information and hence are regarded as a crucial pillar to examine climatic cycles on the time-scale of Earth-orbital phenomena. Since the bottom ice in Dome A is estimated to be older than a million years, a deep drilling there becomes a new focus for ice core studies.展开更多
A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both met...A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a temperature fluctuation amplitude about ±0.6°C at the eastern inland Antarctica during the late Holocene. The average d-excess (or d =δ D-8δ 18O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.展开更多
Stable isotopic composition in Antarctic snow and ice is commonly regarded as one of invaluable palaeoclimate proxies and plays a critically important role in reconstructing past climate change.In this paper we summar...Stable isotopic composition in Antarctic snow and ice is commonly regarded as one of invaluable palaeoclimate proxies and plays a critically important role in reconstructing past climate change.In this paper we summarized the spatial distribution and the controlling factors of δD,δ18O,d-excess and 17O-excess in Antarctic snow and ice,and discussed their reliability and applicability as palaeoclimate proxies.Recent progress in the stable isotopic records from Antarctic deep ice cores was reviewed,and perspectives on bridging the current understanding gaps were suggested.展开更多
基金supported by the National Natural Science Foundation of China(40576001 and 40825017)the Chinese Academy of Sciences(KZCX3SW344 and 100 Talents Project)+1 种基金the Korean Research Council of Public Science and Technology(PP07010)the National Key Technology R&D Program(2006BAB18B01).
文摘The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountain,in the northeastern Tibetan Plateau,China in the past 30 years.The total glacier area decreased from 492.9km2 in 1966 to 458.2km2 in 1999.The volume loss of the studied glaciers reached 1.4 km3 from 1966 to 2000.This agrees with documented changes in other mountain glaciers of the whole Tibetan Plateau.
基金funded by the National Natural Science Foundation of China (Grant No. 40825017)the Chinese Academy of Sciences(Grant No. KZCX3-SW-344 and 100 Talents Project)
文摘The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from -13.4℃ to -1.84℃, indicating the glaciers are cold throughout the boreholes. The negative gradient （i.e., the temperature decreasing with the increasing of depth） due to the advection of ice and climate warming, and the negative gradient moving downwards relates to climate warming, are probably responsible for the observed minimum temperature moving to lower depth in boreholes of the Gyabrag glacier and Miaoergou glacier compared to the previously investigated continental ice core borehole temperature in West China. The borehole temperature at 10m depth ranges from -8.0℃ in the Gyabrag glacier in the central Himalayas to -12.9℃ in the Tsabagarav glacier in the Altai range. The borehole temperature at 10 m depth is 3-4 degrees higher than the calculated mean annual air temperature on the surface of the glaciers and the higher 10 m depth temperature is mainly caused by the production of latent heat due to melt-water percolation and refreezing. The basal temperature is far below the melting point, indicating that the glaciers are frozen to bedrock. The very low temperature gradients near the bedrock suggest that the influence of geothermal flux and ice flow on basal temperature is very weak. The low temperature and small velocity of ice flow of glaciers are beneficial for preservation of the chemical and isotopic information in ice cores.
基金supported by the Natural Science Foundation of China (Grant no. 41330526)Natural Science Foundation of Shanghai (Grant no. 17ZR1433200)National Key R & D Program of China (Grant no. 2016YFC1400302)
文摘Dome Argus （Dome A） in East Antarctica is a potentially likely site to meet one of the major objectives of the International Partnerships in Ice Core Sciences （IPICS） on the oldest ice core, and thus has aroused wide public and scientific interest. Since 2004/2005, many glaciological investigations have been conducted in this region. These have included GPS and ground-penetrating radar surveys, snow pit and ice core drilling, stake network measurements, and meteorological observations. In this article, the main results of these glaciological investigations in the Dome A region are summarized. We present details of the surface mass balance on different timescales and its spatial variability, geochemical characteristics of the surface snow, and paleo-environment reconstruction of ice cores. Finally, perspectives on the prospects for future studies are suggested.
文摘为了解冰川环境抗生素抗性基因(Antibiotic Resistance Genes,ARGs)的存在状况及其与重金属和I型整合子(class I integron,intI)的关系,通过荧光定量PCR(Real-time Quantitative PCR,qPCR),研究青藏高原德普昌达克冰川和南极中山站雪样ARGs、重金属抗性基因(heavy metaI resistance genes,HMRGs)和intI的相对丰度及其相关性。结果表明,大部分基因的相对丰度在德普昌达克冰川小于中山站。德普昌达克冰川tetA、czcD、pcoA、znuA、intI1和intI2的相对丰度随海拔高度的增加而降低;南极的merA、zntA、znuA、sul2、tetA和intI2距离中山站建筑区域越近,相对丰度越高。2个研究位点ARGs均受Zn抗性基因znuA的影响,且znuA与intI之间显著相关。冰川环境虽然远离人类活动,但其ARGs同时受intI和与人类活动有关的重金属Zn的影响。
基金Under the auspices of National Natural Science Foundation of China (No. 40825017, 40576001)100 Talents Project of Chinese Academy of SciencesNational Key Technologies R&D Program of China (No. 2006BAB18B01)
文摘Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altitude） as the primary predictors and incorporates inverse distance weighting （IDW） technique. The method was applied to a high-resolution digital elevation model （DEM） to produce a grid map of multi-year mean δD values with lkm spatial resolution for Antarctica. The mean absolute deviation between observed and estimated data in the map is about 5.4‰, and the standard deviation is 9‰. The resulting δD pattern resembles well known characteristics such as the depletion of the heavy isotopes with increasing latitude and distance from coast line, but also reveals the complex topographic effects.
