【摘要】 湖泊沉积是历史时期气候波动与流域环境变化的记录器.采集黄河源区希门错沉积物,对岩芯的有机质和地球化学元素进行了分析,得到该地近1 720年以来的环境变化记录.结果显示希门错沉积物47cm柱状岩芯的环境演化过程可分为四个阶段:32cm以下(900AD之前),该阶段为气温变冷阶段,降水多;32-20cm之间(900-1300AD),该阶段为气温变暖阶段,和中世纪暖期相对应,降水减少;20-3.5cm之间(1300-1900AD),该阶段为气温变冷阶段,和小冰期较为吻合,降水较多且逐步减少;3.5-0cm(1900AD至今),这个时期为20世纪暖期,降水较少.磷元素含量在近20多年来增加较大,说明人类活动对流域的影响不断增强.在此之前的磷元素沉积含量低且稳定,指示该区域磷的背景值.更多还原

【Abstract】 Lake sediment is the recorder of historical climate fluctuation and basin environment change.This study collected Ximencuo Lake sediment in source area of the Yellow River,the organic matter and geochemical elements of the core were analyzed,obtained nearly 1 720 aenvironment changes.The results showed the environment evolution process of the core can be divided into four stages:below 32cm(before 900AD),this stage corresponding to the cool and wet climate;32~20cm(900AD-1300AD)corresponding to the warming temperature was low and decreasing precipitation;between 20~3.5cm(1300-1900AD),the stage is more consistent with the Little Ice Age,and precipitation gradually reduced;3.5~0cm(since 1900AD),this is the twentieth century warming period with increase temperature and reduced precipitation.Phosphorus content increased rapidly in the last 20 years,it reflects the human continuously enhancing activities.But before the time,the P deposition content is low and stable,indicating the natural background of regional phosphorus.更多还原