近百年来新疆博斯腾湖初级生产力的变化

The change of primary productivity of Lake Bosten in Xinjiang over the past 100 a

本研究选择新疆博斯腾湖不同区域进行沉积岩芯采集.在210Pb、137Cs定年的基础上,利用漫反射光谱分析了湖泊沉积物中叶绿素a的含量,结合沉积速率、烧失量以及开都河的径流量记录等,探讨近百年来湖泊初级生产力的变化.结果表明:开都河的径流量变化对博斯腾湖沉积速率与生产力演化有一定影响,而人类活动干扰则是影响湖泊初级生产力演化的主要原因.1950s开始的新疆第一次大规模开垦活动导致了湖泊的沉积速率及初级生产力开始上升.沉积物的沉积速率以及叶绿素a的沉积通量在1970年左右出现最高值后下降,这与新疆的第二次大规模垦荒有关,同时,周边地区盐碱地除盐方式的改变对湖泊的生态环境变化也有很大影响.从1980s至今,由于流域内人类活动干扰增强,沉积物中的叶绿素a浓度逐渐增加,湖泊初级生产力呈上升的趋势.

Two sediment cores were collected in different areas of Lake Bosten in Xinjiang. Based on 210 Pb and 137 Cs dating, chlo- rophyll-a content analyses using the method of diffuse reflection spectrum, and in combination with studies on deposition rate, loss on ignition and runoff records of Kaidu River, the changes of primary productivity of Lake Bosten during the past 100 a were dis- cussed in this paper. The results showed that runoff changes of Kaidu River have some influences on the dry mass accumulation in Lake Bosten, but the impact of human activities is the main reason for the variation of primary productivity. As a result of Xinjiang＇s first large-scale reclamation in the 1950s, the deposition rate and the primary productivity of Lake Bosten started to rise. The peak of the deposition rate and chlorophyll-a accumu｜ation rate of the lake sediments appeared in the 1970s, which was related to the Xinjiang＇s second large-scale reclamation, and the desalting of alkaline soil also played a significant impact on the ecological change of Lake Bosten. From the 1980s to present, with the intensification of the human activities in surrounding areas, chloro- phyll-a content of the lake sediments gradually increased, and the primary productivity of Lake Bosten showed an increasing trend.