Abstract:Cesium-137(¹³⁷Cs) is an artificial radionuclide. Its distribution in the deposit profile is used as a tool of sedimentary chronology. In order to know the depth distribution profile characteristics and environmental significance of ¹³⁷Cs in the sediment of Chinese lake, the literatures concerned were compared and analyzed in this article. We discussed the whole characteristics and main affect factor of lacustrine sedimentary profile of ¹³⁷Cs in five lake areas by reason of different physiognomy. This research indicated that the ¹³⁷Cs deposit profile related to the physiographic characteristics, rainfall, vegetation and human activity besides latitude and altitude. The atmospheric nuclear experiment in China and the Chernobyl accident in Pre-Soviet Union potentially influenced on the ¹³⁷Cs distribution of some zone.

Abstract:In the Low reaches of Yangtze River and the estuary region, there are rich fish species and high autochthonous species. The economic species that has an obvious fishing season characteristic almost distributes in this area, and the species number of the economic fish and fish catchability ranked first in the whole basin. In recent years the fishery ecological function has been weakened by many factors, such as river-lake disconnection, seawater intrusion, habitat fragmentation and hydrological changes due to the hydraulic engineering, and fish catchability, natural fishery resources, species diversity and idioplasm resources were also influenced seriously. In this paper, the development and status of hydraulic engineering and characteristics of fishery resources in the lower reaches of the Yangtze River have been introduced, basing on some important hydraulic engineering, such as waterpower projects, migration engineering, navigation engineering, bridge construction, and sand digging. Existing and latent impacts of hydraulic engineering on fishery resources and fishery ecological environment have also been discussed. Suggestions on design of hydraulic engineering and compensation methods for fishery ecology have been given. Responsibilities and obligations that the fishery department should take were pointed out. At last the urgent research tasks of protection of fisheries resources and environments in lower reaches of the Yangtze River were put forward.

Abstract:During enacting nutrients criteria, there are five main methods such as direct observation of temporal reference state, direction observation of spatial reference state, population distribution approach, paleolimnological reconstruction, forecast and extrapolate model approach. In this paper, population distribution approach was applied to build the nutrients criteria on the case of Lake Taihu, one of the typical shallow water bodies in eastern China. Then, direct observation of temporal reference state and paleolimnological reconstruction were applied to validate the reference state value of TN and TP. Results showed that the reference state value of TP, TN in Lake Taihu was 0.03mg/L, 0.07mg/L, respectively, and the response indication of Chlorophyll-a and Sacci disk depth was 0.004mg/L and 0.70m, respectively. This study would offer the experience for enacting the criteria and standard in China, also would provide the theoretic support for eutrophication control in China.

Abstract:The sediment samples collected from the different sites of the Lake Taihu, 2006 were cultured on traditional nutrient medium. 603 bacteria strains were separated with 40 different morphological features, and were grouped into 4 clusters and 51 subclusters at the level of 0.75 with numerical classified based on the unweighted pair group method with arithmetic averages (UPGMA) algorithm. Based on the partial sequences of 16SrDNA (540bp) analysis, the bacteria strains sample chosen from each subclusters randomly were ranked into Firmicutes, Actinobacteria and γ-Proteobacteria three groups, and closely related to Bacillus, Paenibacillus, Micrococcus, Arthrobacter, Dietzia and Pseudomonas genera. The dietzia genera was reported in the sediment of freshwater lake in China for the first time.

Abstract:Cyanobacterial bloom occured in Lake Gaoyang, Huangshi Dailizi and Shuangjiang Bridge of the backwater area of Xiaojiang River in Three Gorges Reservoir in late May of 2007. After the survey on the phytoplankton and water quality, it was found that cyanobacteria dominated the phytoplankton, taken up to the 81.43% of the total biomass, among which the Anabaena flos-aquaes was the dominance species. The heterocysts appearing in most species indicated that nitrogen fixation may occur. Low TN:TP ratio in April was that the heavy storm may trigger this nitrogen-fixation algal bloom. Phosphorus limitation was another characteristic, which is the result of the tremendous growth of phytoplankton. Lake Gaoyang may be the source place where algal bloom occured. Cyanobacteria moved downstream with the water flows, assembling at Huangshi Dailizi, where algal bloom was more than that in the Lake Gaoyang. As a result, total biomass and chlorophyll-a in Huangshi Dailizi was the highest among the sampling spots. Water velocity in Shuangjiang Bridge was slower due to the enlarged cross section downstream, offering a proper environment for the growth of cyanobacteria. Accompanied by the large amount of nutrients loads at Yunyang County, this may be the major reason of the detection of algal bloom in Shuangjiang Bridge.

