Abstract:As the final completion of the world-famous Three Gorges Project, the Three Gorges Reservoir(TGR) came into a normal operation stage since the year 2010, with an annual water level fluctuation of 30 m. Reservoir limnology can provide a scientific basis for environment-friendly dam construction and reservoir sustainable management. On the basis of long-term monitoring and investigation on the TGR ecosystem for 8a, this paper described the current status of aquatic environment in the reservoir, and elaborated the spatial-temporal heterogeneity of water environmental dynamics, longitudinal zonation and biological community structure, vertical distribution, and forming and tendency of algal bloom of the TGR. The early warning of algal bloom and eco-hydrological regulation mechanism were also analyzed. Two perspectives of ecological research on TGR were finally pointed out in the paper:1) Limnological observation and research in the large reservoir should have a long-term strategy; 2) Research in near future should focus on the quantification of hydrodynamics mechanism on algal bloom, and the coupling of early warning models of algal bloom and eco-hydraulic regulation platform.

Abstract:With the operation of Three Gorges Project(TGP), water regime of rivers and lakes downstream of the dam changed with the reservoir regulation. The lowering of water level becomes normal after flood season compared with the years before TGP. Here, the water storage of TGP in 2006 was selected as a case to quantitatively investigate the effects of TGP on water regime of Lake Dongting. We applied the coupled hydrodynamic analysis model for the middle Yangtze River to compute the variation of water regime induced by the water storage. During impoundment, the reduction of the water level and discharge are 1.32 m and 466 m³/s, respectively, at Chenglingji, the outlet of Lake Dongting. The bottomlands inside the Lake Dongting are exposed ahead of time and the lake area with over 5 inundation days reach to 287 km². Results also indicate that:1) the impact of TGP on water regime varied with locations:east Lake Dongting takes the first place, the east of South Lake Dongting and the north of West Lake Dongting second, and the west of South Lake Dongting and the south of West Lake Dongting third. 2) The bottomlands which strongly affected by the impoundment are mainly located at East Lake Dongting, South Lake Dongting and the both sides of flood ways. 3) Two influencing mechanisms on water regime are identified:one is the increase of the lake discharge induced by the rapid drawdown of the mainstream of the Yangtze River; the other is the reduction of inflow from the Yangtze River via Sankou distributary channels.

Abstract:Three Gorges Reservoir has become a man-made lake ecosystem where there are a lot of ecological niches left vacant or unused. Alien species appear to be successful invaders to fill these empty ecological niches. In recent years, a total of 23 invasive fish species have been found in this reservoir and the upper reaches of Yangtze River, some of which are in the stage of their population outbreak. The main reasons for this are increased nutrient inputs and thus high primary productivity in the initial time of impoundment. They facilitated the invasion of exotic fish species that have the adaptability to a wide range of environmental conditions. With a competitive advantage over indigenous fishes, invasive alien species can replace them. This may be seriously harmful to the fishery resources and aquatic ecological systems in Three Gorges Reservoir. Evidently, more attention should be paid to affects and other related issues caused by the invasive alien fish. The following measures can be urgently taken:the establishment of the early warning and prevention systems of invasive alien fish species, the assessment on the potential affects of the introduction of alien cultured fishes, and thorough investigations of mechanisms of exotic fish fishes as the successful invaders adapted for the reservoir environmental conditions.

Abstract:Partial pressure of CO₂ (pCO₂) in water column was an importamt indicator for the geochemical characteristics of carbon. Diel samples for pCO₂ and other environmental factors, i. e. pH, DO and water temperature, was taken from Gaoyang backwater area in the Pengxi (Xiaojiang) River, Three Gorges Reservoir in every 6 h. Results showed that in stable metaliminon, vertical pCO₂ increased along with the water depth. Mean value of the pCO₂ at 0.5 m depth was 152 ± 71 μatm, while that of pCO₂ at 10.0 m depth was 4568 ± 1089 μatm. Significant negative correlations between pCO₂ and pH, DO, water temperature were detected, indicating metabolism of microbial and planktonic community and penetrative convection were impacted by water temperature that regulated the distribution of pCO₂. Estimation of the water-air flux of CO₂ indicated that the general characteristic of carbon sink in the Gaoyang backwater area was obvious. A maximum sink flux of -0.33 mmol/(m²·h) was detected in 15:00 while a minimum sink flux of -0.17 mmol/(m²·h) was also detected in 3:00 of the next day.

