南极长城站地区环境演变的生物地球化学研究——古降水的复原与末次冰盖消退时间的推断

BIOGEOCHEMICAL RESEARCH OF ENVIRONMENTAL EVOLUTION IN CHINESE ANTARCTIC GREAT WALL STATION AREA——RECONSTRUCTION OF PALEO-RAINFALL AND THE LAST ICE-CAP MELT

作者在南极地区近代环境的研究中提出了一种新的研究方法——利用生物地球化学指示元素来研究古环境的变迁。通过研究南极长城站地区西湖底沉积物丛其所含的植物残体、复原了约4000年来的年平均降水量的变化,推断了末次冰盖从本区消退的时间为3500年前。研究南极地区近代环境的演变对解决全球性环境演变是不可缺少的内容。

Evolution process of recent enviroment is usually studied by means of annual ring of tree, palynologic analysis and stable isotope assay. In this paper a new research method-biogeochemical indicator element method for study of the evolution process of recent environment is proposed. Based on researching sediments and residual plants in them from West Lake near Great Wall Station, annual rainfall variation about 4000 years and the last ice-cap melt were determined. A kind of water plants lived beneath West Lake water was identified to be Brachytheciaceae Brachythecium populeum (Hedw.)B.S.G. There are also residual plants found in the whole sediment column which is 3.4 m long. There is no obvious variation and seccession either in pattern or in structure of the plant about 4000 years, as shown by electronic microscopic observation. Ca concentration in residual plants is closely related to Ca concentration in the lake water, which are controlled by climatic condition ( mainly rainfall) . Comprehensive analysis of the sediments and residual paints in them makes us possible to suggest that the last ice-cap in this area had melted in 3500 years ago or so.