Abstract:Historical developments of palaeolimnology study abroad as well as in China are reviewed. Two aspects in international palaeolimnology studies were expatiated. The author summarizes the progress of palaeolimnology study since 1950s. To make further progress in palaeolimnology studies, it was also suggested to make efforts in the basic study of lacustrine indexes, improve time-scale resolution, consider human impact on lake environment, carry out the study of water-sediment interface and establish regional archives for environment change and correlate them with global records

Abstract:The present article described the importance of prevention, forecast and warning of cyanobacteria bloom. The recent progresses of formation and forecast of cyanobacteria bloom were reviewed. Based on the theory of “four phases of cyanobacteria bloom development” and the temporal and spatial distribution of cyanobacteria overwintering, recruitment and bloom formation in Lake Taihu, the processes of cyanobacteria blooms and the dominant ecological factors during their development phases were studied. Field observations and laboratory simulating studies were performed to investigate horizontal distribution and life characteristics during the overwintering period. The threshold temperature for the recruitment of cyanobacteria was about 9 in the field resear ℃ ch. It was found that there was a positive relationship between effective accumulated temperatures and recruitment biomass of cyanobacteria. By the methods of frequency of dividing cells, the calculation of the growth rates in situ showed that the growth rates of Microcystis were from 0.2 to 0.4. The dynamics of vertical distribution of cyanobacteria in the transport process between different lake areas were investigated under different meteorological conditions, and the results supported the viewpoint that bloom formation is a shift in the vertical positioning of the cyanobacteria biomass which previously distributed through the water column, since the coefficients of variation of the vertical cyanobacteria distribution at different depths were negatively related to wind speeds. On the basis of the establishment of key factors and their thresholds of bloom formation, the bloom forecast model and flow chart ofcyanobacteria bloom forecast and warning were established. The bloom forecasts in 2007, 2008 and analysis of bloom trends of 2008 were implemented. The retrospective assessment of the forecast showed that it is possible to forecast the probability, location and extent of cyanobacteria bloom. The future research directions were also suggested.

Abstract:The palaeoclimate records from lakes at the arid central Asian region (ACA) climatically dominated by the Westerly circulation shows synchronous and coherent moisture changes during the Holocene. Therefore, the sediment records from lakes in ACA with reliable chronologies and robust proxies were selected to reconstruct moisture histories based on a five-class ordinal wetness index with assigned scores from the driest to wettest periods at individual sites for 200-year time slices. There are 8 lakes suitable for the synthesis. The results show that ACA as a whole experienced a dry early Holocene, a wetter (less dry) early to mid-Holocene, and a moderately wet late Holocene, which is different from Holocene monsoon history recently recovered by documents such as speleothem. We propose that the pattern of Holocene effective-moisture evolution in the westerly dominated ACA was mainly determined by North Atlantic sea-surface temperatures (SSTs) and high-latitude air temperatures that affect the availability, amount and transport of water vapor.

Abstract:A laboratory experiment for studying the effects of sediment dredging on nitrogen release from lake sediments was carried out through one-year incubation of undredged (control) and dredged cores. We found that dredging the upper 30cm layer of the sediment can efficiently reduce organic matter content in the sediment and the interstitial NH₄⁺ concentration. The NH₄⁺ fluxes of the dredged and undredged cores ranged from 5.3 to 18.6mg/(m²·d) and -9.4 to 67.5mg/(m²·d), respectively. The fluxes of the dredged cores were generally lower than those of the undredged(control) cores, with significant(P<0.05)differences in the fluxes of the dredged and undredged cores occurring between May and December of 2006. The NH₄⁺ in the dredged cores had a lower release potential than that in the control cores. Our results suggested that dredging may be a useful approach for decreasing internal nitrogen loading in Lake Taihu once the external loading was first effectively controlled.

