Quantitative reconstruction of the lake water paleotemperature of Daihai Lake, Inner Mongolia, China and its significance in paleoclimate   总被引：5，自引：2，他引：5  

沈吉  Ryo Matsumoto  王苏民  朱育新 《中国科学D辑(英文版)》2002,45(9):792-800

By measuring Sr/Ca ratios of the ostracod shells (Limnocthere cf. inopinata) in sediments of the Daihai Lake, and combined with Sr²⁺/Ca²⁺ ratios of the lake water, this paper obtained paleosalinity of the lake water. Vaporizing experiment of the lake water in laboratory showed that there was a quantitative relationship between salinity and oxygen isotope. Using this relationship, oxygen isotope values of the paleo-lake water were calculated. By measuring the oxygen isotope of the authigenic carbonate in the lake’s sediments, and in combination with the oxygen isotope values of the paleo-lake water, the paleotemperature of the lake water was calculated. Finally, based on these proxies, the paleoclimate in the lake basin was explored.  相似文献   

坝上高原安固里淖粒度年纹层与环境变化   总被引：9，自引：2，他引：9  

翟秋敏  李容全  郭志永 《地理科学》2002,22(3):331-335

在安固里淖湖心区获取一未扰动沉积物样柱，分析发现了由冬季风搬运物与湖心沉积共同形成的粒度年纹层，建立了纹层年表，恢复了安固里淖湖区8507aB.P，以来的环境变化过程。8507-5429aB.P。冬季风活动较弱，后期的所波动；5429-3244aB.P.冬季风活动较强，3244-2494aB.P。冬季风活动减弱；2494-1165aB.P。冬季风活动略有增强；1165aB.P以来，冬季风活动减弱。安固里小淖粒度年纹层反映的冬季风变化情况与我国北方地区同期的环境变化和海平面变化有很好的对应关系。  相似文献   

GIS支持下青海湖地区草地蝗虫发生的地形分析   总被引：7，自引：0，他引：7  

张洪亮  倪绍祥  查勇  韦玉春 《地理科学》2002,22(4):441-444

草地蝗虫发生的地形分析是建立草地蝗虫发生预报模型的基础，以青海湖地区为实验区，在Arc/Info和ArcView地理信息系统的支持下，进行草地蝗虫发生与各地形变量（包括海拔高度、坡度与坡向）的叠置分析，提取草地蝗虫发生的地形信息数据库，然后，分别采用T－检验（对连续变量－海拔高度和坡度）和卡方（Chisquare)检验（对类变量－坡向类型）进行各地形变量对草地蝗虫发生的差异显著性检验，结果表明，海拔高度和坡度对草地蝗虫发生的影响极为显著（显著性水平p=0.000)，而坡向地草地蝗虫发生的影响不是特别明显（显著性水平p=0.039)。  相似文献   

青海省盐湖钾、镁、锂盐资源开发利用探讨   总被引：4，自引：4，他引：4       下载免费PDF全文

严军  黄小良 《盐湖研究》2002,10(4):63-69

论述了青海省盐湖资源中钾、镁、锂盐工业的资源状况、生产现状以及开发利用的迫切性 ,并对钾、镁、锂盐资源的综合利用进行了探讨  相似文献   

卤水法生产硫酸钡技术研究          下载免费PDF全文

孙培霞 《盐湖研究》2002,10(3):17-19

着重解决了以运城盐湖卤水与氯化钡溶液为原料生产硫酸钡的技术难题。目前 ,该技术已被应用到南风集团硫化碱分公司的工业化生产中。  相似文献   

A 1500-year record of climatic and environmental change in ElkLake, Minnesota I: Varve thickness and gray-scale density     

Walter Dean  Roger Anderson  J. Platt Bradbury  David Anderson 《Journal of Paleolimnology》2002,27(3):287-299

The deepest part (29.5 m) of Elk Lake, ClearwaterCounty, northwestern Minnesota, contains a complete Holocene section that iscontinuously varved. The varve components are predominantly autochthonous(CaCO₃, organic matter, biogenic silica, and several iron andmanganese minerals), but the varves do contain a minor detrital-clastic(aluminosilicate) component that is predominantly wind-borne (eolian) andprovides an important record of atmospheric conditions. Singular spectrumanalysis (SSA) and wavelet analysis of varve thickness recognized significantperiodicities in the multicentennial and multidecadal bands that varied inpower (i.e., variable significance) and position (i.e., variable period) withinthe periodic bands. Persistent periodicities of about 10, 22, 40, and 90 years,and, in particular, multicentennial periodicities in varve thickness and otherproxy variables are similar to those in spectra of radiocarbon production, aproxy for past solar activity. This suggests that there may be a solar control,perhaps through geomagnetic effects on atmospheric circulation. Multicentennialand multidecadal periodicities also occur in wavelet spectra of relativegray-scale density. However, gray-scale density does not appear to correlatewith any of the measured proxy variables, and at this point we do not know whatcontrolled gray scale.  相似文献   

Palaeolimnology of Lake Piene-Kuuppalanlampi (Kurkijoki, Karelian Republic, Russia): isolation history, lake ecosystem development and long-term agricultural impact     

Juha Miettinen  Elisabeth Grönlund  Heikki Simola  Pertti Huttunen 《Journal of Paleolimnology》2002,27(1):29-44

