2007/2008年度中国南极冰穹A考察新进展   总被引：1，自引：0，他引：1       下载免费PDF全文

孙波  崔祥斌 《极地研究》2008,20(4):371-378

冰穹A(DomeA)是南极冰盖最高区域,其独特的地理位置和蕴藏的科学资源受到国际科学界的普遍关注,近年来成为国际南极科学考察研究的重要前沿区域。中国第24次南极考察(CHINARE24,2007/2008年度)继续开展DomeA地区考察活动,具体执行内陆建站选址任务和国际极地年中国行动计划--PANDA计划。本次内陆冰盖队在到达DomeA后,在DomeA核心区域以及中山站-DomeA断面上开展了多学科系统性的科考工作,取得了以"南极DomeA科学考察"、"内陆建站选址"和"中国南极内陆考察支撑能力建设"为代表的新进展,提升了我国南极内陆考察的支撑保障能力和科学认知水平。  相似文献   

Temporal variations in the abundance and sinking flux of diatoms under fast ice in summer near Syowa Station, East Antarctica     

Mutsuo Ichinomiya  Yasushi Gomi  Miwa Nakamachi  Masaki Honda  Mitsuo Fukuchi  Akira Taniguchi 《Polar Science》2008,2(1):33-40

To investigate the fate of ice algae released from sea ice, we investigated the abundance, species composition, and sinking flux of diatoms in the water column under fast ice near Syowa Station, Antarctica during the summer of 2005/2006. The diatom assemblage in the water column consisted of chain-forming planktonic species, in contrast to the under-ice assemblage dominated by pennate species reported from this site in the past; this dissimilarity suggests the presence of an unconsolidated platelet ice layer under the congelation ice, within which planktonic species can bloom. Among the dominant diatoms, Porosira pseudodenticulata and Pseudo-nitzschia cf. turgiduloides were dominant in the water column, and their water column stocks were higher than their mass sedimentation. These species apparently maintain their populations in the surface layer, as their production remains in the water column. In contrast, Fragilariopsis kerguelensis and Thalassiosira australis were scarce in the water column but rich in the flux, indicating active sinking and export of their production to the benthic ecosystem. This distinction in buoyancy control and sinking characteristics of the dominant diatoms on release from the fast ice influences the diatom species composition and carbon flow under the ice.  相似文献   

南极中山站附近海域固定冰的夏季变化          下载免费PDF全文

雷瑞波  李志军  张占海  程言峰  窦银科 《极地研究》2007,19(4):275-284

利用中国第21、22次南极科学考察(2004/2005、2005/2006)对中山站附近海域固定冰物理特性系统观测的结果,特别是依据其中2005年11月下旬至2006年1月下旬的现场实测数据详细分析了中山站附近海域固定冰消融过程物理性质的变化特征。结果表明:此区域固定冰从11月下旬开始消融,融冰期为62 d;同时,融冰期冰下水体温度迅速升高;在不断增强的太阳短波辐射和海洋热通量作用下,海冰温度也逐渐上升,并出现"相对冷中间层";热力和动力外强迫作用下,2005年12月18日-2006年1月14日期间此区域固定冰边缘线后退了20.9 km;另外,2005年12月18日固定冰边缘区走航冰厚监测结果还表明,边缘区海冰厚度在向岸方向有明显的增加趋势,并且随着接近海岸海冰厚度的离散程度逐渐减小。  相似文献   

南极海冰导温系数与孔隙率关系初探          下载免费PDF全文

石立琼  白乙拉  李志军  Cheng Bin 《极地研究》2009,21(2):91-99

利用南极中山站附近固定冰不同季节的温度垂直廓线,冰芯盐度、密度数据,基于Cox等发展的冰内孔隙率计算方法,获得冰内孔隙率的垂直廓线。再通过建立分布参数系统最优控制模型,优化辨识在无热源条件下冰内温度垂直廓线对应的海冰导温系数。通过比较7种冰导温系数同孔隙率的关系,选择出海冰导温系数和孔隙率的最优关系式。用该关系式对同一地点不同年份的海冰进行温度垂直廓线计算,比较辨识的导温系数同孔隙率的关系相对于前人理想海冰模型中的导热系数、比热等公式计算对应条件的海冰垂直温度廓线的优势。两种计算结果说明,辨识得到的关系所引起的偏差在趋势和量级上同理想模式计算的结果相同,但辨识得到的关系更简洁,且更具有物理背景。  相似文献   

用雷达电磁波探测研究南极冰盖浅层散射特征:以中山站至Dome A冰盖断面为例   总被引：1，自引：0，他引：1       下载免费PDF全文

蒋芸芸  孙波  柯长青  崔祥斌  唐学远  郭井学  张向培 《极地研究》2009,21(1):48-59

本研究运用双频雷达(60MHz和179MHz)获取的南极中山站-Dome A断面的雷达回波探测数据,对冰盖浅部100-700m的雷达内部反射层和接收功率变化定量计算分析表明,60MHz的雷达回波能量比179MHz衰减得更快;中山站-Dome A断面冰盖浅层700m以上的雷达反射层形成的主导原因是冰密度的变化;断面上不同测站点间同一深度的接收功率差值达到10dB,表明冰盖浅层散射存在显著差异。  相似文献   

