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Environmental characteristics of Mid-Holocene recorded by lacustrine sediments from Lake Daihai, north environment sensitive zone, china

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Science china Earth sciences 2006年第9期49卷 968-981页

作者： SUN Qianli1,2. ZHOU Jie1, SHEN Ji3, CHEN Peng1,2. WU Feng1,2.& XIE Xiuping1,2.1. State Key Lab of Loess and Quaternary Geology, institute of Earth Environment, chinese academy of sciences, Xi’an 710075,{2. 2. Graduate University of chinese academy of sciences, Beijing 100039,{2. 3. nanjing institute of geography and Limnology, chinese academy of sciences, nanjing 2.0008,{2. 1. State Key Lab of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 2. Graduate University of chinese academy of sciences Beijing 100039 China 3. nanjing institute of {2. and Limnology Chinese Academy of Sciences Nanjing 210008 China

Climate proxies, such as total organic carbon and nitrogen (TOC, TN), carbonate content (CaCO3), grain-size and pollen of the sediment core retrieved from enclosed Lake Daihai which lies in the north china environment sensitive zone are analyzed to reconstruct the environment evolution of the area based on high-resolution radiocarbon chronology. The results reveal that the TOC and TN contents of the sediments correlate well with pollen percentage and pollen flux variations during the Holocene, and both reach their peak values simultaneously at 6.7―3.5 ka BP (calendar age, 7.6―3.6 ka BP). Since 6.7 ka BP, both the CaCO3 and organic matter contents of the core have simultaneous variations, and their high values also occur during 6.7―3.5 ka BP. While during 9.0―6.7 ka BP (calendar age, 10―7.6 ka BP) relatively lower level of organic matter content and pollen flux corre- spond to the higher level of carbonate content. The above relations suggest that during 6.7―3.5 ka BP, the productivity and effective precipitation were greatly improved in the lake drainage area, and this would probably strengthen the hydrodynamic conditions, enhancing organic matter, pollen and carbonate inputs from terrestrial sources. Such processes would account for the enrichment of both organic matter and carbonate in the sediments. While during 9.0―6.7 ka BP, the lower level of or- ganic matter, pollen flux but high carbonate content show depressed productivity and declined vege- tation coverage. The higher carbonate content at this stage would have probably resulted from the higher evaporation ratio of the lake water under relatively drier climate conditions. Therefore, it is in- ferred that during 6.7―3.5 ka BP, the climate was more humid with abundant rainfalls and vegetation was more flourishing in the Lake Daihai area. This can be seen as Holocene Climate Optimum (HCO). As a result, this has evident discrepancies with the traditional notion that the HCO occurs at Early Holocene or early Mid

关键词： Lake Daihai, Mid-Holocene, lacustrine sediments, environmental characteristics.

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Geochemical simulation of the formation of brine and salt minerals based on Pitzer model in Caka Salt Lake

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Science china Earth sciences 2004年第8期47卷 720-726页

作者： LIU Xingqi1, CAI Keqin2.& YU Shengsong3 1. nanjing institute of {2. and Limnology, chinese academy of sciences, nanjing 2.0008, china 2. china University of Geosciences, Beijing 100083, china 3. institute of Salt Lakes, chinese academy of sciences, Xining 810008, china 1. nanjing institute of {2. and Limnology Chinese Academy of Sciences 210008 Nanjing China 2. china University of Geosciences 100083 Beijing China 3. institute of Salt Lakes Chinese Academy of Sciences 810008 Xining China

The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared with the hydrochemical compositions of the brine and the salt minerals of the deposit in Caka Salt Lake. The results show that the formation temperature of the lake is between 0°C and 5°C, which is well identical with other studies. The mixing of salt-karst water with the surface waters, neglected by the former researchers, is very important to the formation of the lake, indicating that the initial waters resulting in the formation of the lake are multi-source. It is the first time to use Pitzer model in china for making geochemical simulation of the formation and evolution of inland salt lake and satisfactory results have been achieved.

关键词： Pitzer model,Caka Salt Lake,geochemical simulation,salt-karst water.

