摘要
本文提供了墨西哥中部两个高原湖泊近期环境快速变化的证据。从济拉温湖(米却肯州)和胡安艾卡特兰湖(哈利斯科州)获得了多个沉积物钻芯,利用^(210)Pb和^(14)C,以及火山灰年代测定法确定年代,进行了硅藻组合、磁化率和金属含量分析。在殖民时期,两盆地内有汇水区被扰动的迹象,但这两个地方最显著的特征是,最近20年来硅藻种群组合特征的快速变化,这指示着富营养化的开始。尽管在胡安艾卡特兰湖还没获得这方面的任何数据,但济拉温湖的湖泊学数据支持这种解释。古湖泊学在跟踪近期变化过程,特别是在缺乏常规湖泊监测计划的情况下是一种强有力的工具。这些湖泊对汇水区的开发变化特别敏感,必须在将来的流域管理中予以考虑。
We provide evidence of rapid,recent environmental change in two lakes in the highlands of central Mexico.Multiple sediment cores were obtained from Lago de Zirahuen (Michoacan) and Laguna de Juanacatlan (Jalisco).Analysis of diatom assemblages,magnetic susceptibility,and metal concentrations was carried out,with the chronology provided by 210Pb dating,14C dating,and tephrochronology.There is evidence of catchment disturbance during the colonial period in both basins,but the most striking feature at both sites is the rapid change in diatom assemblages during the last 20 y,indicating the onset of eutrophication.Limnological data from Lago de Zirahuen support this interpretation, although none are available from Laguna de Juanacatlan.Paleolimnology is a powerful tool in tracking recent change,particularly in the absence of regular limnological monitoring programs.These lakes appear to be highly sensitive to changes in catchment exploitation, which must be considered in future drainage basin management.