南极格罗夫山陨石的分类及其研究意义          下载免费PDF全文

缪秉魁  王道德 《极地研究》2009,21(4):95-104

陨石是来自地球之外的岩石样品,是研究太阳系的起源与演化的重要窗口。半个多世纪以来,国际上在南极冰盖上发现了大量陨石样品,证实了南极是地球上最重要的陨石富集区。1998年中国首次在格罗夫山地区发现南极陨石,经过4次南极考察,共收集陨石样品9834块。这不但填补了中国在该领域的空白,也为中国积累了大量珍贵的科学样品。目前,中国先后6年开展了陨石分类研究工作,并取得了显著进展:(1)完成了684块陨石的分类命名,其中发现了许多特殊类型陨石,如火星陨石、橄辉无球粒陨石、碳质球粒陨石等;(2)初步建立了陨石库和资源共享网络平台;(3)通过南极系统分类研究,建立了南极陨石分类程序、样品管理和申请程序;(4)通过国内陨石分类合作研究,培养了一批年轻专业人才。  相似文献   

东南极格罗夫山萨哈罗夫岭漂砾暴露年龄初探          下载免费PDF全文

李广伟  刘小汉  黄费新  孔屏  David Fink  韦利杰  方爱民 《极地研究》2009,21(4):265-271

首次对格罗夫山地区漂砾的暴露年龄进行的研究表明,萨哈罗夫岭冰原岛峰的两块漂砾样品的 Be最小暴露年龄分别为1．24±0．11Ma和1．37±0．12Ma, 。A1最小暴露年龄分别为0．90 4-0．12Ma和0．44±0．04Ma。萨哈罗夫岭附近冰面上的漂砾样品的 Be和 A1最小暴露年龄分别是0．47±0．3Ma和0．44±0．04Ma。考虑到误差,萨哈罗夫岭三块漂砾的最小暴露年龄与相近高程的基岩样品的最小暴露年龄基本一致。因此,在利用原地生成宇宙成因核素测年技术对东南极内陆格罗夫山地区的冰川消涨历史进行研究时,基岩和漂砾暴露年龄所反映出的冰川演化历史是明显吻合的。  相似文献   

Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau’s interior in East Antarctica and Its Climatic Significance     

JianCheng Kang  Jean Jouzel  Michel Stievenar  DaHe Qin  LeiBao Liu  DaLi Wang  ZhongQin Li  Jun Li 《寒旱区科学》2009,1(1):0014-0024

The variations of stable water isotopes of surface snow in east Antarctic Ice Sheet, are discussed by a total of 251 samples, which were taken along a 330 km traverse from Zhongshan Station to the outer edge of the Antarctic plateau and from four snow pits excavated along the route. Analyzing results of the samples showed the expected linear relationship between the parameters ?D and ?18O with slope S1 and intercept d1. When the data set was examined using a sliding window with a width of 5 samples, it was found that there were two areas with different ratios of S1 and d1. The boundary between these two areas occurred at an elevation of about 2,000 m, suggesting two different sources of water vapour. Nearly half (47%) of the fresh-snow samples had negative deuterium excess (d=?D? 8?18O) values, but few of the snow pit samples did, suggesting that variations of ? are quickly smoothed by isotopic diffusion in the near-surface firn. Analysis of the phase relationship between ?D and deuterium excess in the snow pit stratigraphies showed that they were mostly in phase from Jan. 1994 to Sept. 1995, but mostly out of phase from Sept. 1995 to Jan. 1997.  相似文献   

Ripple cross-laminated sediments on the East Antarctic Shelf: evidence for episodic bottom water production during the Holocene?     

P. T. Harris 《Marine Geology》2000,170(3-4):317-330

Biosiliceous sediments sampled from a submarine valley system on the continental shelf of East Antarctica contain intervals of ripple cross-lamination interspersed with massively bedded units. Based on radiocarbon dates from one core collected on the Mac.Robertson Shelf, the most intensely cross-laminated sediments were deposited between 6 and 3.5 kyr BP, with isolated cross-laminae deposited at other times in the Holocene. The cross-laminated sediments are interpreted here as a signal of episodic density currents flowing across the outer shelf, which result from the formation of high salinity shelf water (HSSW). This HSSW is formed in winter by brine rejection during sea ice formation and by the exchange and cooling of upwelled saline slope water, and it contributes to the bottom water produced along the continental margin of Antarctica. If this interpretation of the cross-laminae is correct, then bottom water formation and export from the East Antarctic shelf has exhibited temporal, and probably also spatial, variability throughout the Holocene. Such variability would have implications for oceanographers attempting to quantify Antarctic bottom water production rates based only on present day observations.  相似文献   

Weathering of granite in Antarctica: I. Light penetration into rock and implications for rock weathering and endolithic communities     

Kevin Hall  Mauro Guglielmin  Andrea Strini 《地球表面变化过程与地形》2008,33(2):295-307

Where rocks are composed of translucent minerals, light penetrates the rock and, in so doing, impacts on the thermal conditions. Where minerals are not translucent all the heat transformation must be at the rock surface, and steep thermal gradients can occur. Where light does penetrate, a component of the incoming radiation is transformed to heat at differing depths within the rock, thereby decreasing the thermal gradient. Equally, light transmissive minerals facilitate endolithic communities, which can also play a role in rock weathering. The attribute of light transmission within rock and the impact this has on the resulting thermal conditions has not been considered within rock weathering studies. An attempt was made to monitor the amount of light penetrating the outer 2 mm of coarse granite under Antarctic summer conditions and to evaluate the thermal impact of this. It was found that the amount of light penetration at this site exceeded modeled or postulated values from biological studies and that it could significantly impact the thermal conditions within the outer shell of the rock. Although the resulting data highlighted a number of flaws in the experimental procedure, sufficient information was generated to provide the first assessment of the range of thermal responses due to light transmissive minerals in rock. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献