Abstract:Xiangxi River originates from the Shennongjia Forest region and is the largest tributary in Hubei Province of Three Gorges Reservoir. Three reservoirs(Gudongkou Reservoir 1, Gudongkou Reservoir 2 and Xiangxi Bay of Three Gorges Reservoir) in Xiangxi River Basin were selected to investigate phytoplankton ecology in such a reservoir cascade system. In this study, phytoplankton composition, dominant species, community structure, abundance and biodiversity index were investigated and analyzed from October 2005 to July 2006. A total of 121 species, belonging to 58 genera in 7 phyla were identified, among which Chlorophyta(49 species of 26 genera) is the most important compontent, accounting for 40.50% of the total; followed by Bacillariophyta (41 species of 14 genera) for 33.88%, and Pyrrophyta(11 species of 3 genera) for 9.09%, Cyanophyta(7 species of 5 genera) for 5.79%, Cryptophyta(7 species of 3 genera) for 5.79% and other species for 4.96%. 31 species of 25 genera, 40 species of 29 genera and 81 species of 46 genera were found in Gudongkou Reservoir 1, 2, and Xiangxi Bay, respectively. The dominant species in Gudongkou Reservoir 1 belonged to Bacillariophyta, Chlorophyta, while Bacillariophyta, Cryptophyta and Pyrrophyta dominated in Gudongkou Reservoir 2. Chlorophyta, Bacillariophyta, Pyrrophyta, Cryptophyta also played an important role in Xiangxi Bay. The annual abundance of phytoplankton community in the three reservoirs was 1.110×10⁶, 4.837×10⁵ and 1.734×10⁶ cells/L, respectively. It had highest density in Xiangxi Bay(4.87×10⁶ cells/L) and lowest density in Gudongkou Reservoir 2(5.76×10⁵ cells/L). Principal Component Analysis was applied to analyze the water quality of the three reservoirs. The result implies that the water quality was degrading along the cascade of reservoirs. There were no significant differences in diversity index(H) and evenness(J) among the three reservoirs, while the Margalef index of Xiangxi Bay was significantly larger than that of Gudongkou Reservoir 1 and Gudongkou Reservoir 2. The valuation results by the first two indices and dominant phytoplankton species showed that the cascade reservoirs in Xiangxi River Basin were of intermediate pollution state.

Abstract:Vegetation and soil are the key components of the drawdown area of Three Gorges Reservoir. To investigate characteristics of vegetation and soil from water-level altitude of 160 m and 170 m, three drawdown areas with similar geological environment and history of land-use in Zhongxian County were chosen. Results indicated that percent of annual and perennial herbaceous species in drawdown area were 72.4% and 27.6%, respectively. There were no significant differences in species composition, coverage, biomass and biodiversity index between 160 m and 170 m. With water-level altitude changing, the dominant species of plant community varied. Cynodon dactylon was the dominant species at 160 m, while Conyza japonica at 170 m. Soil bulk density, water content, pH, SOM, TN and TP at 160 m and 170 m did not differ significantly. Therefore, it seems reasonable to suggest that their different dominant species resulted from the different inundation period and water depth in those areas between 160 m and 170 m, which did not play a significant role in current vegetation and soil development.