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THREEDIMENSIONAL NUMERICAL SIMULATION OF WINDINDUCED CIRCULATION IN LAKE TAIHU

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Journal of Hydrodynamics 2004年第3期16卷 341-349页

作者： LUOLian-cong QINBo-qiang nanjinginstituteof{2.andLimnology ChineseAcademyofSciencesNanjing210008China

A three-dimensional (3-D) numerical circulation model for shallow-lake ispresented and described in detail in this paper, which employs model-splitting technique in order tocalculate water level, mean-depth velocities and horizontal and vertical velocities at differentdepth simultaneously. The results show the current circulation pattern features four eddies with twoclockwise and two anticlockwise induced by prevailing wind. Opposite wind field will lead toopposite current pattern with phase shifted by 180° The surface convergence zone is located in theupwind area and the surface divergence part in the downwind region, This results in drastic verticalmovement in the two zones and the return currents at the bottom with phase shifted by 180° fromthe surface current vectors. Thus the water level decreases significantly at the leeward side andincreases quickly at the windward part. Verification and calibration for the model were made basedon the water-level and current data observed during the 9711 Storm in Lake Taihu. The predictedresults are in satisfactory agreement with the observed data, which raises the possibility that thismodel can be used to decide the bottom current stress for sediment resuspension and also tosimulate sediment transportation. It can provide a fundamental tool to study the nutrient releasefrom bottom sediment in Lake Taihu.

关键词： numerical simulation three dimensional hydrodynamics lake taihu

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Evidence from isotopic geochemistry as an indicator of eutrophication of Meiliang Bay in Lake Taihu, china

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Science china Earth sciences 2006年第z1期49卷 62-71页

作者： LIN Lin, WU Jinglu & WANG Sumin nanjing institute of {2. & Limnology, chinese academy of sciences, nanjing 2.0008, china Graduate University of the chinese academy of sciences, Beijing 100039, china chinese Acad Sci Nanjing Inst Geog & Limnol Nanjing 210008 Peoples R China chinese Acad Sci Grad Univ Beijing 100039 Peoples R China

In this paper, Lake Taihu, a large shallow freshwater lake in china, is chosen as an example of reconstruction of eutrophication through the comparison between stable isotopes from dissolved nutrients and plants and water column nutrient parameters and integration of multiple proxies in a sediment core from Meiliang Bay including TN, TP, TOC, C/N, δ15N, δ13C, etc. Differences in aquatic plant species and trophic status between East Taihu Bay and Meiliang Bay are indicated by their variations in δ13C and δ15N of aquatic plants and δ15N of NH4+. A significant influence ofexternal nutrient inputs on Meiliang Bay is reflected in temporal changes in δ 15N of NH4+ and hydro-environmental parameters. The synchronous change between δ13C and δ15N values of sedimented organic matter (OM) has been attributed to elevated primary production at the beginning of eutrophication between 1950 and 1990, then recent inverse correlation between them has been caused by the uptake of 15N-enriched inorganic nitrogen by phytoplankton grown under eutrophication and subsequent OM decomposition and denitrification in surface sediments, indicating that the lake has suffered from progressive eutrophication since 1990. Based on the use of a combination of stable isotopes and elemental geochemistry, the eutrophication of Meiliang Bay in Lake Taihu could be better traced. These transitions of the lake eutrophication respectively occurring in the 1950s and 1990s have been suggested as a reflection of growing impacts of human activities, which is coincident with the instrumental data.

关键词： stable carbon isotope of OM, stable nitrogen isotope, eutrophication, Lake Taihu.

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MAJOR PROBLEMS OF SUSTAINABLE DEVELOPMENT ALONG THE BANK AREA OF THE CHANGJIANG RIVER

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chinese Geographical Science 2000年第2期10卷 97-104页

作者： YANG Gui-shan(nanjing institute of {2. and Limnology,the chinese academy of sciences, nanjng 2.0008, P R. china) nanjing institute of {2. and Limnology the Chinese Academy of Sciences Nanjing P. R. China

Developing the Changjiang(Yangtze) River and building a developed economic zone along the bank area of the Chanajiang River is a great strategic decision of the national macroeconomic development distribution. This decision has both given an impetus to fast development of the regional economy and exacerbated the contradiction among economy and resources and environment. In this paper, some major problems ekisting in economic sustainable development, such as scattered industrial structure, duplicated construction of the great projects, enlarging the development gap of the regional economy and deteriorated environment etc., have been studied. The results show that scattered structure and duplicated distribution of some key industries and projects, especially automobile, electronics and petrochemical industry and communication, power installations, is one of the reasons for low industrial economic benefit; the great development gap among upper, middle and lower reaches areas are enlarging since the 1990’ s; soil erosion, nood disaster and environmental pollution are still exacerliating due to unreasonable over-development. Based on the above analysis, this paper brings out some countermeasures and proposals for increasing the ability of regional sustainable development, including transregional reorganization of industrial structure linking by assets and speeding the process of regional economy integration; gradually controlling and reducing the development gap arnong upper, middle and lower reaches areas through regional cooperation on a mutually beneficial basis; as well as strengthening ecological construction and environmental protection and increasing environmental bearing capacity etc.

