通过对藏南沉错湖芯TC1孔的研究,分析了TC1孔的粒度、TOC、TN、C/N、Fe/Mn、Sr/Ba以及环境磁学参数等环境代用指标,基本上获得了这一地区2万年以来的环境变化记录.结果显示约19800～18000 Cal aBP的温度下降在各指标中具有明显的反映;约...通过对藏南沉错湖芯TC1孔的研究,分析了TC1孔的粒度、TOC、TN、C/N、Fe/Mn、Sr/Ba以及环境磁学参数等环境代用指标,基本上获得了这一地区2万年以来的环境变化记录.结果显示约19800～18000 Cal aBP的温度下降在各指标中具有明显的反映;约16000Cal aBP左右,温度在一次跃动上升之后,随即出现急剧下降;约15200～12000 Cal aBP,是降温之后的缓慢回升过程;约12000～9500Cal aBP,各种指标均显示湖区环境处于不适宜阶段,特别是11600～10400 Cal aBP,湖区环境显著恶化.进入全新世后,湖区环境经历了3次明显的暖期(约9 500～7600 Cal aBP、约6800～5800Cal aBP、约4800～3800 Cal aBP)和2次冷期(约7600～6800 Cal aBP、约5 800～4800 Cal aBP),呈现出暖干/冷湿的交替规律,具有南亚季风(西南季风)区气候变化的特征.沉错湖区2万年来的气候环境变化序列中的某些特征时段与格陵兰冰芯记录和青藏高原其他记录相比具有较好的一致性,反映了湖区及藏南地区的气候环境演变特征具有全球性特征.展开更多
A consecutive sediment core (CC2) was drilledin Chen Co (lake) of southern Tibet using a PISTON samplerin 1998 AD. Cladoceran remains including their species,amount richness and ecological features are analyzed for th...A consecutive sediment core (CC2) was drilledin Chen Co (lake) of southern Tibet using a PISTON samplerin 1998 AD. Cladoceran remains including their species,amount richness and ecological features are analyzed for thetop 117 cm sections of the core, upon which 5 cladoceranassemblages are distinguished. CL0 is an assemblage withoutany cladocera in the depth between 117-105 cm. CL1 as-semblage (depths between 101-77 cm, ca. 1407-1533 AD)possesses total 9 cladoceran species that appear in the core,and performs the greatest richness in the whole sequence.This assemblage reflected that there was plenty of exotic coldwater and organic debrises inputing to the sedimentary siteunder the warmer conditions. The lake was wide and shallowthat satisfied the big hydrophyte living. Cladoceran speciesand richnesses of CL2 assemblage (depths between 77-29cm, ca. 1533-1831 AD) perform much more decreasing thanthose of CL1. There was only less Chydorus sphaericus whichwas acclimatized to wide environmental ranges. This impliedthat the sedimentary environment is so execrable that mostof cladoceran lost their living abilities. Compared with CL1assemblage, CL3 assemblage (depths between 29-10 cm, ca.1831-1941 AD) possesses nearly the same dominant speciesbut lower richnesses. Especially, the cladoceran preferringorganic debris also decrease in their amounts. This meantthat the surface vegetation in the drainage basin was stillpoor though the environment turned to be better. Except the2 zooplankton species, the other 7 species of cladoceran inthis core are found in CL4 assemblage (depths between 10-0 cm, ca. 1941-1998 AD), in which the eurythermal specieshad not performed their competition ability comparing withnarrow-temperatures adapted species. It implied that watertemperatures were stable and much more influenced by airtemperatures under the shallow-water conditions. The envi-ronmental features reflected by cladocera assemblages ofCC2 core are fully supported by the evidences from ostra-coda assemblages, diatom-salinity transfunction, environ-mental magnetism and relative proxies of the parallel CC1 core. Cladoceran assemblages in the lake sediments of Ti- betan Plateau are sensitive to sedimentary environment and very significant to the studies of environmental changes.展开更多
文摘通过对藏南沉错湖芯TC1孔的研究,分析了TC1孔的粒度、TOC、TN、C/N、Fe/Mn、Sr/Ba以及环境磁学参数等环境代用指标,基本上获得了这一地区2万年以来的环境变化记录.结果显示约19800～18000 Cal aBP的温度下降在各指标中具有明显的反映;约16000Cal aBP左右,温度在一次跃动上升之后,随即出现急剧下降;约15200～12000 Cal aBP,是降温之后的缓慢回升过程;约12000～9500Cal aBP,各种指标均显示湖区环境处于不适宜阶段,特别是11600～10400 Cal aBP,湖区环境显著恶化.进入全新世后,湖区环境经历了3次明显的暖期(约9 500～7600 Cal aBP、约6800～5800Cal aBP、约4800～3800 Cal aBP)和2次冷期(约7600～6800 Cal aBP、约5 800～4800 Cal aBP),呈现出暖干/冷湿的交替规律,具有南亚季风(西南季风)区气候变化的特征.沉错湖区2万年来的气候环境变化序列中的某些特征时段与格陵兰冰芯记录和青藏高原其他记录相比具有较好的一致性,反映了湖区及藏南地区的气候环境演变特征具有全球性特征.
基金jointly funded by Knowledge Innovalion Project of Chinese Academy of Sciences(Grant Nos.KZCX3-SW-321 and KZCX3-SW-339)Innovation Project of Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences(Grant No.CXIOG-E01-05-02)Sino-Slovenia Bilateral Technological Cooperation Project of Ministry of Science and Technology China
文摘A consecutive sediment core (CC2) was drilledin Chen Co (lake) of southern Tibet using a PISTON samplerin 1998 AD. Cladoceran remains including their species,amount richness and ecological features are analyzed for thetop 117 cm sections of the core, upon which 5 cladoceranassemblages are distinguished. CL0 is an assemblage withoutany cladocera in the depth between 117-105 cm. CL1 as-semblage (depths between 101-77 cm, ca. 1407-1533 AD)possesses total 9 cladoceran species that appear in the core,and performs the greatest richness in the whole sequence.This assemblage reflected that there was plenty of exotic coldwater and organic debrises inputing to the sedimentary siteunder the warmer conditions. The lake was wide and shallowthat satisfied the big hydrophyte living. Cladoceran speciesand richnesses of CL2 assemblage (depths between 77-29cm, ca. 1533-1831 AD) perform much more decreasing thanthose of CL1. There was only less Chydorus sphaericus whichwas acclimatized to wide environmental ranges. This impliedthat the sedimentary environment is so execrable that mostof cladoceran lost their living abilities. Compared with CL1assemblage, CL3 assemblage (depths between 29-10 cm, ca.1831-1941 AD) possesses nearly the same dominant speciesbut lower richnesses. Especially, the cladoceran preferringorganic debris also decrease in their amounts. This meantthat the surface vegetation in the drainage basin was stillpoor though the environment turned to be better. Except the2 zooplankton species, the other 7 species of cladoceran inthis core are found in CL4 assemblage (depths between 10-0 cm, ca. 1941-1998 AD), in which the eurythermal specieshad not performed their competition ability comparing withnarrow-temperatures adapted species. It implied that watertemperatures were stable and much more influenced by airtemperatures under the shallow-water conditions. The envi-ronmental features reflected by cladocera assemblages ofCC2 core are fully supported by the evidences from ostra-coda assemblages, diatom-salinity transfunction, environ-mental magnetism and relative proxies of the parallel CC1 core. Cladoceran assemblages in the lake sediments of Ti- betan Plateau are sensitive to sedimentary environment and very significant to the studies of environmental changes.