Abstract:The distribution characteristics of organic matter(OM) and total nitrogen(TN) in the soils of water-level-fluctuating zone(WLFZ) of Three Gorges Reservoir were studied during the non-flooded period, while the correlation among the soil physicalchemical characteristics, OM and TN contents was also be analyzed. OM and TN contents in the soils of WLFZ were both fairly low, were 10.70 ± 4.03 and 0.84 ± 0.39 mg/g, respectively; however, they followed the normal distribution. The lower C/N ratio of the soils of WLFZ suggested possibility of releasing of inorganic nitrogen from soil in the WLFZ to overlying water in the flood period. Compared with other study areas, the OM and TN contents were at the low level. The variation coefficients of OM and TN contents of the soil samples of WLFZ were on the low side by comparison with those in control zone. That is why the differences of OM and TN contents among difference WLFZ of study areas could be reduced by cyclic drying and wetting of WLFZ periodically. Correlation analysis showed that pH, oxidation-reduction potential(ORP), TN was significantly and positively correlated with OM. The result indicated that organic nitrogen was the main nitrogen compositions in soils of WLFZ of the study area. Soil C/N ratio was negatively correlated with TN, but insignificantly correlated with OM, suggesting that soil C/N ratio was mainly determined by the content of TN.

Abstract:An investigation was made to study the variations of the environmental factors and the composition of plankton when Microcystis bloomed in Shennong River which is the primary tributary of Three Gorges Reservoir during June and August in 2008. The results show that Microcystis aeruginosa is the absolutely dominant species forming the algal bloom. The Microcystis bloom lasted about 50 d and covered about 0.2 km². The biomass of Microcystis are in direct correlation with the total phosphorus. With Three Gorges Dam stored water, the flow velocity of Shennong River has been slowed down greatly and the self-purification ability of the river declined. As a result, nutrient accumulated constantly and causing the water eutrophication. High content of nutrients in the water of Shennong River is the main reason responsible for the algal bloom formation while suitable natural conditions also contribute to the process. Based on the research, we proposed several strategies to mitigate the eutrophication and control algal blooms in Shennong River including pollution control and river ecosystom management.

Abstract:In order to analyze the phytoplankton diversity in the backwater area of Pengxi River before and after the impoundment of the Three Gorges Reservoir (TGR) to the water level of 156 m, the variation of algae community of Pengxi River had been observed from July 2007 to January 2008. According to the water level variation in TGR, the time was divided into three periods:July-September, October and November-January. The algae diversity of five sites in Pengxi River was assessed using Shannon-Weaver diversity index H'. Moreover, the Connell's intermediate disturbance hypothesis was applied to analyze the impact on algae diversity caused by hydrodynamic conditions' variation during the impoundment process. Before 156 m impoundment, the mean H' index was 3.466 ± 0.317, declined to 3.246 ± 0.338 in October and recovered to 3.431 ± 0.352 during the high water level period. Before impounding, the Pengxi River was of riverine-type, with flow and rainfall being the main physical disturbance factors affected the disturbance intensity and algae diversity. As a result of water level suddenly risen and the flow severely droppen, the disturbance intensity increased compared with the impounding period. After 156 m impounding, the Pengxi River was at the high water phase, the less rainfall and stable flow reduced the physical disturbance, so the H' index recovered and maintained at a relatively stable state.

Abstract:Algal blooms have occurred frequently in the backwater region of the Daning River branch since the impoundment of the Three Gorges Reservoir(TGR). In order to assess the water quality status and the driving factors on algal bloom outbreak, the water quality has been monitored since 2005, and 2 typical algal blooms, occurred in Dongpingba in March and May 2010, were investigated. Results showed that Daning River was mesotrophic and water quality was good, nevertheless the trophic grade was underestimated for the period of algal bloom outbreak. For algal bloom in March, there was a significant negative correlation between Chl. a concentration and velocity, while obvious relationships in Chl. a and pH or DO, indicating that velocity was an important factor for this bloom outbreak and pH, DO were sensitive factors caused by bloom. For algal bloom in May, there was a significant negative correlation between Chl. a concentration and velocity, while a significant positive correlation between Chl. a and flow quantity, and also obvious relationship in Chl. a and pH, SD. It indicated that velocity and flow quantity were important factors for algal bloom outbreak in May, and pH, SD became the sensitive indices. According to the operational schedules of TGR, March and May belong to the period with high water level and discharge, respectively. Schedule times with different hydrodynamics may be responsible for the difference of effect factors on algal bloom, but the mechanism need to be further studied. Results suggested that the algal bloom mechanism in the different operational schedules of TGR is different from each other significantly. Therefore, the study on algal bloom in backwater region of Daning River need to be performed according to the operational schedule of TGR.

