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我实验室引进人才赵艳副教授的最新研究成果引起《Nature-China》杂志的关注

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  最近《Nature》出版集团在其网络杂志《Nature-China》的最新研究亮点栏目中发表评论,对我西部环境教育部重点实验室引进人才赵艳副教授与翠英讲席教授于子成等取得的最新研究成果给予了高度评价。
  评论认为:树轮和冰芯记录很好地记录了青藏高原的气候历史, 但这些记录主要局限于高海拔地区。兰州大学赵艳及其合作者的研究工作证明在低海拔地区,湖泊沉积物中的孢粉可以作为很好的气候指示物。
  赵艳、于子成等在柴达木盆地尕海深水处取得两根短岩芯,对岩芯的年代(由Pb-210 Cs-137)和孢粉以接近年度的分辨率进行分析,指出该区最常见的两种孢粉种类蒿属和藜科的比值显示出孢粉产量和植物可用水的变化;尕海过去50年的蒿/藜比变化与邻近气象站的相对湿度吻合得很好。这反映出更深的岩芯能提供柴达木盆地过去湿度的变化;高海拔敦德冰芯的蒿/藜比与尕海呈现相反的变化趋势,这可能与青藏高原主体和柴达木盆地的地形差异造成的上升下沉气流机制有关。
这一研究成果对于重建干旱区过去气候,特别是湿度的变化以及荒漠化治理具有较重要理论与实践意义。该成果已于2007123Glob. Planet. Change杂志在网上全文发表
doi: 10.1016/j.gloplacha.2007.12.003 (2008). 
 
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Lake sediments: Pollen probes the past

Tim Reid
Pollen trapped in lake sediments on the Tibetan Plateau provides an indicator of the past climate
The climate history of the Tibetan Plateau has been well assessed using tree rings and ice cores, but most of these measurements have been taken at very high elevations that experience extremes of temperature and precipitation.  Yan Zhao at Lanzhou University and co-workers1 have found an alternative climate indicator for lower areas — pollen trapped in lake sediments.
The researchers removed two ice cores from the floor of Gahai Lake in the Qaidam Basin. Individual layers in the cores were dated by measuring lead and caesium isotopes, and the pollen grains trapped in each layer were identified. The ratio of two common pollen species called Artemisia and Chenopodiaceae, or the A/C ratio, shows the water availability at the time, because Artemisia requires more water to grow.
The A/C ratio at Gahai Lake was well correlated with relative humidity measurements taken over the past 50 years at a nearby weather station. This suggests that deeper cores could provide estimates of earlier atmospheric moisture levels in the Qaidam Basin. However, A/C ratios measured in the high-level ice cores showed opposite trends — probably because the monsoon brings increased precipitation to high altitudes, but warm dry air to the basin.
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