Abstract:The samples were taken from the shallow urban lakes(Lake Yuehu) in Wuhan city to optimize the determination of dehydrogenase activity (DHA) in sediment, which gave the following suitable conditions: the sediment sterilized by formaldehyde was used as the control, the concentration of electron acceptor (2,3,5-triphenyl-2H-tetrazolium chloride) was 0.4%, the sediment amount used was 0.5g, pH value was 7.5 and the reaction time was 3h. Under these conditions, the DHA assayed was 3-5 times higher, and its positive relation to the content of organic matter in sediment was more significant, compared to those determined by the unmodified method. The data based on the 23 sites from 3 basins of Lake Donghu demonstrated the feasibility of the method. In the same time, the ecological significance of DHA was further shown in terms of the measurements of microbial activities and organic matter status in lake sediment

Abstract:Indigenous ammonibacteria, nitrosobacteria, nitrifying bacteria and denitrifying bacteria were screened from natural water of Lake Jinshan. The effect of water purification was studied in the demonstration project of Lake Jinshan after immobilization of nitrogen cycling bacteria. The result showed that water quality was improved obviously after running a period of time. NH₄⁺-N, NO₂^--N, NO₃^--N or TN concentration was in dynamic state respectively, and the trend of them was negative. NH₄⁺-N concentration had reached national Ⅱclass of water quality index, TN and COD had reached Ⅳand Ⅲ respectively. NO₃^--N was the main form of TN in the water of Lake Jinshan, which might be in relation to the water environment without aquatic plants. The microorganisms in immobilized nitrogen cycling bacteria area could diffuse in the water and root area of aquatic plants, the number of them was higher 1-3 degrees than that of the comparison group. It was significant that techniques of immobilized nitrogen cycling bacteria can remove NH₄⁺-N, TN and COD in desertification water

Abstract:Biomass (Chl.a) of benthic algae colonized and developed mature community on different artificial substrata was determined in eutrophic lake Donghu, and species composed and structure characteristic of mature diatom communities on artificial and natural substratum were analysed qualitatively. Biomass variance of benthic algae was compared on four different artificial substratum, granite stone, glass, plastic (PVC) and pine wood during the colonization period, and the peak biomass of benthic algae (Chl.a, 71.0μg/cm²) on PVC was significantly higher than that of the other artificial substrata, which showed PVC was the most suitable artificial substratum for benthic algae. Species composition, dominant species, similarity index and diversity index of benthic diatom communities showed a relatively high degree of consistency between natural and granite artificial samplers, which suggested granite should be the most favourable artificial substratum with benthic algae used as indicatory biology that monitored and evaluated water quality.

Abstract:It is becoming an urgent problem in the lake environmental treatment that how to effectively remove the highly frequently cyanobacterial bloom. The purpose of the paper is to research the surfactant—Hexadecyl trimethyl ammonium bromide (CTAB)-mediated in-situ-sediment to remove the cyanobacterial through agitation effect and stimulating the water column disturbing through sediment resuspention generator in the laboratory. The results showed that the blue-green algal's removal efficiency could reach 83.9% after 30min water body still at the dosage adding of CTAB and sediment were (0.30+0.20)g/L; and the removal efficiency reached 98.9% after water body still. Preliminary results showed that the CTAB (0.30g/L dosage) could effectively remove the cyanobacterial in the lab, and also the turbidity of the water body had the corresponding change. The SEM images of the CTAB-flocculated algae showed that the netting and antivirus could be an important role in the alge cell flocculation. However, the antivirus role of CTAB could cause the risk that the cell-inclusion would release to the lake water.