Abstract:Considering the conditions of temperature, humidity, wind speed and sunshine duration, the temporal and spatial distribution of temperature-humidity index(THI) and wind effect index(K) were calculated at 22 weather stations in the Three Gorges Reservoir catchment from January, 1995 to December, 2010 based on GIS technology. The general distribution trend on climate suitability for human settlement in Three Gorges Reservoir was analyzed. The change in climate suitability for human settlement was analyzed before and after impoundment based on the first storage stage of the Three Gorges Project in June, 2003. Correlation analysis of water level and meteorological elements were also investigated. Results show that the climate is not comfortable from November to March in the next year due to the cold temperature. Similarly, the climate is also not comfortable from June to September due to the hot weather. The average annual THI and K exhibit obvious regional difference. The integrative trend of THI and K decreases progressively from central to east and west areas. Climate suitability has changed obviously since the accomplishment of the Three Gorges Project. The results of Pearson's correlation coefficients showed no correlation between THI, K and water level before June 2006, whereas water level showed significantly positive correlation with THI and negative correlation with K after that time.

Abstract:Based on the daily precipitation data in flood season(from May to September) in 1961-2010 from 35 stations over Three Gorges Reservoir area, the extreme precipitation threshold value for all stations are determined firstly, then the frequency of extreme precipitation event in the flood season are counted and their temporal and spatial characteristics are analyzed. Consistent anomaly distribution is the main spatial model of extreme precipitation event frequency in flood season over Three Gorges Reservoir area. The spatial distribution of extreme precipitation event frequency is complex with anomaly difference between in the south and west, and in the east and west of Three Gorges Reservoir area, which can be divided into five main regions. The moving t-test analysis shows that there are abrupt changes of Banan in 1974, Beibei in 1981 and 1993, and Wulong in 1984 for the extreme precipitation event frequency. The Maximum Entropy Spectral and Estimation Power Spectral analysis shows that the periodic oscillations of these regions are not consistent in recent 50 a. The distinct periodic oscillation of the extreme precipitation event frequency of Yichang, Beibei and Wulong is 5, 2.4 and 8.3 a, respectively.

Abstract:System dynamics (SD) model is suitable for the simulation of the complex issues of regional development. Based on the analysis of the relationship among the sub-systems, the various elements of Lake Poyang Region system, the SD model is constructed, and 4 development scenarios are simulated to reveal the characteristics of regional development. Results show that the inertia development pattern not only leads to the slow pace of development, but also results in serious ecological and environmental issues; the pattern of high growth with low environment input maintain rapid economic growth but will lead to a greater damage of environment; meanwhile, the pattern of high growth and high environmental input can maintain the high speed growth of economy and solve the pollution caused by economic growth through increased investment in environmental protection; the industrial upgrading pattern emphasizing on economic restructuring, can ensure a relatively rapid economic development and maintain the virtuous cycle of regional ecology and environment. Account of regional characteristics of Lake Poyang Region and the advantages and disadvantages of each scenario, the recommended development pattern is put forward in this paper to achieve a balance between the economic growth and regional ecology and environment.