关键词： the bank area of the Changjiang River sustainable development structure problems environment deterioration

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Experimental study on phosphorus release from sediments of shallow lake in wave flume

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Science china Earth sciences 2006年第z1期49卷 92-101页

作者： SUN Xiaojing,ZHU Guangwei, LUO Liancong & QIN Boqiang nanjing institute of {2. & Limnology, chinese academy of sciences, nanjing 2.0008, china Graduate School of chinese academy of sciences, Beijing 100039, china 1. nanjing institute of {2. & Limnology Chinese Academy of Sciences Nanjing 210008 China2. Graduate School of Chinese Academy of Sciences Beijing 100039 China

Influence of wave on sediment resuspension and nutrients release from sediments, collected from Lake Taihu and Lake Chaohu, was studied in flume experiments. Under strong-wave conditions, concentrations of suspended solids (SS), total phosphorus (TP) and dissolved total phosphorus (DTP) in overlying water were increased significantly following the sediments re-suspension. During the experiments on sediments of Lake Taihu and Lake Chaohu, TP concentrations increased 6 times and 3 times, and DTP concentration increased 100% and 70% more than it in presuspension, respectively. Concentration of soluble reactive phosphorus (SRP) of experiment on sediment of Lake Taihu increased 2.%. During the massive sediment suspension, the dissolved phosphorus in pore water and much of the phosphorus adsorbed by the sediment particles were released into overlying water. The phenomena in this wave flume experiment are quite similar to the situation observed in situ of Lake Taihu. The critical wave stresses of sediment re-suspension are nearly equal. The change of concentrations of SS, TP, and SRP was the same as that in situ *** study showed that concentrations of TP and SRP in lake water could be increased significantly by wave disturbance. Phosphorus release was significantly enhanced by wave disturbance at the beginning of massive sediment re-suspension, but decreased later.

关键词： shallow lakes, wave disturbance, internal release, phosphorus, wave flume experiment.

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Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern china

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Science china Earth sciences 2006年第8期49卷 881-888页

作者： WANG Jian1 & LI Shuo2.1. Cold and Arid Regions Environmental and Engineering Research institute, chinese academy of sciences, Lanzhou 730000,{2. 2. College of geography, nanjing Normal University, nanjing 2.0097,{2. 1. Cold and Arid Regions Environmental and Engineering Research institute Chinese Academy of Sciences Lanzhou 730000 China 2. College of geography Nanjing Normal University Nanjing 210097 China

Climatic change has significant impacts on snow cover in mid-latitude mountainous re- gions, in the meantime, spatial and temporal changes of snow cover and snowmelt runoffs are con- sidered as sensitive indicators for climatic change. In this study, the upper Heihe Watershed in the Qilian Mountains was selected as a typical area affected by snow cover and snowmelt runoffs in northwestern china. The changes in air temperatures, precipitation, snowfall and spring snowmelt runoffs were analyzed for the period from 1956 to 2.01. The results indicate that climatic warming was apparent, particularly in January and February, but precipitation just fluctuated without a clear trend. The possible changes of snowmelt runoffs in the upper Heihe watershed in response to a warming of 4℃ were simulated using Snowmelt Runoff Model (SRM) based on the degree-day factor algorithm. The results of the simulation indicate that a forward shifting of snow melting season, an increase in water flows in earlier melting season, and a decline in flows in later melting season would occur under a 4℃ warming scenario.

关键词： climatic changes, snowmelt runoff, SRM model, upper Heihe Watershed, simulating.

