青海湖沉积物生物硅的环境意义初步研究  

A PRELIMINARY STUDY ON THE ENVIRONMENTAL SIGNIFICANCE OF BIOGENIC SILICA IN QINGHAI LAKE

作　　者：刘斌[1,2] 徐海[1] 蓝江湖[1,2] 刘晓燕[1] 侯昭华[1] 董吉宝[1] 

机构地区：[1]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710075 [2]中国科学院研究生院,北京100049

出　　处：《第四纪研究》2010年第6期1169-1176,共8页Quaternary Sciences

基　　金：中国科学院西部之光项目(批准号:2007ZD01);国家重点基础研究发展规划项目(973项目)(批准号:2010CB833405)资助

摘　　要：湖泊沉积物中生物硅含量的变化已经被广泛应用于评价湖泊生产力和古气候变化研究,但大型湖泊不同位置生物硅含量的时空变化及其与环境要素之间的关系仍缺乏详细的现代过程研究。通过对青海湖不同位置表层沉积样品的生物硅含量测定,建立其空间分布模式及最近数百年生物硅含量的时间序列。结果表明,青海湖表层沉积物生物硅含量变化范围是1.75%～2.98%,平均值为2.25%。与世界其他湖泊相比,青海湖生物硅含量处于相对较低水平,可能与其特殊的地理位置和气候条件有关。青海湖生物硅含量的空间分布规律与沉积物质量堆积速率以及陆源组分含量(如SiO_2)相反,而与化学/生物沉积组分(如CaCO_3)含量的空间分布规律大体一致,说明生物硅的空间分布受到陆源碎屑物质的"稀释效应"影响。时间序列上,生物硅含量与SiO_2含量呈相反变化趋势,与指示降雨量变化的C/N比值也是反相变化,说明生物硅含量在时间序列上也受与气候条件密切相关的陆源输入的影响。青海湖湖心低沉积速率区域的生物硅指标具有指示古气候变化的潜力。Biogenic silica in lakes has been widely used to investigate the primary productivity of lakes and the environmental condition of the lake region. However the modern process of changes in the accumulation of biogenic silica is still poorly understood. In this study, we measured the content of biogenic silica in the surface sediments of Qinghai Lake to reveal the pattern of spatial and temporal the biogenic silica content in the lake ranges from 1.75% distributions of the biogenic silica. The data indicate that to 2.98% with an average of 2.25%. As compared with other lakes on the globe, Qinghai Lake has a relatively lower content of biogenic silica presumably due to its geographical location and geological setting. The spatial distribution of biogenic silica is inversely related to the mass accumulation rate and the content of terrestrial components （ e. g. SiO2 ）, but positively related to the amount of chemical/biogenic precipitates （ e. g. autogenic carbonates ） , implying the dilution of spatial differences in the formation of biogenic silica by the input of terrestrial materials to the lake. In a vertical sequence, the distribution of biogenic silica is inversely related both to the bulk SiO2 content and to the C/N ratio, denoting that temporal variations of the biogenic silica content might also be obscured by the input of terrestrial materials that is closely associated with the climatic condition of the lake region. Our study suggests that the biogenic silica deposited in the central part of Qinghai Lake where the sedimentation rate is low has the potential to register the history of climate changes in the lake region.

关 键 词：青海湖 生物硅 环境意义 

分 类 号：P343.5[天文地球—水文科学]