Abstract:The composition and origin of the dissolved organic matter (DOM) in some lakes of west Jiangsu was investigated using UV-Vis absorbance and fluorescence spectroscopy. The specific ultraviolet absorption (SUVA) at 254 nm and 280 nm indicated that the aromaticity and molecular weight of DOM ranked in the order of Lake Shaobo, Lake Tiangang, Lake Baima, Lake Shijiu, Lake Hongze, Lake Gucheng, Lake Luoma, Lake Gaoyou and Lake Baoying. The E₂/E₃ and E₃/E₄ values suggested that the DOM of Lake Shaobo and Lake Baima was structural complex with humic acid being the primary component, while other lakes' DOM was less complex and constituted mostly by fulvic acid. The exponential slope parameter (S_275-295nm) values results were consistent with the conclusion obtained from SUVA, E₂/E₃ and E₃/E₄. Fluorescence indexes and biological index of these lakes' DOM were ranged of 1.13-1.30, 0.47-0.67, respectively, suggesting DOM a strong terrestrial origin. Significant correlation was found between the fluorescence intensities per unit organic carbon at different peaks, which indicated that the humic-like and protein-like materials in these lakes have a similar source. Considered the characterization of these lakes and the economic development, it can be deduced that most of these DOM are produced by agriculture and its downstream industries and imported with inflow rivers.

Abstract:In recent years, algae bloom is common in the flowing waters, which has been one of the top scientific problems after the algae bloom in lakes. Due to the water pollution, phytoplankton blooms arose in Qinhuai River between August and September, 2010. Based on the conventional monitoring data in August 15 and September 8, 2010, this paper studied the spatial distribution characteristic of chlorophyll-a and its relationships with environmental factors. Results showed that chlorophyll-a concentration appeared obvious spatial difference from upstream to downstream, with a mean value of 73.7 μg/L and the maximum value occurred in Mamuqiao(184.52 μg/L). The ratio of TN/TP was 26.86, and the logarithmic correlation between chlorophyll-a and TP was positive, but the logarithmic correlation between chlorophyll-a and the TN/TP ratio was negative. It suggested that phosphorous might be the main impact factor for blue-green algae. Significantly positive correlation was found between chlorophyll-a and pH and DO, and significantly positive correlation was found between chlorophyll-a and NO₂^--N, but no significant correlation between chlorophyll-a and NH₄⁺-N, NO₃^--N and TN.

Abstract:The correlation between the storage capacity and runoff, runoff + precipitation, runoff + precipitation-evaporation was analysed at the basis of monthly water balance calculation in the period of 1963 and 1980 according to the real hydrological processes of the research site. At the same time, the intermediate-term changes in the mean value of water level, runoff, precipitation and evaporation were detected with the cumulative sum technique in order to find the reason of water level dropping after 2000. Meanwhile, the distribution and mutual relations of water balance terms in a year was analyzed. Results show that:climate change exhibited a warmer and dryer trend in recent years that might be the major cause for water resources deficit after 2000. The crucial influence on water level comes from runoff, followed by precipitation on the water surface. In April and May of each year, accumulated melt water infiltrate the soil and then recharge the lake, while in the other time the groundwater recharged by the lake.

Abstract:Nitrogen discharged into lake ecosystems typically has different nitrogen stable isotope ratios(δ¹⁵N) and measurement of δ¹⁵N in organisms can be useful indicators of anthropogenic impacts from the watershed. The δ¹⁵N values of Bellamya aeruginosa were investigated in four bays of Lake Taihu. Results showed that δ¹⁵N values in snail ranged from 6.9‰ to 18.1‰, with an average of 11.2‰. Snail δ¹⁵N values displayed a significant variation among four bays. The highest average value was found in Meiliang Bay(17.7‰), followed by Gonghu Bay(13.2‰), East Taihu(10.2‰) and Zhushan Bay(7.8‰). Our investigation suggested that both Meiliang Bay and Gonghu Bay have received tremendous amount of domestic sewage derived from increasing human activities. Therefore, it's necessary to promote investment of sewage treatment plants in surrounding cities including Wuxi and Changzhou. Our research also indicated that Zhushan Bay, which is located in northwest part of Lake Taihu is mainly affected by agriculture non-point source pollution. So it's necessary to reduce the use of fertilizers to improve the water quality of that bay.

