玛纳斯河流域50年绿洲扩张及生态环境演变研究

玛纳斯河流域绿洲开发和经济发展是新疆维吾尔自治区的典范,以不同时相的卫星影像、土地利用图和地形图为数据源,借助遥感和地理信息系统等先进技术,恢复了玛纳斯河流域过去50年来6个时期(1949,1962,1976,1989,1999和2001年)的绿洲分布格局和动态演化过程.研究表明,按照绿洲年扩张速率,该流域的绿洲扩张过程可分为两个阶段:1949~1976年为绿洲化阶段,因人口急剧增加,耕地面积急剧扩大,绿洲总面积从1949年的156.385km2扩张到1976年的3639.491km2;1976~2001

The paleoclimatic events and cause in the Okinawa Trough during 50 kaBP

Planktonic foraminiferal delta O-18 record for core DGKS9603 from the Okinawa Trough shows a series of climatic fluctuations and sudden cooling events in short time scale during 50 kaBP, which appear to correlate closely to the Younger Dryas and Heinrich events H1-5 recorded in Chinese loess, the South China Sea, the North Atlantic cores and the Greenland ice cores. Three polarity reversal events, correlating to Gothenburg, Mungo and Laschamp events, approximately correspond to Heinrich events H1, H3 and H5 respectively, which could be a cause of global climate changes. The delta O-18 curve of the Okinawa Trough is well associated with the grain size record of the Lijiayuan loess profile in northwestern China and is somewhat different from the climate fluctuations documented in the Greenland ice cores. These correlation results indicate that regional factors play an important role in controlling the climate changes in the East Asia, and the East Asian Monsoon could be the prominent regional controlling factor.