基金supported by the Natural Science Foundation of China(Grant nos.41830644,42021001).
文摘Ice cores have revolutionized our views of the Earth system.They record past climatic and environmental parameters that range on time scales from synoptic events to hundreds of thousands of years.For instance,the Vostok ice core reached an age of 420 ka(thousand years)(Figure 1),revealing a close linkage between climate and greenhouse gas concentrations over the last four glacial-interglacial cycles(Petit et al.,1999).
基金supported by the National Natural Science Foundation of China(Grant nos.41771031 and 41673125)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The ^(17)O anomaly of oxygen(Δ^(17)O,calculated from δ^(17)O and δ^(18)O)trapped in ice-core bubbles and dissolved in ocean has been respectively used to evaluate the past biosphere productivity at a global scale and gross oxygen production(GOP)in the mixed layer(ML)of ocean.Compared to traditional methods in GOP estimation,triple oxygen isotope(TOI)method provides estimates that ignore incubation bottle effects and calculates GOP on larger spatial and temporal scales.Calculated from TOI of O_(2) trapped in ice-core bubbles,the averaged global biological productivities in past glacial periods were about 0.83-0.94 of the present,and the longest time record reached 400 ka BP(thousand years before the present).TOI-derived GOP estimation has also been widely applied in open oceans and coastal oceans,with emphasis on the ML.Although the TOI method has been widely used in aquatic ecosystems,TOI-based GOP is assumed to be constant at a steady state,and the influence of physical transports below the ML is neglected.The TOI method applied to evaluate past total biospheric productivity is limited by rare samples as well as uncertainties related to O_(2) consumption mechanisms and terrestrial biosphere’s hydrological processes.Future studies should take into account the physical transports below the ML and apply the TOI method in deep ocean.In addition,study on the complex land biosphere mechanisms by triple isotope composition of O_(2) trapped in ice-core bubbles needs to be strengthened.
基金supported by the National Natural Science Foundation of China(Grant No.31100369,41201067,41171052,41206175)
文摘Over the past 15 years there has been much effort invested in microorganisms of glacial snow and ice on the Tibetan Plateau.These studies include:phenotypic characteristics of recovered isolates;factors(dust,temperature,altitude)influencing microbial abundance,diversity and community in one glacier;distribution of bacterial number,diversity,community along ice core depth;similarities and differences of regionally distributed ice core isolates;seasonal variation of bacterial abundance and diversity.The following need further study.Better methods for more information about the diversity,survival mechanism of glacial microorganism;more research about archaea and fungi;microbial resources;relation of glacial microorganisms with biogeochemical cycle and mass balance;research on altitude distribution.
基金the National Natural Science Foundation of China (Grant Nos. 40620120112 and 40776002)Chinese Academy of Sciences (Grant No. KZCX-SW-354)the Hundred-Talent Project of Chinese Academy of Sciences
文摘Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was -58.3℃ in 2005 and -58.2℃ in 2006, re-spectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δ D) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the "pole of cold" on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.
基金the National Natural Science Foundation of China (Grant No. 40576001)the Chinese Academy of Sciences (Grant No. 100 Talents Project and KZCX3-SW-354)
文摘Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Ant-arctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumu-lation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity.
基金Supported by Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2-SW-354)National Key Technology Research and Development Program (Grant No. 2006BAB18B01)
文摘Ice core records from polar regions are of great value to study long-term climate and environmental change. Greenland ice-core records are celebrated for their high resolution and have provided very important knowledge for understanding the late Quaternary palaeoclimate, especially in reference to millennial-scale abrupt climatic flips during the last glaciation. Recently, a new project to retrieve a deep ice-core from Greenland known as NEEM for North Greenland Eemian Ice Drilling, has been launched with the main target being the last interglacial period. The new core will help us understand further details of climate changes during a period of warmth as the present. Antarctic ice cores have a unique advantage in providing recovery of longer time-scale paleclimate information and hence are regarded as a crucial pillar to examine climatic cycles on the time-scale of Earth-orbital phenomena. Since the bottom ice in Dome A is estimated to be older than a million years, a deep drilling there becomes a new focus for ice core studies.
基金Supported by National Natural Science Foundation of China (Grant Nos. 40825017 and 40576001)One Hundred Talents Program of Chinese Academy of Sciences, Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX3-SW- 354)+1 种基金National Key Technology R & D Program (Grant No. 2006BAB18B01)and the Programme International de Cooperation Scientifique (PICS) Project "Climate and Environment in Antarctica and the Himalayas" (CLEAH, PICS no3499)
文摘A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a temperature fluctuation amplitude about ±0.6°C at the eastern inland Antarctica during the late Holocene. The average d-excess (or d =δ D-8δ 18O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.
基金supported by the National Natural Science Foundation of China (41171052,40825017,41206175 and 41176165)the State Oceanic Administration (CHINARE2012-02-02)Ministry of Education (20110091110025 and 1082020904)
文摘Stable isotopic composition in Antarctic snow and ice is commonly regarded as one of invaluable palaeoclimate proxies and plays a critically important role in reconstructing past climate change.In this paper we summarized the spatial distribution and the controlling factors of δD,δ18O,d-excess and 17O-excess in Antarctic snow and ice,and discussed their reliability and applicability as palaeoclimate proxies.Recent progress in the stable isotopic records from Antarctic deep ice cores was reviewed,and perspectives on bridging the current understanding gaps were suggested.