Abstract:The size, composition, vertical distribution and species diversity of seed bank as well as its relationship with aboveground vegetation were studied in three dominant plant communities(Miscanthus sacchariflorus, Carex sp., and Phalaris arundinacea) distributing with different water levels in Lake Dongting. The density of seed bank was highest in M. sacchariflorus (44656 seeds/m²), followed by P. arundinacea(31725 seeds/m²) and lowest in Carex sp. (15146 seeds/m²). Seeds in the seed bank distributed mainly within 0~5 cm soil layer and decreased rapidly along with the soil depth. The seed banks of the three communities were composed of 53 species belonging to 18 families, 39 genera. Among them, 20 species were perennial while 33 were annual or biannual. The proportions of perennial species were 29.9%, 35.2% and 38.0% in the soil seed bank of M. sacchariflorus, C. sp. and P. arundinacea communities, respectively. The diversity indexes of seed bank and aboveground vegetation were 0.76 and 0.53 in M. sacchariflorus, 0.70 and 0.17 in C. sp., 0.72 and 0.45 in P. arundinacea, respectively. The similarity indexes between seed bank and aboveground vegetation were 0.28 in C. sp., 0.40 in M. sacchariflorus and 0.52 in P. arundinacea, respectively. The diversity index of seed bank was higher than that of aboveground vegetation and the similarity was relatively low. Therefore, perennial aboveground vegetation has limited contribution to the soil seed bank in large Yangtze-connected lake wetlands, where seeds might be mainly imported into seed bank through other pathways, such as water flow.

Abstract:Studies on the size fractions of plankton communities in large shallow lakes are rare. Here we report on size fractionated plankton communities from Lake Taihu based on bimonthly measurements in field from October 2002 to September 2003. Based on the diameter(R) of the plankton community we analyzed size fractions of R ≥ 41 μm, 2 μm ≤ R < 41 μm and R < 2 μm. The fraction larger than 41μm, represented mainly by Microcystis colonies, dominated in Meiliang Bay. The respiration of this fraction contributed over 70% to the total plankton community respiration, while the fraction < 2 μm(mainly bacteria) contributed about 18% of the total plankton community respiration. In the center of the lake, the plankton community with R ≥ 41 μm contributed about 10% to the total plankton community respiration, while the plankton community R < 2 μm contributed about 65% to the total plankton community respiration. For the whole lake, the plankton community with R ≥ 41 μm, particularly the Microcystis colonies, dominated total plankton community respiration in the northern part of the lake while bacterial respiration was most important in the center of Lake Taihu.

Abstract:Neosalanx taihuensis is an annual fish with commercial importance. This species is endemic to China, occurring in inland waters affiliated to the eastern-flowing rivers southern to the Yellow River, e. g. the rivers of Yellow, Huaihe, Yangtze, Ou and Pearl etc. Among these river basins, the Yangtze River tests to be the most important region for this species with the highest fishery stocks and the most populations, and thus to be the core area for its conservation and sustainable exploitation. In the near decades, however, N. taihuensis decreased severely with most of the natural populations extinguished economically or even ecologically. The local population extinction infers that the species' genetic diversity must have suffered bad influence and some genetic types must have lost as result. To test this presumption, we conducted an icefish-specific investigation in the mid-lower reaches of Yangtze River during August, 2006. Totally eight populations were sampled and used in the followed experiment on their genetic diversity. Based on the gene diversity of mitochondrial cytochrome oxidase subunit I(COI), we mainly focus on two points:1) to find out the genetic diversity in single population and among populations for understanding the genetic status of wild N. taihuensis in the river basin, 2) to check the suitability of COI gene for DNA barcoding study in the family of Salangidae. We selected 132 specimens, representing eight different geographic populations in the mid-lower Yangtze River basin, and analyzed their base sequences of COI gene. Among the 630 bp nucleotide sequence of COI gene, eight(1.27%) was variation sites, contributing to eight gene haplotypes. Although the number of gene haplotype and the nucleotide diversity index(π=0.00112 ± 0.00204) were not high, haplotype diversity(h) was fairly rich(h=0.576 ± 0.036) in the populations at river basin scale. Taking spatial distribution pattern into account, most gene haplotypes distributed in spatially narrow region with quite low occurrence incidences of 12.5% or 25.0%, occurred in one or two lakes respectively. Haplotype richness in each population varied significantly from each other, with a high fixation index. The least haplotypes occurred in the two highly isolated lakes of Dongting and Liangzi, and the highest haplotype richness occurred in the two lakes with icefish introduction histories. This result indicates that a high inter-population variation existed in the studied region. So we concluded that wild populations of N. taihuensis have suffered great ecological isolation, although they are geographically near to each other. Comparing with several other salangid fishes, e. g. Protosalanx hyalocranius, Hemisalanx brachyrostralis and N. oligodontis, the inter-specific genetic distance was 4.443%, amounting to some 35 times of that in N. taihuensis populations(0.125%). Compared with other fish taxa, such as Coilia, Culter, Oncorhynchus and Salmo, the intra-specific genetic distance was much smaller within N. taihuensis populations(< 1%). In conclusion, the COI gene is good and suitable to DNA barcode study in species identifying and systematic study, and can be useful in the assessment, monitoring and conservation management of icefish genetic diversity.