Abstract:The acidic heteropolysaccharide released by a water-bloom cyanobacterium Microcystis aeruginosa FACHB-912, which contained 8.3% protein, was used as the carbon source in stable enrichment cultures inoculated with natural aquatic microbial communities. The process of microbial breakdown of the exopolysaccharide and composition of the microbial community related to degrading exopolysaccharide were investigated. After inoculation of aquatic microbial community from Lake Taihu, enrichment cultures were obtained. In the enrichment culture, the exopolysaccharide was degraded immediately. The breakdown of the exopolysaccharide slowed markedly after about 18d, left a nondegraded fraction after 37d. The above data, together with comparison experiments on degradation capability of bacterial communities from various aquatic environments, indicated that the exopolysaccharide from M. Aeruginosa FACHB-912 could indeed be degraded by microorganisms coexisting only with the water bloom in nature. Denaturing gradient gel electrophoresis (DGGE) analysis showed composition of the microbial community did not change significantly during exopolysaccharide degradation. Phylogenetic analysis on DNA fragments, which were excised from DGGE gels, placed three degraders in Sphingomonas, one in Phaeospirillum, one in Pseudomonas, one in Rhodocyclaceae, one in Hylemonella, and one in Mycobacterium.

Abstract:The present study was designed to explore relationship between DNA polymorphism, as revealed by RAPD and PCR-DGGE fingerprintings, and species composition of plankton community in an artificial lake for breeding transgenic fish. Planktonic samples were collected from five sampling sites in the artificial lake, and their similarity was assessed with cluster analysis. The results were: (1) a total of 44 planktonic taxa were identified, among which there were 13 algae, 11 protozoa, 16 rotifer, 2 Cladocera and Copepoda, respectively; (2) 128 observable bands were totally amplified by the 9 random primers screened in RAPD analysis, among which 61.7% and 19.5% were polymorphic bands and specific bands, respectively; (3) there were 87 distinct bands identified by the method of PCR-DGGE, among which 50 were 16S rRNA bands and 37 were 18S rRNA bands. Despite the analysis of morphological identification and DNA fingerprintings had shown a higher species diversity, the cluster of similarity was different: based on species composition, group 1 consisted of B, C sites, group 2 contained D, E sites, and group 3 only comprised of A site. However, according to the DNA fingerprint analysis, the plankton community of C, D, E were similar, and another two sites-A and B were similar. In summary, our results suggested that the species composition was not closely related to the DNA polymorphism of plankton community, and the latter can describe more species. However, the characteristics of biodiversity revealed from different ), 2009, 21(3) 376 a

Abstract:The research of stable carbon and oxygen isotope of Carbonate of lake sediments, is one of the most effective indices to reconstruct paleoclimatic and paleoenvironmental information. Sedimentary carbonate consists mainly of allochthonous carbonates produced by surface runoff and authigenic carbonates produced by inorganic precipitation. However, the authigenic carbonate has the paleoclimatic and paleoenvironmental meaning. Consequently, distinguishing the source of carbonate is the basis and premise for the research of sedimentary carbonates. This paper utilized various methods to prove that the carbonate in Lake Chenghai,Yunnan Province was authigenic, which provided the basis for the research of sedimentary carbonates. Lake Chenghai provides an ideal lacustrine setting for research of stable carbon and oxygen isotope to reconstruct paleoclimate, and the future research will be deserved.

Abstract:Liuxihe Reservoir, located at the tropic of Cancer, is a large valley-type reservoir. In order to understand its limonological features, main limnological variables including hydrological and environmental factors were observed monthly in 2006. Surface water temperature ranged from 14.9 to 31.6 . The thermal stratification ℃ ℃ was monomictic, initiating in the early March when the water temperature reached 20 , and lasting until December. The total precipitation in 2006 was 2960mm, but mainly distributed in ℃ wet season (from April to September). The mean water residence time was about 170 days, being more short in the flooding season (65 days). The mean concentrations of TN, TP, chlorophyll-a and SD were 0.66mg/L, 0.016mg/L, 2.2mg/m³ and 3.1m, respectively, indicating that the reservoir was oligo-mesotrophic. Mass ratio of TN/TP is around 41, 78 for DIN/DIP. Both ratios were much higher than the Redfield ratio, and mean that growth of phytoplankton was strongly limited by phosphorus. The high N/P ratio was attributed to the tropical red soil containing rich iron. A distinct longitudinal pattern and seasonal variability in limnological variables were observed in this reservoir. At the beginning of wet season (April and May), all nutrient concentrations were significantly higher than other period. It confirmed that surface runoff was the main path for nutrient loading into the reservoir. The longitudinal pattern of nutrient and chlorophyll-a concentrations was typical as follows as riverine zone>transition zone>lacustrine zone, and the water transparency correspondingly showed an opposite one. High inflow with monsoon was the main driving force in seasonality oflimnological variables, and resulted finally in a significantly longitudinal gradient of these variables by interacting with the reservoir own morphology.

