Abstract:13 genera and 32 species of ostracodes were identified from lake sediment core HQ in the Heqing Basin, Yunnan Province. Five paleoenvironmental stages with a number of substages were divided in the basin since 150 kaBP based on the abundance, diversity and percentage of ostrocodes, in combination with pollen, total organic carbon (TOC), carbon/nitrogen ratio (C/N), and carbonate content. The general paleoclimatic conditions of the lake area are characterized by the alteration of cold-wet periods with warm-dry periods, with secondary fluctuations superimposed on the macroscopic trend, representing the regional paleoclimatic features. These paleoclimatic stages are generally correlated with the deep sea oxygen isotope stages of equatorial Pacific core V28-238 and those revealed by loess/paleosoil sequences of Mangshan section, in Zhengzhou, which shows the synchronism and differentiation of paleoclimatic changes. Due to the both effects of tectonic and paleoclimatic activities, the lake basin was completely captured by river at ca. 11790 aBP.

Abstract:It is difficult to fully recognize what the mechanisms are behind Holocene climate changes so far. Numerous geological evidences have suggested that several phases of temperature lowering occurred during the Holocene and the cold phases are correlated with events of volcano explosions. Modern observations in climatology have revealed that volcanic dust plays a role on the radiation blocking and leads to temperature lowering on the earth surface when the volcanic dust enter the stratospheric level. This paper is attempted to focus on both volcanic-climatology and volcanic-geology to understand volcano effects on climate changes, by an integration of geological volcano data and simulation of climate model. The compiling volcanic data show that there were five phases of strong volcanic explosions during 12000-1000 a BP. The volcano-tested climate simulations show that the annual mean temperature is generally decreased during the phase of the strong volcano explosions. Compared to phases of the weak- volcano explosion, the decrease in temperature varied from regions and from seasons. The amplitude of temperature lowering is bigger in high latitude than that in low latitude, and higher in winter than in summer. The results in volcano data set and climate simulations provided the data basis to further study the mechanisms of Holocene climate changes and the today-past analogues to finally predict changes in the future climate in the decade-century scales.

Abstract:The paleomagnitism dating of the core Co Ngoin, Qinghai-Tibetan Plateau, a 200-m-depth core taken from Co Ngoin, indicates that the lake emerges at 2.8Ma BP. Lithological property, grain size and magnetic susceptibility (sus) reveal three major significant environmental variations and at least two tectonic uplifts during the last 2.8Ma. Accordingly, pollen associations open out the vegetation changes controlled by the tectonic uplift. Studies show that the major environmental changes were largely controlled by stepwise uplift of the Qinghai-Tibetan Plateau, and those numerous small changes overlapped on the large tectonic background are mainly controlled by the global climatic changes of glacial and interglacial cycles in Quaternary. The thickness of the strata above the B/M boundary is thinner, which might be resulted from the glacial cover to lead the shortage in stratigraphic thickness.

Abstract:Rare earth element(REE) concentration and distribution patterns and vertical distribution of total REE(ΣREE) in sediments from Qinghai Lake are presented in this paper. In combination with total organic carbon (TOC) and Grain Size parameters, the relationship between ΣREE and the climate and environment has been discussed. The result shows that the ΣREE values of the sediments from Qinghai Lake vary over a range of 16.262-89.221mg/kg, with an average of 63.001mg/kg. Indicating that the semi-arid environment was dominant with much weaker chemical weathering. The sediments from Qinghai Lake have very similar ΣREE distribution patterns, which are moderately rich in light rare earth element (LREE), with negative slopes and unclear Ce and Eu anomaly. ΣREE contents have good relationships with TOC and Grain Size. During warmer and wetter climatic episodes, the values of ΣREE in sediments are higher; on the contrary, during colder and drier climatic episodes, the values of ΣREE are lower. The further study has reconstructed the paleoclimate evolution of Qinghai Lake since 8.5kaBP, which includes four main climatic and environmental changes that were warm-moist, cool-dry, warm-moist and cold-dry during late Holocene. Finally, we have concluded that ΣREE in sediments of Qinghai Lake is an effective indicator to reconstruct the paleoclimatic variation in the high-cold semi-arid areas because of its sensitivity to the climatic changes.

Abstract:On the basis of the observed hydrological data in Qinghai Lake Basin, 1959-2000, we studied the dynamic changes of precipitation, runoff, evaporation, lake water level and the supplement of ground water of Qinghai Lake for the past forty years. Estimates revealed that a 3.32 m-drop occurred during 1959-2000, resulting an annual decrease of water quantity of 3.60×10⁸ m³. Moreover, the amount of interbasin diversion required for maintaining ecologic balance and social economic sustainable development was discussed, an annual quantity of 4.1×10⁸ m³ could meet the needs for water resources allocation optimization.

Abstract:On the basis of in-situ nutrients (e.g. N, P) data conveyed in the main channel and tributaries of the Yangtze River, the Three-Gorge Reservoir retention effects on nutrients upstream have been analyzed by a simple model. The model outputs show that the Three-Gorge Reservoir ecosystem would fix 2%-7% dissolved inorganic N and 13%-42% dissolved inorganic P from the upstream, and that the amount of biogenic organic C in the reservoir water would reach 0.84×10⁹-2.65×10⁹ mol. Consequently, the Three-Gorges Reservoir Project would slow down the eutrophication tendency of nutrients in the main channel downstream, while increase N/P ratio in the lower reaches of the Yangtze River to some extent.

