近1000年来青藏高原南部和北部 大气尘埃载荷变化的冰芯记录*

依据青藏高原目前所取得冰芯的尘埃分析结果,初步分析了近1000年来青藏高原南北大气尘埃载荷的时空变化特征。研究表明,高原南部达索普冰芯记录的高尘埃含量时期为1270s~1380s和1870s~1990s,而北部马兰冰芯记录的高尘埃含量时期为1130s~1550s和1770s~1940s。近1000年来青藏高原南北冰芯中尘埃含量呈现不同程度的增加总趋势,这可能指示了环境的变干趋势。青藏高原冰芯记录还反映出,高原北部地区大气中的尘埃载荷明显高于南部地区;高原北部地区大气尘埃载荷春季最大,而南部地区非季风季节最大。另外,通过对高原南北冰芯中尘埃含量记录与δ¹⁸ O记录之间相关关系分析,揭示出大气尘埃载荷变化与气温变化之间关系在高原北部地区呈显著负相关,而在南部地区却呈显著正相关。这说明青藏高原南北气候环境变化的差异性。

VARIATIONS OF ATMOSPHERIC DUST LOADING IN THE SOUTHERN AND NORTHERN TIBETAN PLATEAU OVER THE LAST MILLENNIUM RECORDED IN ICE CORES

Atmospheric dust plays an important role in the Earth system. Usually, atmospheric dust loading and its variation display largely spatial and temporal differences in different regions. It is necessary for us to reconstruct the past variations of atmospheric dust loading in different regions to better understand the interactions between dust and environments. Ice core records can reveal the history of atmospheric dust loading. In this paper, we used the records of dust in the ice cores from the Tibetan Plateau to study the spatial distribution, the seasonal variations and the secular trends of dust loading over the Plateau. It was found out that the mean dust concentration in the past 150 years was one or two times higher in the Guliya and Dunde ice cores from the northern Tibetan Plateau than in the Dasuopu ice core from the southern Tibetan Plateau. During a year, the highest dust concentration occurs in the spring time in the northern Tibetan Plateau while in the non-monsoon season in the southern Tibetan Plateau. Over the last millennium, the Dasuopu ice core record shows that the 1270s - 1380s and 1870s - 1990s were the two epochs with high dust concentration. However, the Malan ice core from the northern Tibetan Plateau indicates that high dust loading occurred in the 1130s - 1550s and 1770s - 1940s. Interestingly, climatic and environmental records of the ice cores from the Tibetan Plateau reflected that the correlation between dust concentration and air temperature was strongly positive in the southern Plateau while negative in the northern Plateau over the last millennium. This implies that climatic and environmental changes existed considerable differences in different parts of the Plateau over the study period.