Abstract:River network plain in Taihu Basin was selected as an experiment place, and triple duplication experiments had been carried out under artificial rainfall conditions to study the characteristics of phosphorus transfer from runoff of farmland. The results indicated that surface runoff was the main way of phosphorus losing from the agricultural field during artificial rainfall. The amount of losing phosphorus caused by surface flow and soil erosion of total phosphorus output accounted for 58.50% and 34.69% respectively, while that by interflow of total phosphorus output was only 6.81%. Particulate phosphorus was the primary pattern of phosphorus transfer which accounted for 60.73% of the total phosphorus losing. Inorganic phosphate was the primary pattern of dissolved phosphorus transfer. Compared with the particulate phosphorus, dissolved phosphorus can move more easily in the soil. Analysis of the characteristics of phosphorus transfer in surface runoff and interflow showed that soil could reduce the concentration of phosphorus when flows passed through it, in particular have obvious effect on reducing the concentration of TPP, up more than 80%. In addition, despite surface runoff was the primary way of phosphorus transfer in rainstorm-runoff process, in such a basin as Taihu, which has abundant rainfall, interflow is the main pattern at normal rainfall conditions, dissolved phosphorus transfer from interflow account for a large percentage of phosphorus loss, which has an important contribution to water environmental degradation of the region. Therefore it is of great significance to strengthen the research of dissolved phosphorus transfer for environment conservation.

Abstract:The South Lake Taihu region is increasingly threatened by water eutrophication, so it is important to understand phosphorus status in sediments and water of the riparian wetlands in this region and develop sound technologies for optimizing wetlands'ecological values. 29 typical sampling sites in this region were chosen for the investigation, and the sites located at Hangzhou West Lake, Deqing Xiazhuohu Wetland, and Changxing Baoyanghe River were selected for static column simulation experiments and steady-flow flume simulation experiments. According to the investigation, total phosphorus (TP) and NaHCO₃ (pH=8.5) extractable phosphorus (Olsen-P) in sediments of the region reached 0.169-1.200g/kg and 7.08-67.08mg/kg, respecially, and the adsorption capacity (Q_max) of sediments varied from 269.5 to 824.5mg/kg. NaOH+EDTA extractable phosphorus (NaOH+EDTA-P) constituted 52.0%±11.6% of TP, while Olsen-P was increased as organic phosphorus accumulated. TP in overlying water was 0.036-0.944mg/L, while dissolved reactive phosphorus (DRP) was relatively and 34.5% of the total sites was below detective limits. Total particle phosphorus (TPP) contributed 70.9%±13.2% of TP in water samples. There was no significant relationship between TP, DRP in overlying water and TP, NaOH+EDTA-P, Olsen-P in sediments, implying that phosphorus status in sediments was not the only factor restricting phosphorus in overlying water. In the static column simulation experiments, DRP in overlying water decreased slowly at the beginning, then decreased fastly later on. A quasi U-pattern curve was found in the steady-flow flume simulation experiments, i.e. DRP in the overlying water decreased at first and then turned to be increasing. It indicated that the role of the sediments might be changed from phosphorus "sink" to "source" when high phosphorus water flow over a wetland in rain season. It was also proved in the simulation experiments that organic matter accelerated the adsorption rates of phosphorus by sediments.