Abstract:The bacterial abundance and active bacterial abundance of water and algae attached, as well as the Chl.a and nutrient concentrations, were investigated, and the metabolism coupling between algae and bacteria were also discussed. The results showed: 1) The bacterial abundances of water increased with the Chl.a concentrations increasing(r²=0.466, P<0.05), although the peak value was delayed with the Chl.a concentration. Variation of the algae attached bacterial abundances were the similar patterns. 2) There was a significantly positive relationship between the active bacterial abundances and total bacterial abundance(r²=0.678,P<0.05). Although the algae attached active bacterial abundance was less than the active bacterial abundance of water, the significantly increased patterns were also founded with the active bacterial abundance of water increasing (r²=0.836, P<0.05). 3)The algae attached bacteria abundances and activities were determined by the algae growth status. The ratio of active algae attached bacteria/total algae attached bacteria was higher than that of total bacteria, and this ratio was increased in the period of May to September during the algal blooms.

Abstract:Bellamya aeruginosa (Reeve) is a predominant benthic macroinvertebrate in many shallow lakes along the middle and lower basins of the Yangtze River, and there is little published information on its production in China by far. This paper dealed with the population dynamics and production of B. aeruginosa, a subtropical, shallow, eutrophic lake located near the middle reaches of the Yangtze River. B. Aeruginosa was sampled monthly at the eleven stations in Lake Donghu from June 1998 to May 1999. The results showed that the annual average density and biomass were 92.2ind./m² and 142.83g/m², respectively, and the density and biomass peaks were observed in June(157ind./m²) and in November(205.78g/m2), respectively. B. aeruginosa population was composed of five year classes, among which the 1998 year class was dominant. The annual production of the animal calculated by instantaneous growth rate method was 91.56g/m² in wet weight and 5.32g/m² in dry weight (unshelled), and corresponding annual P/B ratio was 0.64. The production and P/B ratio of B. Aeruginosa in the present paper were moderate among the values reported. The study on dynamic of mean daily production of B. Aeruginosa showed that the accumulation of production of B. Aeruginosa occurred in Spring, Summer and Autumn, and the value of 1998 year class was dominant in the total production.

Abstract:Lake Fuxian is a representative deep plateau lake located in Yunnan Province, China. To describe crustacean zooplankton's responses to ecological changes, we carried out studies on its community structure and spatial distribution. Altogether 8 taxa of crustacean zooplankton were founded in Lake Fuxian from June to July in 2005, and the average community density 27.6ind./L dominated by Copepoda. Dominant species of Copepoda were Phyllodiaptomus tunguidus Shen et Tai, and dominant species of cladoceran were Ceriodaphnia cornuta Sars and Bosmina sp. Crustacean zooplankton was mainly distributed from surface to 30m vertically, and its density decreased with the depth increase. Cladocera and Nauplii had the dominance in 0-10m layer, but Copepoda had the dominance when depth down to 10m. Average density of crustacean zooplankton was significantly higher in south lake than north lake (P<0.01), while there were no significant differences in average density between near shore region and open water region,and between macrophyte distributed region and no macrophyte distributed region (P>0.05). Correlation analysis indicated that there was significant correlation between the vertical density of crustacean zooplankton and algae density or water physical-chemical factors, but there was no significant correlation between the horizontal density and algae density or water physical-chemical factors. Compared with the surveys in 1980s, Neutrodiaptomus mariadviagae mariadviagae (Brohm), one of the dominant species of crustacean zooplankton, disappeared in the lake and was replaced by P. Tunguidus, which was probably caused by introduction of Neosalanx taihuensi Chen. The density of crustacean zooplankton showed an increasing tendency, but that was still rather low, likely a result of increased nutrient levels and predation by N. Taihuensi

