摘要
大理西湖是洱海上游湖泊,不但对于维系当地生态环境具有重要的作用,对洱海生态环境保护和治理也具有一定的意义。本文以大理西湖为研究对象,对采取的42个湖泊表层沉积物样品进行粒度、烧失量和磁化率分析。根据湖泊形态并考虑水深和入湖河流分布,以湖心岛为分界,大理西湖可分为湖西部和湖东部两个湖区。粒度数据综合分析结果显示,大理西湖西部湖区大面积现代沉积以粉砂组分为主。由于湖区周围风化作用强烈、侵蚀较强,大量外源物质由流水、风力作用搬运进入湖泊,使湖区西部的沉积速率较高。另一方面,湖泊水动力受水生植物影响,使细粒物质沉积过程缩短,湖泊淤积加速。以粒度、磁化率为指标的外源物质输入显示,外源物质输入对东部湖区的贡献较小,较弱的水动力条件也影响了东部湖区沉积环境,致使有机质含量较高的细粒沉积物集中在东部湖区。此外,由于湖区东部水深较浅、形态狭窄,沉水植物、挺水植物生长面积较大,加快了湖泊沼泽化趋势,进而对湖泊发展产生影响,使得西湖整体生态功能降低。
Lake Xihu is one of the upper-reaches of Lake Erhai. It not only possesses an important function on local ecological and environment protection and management, but also is crucial to the ecological and environment protection and management of Erhai. Based on the sampling of 42 surface sediments in Lake Xihu, the grain size, loss on ignition and magnetic susceptibility were analyzed. According to the distribution of inflowing rivers, water depth and lacustrine formation, Lake Xihu was divided into western part and eastern part with boundary of the mid-island. These results showed that the composition of grain size in western part was mainly silt with an obvious fasting sedimentary rate which indicated that exterior materials were mainly forced by the catchment erosion and regional transportation. Meanwhile, the results of grain size and magnetic susceptibility showed that the composition of grain size in eastern part were mainly fine grain with higher content of organic materials which indicated an weak hydrodynamic conditions and regional transportation in this area. Furthermore, the swamping process of Lake Xihu was expedited by shallow water depth, narrow shape and blossoming of water plants, which influenced the development and function of lake, thus reducing the overall ecological function of the west lake.
出处
《环境保护前沿》
2020年第2期135-146,共12页
Advances in Environmental Protection