Abstract:The content and species of 11 heavy metals in surface sediments from 8 typical lakes located in Wuhan, China, were investigated, and the accumulation, contamination, potential ecological risks and possible sources of metals were discussed in this paper. According to the metal geoaccumulation indexes, the results showed that the lake sediments had heavily polluted by Cd and evidently by Zn and Hg. On the whole, heavy pollutions of metals were observed in Lake Longyang and medium pollution in Lake Nantaizi and Lake Moshui, whereas the slight pollution in other lakes. Distribution of metals in sediments was observed to be not significant correlation with physicochemical properties of sediments, whereas distinctly influenced by urban industries. 11 metals distributed differently in lake sediments. The largest percentage of the form of available speciation was Cd in the lake sediments, with much higher potential ecological hazards, followed by Mn, Zn, Co, Cu and Pb. In contrary, As, Sb and Hg were dominantly associated with the residual fraction, indicating rare adverse biological effects. Correlation analysis and principal component analysis indicated that the heavy meal accumulation in the lake sediments were mainly attributed to the combustion of fossil fuel accompanied with metal refining, and followed with the effects of the biogeochemical processes of earth weathering.

Abstract:The humification of peat deposits has been reported as a useful proxy to indicate paleoclimatic changes, but there is no reports focusing on lacustrine sediments. On the basis of analyses of the humification of lacustrine sediment in Lake Barkol, northeastern Xinjiang, and by comparing with results of multi-proxies such as OM, TOC, carbon and oxygen isotopes of carbonate, we considered that higher humification of lacustrine sediment value indicates relatively humid climate, whereas lower humification of lacustrine sediment indicates relatively dry condition. Based on humification proxy and other proxies, the paleoclimate of Lake Barkol could be divided initially into five phases:early Holocene (9.4-7.5cal kaBP), climate is relative cold and dry;mid-Holocene (7.5-5.8cal kaBP), relatively warm and humid climate prevailed, and then climate turned into warm and dry during 5.8-3.3cal kaBP;in late Holocene, climate became cold and dry;in 1.0-0.0cal kaBP from previous relatively cold and wet period lasting from 3.3 to 1.0cal kaBP.

Abstract:The relationship between lake-level changes and lake water salinities has been confirmed as a covariance in closed-basin lakes. According to this principle, lake-level fluctuation history over time can be reconstructed using quantitatively calculation of paleo-salinities in boron concentration of lacustrine mudstone deposition. In this article, boron contents in lacustrine sediments as a salinity index, examples from the Tongtianhe section in the Tuotuohe area of northern Tibetan plateau, vertical lake-level curves inferred from paleo-salinities calculation data was reconstructed during late Oligocene-early Miocene. At the same time, applicability and limitation of this method were also discussed. The results showed that the salinity of paleo-lake water was from brackish to saline water during the upper Yaxicuo Formation deposition. It indicated that late Oligocene was an arid climatic period and lake level was a long low water stand in this area. Conversely, paleo-lake water salinity obviously dropped and reflected water level rise in lower Wudaoliang Fromation. It indicated that Tibetan Plateau climate evolved to enter a humid stage in early Miocene.

Abstract:A laboratory experiment was carried out to study the effects of sediment dredging on phosphorus (P) release from lake sediments using incubation of undredged (control) and dredged cores through a year. We found that dredging the upper 30cm layer of the sediment can efficiently reduce the interstitial PO₄³P concentration and different P forms in the sediment. The P fluxes of the undredged and dredged cores ranged from-237.3 to 3047.6ng/(m²·d) and-143.8 to 14.4ng/(m²·d), respectively. The fluxes of the dredged cores were generally lower than those of the undredged (control) cores, with significan P<0.05 Derences between the fluxes of the dredged and undredged cores occurring between March and October of 2006. The sediment P in the dredged cores had a lower release potential than those in the control cores. Our results suggested that dredging may be a useful approach for decreasing internal P loading in Lake Taihu once the external P loading is effectively controlled in advance.

