【作者】 汪敬忠；

【导师】 杨劭；

【作者基本信息】 华中师范大学 ， 微生物学， 2012， 硕士

【摘要】 在全球变暖大背景下,中国在过去近百年中年平均气温显著增加,特别是近50年来,我国还以每十年0.22℃的速度增加。泸沽湖地处受东南季风、西南季风影响的亚热带地域云贵高原,为一偏僻高海拔半封闭深水贫营养湖泊,人为干扰相对较小。本研究利用泸沽湖柱状沉积物泥芯,通过分析古湖沼代用指标(生物硅、介形类、地化指标),探讨近一百年来他们的变化情况以及他们的成因分析。210pb与137Cs测年结果表明17cm的泥芯基本代表了近100年来的湖泊沉积。沉积记录结果表明,生物硅、介形类以及理化指标等记录特别是在过去70年来均有有显著变化。其中,介形类组合结果表明,冷水种如Cyclocypris, Candona的相对丰度减小,而暖水种如Cypris则有一定的提高,且以Limnocythere为绝对优势种；介形类绝对丰度从上世纪末开始急剧增加后到近几年又急剧下降,此外在该时间段还发现了少量的真星介属Eucypris,该属的耐盐度一般较高,说明此时湖泊水面积相对减少,水的矿化度有所提高；自从1990年以来,生物硅含量基本维持在一个较高的水平,说明泸沽湖的初级生产力相对较强,该变化与温度升高较为密切,综合分析可知由于该地区人为干扰较小,其他自然条件较为稳定,初步认为泸沽湖区域近100年来的气候变化是泸沽湖水生态系统演化的主要原因。更多还原

【Abstract】 In the past century, the average temperature in China has been significantly increasing under the global warming, especially for nearly fifty years, it is still increasing by0.22℃of every ten years. Lake Lugu is a remote, deep, high altitude and oligotrophic lake, located in the subtropical regional yunnan-guizhou plateau, which is affected by southeast and southwest monsoon and under little anthropogenic stress. In this research, biological silicon, ostracods, physical and chemical indices of the sediment cores of Lake Lugu was analyzed to illuminate the effect of regional climate change and water quality on the lake ecosystem in the past century.The results of210Pb and137Cs measurements showed that the sediment core of25cm analyzed in this research represent the past200years of sedimentary in Lake Lugu. Biological silicon, Ostracods and physical and chemical indices changed greatly with the depth of the sediment, especially14.5cm which represent for the past70years. The results of ostracods combination showed that the cold water species such as Cyclocypris and Candona were reduced while the warm water species like Eucypris and Cypris increased in the relative abundance with the time. Limnocythere was the dominant species. The absolute abundance of ostracoda increased sharply from the end of last century and reduced rapidly in recent years. Eucypris, a species with resistance to high salinity, was found in the depth of recent years, implying that the water salinity increased which may be caused by the reduced area of the lake. The content of biological silicon was kept at a relative higher level since1990, which indicated that the primary productivity is relatively high in Lake Lugu during this period. It can be resulted from the increasing temperature or the increasing load of nutrient caused by the human activities. However, Lake Lugu is supposed to be less affected by human activities as we mentioned above. Therefore, the changes was mainly due to the increasing temperature caused by global warming. In conclusion, climate change may be the main force driving the changes of the ecosystems in Lake Lugu for the recent100years, since the anthropogenic influence may be slight and other natural conditions were relatively stable.更多还原