湖光岩玛珥湖沉积物硅藻硅同位素环境示踪  

Silicon Isotope Compositions of Diatoms as Indicators of Environmental Change in the Sediment of Maar Lake Huguangyan,Guangdong Province,China

作　　者：李键[1] 张维 田世洪[3] 陈敬安[1] 

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵州贵阳550002 [2]贵州省环境科学研究设计院,贵州贵阳550002 [3]中国地质科学院同位素地质重点实验室,北京100037

出　　处：《矿物学报》2009年第4期530-535,共6页Acta Mineralogica Sinica

基　　金：国家自然科学基金面上项目(40303014);国家自然科学基金国际合作项目(40610021)

摘　　要：硅是硅藻生长所必需的养分,硅藻在生长过程中从水体吸收主要以硅酸(H4SiO4)形式存在的溶解硅。硅藻δ30Sidiatom可反映硅藻吸收硅酸比例的变化,进一步可以反映湖区气候与环境变化。为探索湖泊沉积物硅藻δ30Sidiatom在指示湖泊古环境方面的潜力,我们测定了湖光岩玛珥湖沉积物硅藻硅同位素变化。研究结果表明,沉积物δ30Sidiatom变化与生物硅和有机碳含量变化呈显著相似性,可作为一种有效的古环境代用指标。同时,与已有温度记录的对比分析表明,两者具有很好一致性。较高的30Sidiatom指示了温度较高的气候条件下硅藻对硅酸的利用率较高;当30Sidiatom较低时,对应着在温度较低的气候条件下硅藻对硅酸的利用率较低。目前,热带陆地区域古气候重建的方法中可用的温度代用指标很少,此项研究证明了δ30Sidiatom是一种很有潜力的古环境代用指标,有望在低纬度地区古温度重建中发挥重要作用,值得进一步深入研究。Silicon is essential for the growth of diatoms, which utilize dissolved silicic acid in lake water and form opaline silica （SiO2·nH2O）. The silicon isotope compositions of diatom silica （δ^30Sidiatom） may thus record changes in the percentages of the utilization of dissolved silicie acid by diatoms, which can further reflect the changes of climate/ environment. With the aim of exploring the potential of δ^30Sidiatom as an indicator of lacustrine environment, in this study, δ^30Sidiatom in the sediment core from Lake Huguangyan, a closed crater lake in Zhanjiang City, Guangdong Province, China, were firstly measured. The result shows that δ^30Sidiatom displays broad similarities of variations in contents of biogenic silica and organic carbon throughout the sediment core. δ^30Sidiatom is a reliable paleotemperature proxy in Lake Huguangyan, which is supported by good correlation between δ^30Sidiatom and available temperature records. Heavier δ^30Sidiatom indicates greater dissolved silieie acid utilization at higher temperature while lighter δ^30Sidiatom, reflects decreased utilization at lower temperature. There are few means by which to reconstruct the history of temperature changes in tropical terrestrial region. ~3~Si~ in this study, has been proven to be a new promising paleotemperature proxy in lacustrine sediments, and to play an important role in reconstructing past temperature changes at low latitudes in the future. Detailed investigations on the silicon isotopes of diatoms in more lakes would be desirable in further research.

关 键 词：硅同位素 硅藻 古环境代用指标 湖光岩玛珥湖 

分 类 号：P532[天文地球—古生物学与地层学] P597[天文地球—地质学]