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Estimation of annual actual evapotranspiration from nonsaturated land surfaces with conventional meteorological data

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Science china Earth sciences 2004年第3期47卷 239-246页

作者： QIU Xinfa1, ZENG Yan2. MIAO Qilong1 & YU Qiang2.1. Department of geography, nanjing {2. of Meteorology, nanjing 2.0044, china 2. {2. of Geographic sciences and Natural Resources Research, chinese academy of sciences, Beijing 100101, china nanjing Inst Meteorol Dept Geog Nanjing 210044 Peoples R China chinese Acad Sci Inst Geog Sci Beijing 100101 Peoples R China chinese Acad Sci Nat Resources Res Beijing 100101 Peoples R China

Views diverge greatly on the relationship between actual evapotranspiration (AE) and potential evapotranspiration (PE). Penman showed that AE is determined in intensity by PE and changes proportionally as a function of PE. In contrast, Bouchet indicated that AE deter-mines PE and varies inversely with PE. Based on nearly 30 years data from 432.weather stations and 512.hydrological stations in china, the two different theories, Penman抯 assumption and Bouchet抯 complementary relationship between AE and PE, were tested on nine river basins. With data integration technique, the complementary relationship between AE and PE was dis-played entirely. A general model to estimate the actual evapotranspiration from nonsaturated surfaces by routine meteorological observations has been established on the basis of thorough analysis of the concept of PE. The results show that the calculations are all in error control of <10%, except for a few years over the Yellow River Basin.

关键词： complementary relationship of evapotranspiration, potential evapotranspiration, actual evapotranspiration.

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Research on the evaluation model of the modernization level of urban construction in Jiangsu Province,china

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Science china(Technological sciences) 2010年第9期53卷 2510-2514页

作者： YANG JunYan1 & CHEN Wen2.1 School of Architecture,Southeast University,nanjing 2.0096,china 2.nanjing institute of geography and Limnology,chinese academy of sciences,nanjing 2.0008,china 1. School of Architecture Southeast University Nanjing 210096 China2. Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

The modernization of urban construction is a key index in the process of urbanization,and also is an important index to measure the level of socio-economic and cultural *** paper analyzes and explores the related concepts of modernization of urban construction,analyzes the situation and identity of urban construction layer by layer so as to establish an evaluation index system of the modernization level of urban construction and then the paper evaluates the modernization level of urban construction from four different angles,which are the perspectives of the urban planning control,the level of urban facilities,urban management,urban construction *** later analyzes the evaluation results by choosing Jiangsu Province as a research hierarchy from the scale chains of urban study and makes efforts to the operative and directive development direction.

关键词： modernization of urban construction index system evaluation model

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Chronology of Holocene lacustrine sediments in Co Ngoin, central Tibetan Plateau

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Science china Earth sciences 2006年第9期49卷 991-1001页

作者： WU Yanhong1, WANG Sumin1& HOU Xinhua1,3 1. Key Laboratory of Lake Sedimentation and Environment, nanjing institute of {2. and Limnology, chinese academy of sciences, nanjing 2.0008, china 2. institute of Tibetan Plateau Research, chinese academy of sciences, Beijing 10085, china 3. Graduate University of chinese academy of sciences, Beijing 100039, china 1. Key Laboratory of Lake Sedimentation and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China 2. institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 10085 China 3. Graduate University of chinese academy of sciences Beijing 100039 China

Chronology is the basis for using lacustrine sediments to reconstruct the history of en-vironmental change. Radioactive-nuclides such as 14C, 2.0Pb and 137Cs dating are mainly used to establish the chronology for recent several ten thousand years. Because of being mixed with “dead carbon”, the measured 14C age is always older than the actual age which is recognized as “reservoir effect”. Cs is a kind of active metal element, and easy to migrate vertically in the sediment that leads to the error of the time marker. 2.0Pb dating should make sure to select CIC model or CRS model. On the Tibetan Plateau, most of the lakes are alkaline closed lake where Cs is more moveable in the sediment and the reservoir effect caused by “dead carbon” on 14C dating is stronger. Based on the analysis on results of 14C, 2.0Pb and 137Cs of the lacustrine sediments from Co Ngoin, central Tibetan Plateau, we use the simple regression method to re-calculate the 14C calendar ages, and establish the time sequence for cores CE-1 and CE-2.with result of 2.0Pb CRS model for the upper 35 cm and re-calculated 14C calendar age for sediments bellow 35 cm. Since 1400 cal. a BP, sedimentation inter-rupted for more than 1000 years. According to this time sequence, variations of environmental proxies confidently reflect the major climatic events in Holocene.

关键词： 14C, 2.0Pb and 137Cs, chronology, lacustrine sediments, climatic event, Co Ngoin, central Tibetan Plateau.

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