青海湖:研究地质微生物的天然实验室

青海湖位于青海省的东北部，是中国境内最大的内陆高原咸水湖泊。由于青藏高原的不均匀隆升，使这些湖泊形成了封闭的水系和地球化学物质循环特征。青海湖有限的几条供给河流的水化学受其所经过岩石的化学成分控制，而湖水的化学成分和物理化学特征则受补给水系的影响。湖泊的碳循环除受盆地周围风化搬运作用以外，主要碳源为湖泊以及周围的生物群落。青海湖水的物理化学特征本身由于受补给水源和深度的影响而具不均一性，并随季节温度的变化而发生调整。这些特征预示其独特的微生物生态系统和与之有关的碳循环和元素地球化学循环特征。丰富的铁、硫酸根、碳酸根和钙镁离子为其中嗜铁和嗜硫的微生物繁盛以及随后的矿化作用提供了有利的条件。藻类也具有很高的多样性并且不同种类具有明显的随季节或气温变化的特点。这些微生物活动会在湖泊沉积物中形成有机的和无机的生物标记化合物或矿物。进一步揭示这些生物标记化合物与局部环境的碳循环、元素循环、微生物生态以及相关环境变迁的关系将具有重要意义。

Qinghai Lake: A Natural Laboratory for Geomicrobiological Research

Qinghai Lake is located in the northeastern edge of the Tibetan-Qinghai Plateau. It is the largest saline lake in China. Due to uneven uplift of the plateau, some of the basins formed lakes in an isolated drainage system. The geochemistry of bedrocks affects the hydrological chemistry of drainage area and the physicochemical features of the Qinghai Lake. The main source of organic carbon is the ecological system surrounding the lake; Weathering of rocks also contributes to the carbon source in the lake. The chemistry of the Lake is heterogeneous in both vertical and horizontal dimensions; Changing of seasons also influences the hydrochemistry. These characteristics bring forth a unique microbiological ecology as well as a coupled carbon and metal cycling system. Enhanced concentrations of Fe, SO 2-_4, CO_3 2-, Ca, Mg ions provide sufficient nutrients for the prosperity of a complex ecological system. This biological cycling consequently provides sufficient chemicals for biomineralization. As has been surveyed, the lake is of high diversity of algae, whose populations and community structures change seasonally. As a part of the evolution of the lake, the biological relics have been recorded as organic or inorganic biosignatures in the bottom sediments. Further study of the biological records and their relationship to the evolution of the local microbial ecology and cycling of carbon and other elements is expected to have important implications for climatic and environmental changes in the Tibetan-Qinghai Plateau.