Abstract:Fishery is one of the main functions of Lake Taihu, which plays an important role in improving the water environment. However, it is also influenced to a large degree by the environmenal change. Recently, the main problems facing the natural fishery in Lake Taihu are the over-intensive catching and irrational utilization of natural resources. This paper, based on the data of many years'catches in Lake Taihu, analyzed the community structure of fishes in Lake Taihu and their succession dynamics. According to the fish yields and compositions in different area of Lake Taihu, the natural fishery characteristics and problems were studied. Some ideas were presented to develop the natural fishery based on the present research, such as controlling the fishing gear specifications and catching intensity, adjusting the catching time, regulating the structure and proportion of stocking fish species and developing lake fishery in a reasonable way. Meanwhile, the potential of natural fishery was analyzed on the basis of present biological resources in Lake Taihu. It suggested that the construction of fishery environment and studies on influence of fishery on water environment should be strengthened for the further development of lake fishery.

Abstract:Dajingshan Reservoir, located in Zhuhai City, South China, is a medium-size water body. It supplies drinking water for the Zhuhai City and Macau in dry seasons. Water is pumped into the reservoir from a nearby river in dry seasons so as to enhance the water storage. Pumped water modified the hydrodynamic processes and ecosystem dynamics. In order to understand the dynamic of rotifer community and the relationships between specific composition of rotifers and the environmental variables, an investigation was conducted monthly in 2005. Altogether 32 species of rotifer were identified, among which 12 species were belonged to Brachionidae, 4 species to Trichocereidae and 4 species to Lecanidae. The majority of the species are tropical or sub-tropical species. Keratella tropica, Trichocerea stylata, Keratella cochlearis, Filinia maior, Anuraeopsis fissa, Brachionus angularis, Brachionus forficula, Ascomorpha ovalis and Collotheca pelagica were the dominant species. They had small body size and lorica. The diversity index of rotifers ranged from 0.29 to 0.8, which were lower than that in Lake Donghu and Lake Xinghu. The abundance and biomass of rotifers ranged from 21 to 1094ind./L and from 4.04 to 1127μg/L, respectively. The maximal abundance and biomass occurred in February and May, respectively. The body length of rotifers ranged from 50μm to 620μm. The total abundance of rotifers was contributed by of small-sized species with a body size less than 200μm, while the rotifers biomass was dominated by medium-sized species with body size from 200-400μm. Secchi disk depth, temperature, total phytoplankton biomass and Cyanophyta biomass were the main factors affecting the species composition and quantitative dynamics of the rotifer community.

Abstract:Limnoithona sineseis is considered as an endemic species in rivers of China with strong invasive ability. It was introduced to some reservoirs by pumping water and becomes the dominant species in the new water bodies. To understand the population dynamics of Limnoithona sineseis and its effects on the pelagic crustaceans, we investigated Dajingshan reservoir, a typical pumped storage reservoir located in Zhuhai City, South China in 2005 and 2006. In total, 13 species of crustaceans including 9 copepods(4 family 7 genera) and 4 cladocerans (3 family 4 genera) were identified. Limnoithona sineseis was dominant over the sampling periods. The abundance of the crustaceans ranged from 3.82ind./L to 364.85ind./L, with high abundance in spring. Limnoithona sineseis and its nauplius covered more than 50% of the total abundance. The body size of crustacean community in the reservoir had a range from 0.07mm to 1.25mm, and small-size species (within 0.07-0.4mm) was dominant. Population of Limnoithona sineseis was mainly composed of stageI nauplii, copepodite stage and adults. Nauplii had a much higher abundance than copepodites and adults. The abundance of Limnoithona sineseis was positively related to chlorophyll-a concentration, and negatively related to the pumped water volume. It meant that food was the principle factor affecting the animal population, and the animal had adapted well to its new habitat with relatively unconstant salinity, and its abundance was reduced by flushing of pumped water. As an invasive species, Limnoithona sineseis had become the dominant species by replacing the former ones (Mesocyclops), and its high abundance reduced biodiversity of crustaceans.

