湖北梁子湖近百年来环境演变历史及驱动因素分析

湖泊生态系统的修复必须建立在历史生态环境演化过程与驱动机制认识的基础之上.针对草型湖泊演化历史研究相对不足的现状,以长江中游典型草型湖泊梁子湖为研究对象,结合210Pb和137Cs年代测试,通过对沉积柱高分辨率的多指标分析(硅藻、元素地球化学和粒度)以及流域历史资料重建近百年来梁子湖生态环境的演化过程,并在此基础上利用冗余分析定量区分影响该湖泊生态环境演化的关键驱动因子.结果显示,沉积物总磷和重金属元素Cu是影响该湖泊生态环境演化的2个显著变量,它们分别单独解释硅藻组合的12.7%和8.5%变率.这表明近百年来人类活动引起的营养输入对梁子湖生态环境演化起关键性作用,而重金属污染也是影响梁子湖环境演变的重要因子.本研究结果可以为梁子湖及长江中下游其他类似湖泊的环境治理提供科学依据.

Environmental evolution of Lake Liangzi and its driving factors over the past 100 years, Hubei Province

The restoration of lake ecosystems requires a good knowledge on the history in the lakes and the driving mechanism of environmental changes. Aimed at current situation of limited study on past environmental changes of macrophyte-dominated lake, Lake Liangzi, located in the middle reach of the Yangtze River, was selected for historical environment study. High-resolution multi-proxy(i.e. diatom, geochemistry and grain size), ²¹⁰Pb/¹³⁷Cs dating of a sediment core collected from this lake and documentary data(i.e. population and air temperature) were analyzed to investigate environmental changes during the past one-hundred years. Furthermore, effects of key driver on the evolution of ecological environment were estimated quantitatively using the redundancy analysis. Results showed that total phosphorus and heavy metal element Cu from the sediments were two significant variables, explaining solely 12.7% and 8.5% of the variances in diatom data, respectively. Therefore, anthropogenic nutrient input was the most important factor on the environmental evolution of Lake Liangzi. Meanwhile, heavy metal pollution also imposed an important effect on this lake. The results of this study can provide a baseline of scientific information for environment restoration in the present lake and other similar lakes in the Yangtze floodplain.