Abstract:The scare of fresh water has been becoming a focus issue in the world, while water quality deterioration enhances the seriousness of the problem. To assess the water quality and its impact factors can provide basic information for water resource management. This paper verified the usefulness of water quality indices (WQI) to assess the water quality from multiple measured parameters, and to evaluate the spatial and temporal change. The WQI which takes into consideration all the measured parameters not only shows a similar trend to the results of analyzing separate parameters and the index of compositive pollution, but also display the overall water quality and can predict precisely the change trend of water quality. As a case study, we use the WQI to evaluate spatial and temporal changes in the water quality from Xitiaoxi Catchment, upper reaches of Taihu Basin, and assess the degree of factors influencing water quality. The nonpoint source pollution caused by land use produces a serious and negative effect on the water quality because only controlling and management point sources only increase 6.5% of water quality. The water quality gradually deteriorated along the river from upper reaches to lower reaches mainly due to the land use change. So, in the future, the highest priority measure to improve water quality of Xitiaoxi Catchment should be controlling non-point pollution resources.

Abstract:The relationship between dissolved oxygen and nutrient cycle in low-wetland fishponds of the Huanghe-Huaihe-Haihe plain was studied. The results show that:1) The dissolved oxygen content depended on the photosynthesis of algae and the consumption of other organisms, which can be significantly improved by mixing. 2) The heterotrophic bacteria number of pond water was correlation with organic matter in addition to the dissolved oxygen. This change was more clearly especially in the sediments. 3) The dissolved oxygen of pond water significantly affected the changes of ammonification intensity and phosphorous decomposition intensity. When the dissolved oxygen was increased, the heterotrophic bacteria number and active were also improved, which caused the ammonification intensity and phosphorous decomposition intensity was significantly increased. This situation was more clearly in the sediments. 4) The nitrate reduction intensity and sulfate reduction intensity was negative correlation with the dissolved oxygen content. When the dissolved oxygen was decreased, the nitrate reduction intensity and sulfate reduction intensity were significantly increased. This situation also was more clearly in the sediments.

Abstract:The extracts of thoracic ganglion from adult Macrobrachium rosenbergii were chromatographed on a Sephadex G-50 column, the resulting second peak was further isolated by HPLC, and 9 fractions were obtained. Among the fractions only the first fraction significantly increased the oocyte diameter in vitro of the stage Ⅲ ovary in M. rosenbergii. The increasing effects were depended on the protein concentration of the fraction for culture. The molecular weight of the substance in the fraction 1 was about 1.3kDa.The results show that the thoracic ganglion of M. rosenbergii can secrete peptide hormone which stimulates the oocyte development of the prawn.

Abstract:The ecological theories for sustainable fishery of freshwater lakes are fisheries ecology and fisheries limnology. Fisheries ecology focuses on biology of fishery species, potential production, optimal stocking density and size, rational input of subsidy energy, and rational catch strategy, and so on. Fisheries limnology researches the stress of fishery on the freshwater resource and biodiversity in lake ecosystems, which can define fishery size and fishery model. The macrophytic lakes along the mid-lower reaches of Yangtze River become the main freshwater fishery base with high quality and high efficiency in China in recent years because of its good water quality and rich bioresource. When some high-market-price species, such as Eriocheir sinensis and Siniperca chuatsi, are stocked as main fishery species, ecological management is very important. The authors emphasize the following three aspects:1. The submerged macrophyte community, which is the basic and key factor of sustainable fishery, must be used rationally, protected carefully and rationalized for fishery. When the community collapses, restoration is necessary. 2. The basic links of food chains webs must be protected to raise their biomass and production for fishery species. 3. Good strategies of stocking and catching are also very important for fishery ecosystem.

Abstract:The production of Sphaerium. lacustre in Lake Houhu was estimated by two methods. The results were:1.048 g/(m²·a) of fresh weight with shell or 0.0599g/(m²·a) of dry weight shell-free by size-frequency method; 1.178 g/(m²·a) of fresh weight with shell or 0.0673 g/(m²·a) of dry weight shell-free by instantaneous growth method. The corresponding P/B ratio were 3.2 3.4, respectively. Thus, the results by the two methods are coincided each other.

Abstract:It took a long time for regular survey in the change of water surface, and sometimes almost impossible in some areas of the plateau. With the development of earth observation and geography information science, the use of remote sensing techniques is at present the primary, and in many places the only, means of measurement. At the same time, GIS provides an efficient tool to analyze the status and the changes of lake. In this study, for the example of Ebinur lake lies in the west of Xinjiang, we use 1950-2000 serial map, photo and TM Landsat data, to coregistrate all images and construct lake border maps in GIS, then use the function of overlay analysis in GIS to measure lake area changes. The result shows that there were several fluctuations of water level in the past 50 years. Moreover, we put forward some analysis on the main reasons to influence the level.

Abstract:Based on the recent international publications, this study explained the modification of taxonomic name in three common phytoplankton genera. The new classification systems of Oscillatoriales and Bacillariophyceae were also introduced. According to the taxonomy of Anagnostidi & Komárek (1988), the former cyanobacteria genus Oscillatoria was split up. Most of the planktonic species of this group can now be found in two new genera Planktothrix and Limnothrix. About 70 other species in this group were shifted into the genus Phormidium. According to the taxonomy of Kramme and Lange-Bertalot (1991), all the planktonic species of the former diatom genus Melosira formed a new genus Aulacoseira. Some other species in this group were moved into the genera Orthoseira and Ellerbeckia. Most of the planktonic species of the former diatom genus Synedra were altered back to the genus Fragilaria. Some other species can now be found in the genera Nitzschia and Hantzschia.