Abstract:Lake Ulungur is one of the most important fishery ground in Chinese inland area. To exploit the potential fishery resources, 15 species of fishes were introduced in the past 40 years. By far, most of the niches to the fishes endemic in Lake Ulungur were occupied by the introduced fishes. Perch(Perca fluviatilis Linnaeus) as the most economic important fish has endangered. The age structure and growth of perch population were studied in 2007-2008, and compared with the corresponding data in 1987-1989 to analyze the reason why population size decreased sharply. Body weight and length of captured perch were both smaller than those in 1987-1989 at each age except age 1⁺. The growth parameters using Von Bertalantty equations were L_∞=41.317cm, W_∞=15475.1g, k=0.1649, t₀=-0.2626;growth performance indices were Ф=2.4493. L_∞ and Ф reduced since 1987-1989 while k increased. However, the growth inflection point of body weight was the same as 1987-1989 (t=7). This investigation confirmed the remarkable effects of environment factors on perch growth and the effect mode of fish invasion on Perch(Perca fluviatilis Linnaeus) growth in Lake Ulungur were also revealed.

Abstract:Microcystis aeruginosa, dominance specie in the cyanobacterial bloom, was cultured under the different initial pH values in order to study the effect of the growth of M. aeruginosa on the pH value and the nitrogen transformation in the medium. The results showed that the pH value rose in the lag phase and exponential phase of M. aeruginosa, and the maximum pH values rose from 7.2, 8.0 and 8.8 to 10.02, 10.34 and 10.94 respectively, then decreased in the stationary phase and the decline phase of M. aeruginosa. While initial pH value was 8.8, it decreased to 8.66 at the end of the experiment. NO3-concentration decreased and NO2-concentration rose earlier then decreased later in the medium during the growth period of M. aeruginosa. Both the concentrations of NO3-and NO2-decreased next to zero in the 60th and the 67th days, respectively. Compared with the initial total nitrogen content, the final total nitrogen contents decreased 25.97%, 27.52% and 28.16% under different initial pH values, respectively. The nitrogenous compound was transformed to N2 through denitrification. Thus, there is distinct decrease of nitrogenous compound by denitrification in M. aeruginosa bloom.

Abstract:Comprehensive field investigations had been conducted for three times on Nam Co, central Tibet during 2005-2007. Here we presented the preliminary results focusing on bathymetric survey and water quality measurements. Isobathic map showed that Nam Co is a high altitude deep lake where a flat and large basin lies in the central part with more than 90m water depth. Data on water depth in northwestern bank areas of Nam Co provided unquestionable evidence for water level rising in the recent three decades due to the formation of two small islands which were peninsulas in 1970s. Water quality at 16 stations covering more than half of the whole lake showed that temperature, pH, dissolved oxygen, conductivity and photosynthetically active radiation (PAR) of surface water was averagely 11.63℃, 9.13, 7.93mg/L, 1839μS/cm and 2582μmol/(s·m²), respectively. According to the vertical variations of water quality parameters, water column in relatively deep lake areas of Nam Co could be divided into three layers with distinctly various features. The first layer was from surface to about 18~20m depth in which parameters was stable with higher temperature and abundant sunlight;the second layer ranged about 20m to 60m where thermocline developed;and the bottommost layer was characterized as also very stable with low temperature and no light, forming a cold and dark underwater world.

Abstract:We use the visualization package XmdvTool to enhance the evaluation of the spatio-temporal patterns of the dam-induced hydrologic alternation dominated the middle and upper reaches of East River, south China during non-flood seasons (1952-2002). Results indicate that:1) Along the East River, dams had greatly altered the natural flow regime, range condition and the spatial variability;2) The 6 most remarkable indicators of hydrologic alternation induced by dam-construction were the rise rate, 3-day maximum, Low pulse duration, January and July of the East River during 1952-2002;3) The spatio-temporal hydrologic alternations were different among 3 stations. Under the influences of 2 large multi-purpose dams, the rank of the overall degree of hydrologic change were Lingxia, Heyuan and Longchuan station along the middle and upper reaches of East River. Visualization techniques for the high-dimensional hydrological datasets, together with RVA approach, might be useful to detect the spatio-temporal hydrologic changes. The unique way of integrating spatial, temporal and multi-element hydrological components provided visually-enhanced insights that were not possible with traditional analysis tools for water resources management.