| 摘要: |
| 双壳微体甲壳类动物介形虫,广泛分布于各类湖泊体系中,其碳酸盐壳化石通常在湖泊沉积物中保存完好.介形类的古生态学,尤其是介壳的地球化学在环境变化研究中,近年来得到越来越广泛的应用.介壳的氧同位素组成由形成壳体时湖水的同位素组成和温度决定,可以反映由蒸发和降水的变化所引起的湖水水化学以及与之关联的气候变化情况.一般而言,低δ18O反映了温暖潮湿的气候;高δ18O反映了寒冷干燥的气候.碳同位素可以反映总溶解无机碳的组成以及影响其组成的诸因素的变化,多数情况下可以反映湖泊古生产力的大小及变化.介壳中Mg和Sr的含量,往往与其宿生水体的盐度和温度呈一定的函数关系,据此可以恢复湖泊的温度,尤其是盐度的变化.为了满足高分辨率环境变化,特别是定量研究的要求,必须充分了解介形类各个种属的生命历史和生态消长的过程;通过定期收集野外介壳和水样进行化学分析,了解湖水水化学和温度对介壳稳定同位素和微量元素组成的影响;详细了解湖泊湖沼学,包括湖水的同位素组成和M/Ca(M指微量元素Mg、Sr等)与盐度的关系以及它们随空间和季节变化的特征;开展实验室养殖培养实验,测定单个种属介壳与水体的氧同位素分馏系数,建立微量元素吸收的生理效应 |
| 关键词: 湖泊 介形类 稳定同位素 微量元素 环境变化 |
| DOI：10.18307/20010413 |
| 分类号: |
| 基金项目:中国科学院创新项目(KZCX1-Y-05);中国科学院资源环境重大项目(KZ951-A1-402);国家自然基金项目(49971074)联合资助 |
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| Lacustrine Ostracodes as Environmental Change Indicators:Application and Advance |
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LI Jun, YU Junqing
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Institute for Salt Lake studies, Chinese Academy of Sciences, Xi'an 710043, P. R. China
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| Abstract: |
| Ost racodes, the microscopic bivalved crustaceans, survive in a wide diversity of lakes and ostracod fossil valves are often found well preserved in the lake sedimentsequences.The characteristics of ostracod palaeoecology and particularly geochemical characteristics of fossil ostracod shells buried in the lake sedimentsequences are increasingly studied and used to indicate the past environmental changes on the globe.The isotopic composition and temperature of the lake water in which the shells formed determine the oxygen iso topic composition of shells.Changes in δ18Oostracod in a sedimentsequence may reflect the past variations of δ18Owater relating to climate-induced changes in precipi tation-to-evaporation balance.In general, low δ18 Oost racod may reflect warm or moist climate, while high δ18Oostracod may represent cold or dry climate.The δ13Costracod may reflect the iso topic ratios of total dissolved inorg anic carbon (TDIC)and the changes of factors controlling δ13CTDIC value, especially palaeoproductivity of a lake.The uptake of Mg and Sr into ost racod shells may be a function of salini ty and temperature of host water, which can be used to reconst ruct palaeosalini ty and palaeotemperature of a lake.The following aspects are required in order to conduct quantitative research:(1)firm understanding of the life history and ecological procedure of the ostracod species concerned, (2)analyzing field regular collect ions of ostracod shells and lake waters, to learn the controls of the water chemistry and temperature on the composition of stable isotopes and trace elements of ost racod shells, (3)detailed know ledge of the limnology of the lake investigated, including the relationship between M/Ca and salinity, the iso topic composition and the spatial and seasonal variations in these properties, and (4)culture experiments for each species used, to establish the effects of phy siology on the trace elements uptake and determine the isotopic behavior of indivdual ostracod species with host water. |
| Key words: Lakes ostracodes stable isotopes trace elements environmental indicators |