Abstract:The results of a transparency (SD) contrast test between different Chinese sturgeon polyculture models with freshwater mussel Anodonta woodiana and silver carp Hypophthalmichthys molitrix, bighead carp Aristichthys nobilis indicated that the average transparencies were 11.92, 16.45, 17.45 cm which increased by 26.69%, 56.67%, 66.19% compared with background value before the test for pond 1 (control group), pond 2 (A. woodiana-polyculture group), pond 3 (H. molitrix, A. nobilis-polyculture group), respectively. The overall transparency level of pond 2 and 3 were significantly higher than that of pond 1, highest reached to twice. The panel data models of three ponds'transparency and other water quality parameters were:SD₁=-0.0072 TSS + 0.8353 NH₄⁺-N-2.1711 TN + 0.6195 TP-0.0405 COD + 16.7815, SD₂=0.0030 TSS + 3.8864 NH₄⁺-N + 0.1893 TN-12.4585 TP^***-0.0104 COD + 24.5306, SD₃=0.0381 TSS^* + 3.7821 NH₄⁺-N + 0.6003 TN-15.0444 TP^***-0.4078 COD^** + 34.2992. Total phosphorus (TP) was the main index, with ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), chemical oxygen demand (COD) as indirect ones, TSS as direct one, influencing the transparency of Chinese sturgeon culture pond. Polyculture with H. molitrix and A. nobilis excels the treatment hanging A. woodiana in transparency rise effects in the Chinese sturgeon culture pond with muddy water and high concentration of total suspended solids.

Abstract:The main objective of the project is to obtain completely halophile germplasm resources from Lake Qinghai, to construct stocks phyletic evolution tree of halophilic bacterium and determine the evolution position. 35 strains were isolated from 20 water samples taken from Lake Qinghai using the high salty medium. Resistant to salt gradient experiment shows that moderate halophilic bacteria account for about 62.85% in the water, mild halophilic bacteria account for about 22.85%, non halophilic bacteria and salt resistance bacteria account for 14.28%. Moderate halophilic bacteria could grow in the temperature of 10~45℃ and pH 5.5~11.0, which is related to the local salinization environment and has characteristic of hasophilic microorganisms.

Abstract:Lake Yuxingze is a famous ancient lake in China because it was recorded in a Chinese classic geography book of The Tribute of Yu (Yugong) and there have been some different opinions about its location, age and forming conditions. Based on the documentary records and field investigations, we study systematically the lake-appearance stratum in the trough wash of Xingyang region, including the geological conformation, the distribution of stratum and the ancient geographical surroundings. Especially according to the data of measured ¹⁴C age, we think that this lake-appearance stratum had been made from the ancient lake described in The Tribute of Yu (Yugong) saying that the Jishui River flowed into the Yellow River but when it flooded, the name of this area was Xing, so we call this ancient lake the Lake Yuxingze. This ancient lake functioned actually as a natural flood detention area of the Yellow River then.