The post-glacial history of Lake Pieni-Kuuppalanlampi, western Lake Ladoga region, was studied by means of stratigraphic pollen and diatom analyses. Diatoms were analysed to track the isolation history of the basin and the limnological effects of the early land-use phases indicated by pollen analysis. Chrysophycean stomatocysts and Isoëtes spores were also employed in the limnological reconstructions. Sediment dating was provided by six conventional radiocarbon dates.The lower part of the 370-cm long sediment sequence represents early Holocene, large lake conditions: the (freshwater) Yoldia and Ancylus stages of the Baltic basin, with a short-term lagoonal or isolation phase at the end of Yoldia. The basin was isolated due to Ancylus lake regression at 9785 cal B.P. For the small-lake sequence (0–250 cm) we used diatom inferences (WA-method) for hindcasting water chemistry. The post-isolation limnology of Pieni-Kuuppalanlampi reflects the development of vegetation on its small hill-top catchment. In its early development, the lake was mesotrophic, but became more acidic (pH about 6) and oligotrophic after the decline of temperate hardwood trees and the spread of spruce to the area after around 5000 B.P. The lake ecosystem appears to have reacted sensitively to agricultural land-use in the catchment from AD 400–800 onwards: inferred total phosphorus levels and pH both rise during these periods.  相似文献   

Combining ordination techniques and geostatistics to determine the patterns of diatom distributions at Lake Lama, Central Siberia   总被引：4，自引：0，他引：4  

Ulrike Kienel  Thomas Kumke 《Journal of Paleolimnology》2002,28(2):181-194

The patterns of spatial variation of diatom assemblages from surface sediments in Lake Lama were quantified using a combined approach of ordination and geostatistics. The aims were (i) to estimate the amount of variation between diatom assemblages within the lake, (ii) to model the spatial variability of the diatom assemblages and their diversity, and (iii) to map the diatom distributions in the lake. A correspondence analysis (CA) separated the diatom assemblages into a planktonic and a periphytic group. Rheophilic taxa were found within the periphytic group. Variogram analysis showed that only the sample scores of the first CA axis and the Shannon diversity index were spatially structured. The range of spatial correlation was estimated to be 55 km for both variables. The diversity and, to a lesser extent, the sample scores had considerable small-scale variability of about 20 and 3%, respectively. Estimates of the first component of the CA and the Shannon index were derived using block-kriging. The maps of the estimates provided a basis for partitioning Lake Lama according to the spatial structures into an eastern and a western basin, a north–south connection between the basins, and a north–south directed tip at the far eastern end. It was shown that variation in diatom assemblages is mainly spatially structured at the catchment scale and that there is a considerable amount of variation at smaller scales. According to the modeled spatial distribution, the assemblages are most likely affected by the lake size, morphology, and the water and nutrient input introduced by rivers. This has to be taken into account when paleolimnological interpretations are drawn from records of complex lake systems like Lake Lama.  相似文献   

Wetland vegetation biomass estimation and mapping from Landsat ETM data:a case study of Poyang Lake     

LI Ren-dong  LIU Ji-yuan 《地理学报》2002,12(1):35-41

Poyang Lake is the largest freshwater lake in China. This paper conducted a digital and rapid investigation of the lake’s wetland vegetation biomass using Landsat ETM data acquired on April 16, 2000. First, utilizing the false color composite derived from the ETM data as one of the main references, the authors designed a reasonable sampling route for field measurement of the biomass, and carried it out on April 18-28, 2000. Then after both the sampling data and the ETM data were geometrically corrected to an equal-area projection of Albers, linear relationships among the sampling data and some transformed data derived from the ETM data and the ETM 4 were calculated. The results show that the sampling data is best relative to the band 4 data with a high correlation coefficient of 0.86, followed by the DVI and NDVI data with 0.83 and 0.80 respectively. Therefore, a linear regression model, which was based on the field data and band 4 data, was used to estimate the total biomass of entire Poyang Lake, and then the map of the biomass distribution was compiled.  相似文献   

Spatially irregular sedimentation in a small, morphologically complex lake: implications for paleoenvironmental studies     

Robert Gilbert 《Journal of Paleolimnology》2003,29(2):209-220

A sub-bottom acoustic survey of Devil Lake on the Canadian Shield in southern Ontario reveals three acoustic facies: (I) a moderately acoustically transparent, laminated sequence interpreted as a glacilacustrine deposit in glacial Lake Iroquois or a subsequent phase in water depths up to 200 m greater than at present, (II) a transitional more transparent, less layered facies interpreted as being deposited in a more distal glacial lake from erosion of sediment in the watershed exposed by the failure of the ice dam and lowering of the glacial lake before stabilization by the development of forests, and (III) an acoustically transparent facies with similar transmissivity to the water column, interpreted as Holocene gyttja. Each is spatially variable in extent and thickness in response to those processes. There is only a very weak relation between sediment thickness and the water depth in which it was deposited. Wave processes prevent deposition in water depths less than about 6 m and evidence of erosion to the greatest depths of the lake (>40 m) is pervasive. The data demonstrate the value of acoustic survey in assessing lacustrine processes and the history of lakes, and the significance of such documentation in planning a coring program and in interpreting the results.  相似文献