Abstract:Daphnia carinata is a large zooplankter in many eutrophic lakes and has a high efficiency to graze phytoplankton. The effects of Daphnia carinata on chlorophyll-a and the community structure of phytoplankton of Lake Xuanwu in Nanjing was studied experimentally. The results showed that the density of phytoplankton decreased 83% and the chlorophyll-a decreased 81% in the Daphnia carinata treatment comparing with the control. There is no significant relationship between nitrogen, phosphorus and chlorophyll-a in the Daphnia treatment. When Daphnia presented, the community structure of phytoplankton had changed. The proportion of Cyanophyta, Chlorophyta and Bacillariophyta obviously increased and the proportion of Cryptophyta obviously decreased. The Chrysophyta, Pyrrophyta, and Euglenophyta were not found at the end of the experimentation. Our experiments showed that Daphnia carinata can efficiently control the biomass of phytoplankton and change the community structure of phytoplankton.

Abstract:Allocation of light in the aquatic ecosystems determined the ecosystem function and type. Based on the measured data of optical properties and the concentrations of water substances in Lake Taihu during November to December, 2007, the optical parameters (diffuse attenuation coefficient, the average cosine) and impact factors (the proportion of absorption) were studied. The results showed that: the irradiation showed a single peak distribution and the max value was at 583nm wavelength; the dominant degree of CDOM and Non-pigment particles could be divided into weak, strong, stronger according to the K_d; the average value of K_d (PAR) and depth of the euphotic zone is 4.61±1.54m^-1 and 1.11±0.35m, respectively; solar energy was mainly distributed in the cyan, green and yellow wavelength range, which was about 60 percent of the total energy, it just about 30 percent in blue and red wavelength. This spectral structure favored the growth of Microcystis aeruginosa and Scenedesmus obliquus.

Abstract:This paper based on the conventional monitoring data from in 2005–2007, and studied the distributing of chlorophyll-a with temporal and spatial distribution, and the relationship between the chlorophyll-a and TN, TP concentrations. The results showed that chlorophyll-a concentration appeared obvious temporal and spatial changes, and the values were arranged according to May>July, August>October>September>June. Chlorophyll-a concentration of May and October higher than others. The supply water of Lake Ulansuhai occurred form drainage of Hetao in May and October, and there is a lot of nutrition was bring into Lake Ulansuhai, which induced growth of algae. By analyzing, the relationships between chlorophyll-a concentration and TN and TP concentration appeared evidently in May and October of 2006, and the relationships in August were not remarkable, and no relationship in other months

Abstract:Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, Mann-Kendall trend test, correlation analysis and principal component analysis were applied to determine trend of pan evaporation and its relation with meteorological factors (net solar radiation, temperature, relative humid, wind speed etc.). Analysis results demonstrate: pan evaporation presents a significant decrease trend in the 41 years (99% confidence level). This decrease trend is especially more significant in winter, spring and summer seasons. Spatially, significant decrease of pan evaporation occurs in the east area and part of the west area, and seldom occurs in the other areas. The pan evaporation decrease is primarily resulted from reduction of net solar radiation.

Abstract:TOPMODEL is a semi-distributed model in which the predominant factors determining the formation of runoff are represented by the topography of the basin. In this paper we dealed with DEM information of Buliu river basin, extracting drainage network, sub-basin area, topographic index and distribution of runoff distance, and applied TOPMODEL in the basin. For the sake of comparison, the Xin'anjiang model was also applied in the basin. Here we analyzed the difference of simulation function due to the frameworks of the two models. The simulation results of the two models have little difference; moreover TOPMODEL realized the visualization of spatial source area distribution