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中山站至Dome A表面雪和雪芯稳定同位素组成及气候意义

项目名称: 中山站至Dome A表面雪和雪芯稳定同位素组成及气候意义
项目类型: 国家自然科学基金面上项目
项目负责人: 阎明
项目成员: 汪大立; 凌晓良; 谭德军
项目编号: 40103002
父项目编号:
规划期:
立项时间: 2002-01-01
预期结束: 2004-12-01
实际结束:
金额(万元): 17
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项目简介

   研究了南极中山站至Dome A剖面1998/1999年度表面雪样氧同位素组成,结果表明其变化范围相当大(-22.51‰-50.67‰),且线性回归分析显示表面雪样氧同位素组成与距中山站距离、海拔高度和纬度存在着很好的相关性,这实际上反映出稳定同位素组成和温度之间的密切联系;研究了南极中山站至Dome A剖面DT401点一支11米雪芯氧同位素组成记录,结果显示二十世纪的气温有逐渐增加的趋势,特别是过去二十年尤为明显,并反映出扩散作用对南极内陆低积累率地区雪冰稳定同位素记录的改造;研究了极地冰芯中记录的火山作用及其对气候的影响,结果显示大多数火山喷发以强酸(主要是硫酸)的形式在极地冰芯中留下痕迹,通过冰芯连续电导率或各个雪冰样品硫酸根浓度测定能够恢复历史上的火山作用,单个火山喷发通常会导致数月至数年的半球乃至全球范围的气候相对变冷(这种现象在极区变得更明显),但过去大规模爆炸性火山喷发对气候的影响及其与气候变化之间的联系仍有待于进一步研究。

introduction

   Oxygen isotope composition of surface snow sampled in the austral summer of 1998/1999 along the traverse route from Zhongshan Station to Dome A, Antarctica varies in a wide range from -22.51‰ to -50.67‰. The linear regression analyses indicate tnat there exists good correlation between oxygen isotope composition of surface snow and distance from Zhongshan Station, altitude or latitude, which actually reflects the close relation between stable isotope composition and temperature. The oxygen isotope composition of a 11-m snow core retrieved from DT401, East Antarctica shows that the air temperature of past century is gradually increasing with relatively rapid rise in recent two decades, and the isotopic variations clearly reveal the effects of vapor diffusion on isotope signals in low accumulation areas. Major volcanic eruptions leave traces in polar ice mainly as strong acids like sulphuric acid. Historical volcanism can be detected in polar ice by continuous ECM (Electrical Conductivity Method) measurements or sulfate concentrations in melted samples. A single volcanic eruption usually leads to relative climate cooling of several months to a few years on hemispherical or even global scale, but further work is needed to improve understanding of the climate-volcanism connection and the effects of large-scale volcanic eruptions on long-term (several decades or more) climate changes.