滇中抚仙湖沉积物元素特征与流域侵蚀研究

通过对云南滇中盆地高原深水湖泊抚仙湖沉积岩芯进行X射线荧光光谱（XRF）元素与磁化率连续扫描，结合聚类分析、主成分分析方法和其它相关环境代用指标，探讨了抚仙湖流域自1840年以来的流域侵蚀与人类活动特征.研究结果表明，抚仙湖XRF元素扫描的聚类分析结果具有明显的阶段性特征，可将其大致划分为3个阶段，即34~24cm（约1715~1813年），24~9cm（约1813~1947年）和9~0cm（约1947~2018年）.基于抚仙湖沉积物岩芯中元素比值和低频磁化率的主成分分析，识别出的主成分1与主成分2的方差贡献分别为37.72%和25.73%.指示抚仙湖流域侵蚀强度的元素比值Rb/Sr、Ti/Sr、Ti/Rb公因子载荷较大（>0.6），该结果表明，抚仙湖外源碎屑沉积物的元素比值对流域侵蚀与人类活动具有良好的指示意义.因此，本文使用湖相沉积中的环境代用指标对抚仙湖流域侵蚀与人类活动强度进行重建.研究结果表明，1840年以来人类活动加剧了流域侵蚀强度.自1990年以来随着流域生态环境的逐步恢复，侵蚀强度总体较弱.

Study on elemental characteristics of lacustrine sediments and catchment erosion of Fuxian lake in central Yunnan plateau

Based on the analysis of X-ray fluorescence (XRF) elements and magnetic susceptibility (MS) of Fuxian Lacustrine sediments, the characteristics of soil erosion and human activity had been discussed since 1840AD combined with cluster analysis, principal component analysis and other environmental proxies. The results showed that the characteristics of XRF core-scanning elements by the cluster analysis could be divided into 34~24cm(1715~1813AD), 24~9cm(1813~1947AD) and 9~0cm(1947~2018AD). The principal component analysis of element ratios and MS showed that the variance contribution rates of principal component 1 and 2 were 37.72% and 25.73%, respectively. The factor loading of Rb/Sr, Ti/Sr and Ti/Rb, which indicated the erosion strength of the lake catchment, were exceed 0.6. It indicated that the element ratios of exogenous detrital sediment had the better indicative implications for erosion and human activity intensity of Fuxian lake catchment. Therefore, the erosion and human activity intensity of lake catchment had been reconstructed by using the environmental proxies of lacustrine sediments. Human severe activities enhanced the erosion of Fuxian lake catchment since 1840. From 1990s, erosion intensity exhibited overall weak because of the ecological restoration of lake catchment.